Halogenated Gallium Corroles:DNA Interaction and Photodynamic Antitumor Activity

Article abstract of DOI:10.1021/acs.inorgchem.0c03016

A series of halogenated gallium corroles were synthesized and characterized by UV-vis, HRMS, NMR, and FT-IR. The interaction between these gallium corroles and calf thymus DNA had been investigated by spectroscopic methods. These gallium corroles would interact with CT-DNA via an outside binding mode. The photodynamic antitumor activity in vitro of these gallium corroles toward different cell lines had also been tested. 3-Ga displayed low cytotoxicity to normal cells under both light and dark conditions but high phototoxicity to liver cancer cells HepG2. The vitro experiment results showed that 3-Ga could be efficiently absorbed by tumor cells. After light illumination, it may induce reactive oxygen species (ROS) and cause destruction of the mitochondrial membrane potential, which may finally trigger tumor cell apoptosis. Flow cytometry results showed that HepG2 cells were mainly distributed in the sub-G0 phase, which corresponds to cells with highly fragmented DNA or dead cells generally. This suggests that 3-Ga could lead to tumor cell apoptosis after light illumination.

Full text of DOI:10.1021/acs.inorgchem.0c03016

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Article
Halogenated Gallium Corroles:DNA Interaction and Photodynamic
Antitumor Activity
Ling-Gui Liu, Yan-Mei Sun, Ze-Yu Liu, Yu-Hui Liao,* Lei Zeng, Yong Ye, and Hai-Yang Liu*
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ABSTRACT: A series of halogenated gallium corroles were synthesized and characterized by UV−vis, HRMS, NMR, and FT-IR.
The interaction between these gallium corroles and calf thymus DNA had been investigated by spectroscopic methods. These
gallium corroles would interact with CT-DNA via an outside binding mode. The photodynamic antitumor activity in vitro of these
gallium corroles toward different cell lines had also been tested. 3-Ga displayed low cytotoxicity to normal cells under both light and
dark conditions but high phototoxicity to liver cancer cells HepG2. The vitro experiment results showed that 3-Ga could be
efficiently absorbed by tumor cells. After light illumination, it may induce reactive oxygen species (ROS) and cause destruction of
the mitochondrial membrane potential, which may finally trigger tumor cell apoptosis. Flow cytometry results showed that HepG2
cells were mainly distributed in the sub-G0 phase, which corresponds to cells with highly fragmented DNA or dead cells generally.
This suggests that 3-Ga could lead to tumor cell apoptosis after light illumination.
agents. Previous studies have shown that metal corroles had
the ability to interact with DNA.9 Here, we also have
investigated the interaction between CT-DNA and halogen-
ated gallium corroles in order to check their DNA binding
affinity. It should be pointed out that the DNA binding
between these gallium corroles and DNA in the nucleus is not
expected when they are used as PDT photosensitizers,
considering the risk of mutagenicity.
It is known that the heavy atom effect can improve the
capability of the photosensitizer in producing singlet oxygen
and enhance the PDT efficiency.10 We found that halogen
substituent at the meso-phenyl group of corroles may tune
their photophysical properties via heavy-atom effects.11
Heavier halogen atoms are able to reduce the fluorescence
quantum yield and lifetime, leading to the increase of the
intersystem crossing rate and improvement of singlet oxygen
INTRODUCTION
■
Photodynamic therapy (PDT) has been developed as an
emerging cancer treatment method. As compared to traditional
cancer treatment methods such as chemotherapy, radiotherapy,
and surgery, PDT has the advantages of little invasivity, low
toxicity to normal tissues, less drug resistance, and controllable
treatment area selection.1 Porphyrin and its derivatives have
been proved extensive applications in medicine.2 Some
porphyrin derivatives have been used as photosensitizers
clinically in the photodynamic treatment of cancer.3 Corrole
is a tetrapyrrole macrocyclic compound similar to porphyrin. It
has a smaller inner ring cavity, which enables corrole to
coordinate with higher oxidation metal ions.4 Because of their
unique structure and electronic properties, corrole and metal
corrole have been widely used in various fields, such as anti-
tumor,5 sensors,6 and catalysis.7
Cancer has always been an intractable problem in the
medical field, and the development of new and efficient
anticancer drugs is an urgent task to be solved. Many
anticancer drugs, such as chemotherapy drug cisplatinum,
can crosslink with the purine bases on the DNA, interfering
with DNA repair mechanisms, causing DNA damage, and
subsequently inducing apoptosis in cancer cells.8 Therefore,
molecules with strong affinity for DNA are potential anticancer
Received: October 11, 2020
Published: January 22, 2021
https://dx.doi.org/10.1021/acs.inorgchem.0c03016
© 2021 American Chemical Society
Inorg. Chem. 2021, 60, 2234−2245
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Scheme 1. Synthetic Procedure of the Halogenated Gallium(III) Corroles
1
quantum yield.12 The center metal ions also have significant
impacts on anti-tumor effects.13 Gallium corrole complexes
have been reported to exhibit good anti-tumor activities.14
Early studies showed that gallium anionic corrole could
penetrate the cell membrane and achieve tumor target delivery
after binding the carrier protein.15 Our previous work showed
that the neutral gallium corrole could easily penetrate the cell
membrane and produce singlet oxygen in the cell after
illumination, resulting in cell apoptosis.14 As compared with
other metals such as iron, manganese, or copper, the
introduction of gallium was found to be more efficient in
enhancing the PDT activity of freebase corrole.16 Hence, in
order to facilitate PDT activity of corrole derivatives by using
the heavy atom effect and gallium, we hereby wish to report
the preparation of a series of halogenated gallium corroles
(Scheme 1) and their photodynamic antitumor activity toward
tumor cells in vitro. Their DNA binding capability and acute
toxicity were also tested. It turned out that 3-Ga generated
singlet oxygen as effective reactive oxygen species with a high
quantum yield due to the heavy atom effect and exhibited
remarkable PDT activity under near-IR light with selectivity
toward liver cancer cells (HepG2) over normal cells.
(5.18), 565 (4.40), 613 (4.18). H NMR (400 MHz, CDCl3) δ 9.11
(d, J = 4.2 Hz, 2H), 8.75 (d, J = 4.5 Hz, 2H), 8.68 (d, J = 4.7 Hz, 2H),
8.58 (d, J = 4.1 Hz, 2H), 7.65 (dd, J = 8.4, 2.8 Hz, 1H), 7.40 (td, J =
8.6, 2.8 Hz, 1H), 7.25−7.21 (m, 1H). 19F NMR (471 MHz, CDCl3) δ
−125.05 (s), −137.83 (dd, J = 25.2, 6.6 Hz), −152.34 (t, J = 20.8
Hz), −161.50 (ddd, J = 30.1, 22.6, 8.5 Hz). HRMS-ESI: m/z: calcd
for C37H16F11N4O: 741.1143, found: 741.1151 [M + H+].
10-(2-Hydroxyl-5-chlorophenyl)-5,15-bis(pentafluorophenyl)-
corrole (2). UV−vis (CH2Cl2), λmax/nm (logε/(M−1 cm−1)): 412
1
(5.09), 565 (4.33), 613 (4.13). H NMR (500 MHz, CDCl3) δ 9.11
(d, J = 4.2 Hz, 2H), 8.74 (d, J = 4.6 Hz, 2H), 8.67 (d, J = 4.6 Hz, 2H),
8.58 (d, J = 4.1 Hz, 2H), 7.91 (d, J = 2.1 Hz, 1H), 7.64 (dd, J = 8.8,
2.1 Hz, 1H), 7.23 (d, J = 8.8 Hz, 1H). 19F NMR (471 MHz, CDCl3) δ
−137.84 (dd, J = 25.5, 8.6 Hz), −152.30 (t, J = 21.8 Hz), −161.49
(dd, J = 31.2, 7.6 Hz). HRMS-ESI: m/z: calcd for C37H16ClF10N4O:
757.0847, found: 757.0863 [M + H+].
10-(2-Hydroxyl-5-bromophenyl)-5,15-bis(pentafluorophenyl)-
corrole (3). UV−vis (CH2Cl2), λmax/nm (logε/(M−1 cm−1)): 412
1
(5.13), 565 (4.34), 613 (4.11). H NMR (500 MHz, CDCl3) δ 9.11
(d, J = 4.2 Hz, 2H), 8.75 (d, J = 4.6 Hz, 2H), 8.67 (d, J = 4.7 Hz, 2H),
8.59 (d, J = 4.2 Hz, 2H), 8.05 (d, J = 2.4 Hz, 1H), 7.78 (dd, J = 8.8,
2.4 Hz, 1H), 7.17 (d, J = 8.8 Hz, 1H). 19F NMR (471 MHz, CDCl3) δ
−137.83 (dd, J = 25.8, 10.1 Hz), −152.26 (t, J = 21.9 Hz), −161.45
(dd, J = 29.4, 6.3 Hz). HRMS-ESI: m/z: calcd for C37H16BrF10N4O:
801.0342, found: 801.0356 [M + H+].
10-(2-Hydroxyl-5-iodophenyl)-5,15-bis(pentafluorophenyl)-
EXPERIMENTAL SECTION
corrole (4). UV−vis (CH2Cl2), λmax/nm (logε/(M−1 cm−1)): 412
■
Materials. All reagents were purchased commercially and not
further purified prior to using unless specifically mentioned. The
1
(5.05), 565 (4.25), 613 (4.00). H NMR (500 MHz, CDCl3) δ 9.12
(d, J = 4.2 Hz, 2H), 8.75 (d, J = 4.6 Hz, 2H), 8.67 (d, J = 4.6 Hz, 2H),
8.59 (d, J = 4.1 Hz, 2H), 8.24 (s, 1H), 7.96 (d, J = 8.7 Hz, 1H), 7.08
(d, J = 8.7 Hz, 1H). 19F NMR (471 MHz, CDCl3) δ −137.83 (dd, J =
25.6, 9.4 Hz), −152.25 (t, J = 21.8 Hz), −160.31 − −162.83 (m).
HRMS-ESI: m/z: calcd for C37H16F10IN4O: 849.0204, found:
849.0218 [M + H+].
ultrapure water was used in all biological experiments. H, 19F, and
1
13C nuclear magnetic resonance (NMR) spectra were recorded on a
Bruker Ascend 500 spectrometer in CDCl3 or DMSO-d6 solution.
High-resolution mass spectrometry (HRMS) spectra were acquired
by a Bruker maXis impact mass spectrometer with an electrospray
ionization source. The UV−vis absorption spectra were obtained
using a Hitachi 3900H UV−vis spectrometer, and the fluorescence
emission spectra were measured with a Hitachi F-4500 fluorescence
spectrophotometer at room temperature. The Fourier transform
infrared (FT-IR) spectrum was obtained on a Bruker Vertex 70 FT-IR
spectrometer. The electron paramagnetic resonance (EPR) spectrum
was detected by a Bruker Elexsys-II E500 CW-EPR spectrometer. The
cells were observed by using an Olympus IX73 fluorescence
microscope, Nikon Ti2-U fluorescence microscope, and Leica TCS
SP8 laser scanning confocal microscope. A BD FACS Celesta flow
cytometer was used for flow cytometry analysis. The light source for
photodynamic therapy was from a red LED lamp (625 2 nm, 3 W/
m2). All cell lines were bought from the American Type Culture
Collection, and the BALB/c mice were purchased from the laboratory
animal center of South China University of Technology.
Synthesis of Gallium(III) Corroles. 10-(2-Hydroxyl-5-fluoro-
phenyl)-5,15-bis(pentafluorop-henyl)corrole gallium (III) (1-Ga). A
total of 30 mg corrole 1 (0.037 mmol) was dissolved in 10 mL
pyridine, and 70 mg GaCl3 (0.4 mmol) was added. The mixture was
stirred for 2 h under a nitrogen atmosphere at 120 °C. The reaction
mixture was cooled down to room temperature. Then, 30 mL CH2Cl2
was added to the reaction mixture. The resulted solution was washed
with saturated brine five times, and the organic layer was collected
and dried by using anhydrous sodium sulfate. CH2Cl2 solvent was
removed by a rotary evaporator, and the crude product was obtained.
The product was purified by silica gel column chromatography using
CH2Cl2/CH3OH (100:1) as eluent. A purple-red solid product was
obtained by recrystallization with CH2Cl2/hexane as the solvent.
Yield: 82.3%. 1H NMR (500 MHz, DMSO-d6) δ 9.39 (s, 1H), 9.29 (s,
2H), 8.98 (s, 2H), 8.89 (s, 2H), 8.68 (s, 2H), 8.46 (s, 2H), 7.79−7.69
(m, 2H), 7.47 (t, J = 8.5 Hz, 1H), 7.38−7.32 (m, 2H), 7.31−7.24 (m,
1H). 19F NMR (471 MHz, DMSO-d6) δ −127.22 (s), −139.08 (d, J =
30.5 Hz), −154.66 − −156.08 (m), −162.43 − −164.19 (m). 13C
NMR (126 MHz, DMSO-d6) δ 156.01, 154.15, 149.83, 147.17,
145.34, 143.95, 140.94, 136.81, 134.79, 130.11, 129.83, 127.22,
126.13, 124.65, 121.72, 121.55, 118.00, 116.45, 116.06, 107.08, 96.67.
HRMS-ESI: m/z: calcd for C37H12F11GaN4NaO: 828.9983, found:
Synthesis of Free Base Corroles. 10-(2-Hydroxyl-5-fluorophen-
yl)-5,15-bis(pentafluorophenyl)corrole (1), 10-(2-hydroxyl-5-chloro-
phenyl)-5,15-bis(pentafluorophenyl)corrole (2), 10-(2-hydroxyl-5-
bromophenyl)-5,15-bis(pentafluorophenyl)corrole (3), and 10-(2-
hydroxyl-5-iodophenyl)-5,15-bis(pentafluorophenyl)corrole (4) were
synthesized according to the procedures described in the Supporting
Information.
10-(2-Hydroxyl-5-fluorophenyl)-5,15-bis(pentafluorophenyl)-
+
corrole (1). UV−vis (CH2Cl2), λmax/nm (logε/(M−1 cm−1)): 412
828.9986 [M-pyridine + Na] .
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F
F
10-(2-Hydroxyl-5-chlorophenyl)-5,15-bis(pentafluorophenyl)-
corrole gallium (III) (2-Ga). The synthetic procedures were similar to
1-Ga. Yield: 81.6%. H NMR (500 MHz, DMSO-d ) δ 9.70 (s, 1H),
0
= 1 + Ksv[Q ]
(2)
1
6
9.29 (s, 2H), 8.99 (s, 2H), 8.90 (s, 2H), 8.66 (s, 2H), 8.47 (s, 2H),
7.93 (s, 1H), 7.79−7.62 (m, 2H), 7.39−7.28 (m, 3H). 19F NMR (471
MHz, CDCl3) δ −135.54 − −137.24 (m), −153.65 (s), −160.75 −
−162.52 (m). 13C NMR (126 MHz, DMSO-d6) δ 158.99, 156.73,
149.87, 147.22, 145.31, 143.94, 140.95, 136.80, 134.78, 130.63,
129.48, 127.24, 126.05, 124.95, 124.37, 122.07, 118.02, 117.36,
116.00, 106.77, 96.72. HRMS-ESI: m/z: calcd for
C37H12ClF10GaN4NaO: 844.9688, found: 844.9711 [M-pyridine +
where [Q] is the concentration of CT-DNA and F0 and F are the
fluorescence intensities in the absence and presence of CT-DNA,
respectively.
Singlet Oxygen Detection. The absorbance of 1,3-diphenyliso-
benzofuran (DPBF) would decrease as a result of reaction with singlet
oxygen. Therefore, DPBF was used as a singlet oxygen capture agent
to detect the singlet oxygen quantum yield of gallium corroles by
measuring the change of its absorbance. The solution of DPBF (40
μM) in DMF was prepared in the absence (control) and presence of
gallium corroles (10 μM), and then the absorption spectrum was
determined every 10 s after light irradiation (625 2 nm, 3 W/m2) at
room temperature. Meanwhile, 5,10,15,20-tetraphenylporphyrin
(TPP) was used as a reference substance to evaluate the singlet
oxygen production of gallium corroles. The values of ΦΔ were
calculated by the following equation:19
+
Na] .
10-(2-Hydroxyl-5-bromophenyl)-5,15-bis(pentafluorophenyl)-
corrole gallium (III) (3-Ga). The synthetic procedures were similar to
1
1-Ga. Yield: 80.7%. H NMR (500 MHz, DMSO-d6) δ 9.77 (d, J =
11.4 Hz, 1H), 9.29 (d, J = 3.1 Hz, 2H), 9.00 (s, 2H), 8.90 (s, 2H),
8.67 (s, 2H), 8.41 (dd, J = 24.5, 6.7 Hz, 2H), 8.06 (s, 1H), 7.84−7.66
(m, 2H), 7.39−7.24 (m, 3H). 19F NMR (471 MHz, DMSO-d6) δ
−139.07 (d, J = 32.4 Hz), −155.32 (d, J = 23.0 Hz), −163.22 (d, J =
27.2 Hz). 13C NMR (126 MHz, DMSO-d6) δ 157.17, 149.89, 145.28,
143.94, 140.94, 138.85, 137.52, 136.78, 136.61−136.58, 134.83,
132.39, 131.20, 127.28, 126.06, 124.97, 124.36, 117.98, 115.99,
109.69, 106.73, 96.75. HRMS-ESI: m/z: calcd for
C37H12BrF10GaN4NaO: 888.9183, found: 888.9243 [M-pyridine +
KSample
KRef
F
Ref
Φ = ΦRef
×
×
Δ
FSample
(3)
where k is the slope of the plot of DPBF absorbance (at 417 nm) vis
irradiation time and F is the absorption correction factor given by F =
1−10−OD (OD is optical density of photosensitizer at the irradiation
wavelength).
The ability to generate singlet oxygen of gallium corroles was
further confirmed by using the electron paramagnetic resonance
(EPR). TEMP and DABCO were used as a trapping agent and a
quenching agent for singlet oxygen, respectively.
Photostability Study. The photostability of gallium corroles was
studied by UV−vis absorption spectroscopy. The absorption spectra
of gallium corroles solution (10 μM, in DMF/Tris) under different
illumination times were determined. Each exposure time was 10 min
(625 2 nm, 3 W/m2).
Aggregation Study in Solution. The possible aggregation of
gallium corroles was investigated by UV−vis absorption spectroscopy.
The absorption spectra of gallium corroles solution in different
concentrations were determined. The change of the Soret band was
monitored to determine whether the gallium corroles had self-
aggregation in solution.
Cytotoxicity Assays. Inhibition of cell growth by gallium corroles
was measured by a 3-(4,5-dimethylthiazole)-2,5-diphenyltetraazolium
bromide (MTT) assay. First, cells were seeded in 96-well plates at a
density of 5 × 103 cells per well and cultured in a cell incubator (37
°C, 5% CO2) overnight. A series of gallium corroles were dissolved
with DMSO (final concentration ≤ 1% V/V in the culture medium)
and diluted by a DMEM medium to obtain different concentrations of
samples. Then, samples of different concentrations were added into
cell plates and cells of control wells were treated with the same
conditions without gallium corroles. After culturing for 4 h, the cells
were illuminated by red light (625 2 nm, 3 W/m2) for 1 h, and
subsequently, the cells were incubated for another 24 h. After that, the
culture medium with samples was removed and the culture medium
with MTT dye solution (20 μL, 5 mg/mL) was added into all wells.
After 4 h, DMSO (100 μL) was used to replace the culture medium.
The optical density (OD) value of cell plates was acquired by a
Thermo Scientific Microplate Reader at 495 nm. In order to minimize
the error, each experiment was repeated three times.
Cellular Uptake. HepG2 cells were first cultured in glass-
bottomed dishes (20 mm) with approximately 2 × 105 cells in each
well for 24 h in a 5% CO2 incubator at 37 °C. Then, the cells were
treated with 3-Ga (10 μM) and incubated for 4 h. After that, the cells
were stained with 2-(4-amidinophenyl)-6-indolecarbamidine (DAPI)
and washed with PBS solution for three times. Finally, the cells were
observed and photographed with laser confocal fluorescence
microscopy (oil objective 63×; magnification 630×; laser intensity
15%; gain at 800 V; DAPI excitation laser, 405 nm; DAPI detector,
410−500 nm; 3-Ga excitation laser, 561 nm; 3-Ga detector, 570−720
nm).
+
Na] .
10-(2-Hydroxyl-5-iodophenyl)-5,15-bis(pentafluorophenyl)-
corrole gallium (III) (4-Ga). The synthetic procedures were similar to
1
1-Ga. Yield: 85.4%. H NMR (500 MHz, DMSO-d6) δ 9.72 (s, 1H),
9.29 (s, 2H), 8.97 (s, 2H), 8.89 (s, 2H), 8.64 (s, 2H), 8.50 (s, 2H),
8.19 (s, 1H), 7.92 (d, J = 7.3 Hz, 1H), 7.77 (s, 1H), 7.37 (s, 2H), 7.15
(d, J = 8.1 Hz, 1H). 19F NMR (471 MHz, DMSO-d6) δ −139.08 (d, J
= 29.3 Hz), −154.64 − −156.09 (m), −163.25 (d, J = 24.3 Hz). 13C
NMR (126 MHz, DMSO-d6) δ 157.73, 149.84, 147.16, 145.28,
143.93, 143.35, 140.93, 140.34, 138.84, 138.20, 136.84, 134.80,
131.70, 127.22, 126.08, 124.92, 124.42, 118.25, 106.77, 96.69, 80.61.
HRMS-ESI: m/z: calcd for C37H12F10GaIN4NaO: 936.9044, found:
+
936.9053 [M-pyridine + Na] .
UV−vis Absorption Spectrum Titration Experiment. The
gallium corroles were diluted to 3 mM with DMF. Buffer solution I (5
mM Tris, 50 mM NaCl, HCl, pH = 7.2) was mixed with DMF as the
control solution. Then, the gallium corrole solution (5 μL, 3 mM) was
mixed with the control solution as the sample solution, keeping the
concentration of gallium corrole constant. The UV−vis absorption
spectrum of the sample solution was recorded ranging from 300 to
800 nm. After that, CT-DNA (2 μL, 1.5 mM) was added into the
control solution and the sample solution successively, and the
absorption spectrum was recorded after waiting for 5 min at a time.
The measurement was stopped when the change in the spectrum was
small. The intrinsic binding constant (Kb) of the samples with CT-
DNA can be obtained by following equation:17
[DNA]
εa − εf
[DNA]
εb − εf
1
=
+
Kb(εb − εf)
(1)
where εa is the extinction coefficient of the compound in the presence
of DNA, εf and εb are the extinction coefficient of the compound
when bound to DNA incompletely and completely respectively,
[DNA] is the concentration of DNA. Kb is the ratio of the slope to the
intercept of the graph of [DNA]/(εa− εf) versus [DNA].
Fluorescence Spectrum Titration Experiment. First, gallium
corrole (5 μL, 3 mM) was mixed with solution of buffer I and DMF as
the sample solution, keeping the concentration of gallium corrole
constant. The fluorescence emission spectrum of the sample solution
was recorded with appropriate excitation wavelength. After that, CT-
DNA (2 μL, 1.5 mM) was added into the sample solution
successively, and fluorescence emission spectrum was recorded after
waiting for 5 min at a time. The measurement was stopped when the
change in the spectrum was small. The quenching constants (Ksv) can
be obtained by following Stern−Volmer equation:18
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Flow cytometry was used to further detect the time-dependent
uptake. HepG2 cells were first cultured in a 12-well plate for 24 h.
After that, previous medium was replaced with a new medium
containing 3-Ga (10 μM). Fluorescence intensity was measured after
additional incubation for 2, 4, and 6 h.
Reactive Oxygen Species (ROS) Detection in Cells. HepG2
cells were seeded in 12-well plates with approximately 2 × 105 cells in
each well and incubated in a cell incubator for 24 h. Then, 3-Ga (10
μM) were added into the wells. The cells were cultured for 4 h and
exposed to light irradiation as previously described. After further
incubation for 24 h, the culture medium was removed and the
medium containing 2′,7′-dichlorodihydrofluorescein diacetate
(DCFH-DA, 10 μM) was added. After sustained incubation for 30
min, the cells were rinsed with PBS for three times and observed
under a fluorescence microscope (magnification 100×; exposure 200
ms; gain 3.4×; DCFH-DA excitation, 488 nm; DCFH-DA emission,
525 nm).
Figure 1. UV−visible absorption spectrum (a) and fluorescence
emission spectrum (b) (λex = 434 nm) of 1-Ga, 2-Ga, 3-Ga, and 4-Ga
in DMF solution (10 μM).
Table 1. Photophysical Data of Gallium Corroles
absorption [nm] (logε(M−1 cm−1))
Mitochondrial Membrane Potential Assay. HepG2 cells were
seeded in 12-well plates at a density of 2 × 105 cells per well and
incubated in a cell incubator for 24 h. Afterward, the cells were treated
with 3-Ga (10 μM) and illuminated as previously described
immediately after incubation for 4 h. Followed by incubation for 24
h, the medium containing 5,5′,6,6′-tetrachloro-1,1′,3,3′- tetraethyli-
midacarbocyanine iodide (JC-1) was injected into each well and
incubated for another 20 min in a cell incubator. After that, the cells
were washed with PBS over three times and observed with a
fluorescence microscope (magnification 100×; exposure 800 ms; gain
17.1×; JC-1 monomers excitation, 490 nm; JC-1 monomers emission,
530 nm; JC-1 aggregates excitation, 525 nm; JC-1 aggregates
emission, 590 nm).
λem
a
b
corrole Soret band
Q band
576(4.38)
576(4.38)
576(4.35)
577(4.47)
(nm)
ΦF
Φ△
1-Ga
2-Ga
3-Ga
4-Ga
423(5.29)
423(5.30)
423(5.30)
423(5.35)
603(4.52)
604(4.52)
604(4.48)
605(4.61)
613
613
613
614
0.33
0.32
0.22
0.13
0.18
0.24
0.32
0.25
TPP as a reference in toluene (ΦF = 0.11).21 TPP as a reference in
a
b
DMF (Φ△ = 0.62).22
Apoptosis Assay by Flow Cytometry. For the apoptosis assay,
HepG2 cells were first seeded in 6-well plates for 24 h (37 °C in 5%
CO2). Then, the cells were incubated with the culture medium
containing 3-Ga (10 μM) or not. After further incubation for 4 h, the
cells of light group were given irradiation (625 2 nm, 3 W/m2) for 1
h and sequentially cultured for 24 h. After that, the cells were
collected, centrifuged, resuspended with PBS, re-centrifuged, and then
stained with propidium iodide (PI, 50 mg/mL) and Annexin V-FITC
(1 mg/mL) in PBS. At last, apoptosis was detected by using a BD
FACS Celesta flow cytometer.
Cell Cycle Assay. For the cell cycle assay, HepG2 cells were
cultured in 6-well plates. After incubating for 24 h (37 °C in 5%
CO2), the previous culture medium was replaced by a fresh culture
medium containing 3-Ga (10 μM) or not and irradiation was given to
the cells of light group after 4 h. After 1 day, the cells were collected,
centrifuged, resuspended with PBS, re-centrifuged, and then fixed
with 70% ice ethanol at 4 °C overnight. After that, the cells were
centrifuged, resuspended with PBS, re-centrifuged, and stained with
RNase A (0.2 mg/mL) and PI (0.02 mg/mL) for 30 min at 37 °C in
the dark. Finally, cell cycle was analyzed by using a BD FACS Celesta
flow cytometer.
Figure 2. Changes in absorption spectra of 1-Ga (a), 2-Ga (b), 3-Ga
(c), and 4-Ga (d) upon consecutive addition of CT-DNA.
Acute Toxicity Studies In Vivo. Acute toxicity in vivo of 3-Ga
was tested by using BALB/C mice (4−5 weeks). The mice were
divided into four groups (two groups of females and two groups of
males) at random, and each group consists of three mice. The mice of
experimental groups were injected 3-Ga in a single dose of 10 mg/kg
through the tail vein. The mice of control groups were given a single
injection of 100 μL normal saline. After administration, the body
weight, behavioral characteristics, and possible symptoms of the mice
were monitored every day. Two weeks after the injection, the mice
were euthanized, and their major organs, including the heart, liver,
spleen, lung, and kidney, were quickly removed and weighed. Then,
the organ coefficients were obtained by the ratio of the weight of each
organ to the body weight of mice.
Table 2. Intrinsic Binding Constants of Gallium Corroles
Binding with CT-DNA
a
bb
corrole Δλ (nm)
H
(%) Kb (×105 L/mol) Ksv (×104 L/mol)
1-Ga
2-Ga
3-Ga
4-Ga
1
1
1
0
28.62
24.35
15.91
17.47
1.04 0.09
0.73 0.10
0.39 0.03
0.62 0.05
6.13 0.64
5.90 0.45
5.22 0.61
3.25 0.38
a
Δλ represents the red shift of the Soret band induced by interaction
b
between gallium corroles and CT-DNA. H represents the
hypochromism of Soret band obtained by H% = (Afree − Abound)/
Afree × 100%.
RESULTS AND DISCUSSION
■
spectroscopy, and mass spectrometry (HRMS-ESI). All gallium
corroles were obtained by the reflux reaction of gallium
chloride and freebase corroles in pyridine solvent under the
protection of nitrogen. The final products were separated and
Synthesis and Characterization. Corroles 1−4 were
obtained according to a method published formerly and
1
characterized by H NMR, 19F NMR spectroscopy, UV−vis
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Table 3. IC50 (μM) Values of Gallium Corroles toward
Various Tumor Cells
tumor cell
1-Ga
2-Ga
>100
light 1.3 0.1 >100
3-Ga
>100
4-Ga
>100
temoporfin
231
dark >100
47.4
16.9
0.6 0.3
>100
74.4
18.9
A549
dark >100
light 10.9
2.5
>100
47.2 8.0 >100
>100
>100
>100
>100
0.5 0.2
HepG2
dark >100
46.9
20.6
>100
>100
71.5
14.8
light 9.3 1.1 4.8 13
10.0 1.6 9.9 2.0 8.4 1.8
HSF
dark >100
light 1.3 0.6 69.2
19.9
>100
>100
94.5
18.7
>100
>100
43.3 5.3 1.5 0.4
Figure 3. Changes in fluorescence spectra of 1-Ga (a), 2-Ga (b), 3-
Ga (c), and 4-Ga (d) upon consecutive addition of CT-DNA.
Huvec
dark >100
light 26.7
3.7
>100
>100
>100
97.0
17.5
>100
>100
>100
2.1 0.2
a
SI
SI
0.1
2.9
14.4
>1.4
9.4
9.7
4.4
>10.1
0.2
0.25
b
a
b
SI = light IC50 values of HSF/light IC50 values of HepG2. SI = light
IC50 values of Huvec/light IC50 values of HepG2.
Table 4. Chemical Properties of Prepared Gallium
d
Corroles
a
b
c
compounds
Mr
tPSA
cLogP
1-Ga
2-Ga
3-Ga
4-Ga
806.00
821.97
865.92
913.91
35.85
35.85
35.85
35.85
13.52
14.09
14.24
14.50
a
b
Molecular weight. Calculation of the polar surface area based on
c
fragment contributions. Calculated logP based on the Biobyte
algorithm. ChemBioDraw Ultra (version 14.0).
d
state (S2), and three weak Q bands at 500−650 nm, attributed
to π−π* electronic transitions from the ground state (S0) to
the first excited state (S1).20 The type of halogen atom
introduced seemed to have no obvious effect on the maximum
absorption wavelength of gallium corroles. As shown in Figure
1b, all gallium corroles exhibited strong fluorescence with a
maximum peak around 613 nm. The fluorescence intensity and
fluorescence quantum yield (ΦF) of gallium corroles decreased
due to the heavy atom effect. All photophysical data of the
gallium corroles are listed in Table 1.
DNA Binding. UV−vis absorption spectrum titration
experiment is one of the simplest and most commonly used
ways to identify binding mode between compound and DNA.
When the complex binds to DNA, the surrounding environ-
ment of the complex changes, and the electronic structure is
disturbed, resulting in the change of UV−vis absorption
spectrum of the complex. The binding strength and binding
pattern between the complex and DNA can be inferred from
the spectral variation. As for porphyrins, the intercalative
binding commonly generates an obvious red shift (Δλ ≥ 15
nm) and a large hypochromism (H ≥ 35%), and the outside
binding mode usually induces a slight red shift (Δλ ≤ 8 nm)
and a small hypochromism (H ≤ 10%).23 Figure 2 displays
Figure 4. (a) Changes in absorbance of DPBF (417 nm) in the
presence of gallium corroles (10 μM) with the irradiation time (625
2 nm, 3 W/m2). EPR spectra of 1-Ga (b), 2-Ga (c), 3-Ga (d), and 4-
Ga (e) after irradiation in the presence of the trapping agent (TEMP)
and quenching agent (DABCO).
purified by column chromatography and well characterized by
1H NMR, 19F NMR, 13C NMR spectroscopy, UV−vis
spectroscopy, HRMS-ESI, and FT-IR (Figures S1−S32).
Photophysical Properties. The photophysical properties
of the gallium corroles were measured in DMF solutions.
Figure 1a shows UV−vis spectrum of prepared gallium
corroles, which exhibited similar typical absorption spectra
characteristics. The gallium corroles exhibited an intense Soret
band centered at 423 nm, arisen due to the π−π* electronic
transition from the ground state (S0) to the second excited
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Figure 5. (a) Confocal images of HepG2 treated with 3-Ga (10 μM) and stained with DAPI (scale bar is 50 μm). (b) Time-dependent uptake of 3-
Ga (10 μM) in HepG2 cells detected by flow cytometry.
mode.24 In addition, the increase of CT-DNA to 1-Ga solution
led to a 28.62% hypochromicity and a bathochromic shift of 1
nm, and the intrinsic binding constant (Kb) between 1-Ga and
CT-DNA came out to be 1.04 × 105 M−1, which was larger
than other gallium corroles. This implied that compared to
other gallium corroles, 1-Ga may have stronger interaction
with CT-DNA. All spectroscopic titration data are listed in
Table 2.
The fluorescence spectrum titration experiment is also a
common method to study the interaction between complexes
and DNA. The fluorescence of complexes is usually enhanced
when the complexes are inserted into DNA base pairs, as DNA
prevents the complexes from colliding with solvent mole-
Figure 6. Intracellular ROS generation induced by 3-Ga (10 μM) in
HepG2 cells upon irradiation (625
cules.25 However, the fluorescence spectrum can also change if
2 nm, 3 W/m2, 1 h) using
the complexes interacted with DNA in other ways. Figure 3
shows the fluorescence spectrum of these gallium corroles
interacted with CT-DNA. With the increase of CT-DNA
concentration, the intensity of the fluorescence of these gallium
corroles gradually weakened. It could be inferred that these
gallium corroles had some interaction with CT-DNA. Also, 1-
Ga had a stronger interaction with CT-DNA according to the
quenching constant (Ksv), which was consistent with the
consequence of absorption spectrum titration experiment.
DCFH-DA as a probe (scale bar is 100 μm).
electronic absorption spectral changes of gallium corroles.
With the gradual increase of CT-DNA concentration, the
absorbance intensity of the Soret band of several gallium
corroles gradually decreased. Although the hypochromism of
these gallium corroles existed, no obvious red shift or blue shift
was observed at the Soret band. It could be speculated that
these gallium corroles bound to DNA via an outside binding
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DMF/Tris−HCl (pH 7.2) buffer mixture solution. Whether it
was in DMF or DMF/Tris solutions, there was no significant
red shift or blue shift in the Soret band (Figures S33−S34),
indicating that gallium corroles did not aggregate within the
range of concentration tested.
Photostability is an important index of PDT and photo-
chemical reaction photosensitizers. The photostability of
gallium corroles were examined by observing the bleaching
of the Soret band under illumination. With the increase of
exposure time, gallium corroles showed different degrees of
bleaching (Figure S35), among which 2-Ga was the most
obvious, while 3-Ga showed good photostability.
Cytotoxicity. The cytotoxicity of gallium corroles were
detected by the MTT assay under dark or light conditions
against three cancer cells, A549 (lung), 231 (breast), HepG2
(liver), and two normal cells, HSF and Huvec. Succinic acid
dehydrogenase in the mitochondria of living cells reduced
exogenous MTT into water-insoluble blue-purple crystal
formazan.29 After formazan deposited in the cells, DMSO
was added to dissolve it and the cell viability could be
indirectly reflected by the absorbance at 495 nm. The IC50
values of several gallium corroles to different cells are
summarized in Table 3. The dark toxicity and phototoxicity
of gallium corroles toward tumor cells depended on the type of
cell, while these gallium corroles had little toxicity to two
normal cells under dark conditions. At the same time, 1-Ga
had little dark toxicity but high phototoxicity against two tested
normal cells. 4-Ga also exhibited significant phototoxicity to
normal cells HSF. In contrast, 3-Ga showed low cytotoxicity to
all tested normal cells under both light and dark conditions,
but high phototoxicity to HepG2 liver cancer cells with an
IC50 value of 10.0 1.6 μM. It displayed a remarkable dark−
light cytotoxicity difference in inducing HepG2 toxicity too.
The phototoxicity of 3-Ga toward HepG2 cells is even
comparable to clinically used photosensitizer temoporfin. Also,
of all prepared corrole photosensitizers, 3-Ga showed minimal
toxicity to tested normal cells whether under light or dark
conditions. Encouraged by above results, we further explored
photodynamic performance of 3-Ga in HepG2 cells.
Cellular Uptake. Stimulated by the good phototoxicity of
3-Ga toward HepG2 cells, we tested its uptake in HepG2 cells.
Even though the mechanisms of uptake of gallium corroles
remain unknown, chemical properties such as lower molecular
weight (Mr), smaller polar surface area (tPSA), and higher
lipophilicity (cLogP) have been proved to enhance cellular
uptake of drugs.30 Therefore, we first used ChemDraw
software to obtain the related properties of several prepared
gallium corroles (Table 4). Compared with the previously
reported carboxylated gallium corroles,30a 3-Ga showed lower
Mr, smaller tPSA, and larger cLogP, which may enhance cell
uptake and permeability. For cellular uptake experiment, cells
were treated with 3-Ga and stained with DAPI, which is a blue
fluorescent dye that strongly binds to DNA. The uptake results
of 3-Ga by HepG2 cells were depicted in Figure 5. Obviously,
the strong red fluorescence in HepG2 cells indicated the
effective uptake of 3-Ga by HepG2 cells. Also, the red
fluorescence was distributed around the nucleus, mainly in the
cytoplasm (Figure 5a). In addition, the flow cytometry was
also used to investigate the time-dependent uptake of 3-Ga in
HepG2 (Figure 5b). The intracellular fluorescence intensity
increased about one order at the first 2 h incubation. With the
further extension of culture time from 2 to 6 h, the intracellular
fluorescence intensity increased slightly. These observations
Figure 7. Mitochondrial membrane potential destruction of HepG2
cells induced by 3-Ga (10 μM) under (a) dark or (b) light (625
2
nm, 3 W/m2, 1 h) by using JC-1 as fluorescence probe (scale bar is
100 μm); chloro carbonyl cyanide phenyl hydrazone (CCCP) is used
as the positive control.
Photodynamic Properties. The ability of a photo-
sensitizer to produce singlet oxygen is the key to evaluate
the treatment effect in photodynamic therapy. The photo-
sensitizers transfer from the ground state to the excited state
upon irradiation, then cross back to the ground state through
inter system crossing and transfer energy to triplet molecular
oxygen to generate singlet oxygen, which is considered to play
a major role in cell killing.26 The single oxygen yield of
prepared gallium corroles were measured indirectly by using
DPBF, as shown in Figure 4a, after adding prepared gallium
corroles into the DPBF solution, the absorbance of DPBF
decreased with the illumination time, indicating that the
synthesized gallium corroles produced singlet oxygen under
the light condition. From Figure 4, although it seems that 4-Ga
1
has the highest O2 production quantum yield, the calculated
1O2 quantum yield of 4-Ga is lower than that of 3-Ga due to its
significant higher molar extinction coefficient at illumination
wavelength 625 nm (eq 3). Also, 3-Ga has the strongest ability
to produce singlet oxygen, whose singlet oxygen yield (Φ△) is
0.32 (Table 1).
The photo-induced singlet oxygen was further investigated
by EPR with TEMP serving as the trapping agent. Upon
irradiation with a 625 nm laser for 1 min, a significant intensive
EPR signal appeared (Figure 4b−e), which was in accordance
with a typical EPR spectrum of the TEMPO-1O2 adducts with
a three-line signal of 1:1:1.27 After the addition of quenching
agent, DABCO, the signal was dramatically weakened, which
further proved the generation of singlet oxygen.
The self-aggregation of porphyrins in solution is very
common, mainly due to strong attractive interactions between
conjugation structures, but it will reduce the activity of
porphyrins.28 Therefore, we studied aggregation behavior of
prepared gallium corroles by UV−vis spectra in DMF and
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Figure 8. Annexin-V FITC and propidiun iodide (PI) staining of HepG2 cells by flow cytometry analysis. (a) Control group in the dark, (b) cells
treated with 3-Ga (10 μM) in the dark, (c) cells in the light, (d) cells treated with 3-Ga (10 μM) and irradiation (625 2 nm, 3 W/m2, 1 h), and
(e) data of late apoptotic (AV+/PI+) cells in the different groups.
indicated that 3-Ga could efficiently penetrate HepG2 cells
without the addition of any external carrier protein and was
mainly localized in the cytoplasm. This is different from
previously reported gallium sulfonated corrole in which the
additive carrier protein is needed to assist the cellular
uptake.15a Since the gallium corrole 3-Ga could not enter
the nucleus, its interaction with nuclei DNA was not possible
and the mutagenic risk was avoided. This is the advantage of 3-
Ga as an ideal photosensitizer.
Detection of Intracellular ROS. The production of
reactive oxygen species (ROS) plays an important role in the
process of cell death and has been thought to regulate the
process involved in the initiation of apoptotic signaling.31
Herein, we used 2′,7′-dichlorodihydrofluorescein diacetate
(DCFH-DA) and Rosup as fluorescent dyes and positive
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Figure 9. Cell cycle distribution of HepG2 by flow cytometry analysis. (a) Control group, (b) cells treated with 3-Ga (10 μM) in the dark, and (d)
cells treated with 3-Ga (10 μM) and irradiation (625 2 nm, 3 W/m2, 1 h). (c) Graph of the cell cycle distribution.
laser irradiation, resulting in oxidative damage of cells, which is
an important condition as a potential PDT photosensitizer for
the treatment of liver cancer.
Mitochondrial Membrane Potential Assay. The loss of
mitochondrial membrane potential is one of the key events of
cell apoptosis and the decrease of mitochondrial membrane
potential indicates the occurrence of early cell apoptosis.32 JC-
1 is a kind of fluorescent probe widely used to detect the
mitochondrial membrane potential. When the mitochondrial
membrane potential is high, JC-1 aggregates in the
mitochondrial matrix to form a polymer that can emit red
fluorescence; when the mitochondrial membrane potential is
low, JC-1 exists as a monomer and emits green fluorescence.
Hence, the decrease of the mitochondrial membrane potential
can be easily detected by fluorescence color transformation of
JC-1, which can also be regarded as an indicator of early
apoptosis. As shown in Figure 7, much like the control group,
JC-1 effectively aggregated and emitted red fluorescence in
cells treated with light and 3-Ga alone, attributed to a high
mitochondrial membrane potential. However, the group of 3-
Ga + light was consistent with the positive control group, JC-1
existed in a monomer form and emitted green fluorescence,
indicating that the mitochondrial membrane potential of
HepG2 cells treated with 3-Ga PDT was significantly
decreased. These results further demonstrate that 3-Ga has
no obvious damage to cells in the dark, while under light
conditions, 3-Ga is highly toxic and may induce apoptosis of
HepG2 cells.
Figure 10. In vivo acute toxicity of gallium corrole 3-Ga. (a) Body
weight changes, (b) organ coefficients.
controls, respectively, to detect the ROS production of 3-Ga in
HepG2 cells. DCFH-DA itself has no fluorescence, but it can
pass through the cell membrane freely and enter the cell. After
entering the cell, it can be hydrolyzed by intracellular esterase
to produce DCFH. Intracellular ROS can oxidize the non-
fluorescent DCFH to produce the compound DCF with green
fluorescence. The level of intracellular ROS can be determined
by measuring the fluorescence of DCF. As shown in Figure 6,
no green fluorescence was observed in cells treated with light
and 3-Ga alone, which has no difference when compared with
the control group. However, in the 3-Ga + light group, obvious
green fluorescence could be observed, indicating that the ROS
level in HepG2 cells was significantly increased, which was
similar to the positive control group. These results suggested
that 3-Ga had little ability to produce ROS in the dark.
Nevertheless, its ability to generate ROS is activated under
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Apoptosis Assay. For apoptosis assay, the cells were
simultaneously stained with Annexin V-FITC and propidium
iodide (PI). Annexin V-FITC staining can directly detect
phosphatidylserine valgus, an important feature of apoptosis,
and PI can stain necrotic cells or cells that have lost membrane
integrity in late-stage apoptosis. The necrotic cells, late-stage
apoptotic cells, early-stage apoptotic cells, and living cells
correspond to quadrants 1, 2, 3, and 4, respectively. As is
shown in Figure 8c, cell apoptosis percentage treated with 3-
Ga under dark conditions showed little difference to the
control group (13.65% and 11.67%, respectively), while the
apoptosis ratio of cells treated with 3-Ga under illumination
was twice more than that of the control group. Meanwhile, the
HepG2 cell viability after PDT treatment with 3-Ga dropped
to 68.4% and the percentage of apoptotic and necrotic cells
reached 30.8% (Figure 8d). These results suggested that 3-Ga
could lead to apoptosis under light conditions while having less
dark toxicity, which was consistent with previous experimental
results.
Cell Cycle Assay. In order to investigate the potential
mechanism of prepared gallium corrole induced cytotoxic
effect, we used flow cytometry to detect the cell cycle
distribution. HepG2 cells after PDT treatment with samples
showed significant changes in cell cycle. As depicted in Figure
9, compared with the control group, HepG2 cell cycle
distribution treated with 3-Ga under dark condition did not
exhibit significant changes, indicating that 3-Ga had little
influence on cell cycle distribution under dark conditions.
While under the light conditions, after 3-Ga treatment, the
percentage of cells during sub-G0 phase increased from 7.24 to
78.8%, and the percentage of cells in other phases all decreased
sharply, which is mainly due to cell apoptosis caused by 3-Ga.
In Vivo Acute Toxicity. It is necessary to carry out
toxicological experiments for the safe application of drugs in
biomedicine. Therefore, healthy BALB/c mice were chosen for
a simple assessment of acute toxicity of 3-Ga in vivo. As shown
in Figure 10a, the body weight of mice in the experimental
groups and control groups increased steadily within 2 weeks
after administration, and no abnormalities or lesions were
observed in all mice during the observation period, indicating
that 3-Ga basically did not affect the normal growth of mice. In
addition, Figure 10b shows that organ coefficients of mice
treated with 3-Ga were not significantly different from those of
the control groups, and there were no significant changes in
the appearance of major organs (Figure S36). Based on the
above results, 3-Ga may have no obvious acute toxicity in
BALB/C mice when the tail vein injection dose is no more
than 10 mg/kg. More detailed and in-depth biochemical
analysis is needed to demonstrate that 10 mg/kg of 3-Ga is a
safe dose for BALB/c mice.
after illumination, which corresponds to cell apoptosis. In
addition, the in vivo test showed that 3-Ga had very low acute
toxicity at a dose of 10 mg/kg. The preliminary results showed
that 3-Ga is a promising PDT photosensitizer.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c03016.
■
sı
Details of characterization data, including NMR, HRMS,
and FT-IR spectral data, aggregation, photo-degradation,
and acute toxicity study (PDF)
AUTHOR INFORMATION
Corresponding Authors
■
Yu-Hui Liao − Molecular Diagnosis and Treatment Center for
Infectious Diseases, Dermatology Hospital, Southern Medical
University, Guangzhou 510091, China; orcid.org/0000-
0003-4702-9516; Email: liaoyh8@mail.sysu.edu.cn
Hai-Yang Liu − School of Chemistry and Chemical
Engineering, Key Laboratory of Functional Molecular
Engineering of Guangdong Province, South China University
of Technology, Guangzhou 510641, China; orcid.org/
0000-0002-1793-952X; Email: chhyliu@scut.edu.cn
Authors
Ling-Gui Liu − School of Chemistry and Chemical
Engineering, Key Laboratory of Functional Molecular
Engineering of Guangdong Province, South China University
of Technology, Guangzhou 510641, China
Yan-Mei Sun − School of Chemistry and Chemical
Engineering, Key Laboratory of Functional Molecular
Engineering of Guangdong Province, South China University
of Technology, Guangzhou 510641, China
Ze-Yu Liu − School of Chemistry and Chemical Engineering,
Key Laboratory of Functional Molecular Engineering of
Guangdong Province, South China University of Technology,
Guangzhou 510641, China
Lei Zeng − Foresea Life Insurance Guangzhou General
Hospital, Guangzhou 511300, China
Yong Ye − School of Chemistry and Chemical Engineering, Key
Laboratory of Functional Molecular Engineering of
Guangdong Province, South China University of Technology,
Guangzhou 510641, China; orcid.org/0000-0002-9535-
8800
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c03016
Funding
We gratefully acknowledge financial support from the National
Natural Science Foundation of China (no. 21671068).
Notes
CONCLUSION
■
In summary, we prepared a series of new halogenated gallium
corroles for photodynamic therapy. These gallium corroles
bind to CT-DNA via an outside binding mode and can
efficiently produce singlet oxygen under light illumination.
Among all synthesized gallium corroles, 3-Ga has the best
photodynamic antitumor activity against HepG2 cells. The
fluorescence microscope showed that 3-Ga could entrance
HepG2 cells smoothly, generate ROS in cells after illumina-
tion, and lead to the destruction of the cell mitochondrial
membrane potential. Flow cytometry results further showed
that 3-Ga could lead to an increase of cells at the sub-G0 phase
The authors declare no competing financial interest.
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