Brasilane sesquiterpenoids and alkane derivatives from cultures of the basidiomycete Coltricia sideroides

Article abstract of DOI:10.1016/j.fitote.2015.05.009

Three new brasilane-type sesquiterpenoids, brasilanes A-C (1-3), together with two new alkane derivatives, colisiderin A (4) and 7(E),9(E)-undecandiene-2,4,5-triol (5), were isolated from cultures of the basidiomycete Coltricia sideroides. Their structures were elucidated by NMR and MS data analyses. The absolute configuration of 4 was determined by TDDFT ECD calculations while brasilane-type sesquiterpenoids were isolated from cultures of mushroom for the first time. Compounds 2 and 4 showed weak cytotoxicities against HL-60 and SW480, respectively.

Full text of DOI:10.1016/j.fitote.2015.05.009

Fitoterapia 104 (2015) 50–54
Contents lists available at ScienceDirect
Fitoterapia
journal homepage: www.elsevier.com/locate/fitote
Brasilane sesquiterpenoids and alkane derivatives from cultures of the
basidiomycete Coltricia sideroides
Dong-Bao Hu a,b, Shen Zhang a,b, Jiang-Bo He a,b, Ze-Jun Dong , Zheng-Hui Li , Tao Feng ⁎, Ji-Kai Liu ⁎
a
a
a,
a,
a
State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
b
University of Chinese Academy of Sciences, Beijing 100049, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Three new brasilane-type sesquiterpenoids, brasilanes A–C (1–3), together with two new alkane derivatives,
colisiderin A (4) and 7(E),9(E)-undecandiene-2,4,5-triol (5), were isolated from cultures of the basidiomycete
Coltricia sideroides. Their structures were elucidated by NMR and MS data analyses. The absolute configuration
of 4 was determined by TDDFT ECD calculations while brasilane-type sesquiterpenoids were isolated from cul-
tures of mushroom for the first time. Compounds 2 and 4 showed weak cytotoxicities against HL-60 and
SW480, respectively.
Received 15 April 2015
Received in revised form 9 May 2015
Accepted 14 May 2015
Available online 16 May 2015
Keywords:
©
2015 Elsevier B.V. All rights reserved.
Coltricia sideroides
Brasilane-type sesquiterpenoids
Alkane derivatives
Cytotoxicities
1
. Introduction
2. Experimental section
2.1. General experimental procedures
Our recent investigations on the secondary metabolites of higher
fungi have obtained more and more sesquiterpenoids with structure di-
versity. For instance, conosilane A is an unprecedented sesquiterpenoid
skeleton with a four-ring system from cultures of Conocybe siliginea [1],
while trefolane A is another sesquiterpenoid with a new skeleton from
cultures of Tremella foliacea [2]. The fungus Coltricia sideroides is one of
the polypore species, which belongs to the wood-decaying fungi family.
However, there was not any report about chemical or biological activity
studies on this fungus yet. Therefore, we interestedly investigated on
the chemical constituent of cultures of C. sideroides, searching for new
natural products. As a result, three new brasilane-type sesquiterpenoids
Optical rotations were measured on a Jasco-P-1020 polarimeter. IR
spectra were obtained by using a Bruker Tensor 27 FT-IR spectrometer
with KBr pellets. NMR spectra were acquired with instruments of
Avance Ш 600 and AM-400. HREIMS was measured on a waters
autoSpec Premier P776 instrument. Silica gel (300–400 mesh, Qingdao
Marine Chemical Inc., China) and Sephadex LH-20 (Amersham Bio-
sciences, Sweden) were used for column chromatography. Fractions
were monitored by TLC and spots were visualized by heating silica
2 4
gel plates immersed in vanillin-H SO in EtOH, in combination with
(1–3), together with two new alkane derivatives, colisiderin A (4) and
Agilent 1200 series HPLC system (Eclipse XDB-C18 column, 5 μm,
7
(E),9(E)-undecandiene-2,4,5-triol (5), were isolated from cultures
4.6 × 150 mm).
of mushroom C. sideroides (Scheme 1). To date, only five brasilane
derivatives have been isolated from the liverwort Conocephalum
conicum [3] and the endophytic fungus Xylaria sp. NCY2 [4], while
only four halogenated brasilane derivatives were reported, which
were isolated from the red alga Laurencia obtuse [5,6]. Compounds
2.2. Fungal material
Fruiting bodies of C. sideroides were collected at Fengkai, Guangdong
Province, China in 2010 and identified by Prof. Yu-Cheng Dai (Beijing
University). The voucher specimen (no. HFG20100917) was deposited
at herbarium of Kunming Institute of Botany. Culture medium: glucose
1
–5 were evaluated for their cytotoxicities against five human cancer
cell lines.
(
2 4 4
5%), pork peptone (0.15%), yeast (0.5%), KH PO (0.05%), and MgSO
(
0.05%). Culture conditions: dark culture at 24 °C and 150 rpm for
⁎
Corresponding authors.
E-mail addresses: fengtao@mail.kib.ac.cn (T. Feng), jkliu@mail.kib.ac.cn (J.-K. Liu).
twenty-five days.
http://dx.doi.org/10.1016/j.fitote.2015.05.009
367-326X/© 2015 Elsevier B.V. All rights reserved.
0

D.-B. Hu et al. / Fitoterapia 104 (2015) 50–54
51
Scheme 1. Structures of compounds 1–5.
15
2
.3. Extraction and isolation
Brasilane C (3): colorless oils, [α]
D
+ 15.1 (c 0.24 MeOH); IR (KBr)
ν
max 3428, 2952, 2925, 2855, 1638,1461, 1380, 1262, 1098, 1026,
−
1
1
13
The culture broth (20 L) was concentrated under vacuum, extracted
three times with EtOAc. The organic layer was evaporated in vacuum to
give a crude extract (23 g), which was separated firstly by Sephadex LH-
803 cm
;
H NMR data (see Table 2); C NMR data (see Table 1);
+
HREIMS m/z 238.1938 [M] (calcd for C15
H
26
O
2
, 238.1933).
13
Colisiderin A (4): white, amorphous solid, [α]
D
− 47.5 (c 0.11
2
0 (MeOH) column chromatography to remove impurities, then sepa-
rated by reversed-phased C18 column (MeOH/H O, from 20:80 to
00:0) to give fractions A–D. Fraction A (1.9 g) was separated by
Sephadex LH-20 (MeOH) column chromatography to afford sub-
fraction A (56.3 mg), which was further purified by Sephadex LH-20
Me CO) to yield 1 (9.1 mg, concentration in extract (C/E) =
MeOH); UV (MeOH) λmax (log ε) 224 (4.27), 200 (4.09) nm; IR (KBr)
νmax 3451, 2958, 2929, 2859, 1740, 1636,1424, 1414 cm ; H NMR
data (see Table 2); C NMR data (see Table 1); HREIMS m/z 256.1311
20 5
[M] (calcd for C13H O , 256.1311).
−
1 1
2
13
1
+
1
7(E),9(E)-Undecandiene-2,4,5-triol (5): white, amorphous solid, UV
(MeOH) λmax (log ε) 227 (4.52), 195 (4.09) nm; IR (KBr) νmax 3419,
3018, 2964, 2930, 2857, 1630,1444, 1412, 1377, 1344, 1309, 1108,
(
2
−
2
3
2
.9 × 10 %). Fraction B (729.3 mg) was separated by Sephadex LH-
0 (MeOH) column chromatography to afford sub-fractions B and B
(102.5 mg) was further purified by silica gel (petro-
−
1
1
13
1
2
.
1052, 987 cm
Table 1); HREIMS m/z 200.1418 [M] (calcd for C11
;
H NMR data (see Table 2); C NMR data (see
+
The sub-fraction B
leum ether–Me CO, 10:1) to yield 2 (2.0 mg, C/E = 8.7 × 10 %) and 4
11.1 mg, C/E = 4.8 × 10 %). The sub-fraction B
ther purified by HPLC (MeCN–H O, from 60:40 to 70:30 in 20 min, re-
1
20 3
H O , 200.1412).
−
3
2
−
2
(
2
(28.9 mg) was fur-
2
−
3
tention time = 13.3 min) to obtain 3 (2.2 mg, C/E = 9.6 × 10 %).
Table 1
13
Fraction C (975.9 mg) was separated by Sephadex LH-20 (MeOH) col-
C NMR data for compounds 1–5 (δ in ppm).
umn chromatography to afford sub-fraction C
further purified by silica gel (petroleum ether–Me
1
(247.1 mg), which was
CO, 4:1) to give 5
1a
2b
CDCl
3b
CDCl
4a
DMSO-d
5a
CDCl
3
No.
2
(aglycone) methanol-d
4
3
3
6
−
1
(
53.0 mg, C/E = 2.3 × 10 %).
Brasilane A (1): white, amorphous solid, [α]15
MeOH); IR (KBr) νmax 3439, 2953, 2926, 2869, 1641,1384, 1024 cm
1
2
3
4
5
6
7
8
9
46.8 d
42.0 t
34.2 s
45.2 t
44.8 d
41.0 t
33.6 s
44.3 t
137.1 s
49.7 d
31.4 t
28.5 t
40.1 d
127.1 s
65.6 t
18.1 q
32.5 q
26.1 q
65.4 t
37.9 d
41.2 t
32.7 s
49.1 t
77.3 s
48.5 d
23.7 t
26.7 t
42.4 d
152.2 s
109.5 t
20.1 q
34.7 q
28.0 q
65.1 t
173.4 s
134.9 s
148.4 s
83.7 d
68.2 d
33.8 t
25.5 t
28.6 t
31.2 t
22.0 t
23.5 q
65.1 d
39.2 t
70.9 d
74.1 d
35.2 t
127.0 d
133.6 d
131.2 d
128.3 d
18.0 q
D
+ 99.0 (c 0.21
−
1
;
1
13
H NMR and C NMR data for glucoside moiety, δ
H
4.76 (1H, d, J =
140.4 s
49.2 d
32.3 t
34.5 t
33.1 d
124.6 s
70.0 t
18.0 q
32.8 q
26.6 q
18.4 q
3
1
3
6
5
.6 Hz, H-1′), 3.85 (1H, dd, J = 3.6, 2.4 Hz, H-2′), 3.66 (1H, dd, J = 2.3,
.8 Hz, H-3′), 3.36 (1H, t, J = 9.3 Hz, H-4′), 3.64–3.60 (1H, m, H-5′),
.81 (1H, dd, J = 8.6, 2.2 Hz, H-6′a), 3.71 (1H, dd, J = 12.9, 4.2 Hz, H-
′b), 1.96 (3H, s, CH
3
CO)
;
δ
c
3
173.5 (CH CO), 22.6 (CH
3
CO), 96.6 (C-1′),
1
10
5.5 (C-2′), 72.6 (C-3′), 72.4 (C-4′), 73.8 (C-5′), 62.7 (C-6′); H NMR
13
11
13.9 q
10.3 q
163.7 s
and C NMR data for aglycone moiety, see Tables 2 and 1, respectively;
1
1
2
3
+
HREIMS m/z 425.2786 [M] (calcd for C23
Brasilane B (2): colorless oils, [α]15
max 3427, 2952, 2922, 2870, 2853, 1631,1465, 1383, 1364, 1254, 1030,
H39NO
6
, 425.2777).
D
− 10.8 (c 0.38 MeOH); IR (KBr)
14
15
ν
9
−
1
1
13
99.8 cm ; H NMR data (see Table 2); C NMR data (see Table 1);
a
Data were recorded at 100 MHz.
Data were recorded at 150 MHz.
+
b
26 2
HREIMS m/z 238.1929 [M] (calcd for C15H O , 238.1933).

52
D.-B. Hu et al. / Fitoterapia 104 (2015) 50–54
Table 2
1
H NMR data for compounds 1–5 (δ in ppm, J in Hz).
No.
1a
2b
3b
4a
5b
(
aglycone) methanol-d
4
CDCl
3
CDCl
3
DMSO-d
6
CDCl
3
1
2
1.69 m
1.39 dd (12.9, 2.8)
1.70 m
1.51, dd (12.0, 5.4)
1.14, dd (12.0, 7.1)
2.03 m
1.54 overlapped
1.08 m
1.23 d (6.3)
4.12 m
1.20 t (12.9)
3
4
1.67 m
1.50 m
2.44 d (13.7)
.62 d (13.7)
2.31 d (13.7)
1.56 d (13.7)
1.37 d (13.5)
1.26 d (13.5)
5.04 br. s
3.89 m
1
5
6
3.95 t (6.6)
1.52 m
3.60 m
2.29 m
2.04 m
2.15 m
1.86 m
1.54 overlapped
2.19 m
7
8
9
2.08 m
1.60 m
1.93 m
1.22 m
2.03 m
1.43 m
1.14 m
1.83 m
1.35 m
2.14 m
1.41 m
1.25 br. d
1.25 br. d
5.53 dt (16.0, 7.3)
1
.62 m
2.09 m
.12 m
6.08 dd (16.0, 8.0)
1
1.99 m
1.25 br. d
1.25 br. d
0.85 d (6.8)
6.02 ddd (14.4, 10.5, 1.3)
5.61 dq (14.4, 6.7)
1.72 d (6.7)
1
1
0
1
4.18 d (11.1)
4.13 d (11.2)
3.90 d (11.2)
1.82 s
0.91 s
0.78 s
4.95 s
4.73 s
1.69 d (0.8)
0.87 s
1.06 s
3.92 d (11.1)
1
1
1
1
2
3
4
5
1.84 s
0.97 s
0.83 s
0.82 d (6.9)
2.04 d (1.5)
3.61 dd (10.5, 6.5)
3.63 dd (10.2, 6.6)
3.33 dd (10.2, 7.2)
3
.33 dd (10.5, 7.3)
a
Data were recorded at 400 MHz.
Data were recorded at 600 MHz.
b
2
.3.1. Acid hydrolysis of 1 and identification of the sugar
A mixture of 1 (4.0 mg) and 3 N HCl (10 mL) was heated at 10 °C for
allowed to adhere for 12 h before drug addition, while suspended cells
were seeded just before drug addition with an initial density of
1 × 105 cells/mL. Each tumor cell line was exposed to the test compound
dissolved in DMSO at concentrations of 0.0625, 0.32, 1.6, 8, and 40 μmol in
triplicates for 48 h, with cisplatin (Sigma, USA) as the positive controls
(Table 3). After compound treatment, cell viability was detected and a
cell growth curve was graphed. IC50 values were calculated by Reed and
Muench's method [14].
3
2
h. After neutralizing with 1 N NaOH/H O, the solution was extracted
with Et
2
O (10 mL × 3) and the combined organic phase was evaporated
to dryness under reduced pressure to yield aglycone (0.8 mg). The aque-
ous layer was evaporated to dryness under reduced pressure and subject-
ed to silica gel CC to afford 2-amino-2-deoxy-D-glucose (1.3 mg). The
optical rotation value was as follows: [α]2
5
+ 63 (c 0.5, H
D
2
O) (+70 in
literature [7]).
3. Results and discussion
2
.4. Computational methods
All DFT and TDDFT calculations were carried out at 298 K in the gas
Compound 1 was obtained as white, amorphous solid. Its molecular
formula was assigned as C23
showed a molecular ion peak at m/z 425.2786 (calcd for C23
H
39NO
6
on the basis of the HREIMS, which
39NO
H
6
,
phase with Gaussian 09 [8]. Conformational searches were carried out at
the molecular mechanics level of theory employing MMFF force fields
1
4
(
25.2777), suggesting five degrees of unsaturation. The H NMR
Table 2) and 13C NMR data of 1 (Table 1) showed the presence of five
methyls, six methylenes, eight methines, and four quaternary carbons.
The 13C characteristic NMR signals of δ
96.6 (C-1′, d), 55.5 (C-2′, d),
2.6 (C-3′, d), 72.4 (C-4′, d), 73.8 (C-5′, d), and 62.7 (C-6′, t), together
[
1
9]. For compound 4, the conformers with relative energy within
0 kcal/mol of the lowest-energy conformer were selected and further
C
geometry optimized at the B3LYP/6-311++G(2d,p) level [10]. All the
lowest-energy conformers, which correspond to 99% of the total
Boltzmann distribution, were selected for ECD spectra calculation. The
Boltzmann factor for each conformer was calculated based on Gibbs
free energy [11]. Vibrational analysis at the B3LYP/6-311++G(2d,p)
level of theory resulted in no imaginary frequencies, confirming the
considered conformers as real minima. TDDFT was employed to calcu-
late excitation energy (in nm) and rotatory strength R in dipole velocity
form, at the B3LYP/6-311++G (2d,p) level [12].
7
1
H
with H NMR signals of δ 4.76 (1H, d, J = 3.6 Hz, H-1′), 3.85 (1H, dd,
J = 3.6, 2.4 Hz, H-2′), 3.66 (1H, dd, J = 2.3, 1.8 Hz, H-3′), 3.36 (1H, t,
J = 9.3 Hz, H-4′), 3.64-3.60 (1H, m, H-5′), 3.81 (1H, dd, J = 8.6,
2
.2 Hz, H-6′a), and 3.71 (1H, dd, J = 12.9, 4.2 Hz, H-6′b) indicated the
presence of a glucoside moiety, similar to that reported in the literature
7]. However, in compound 1, the glucoside moiety is a 2-acetamido-2-
deoxy-glucoside according to the HMBC correlations from H-2′ to acetyl
group [δ 173.5 (C_O), 22.6 (O_C–CH , q)]. In addition, two quater-
nary olefinic carbon signals at δ 140.4 (C-5) and 124.6 (C-10) sug-
[
C
3
C
2
.5. Cytotoxicity assay
gested a double bond. Apart from these, the remaining two degrees
of unsaturation in 1 suggested a two-ring sesquiterpenoid. Prelimi-
nary analyses of 1H– H COSY and HMBC data (Fig. 1) suggested
1
Five human cancer cell lines, human myeloidleukemia HL-60, hepato-
cellular carcinoma SMMC-7721, lung cancer A-549, breast cancer MCF-7,
and colon cancer SW480 cells, were used in the cytotoxicity assay. All the
cells were cultured in RPMI-1640 or DMEM medium (Hyclone, USA), sup-
Table 3
Cytotoxicities of compounds 2 and 4 (IC50, μmol).
2
plemented with 10% fetal bovine serum (Hyclone, USA) in 5% CO at 37 °C.
The cytotoxicity assay was performed according to the MTS (3-(4,5-
dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfopheny)-
Entry
HL-60
SMMC-7721
A-549
MCF-7
SW480
2
4
23.4
N40
2.1
N40
N40
7.7
N40
N 40
6.7
N40
N40
16.4
N40
34.3
15.7
2H-tetrazolium) method in 96-well microplates [13]. Briefly, 100 μL of ad-
Cisplatin
herent cells was seeded into each well of 96-well cell culture plates and

D.-B. Hu et al. / Fitoterapia 104 (2015) 50–54
53
Compound 2 was isolated as a colorless oil. The molecular formula
was established to be C15
H
H
26
O
2
on the basis of HREIMS at m/z
, 238.1933). The C NMR spectrum
+
13
2
38.1929 [M] (calcd for C15
26
O
2
displayed fifteen carbon resonances with similarities to those data of
the aglycone in compound 1 (Table 1) except that the methyl of C-15
in 1 was oxygenated into an oxymethylene (δ
by the HMBC correlation from δ 3.61 (1H, dd, J = 10.5, 6.5 Hz, H-15a)
and 3.33 (1H, dd, J = 10.5, 7.3 Hz, H-15b) to δ 40.1 (d, C-9). Analyses of
C
65.4, t) in 2, as supported
H
C
ROESY data suggested that the relative configuration of 2 was the same
to that of 1. Therefore, the structure of compound 2 was established and
named brasilane B.
Compound 3 was isolated as a colorless oil, possessing a molecular
+
formula C15
H
26
O
2
as deduced from HREIMS at m/z 238.1938 [M]
(
26 2
calcd for C15H O , 238.1933). On the basis of extensive 2D NMR data
analysis, we established that compound 3 was a derivative of compound
. However, a terminal double bond should be located between C-10
2
3
and C-11, and C-5 should be an oxygenated sp quaternary carbon,
which was suggested by the HMBC correlation from δ 1.69 (3H, d,
J = 0.8 Hz, H-12) to δ 152.2 (s, C-10) and δ 109.5 (d, C-11) and from
1.37 (1H, d, J = 13.5 Hz, H-4a), 1.26 (1H, d, J = 14.4 Hz, H-4b), and
.54 (overlapped, H-6) to δ 77.3 (s, C-5). The ROESY correlations of
H
Fig. 1. Key 2D NMR correlations of compound 1.
C
C
δ
1
H
C
that compound 1 should be a brasilane-type sesquiterpenoid glyco-
H-1/Me-14, H-1/CH -15, and H-1/H-6 suggested that H-1, H-6, Me-14
2
side [15]. The double bond was located between C-5 and C-10 as sup-
and CH -15 were in the same side, while the ROESY correlation of H-
2
ported by HMBC correlations from δ
s, C-10) and from δ 2.44 (1H, d, J = 13.7 Hz, H-4a), 1.62 (1H, d,
J = 13.7 Hz, H-4b) and δ 2.04 (1H, m, H-6) to δ 140.4 (s, C-5). In ad-
H
1.84 (3H, s, H-12) to δ
C
124.6
6/Me-12 suggested that the OH at C-5 should be in the other side.
Thus, the structure of compound 3 was deduced as brasilane C.
Compound 4 was obtained as white, amorphous solid. HREIMS ion
(
H
H
C
dition, the methyl of C-11 was oxygenated into an oxymethylene,
while the glucosidic bond of C-1′–O–C-11 was also established by
peak at m/z 256.1311 (calcd for C13H20O , 256.1311) gave the molecular
5
13
formula C13H20O , suggesting four degrees of unsaturation. The
5
C
HMBC correlation from δ
H
4.76 (1H, d, J = 3.6 Hz, H-1′) to δ
C
70.0
NMR spectrum revealed two carbonyl carbons (δC 173.4 and 163.7)
(
t, C-11). The relative stereochemistry of aglycone was established
together with a fully substituted double bond (δ 134.9 and 148.4).
C
1
1
by an ROESY experiment (Fig. 1) with reference to those analogues
reported previously [5,6]. The ROESY correlations of H-1/Me-14, H-
1
The H– H COSY spectrum revealed a spin system consistent with an
n-heptyl chain (from C-5 to C-11) terminating in an oxymethine of C-5
(δH 3.95; δ 68.2), which had HMBC correlations extending to δ 83.7
/Me-15, and H-1/H-6 suggested that H-1, H-6, C-14 and C-15 were
C
C
in the same side [3], and they were arbitrarily assigned as being β
oriented, while the ROESY correlation of H-4/H-11 suggested the
olefinic double bond (Δ5 ) to be an E configuration. Based on the
observed coupling constant (J1′,2′ = 3.6 Hz) of H-1′, the sugar was as-
sumed to be an α-pyranose form. To clarify the configuration of the
sugar, the compound was subjected to hydrolysis with 3 N HCl and
the liberated D-glucosamine was identified by a comparison of its op-
(d, C-4) and δ 148.4 (s, C-3). The HMBC correlations from δH 5.04 (1H,
C
br.s, H-4) to C-2 (δ 134.9), C-3 (δ 148.4) and C-1 (δ 173.4) constructed
C
C
C
,10
an α,β-unsaturated five-member lactone ring. In addition, a methyl group
substituted at C-2 was supported by the HMBC correlations of C-12
(δH 2.04, δC 10.3) to C-1, C-2, and C-3, and a carboxyl substituted at
C-3 was supported by the correlations of H-4 to C-13. These data sug-
gested that compound 4 might be a lichesterinic acid derivative [15]. In
order to determine the absolute configuration, TDDFT-ECD calculation
protocol was pursued. As can be seen from the Fig. 2, ECD curves for the
four possible stereostructures (4R/5S; 4S/5R; 4R/5R; 4S/5S) were calculat-
ed using the TD-DFT theory method. The calculated curves of 4R/5S were
2
5
tical rotation value [[α]
D
= +63 (c 0.5, H
2
O)] with that in literature
(
+70) [7]. Thus, the sugar part of this molecule was determined as
2
-acetamido-2-deoxy-α-D-glucose. Therefore, compound 1 was
established and named brasilane A.
Fig. 2. Results of the TDDFT CD calculations and their comparison with the experimental CD spectrum of (4R,5S), (4S,4R), (4S,5S), and (4R,5R) configurations for colisiderin A (4).

54
D.-B. Hu et al. / Fitoterapia 104 (2015) 50–54
in good agreement with the experimental CD spectrum. Thus, the abso-
lute configurations of chiral carbons of 4 were established as 4R and 5S.
Finally, compound 4 was identified and named colisiderin A.
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Conflict of interest
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The manuscript titled “Brasilane sesquiterpenoids and alkane deriv-
atives from cultures of the basidiomycete Coltricia sideroides” has been
submitted to journal Fitoterapia. The authors declare that there is no
conflict of interest, and do agree that the manuscript is to be published
in Fitoterapia.
2
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This work was financially supported by the National Natural Science
Foundation of China (81373289, U1132607), and the West Light Foun-
dation of CAS (2013312D11016).