Synthesis, antibacterial and antitubercular evaluation of cardanol and glycerol?based β?amino alcohol derivatives

Article abstract of DOI:10.21577/0103-5053.20170178

The synthesis of novel amino alcohol derivatives based on cardanol and glycerol were achieved in good yields and characterized by¹H and¹³C NMR (nuclear magnetic resonance) and MS (mass spectrometry). In addition, we evaluated the in

Full text of DOI:10.21577/0103-5053.20170178

http://dx.doi.org/10.21577/0103-5053.20170178
J. Braz. Chem. Soc., Vol. 29, No. 3, 639-648, 2018.
Printed in Brazil - ©2018 Sociedade Brasileira de Química
Article
Synthesis, Antibacterial and Antitubercular Evaluation of Cardanol and
Glycerol‑Based β‑Amino Alcohol Derivatives
Bhaskar R. Manda,a Avvari N. Prasad,a Narendar R. Thatikonda,a
Valdemar Lacerda Jr.,b Layla R. Barbosa,b Heloa Santos,b Wanderson Romão,b
Fernando R. Pavan,c Camila M. Ribeiro,c Edson A. dos Santos,d Maria R. Marques,d
Dênis P. de Lima,a Ana C. Micheletti*,a and Adilson Beatriz*,a
aInstituto de Química (INQUI), Universidade Federal do Mato Grosso do Sul,
Av. Senador Felinto Müller, 1555, 79074-460 Campo Grande-MS, Brazil
bDepartamento de Química, Universidade Federal do Espírito Santo (UFES),
29075-910 Vitória-ES, Brazil
cFaculdade de Ciências Farmacêuticas, Universidade Estadual Paulista,
14801-902 Araraquara-SP, Brazil
dInstituto de Biociências (INBIO), Universidade Federal de Mato Grosso do Sul,
Cidade Universitária, s/n, CP 549, 79070-900 Campo Grande-MS, Brazil
The synthesis of novel amino alcohol derivatives based on cardanol and glycerol were achieved
in good yields and characterized by 1H and 13C NMR (nuclear magnetic resonance) and MS (mass
spectrometry). In addition, we evaluated the in vitro antimicrobial activity against Gram-positive
(Staphylococcus aureus, standard and clinical strains), Gram-negative (Escherichia coli) and
M. tuberculosis bacterial strains. The bioassay results indicated that four compounds showed
activity against S. aureus, including the clinical resistant strain, with MIC (minimum inhibitory
concentration) ranging from 3.90 to 15.60 µg mL-1 and M. tuberculosis, with MIC90 (minimum
inhibitory concentration required to inhibit the growth of 90% of organisms) ranging from 3.18
to 7.36 µg mL-1.
Keywords: CNSL, cardanol, amino alcohols, epoxide ring opening, antimicrobial activity
Introduction
high-value fine chemicals and supramolecular structures.
Its derivatives present many biological activities such
as: fungicidal, bactericidal, molluscicidal, larvicidal,
anti-inflammatory, antioxidant and, towards serious
disorders like cancer and obesity.2-9 It is also described
in the literature in recent years, that cardanol frameworks
are involved to build phenolic resins,10-12 bio-based
polymers,13 epoxy curing resins,14-16 reactive diluents,17,18
and fluorescent compounds.19,20 Similarly, glycerol is
another important renewable material used in the synthesis
of higher value-added fine chemicals through green
chemistry procedures in the last years. It may be applied,
for instance, to generate hydrogen gas,21 potential fuel
additive,22 ethanol,23 acrolein and,24,25 epichlorohydrin.26
Accordingly, studies aiming to new industrial applications
for glycerol are of great industrial, social, economic, and
environmental interest.27,28
The synthesis of fine chemicals from natural renewable
resources has received great interest in synthetic community
and is becoming a significant and challenging theme for
researchers of both the academic and industrial sectors.
Among the renewable materials, cardanol has attracted
considerable attention due to its unique nature.1 Cardanol
is a low cost, naturally occurring renewable non-isoprenoic
phenolic lipid-mixture of cashew nut shell liquid (CNSL).
The structural benefits of cardanol are carrying reactive
phenolic group and hydrophobic alkyl/alkenyl side chain
at meta-position of phenolic group. With these unique
structural features, cardanol and its derivatives are
renowned amphiphilic building blocks and precursors of
*e-mail: anamicheletti@gmail.com; adilson.beatriz@ufms.br

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Synthesis, Antibacterial and Antitubercular Evaluation of Cardanol and Glycerol-Based β-Amino Alcohol Derivatives J. Braz. Chem. Soc.
Cardanol and glycerol can be starting materials to
Thin layer chromatography (TLC) analyses were performed
on glass plates coated with silica gel 60 F254. The plates
were visualized using UV light (254 nm) and/or iodine.
Column chromatography was performed on silica gel
prepare β-amino alcohols which is a vital interesting class
of organic intermediates due to their abundant existence in
nature and they are useful in the preparation of wide range
of biologically active natural and synthetic frameworks,
pharmaceuticals (e.g. β-blockers), unnatural β-amino
acids, pesticides and chiral auxiliaries.29-32 Additionally,
β-amino alcohols have many applications as antibiotics,
anti-bacterial drugs and, steroids.33 One of the most classical
approaches toward the synthesis of β-amino alcohols is the
direct ring opening by amines of epoxides. The existing
protocols of β-amino alcohols have been achieved by
ring opening of epoxides with simple amines (aromatic/
aliphatic) in the presence of various catalysts including
metals such as Cu,34,35 Fe,30,36,37 Zn,38 metal tiflates,39,40 metal
amides,41 metal alkoxides,42,43 and other metal salts,44-48
microwave assisted montmorillonite clay,49 amberlist-15,50
zirconia-based materials,33,51 ionic liquids,52 and few organic
reagents have also been explored for β-amino alcohols
namely, DABCO (1,4-diazabicyclo[2.2.2]octane),53
β-cyclodextrin,54 and Bu3P.55 These protocols were
significant, however, some of them have some drawbacks
including the use of expensive chemicals, air and moisture
sensitive reagents or catalysts, high pressures, inert
atmospheric conditions, the requirement for protracted
work-up procedures and so on. Therefore, there is a demand
to develop new and efficient methods for the preparation
of β-amino alcohols under mild conditions.
Considering these significant characteristics of
renewable materials such as cardanol and glycerol as well as
ample biological activities of lipophilic β-amino alcohols,
our research group aims to combine their properties into
single compounds with their unique qualities. Lipophilic
character of some antibiotic has a significant influence
on the antibacterial activity,56-58 which prompted us to the
design of new biologically active molecules. Herein we
report a new strategy for the synthesis of β-amino alcohols
by reacting cardanol epoxide with diverse amines (aliphatic/
aromatic) under catalyst-free and mild conditions in which
ethanol is used as the reaction medium. Subsequently, these
synthesized amino alcohols were subjected to antimicrobial
evaluation.
1
(60 × 120 mesh) into a glass column. H and 13C NMR
(nuclear magnetic resonance) spectra were recorded on
a Bruker Avance DPX-300 spectrometer using TMS
(tetramethylsilane) as an internal standard. Chemical shifts
(d) were recorded in ppm with respect to TMS and coupling
constants (J) were given in hertz (Hz). High-resolution mass
spectrometry (HRMS) coupled to positive-ion electrospray
ionization (ESI) mode, ESI(+), were performed on a Fourier
transform ion cyclotron resonance mass spectrometer
(FT-ICR MS, model 9.4 T Solarix, Bruker Daltonics
Bremen, Germany).
Experimental procedure
To the solution of cardanol epoxide19 (1 mmol) in
ethanol, amine (1.5 mmol) was added at room temperature
and stirred under reflux for 8-12 h. After completion of
the reaction (monitored by TLC), the reaction mixture
was allowed to cool to room temperature and ethanol
was removed under vacuum. Then the reaction mixture
was partitioned between water (30 mL) and ethyl acetate
(40 mL), the organic layer was separated and the aqueous
layer was extracted with ethyl acetate (2 × 40 mL) and
dried over Na2SO4. Solvent was removed in vacuum and the
crude compound was purified by column chromatography
using 20-50% of EtOAc in hexane as eluent to afford the
desired amino alcohol derivative of cardanol. To prepare
compound 2d, 2.1 equivalents of cardanol epoxide (1)
were used.
1H NMR, 13C NMR, and MS data of isolated compounds
1-Morpholino-3-(3-pentadecylphenoxy)propan-2-ol (2a)
Yield: 87%; light yellow solid; mp 45-47 °C; 1H NMR
(300 MHz, CDCl3) d 7.18 (t, J 7.74 Hz, 1H), 6.81-6.70
(m, 3H), 4.11 (sextet, J 4.97 Hz, 1H), 3.98 (d, J 4.97 Hz,
2H), 3.77-3.67 (m, 4H), 3.22 (bs, 1H), 2.72-2.42 (m, 8H),
1.60 (quintet, J 7.31 Hz, 2H), 1.37-1.19 (m, 24H), 0.88
13
(t, J 6.87 Hz, 3H); C NMR (75 MHz, CDCl3) d 158.6,
Experimental
144.6, 129.1, 121.2, 114.8, 111.3, 70.0, 66.9, 65.5, 61.1,
53.7, 36.0, 31.9, 31.3, 29.6, 29.5, 29.4, 29.3, 22.6, 14.1.
HRMS (ESI): C28H49NO3 calcd. 448.37803; m/z [M + H]+
found 448.37852.
General methods
All the starting materials employed were obtained
from commercial sources and used as received. Catalytic
hydrogenation was carried out in a Parr Hydrogenation
apparatus, according to our previously reported method.19
1-(3-Pentadecylphenoxy)-3-(piperidin-1-yl)propan-2-ol (2b)
Yield: 83%; light yellow oil; H NMR (300 MHz,
CDCl3) d 7.17 (t, J 7.89 Hz, 1H), 6.80-6.70 (m, 3H),
1

Vol. 29, No. 3, 2018
Manda et al.
641
4.13-3.91 (m, 3H), 3.60 (bs, 1H), 2.67-2.32 (m, 8H),
J 6.43 Hz, 6H), 0.87 (t, J 6.87 Hz, 3H); 13C NMR (75 MHz,
CDCl3) d 158.8, 144.4, 129.0, 120.9, 114.7, 111.3, 70.5,
65.4, 48.5, 47.3, 35.9, 31.8, 31.3, 31.8, 31.3, 29.6, 29.5,
29.4, 29.2, 22.6, 22.0, 19.4, 14.0. HRMS (ESI): C30H55NO2
calcd. 462.43056; m/z [M + H]+ found 462.43011.
1.66-1.41 (m, 8H), 1.35-1.17 (m, 24H), 0.89 (t, J 7.02 Hz,
13
3H); C NMR (75 MHz, CDCl3) d 158.7, 144.5, 129.0,
121.0, 114.8, 111.4, 70.3, 65.3, 61.2, 54.7, 36.0, 31.9, 31.3,
29.6, 29.5, 29.4, 29.4, 29.3, 26.0, 24.2, 22.6, 14.1. HRMS
(ESI): C29H51NO2, calcd. 446.39900; m/z [M + H]+ found
446.39926.
1-((4-Methoxyphenyl)amino)-3-(3-pentadecylphenoxy)
propan-2-ol (2g)
1-(3-Pentadecylphenoxy)-3-(pyrrolidin-1-yl)propan-2-ol (2c)
Yield: 64%; light yellow solid; mp 50-51 °C; 1H NMR
(300 MHz, CDCl3) d 7.19 (t, J 7.89 Hz, 1H), 6.84-6.71 (m,
5H), 6.66 (d, J 8.92 Hz, 2H), 4.28-4.21 (m, 1H), 4.09-3.98
(m, 2H), 3.75 (s, 3H), 3.39 (dd, J 12.79 and 4.20 Hz, 1H),
3.25 (dd, J 12.79 and 7.24 Hz, 1H), 2.57 (t, J 7. 89 Hz, 2H),
2.26 (s, 3H), 1.60 (quintet, J 6.43 Hz, 2H), 1.37-1.20 (m,
24H), 0.88 (t, J 6.87 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d 158.4, 144.8, 129.2, 121.4, 117.6, 115.2, 115.0, 114.8,
111.4, 69.6, 69.5, 68.5, 58.4, 55.7, 36.0, 31.9, 31.4, 29.7,
29.6, 29.5, 29.3, 22.7, 14.1.
1
Yield: 85%; light yellow oil; H NMR (300 MHz,
CDCl3) d 7.14 (t, J 7.75 Hz, 1H), 6.80-6.68 (m, 3H), 4.17-
4.06 (m, 1H), 4.02-3.90 (m, 2H), 3.80 (bs, 1H), 2.90-2.49
(m, 8H), 1.95-1.74 (m, 4H), 1.67-1.51 (m, 2H), 1.39-1.16
(m, 24H), 0.87 (t, J 6.87 Hz, 3H); 13C NMR (75 MHz,
CDCl3) d 158.6, 144.5, 129.0, 121.0, 114.7, 111.3, 70.2,
67.2, 58.7, 54.2, 35.9, 31.8, 31.3, 29.6, 29.6, 29.6, 29.6,
29.6, 29.6, 29.6, 29.6, 29.5, 29.4, 29.3, 29.2, 23.5, 22.6,
14.0. HRMS (ESI): C28H49NO2 calcd. 432.38332; m/z
[M + H]+ found 432.38361.
1-(3-Pentadecylphenoxy)-3-(p-tolylamino)propan-2-ol (2h)
Yield: 76%; light yellow solid; mp 49-50 °C; 1H NMR
(300 MHz, CDCl3) d 7.20 (t, J 7.75 Hz, 1H), 7.01 (d,
J 8.04 Hz, 2H), 6.84-6.71 (m, 3H), 6.62 (d, J 8.33 Hz, 2H),
4.27-4.21 (m, 1H), 4.09-4.01 (m, 2H), 3.42 (dd, J 12.94 and
4.24 Hz, 1H), 3.28 (dd, J 12.94 and 7.16 Hz, 1H), 3.01-2.85
(bs, 1H), 2.58 (t, J 7.60 Hz, 2H), 2.26 (s, 3H), 1.61 (quintet,
J 6.28 Hz, 2H), 1.37-1.23 (m, 24H), 0.89 (t, J 6.87 Hz, 3H);
13C NMR (75 MHz, CDCl3) d 158.4, 145.7, 144.8, 129.8,
129.2, 127.3, 121.5, 114.7, 113.5, 111.5, 70.0, 68.8, 47.0,
36.0, 31.9, 31.4, 29.7, 29.6, 29.5, 29.3, 22.7, 20.4, 14.1.
HRMS (ESI): C31H49NO2 calcd. 468.3853; m/z [M + H]+
found 468.3836.
3,3’-(Piperazine-1,4-diyl)bis(1-(3-pentadecylphenoxy)
propan-2-ol) (2d)
1
Yield: 64%; white solid; mp 54-55 °C; H NMR
(300 MHz, CDCl3) d 7.18 (t, J 7.80 Hz, 2H), 6.81-6.68 (m,
6H), 4.09 (dd, J 4.82 and 4.68 Hz, 2H), 3.98 (d, J 4.82 Hz,
4H), 2.81-2.45 (m, 16H), 1.59 (quintet, J 7.45 Hz, 4H),
1.39-1.15 (m, 48H), 0.88 (t, J 6.87 Hz, 6H); 13C NMR
(75 MHz, CDCl3) d 158.7, 144.7, 129.1, 121.2, 114.9,
111.4, 70.1, 65.6, 60.5, 53.4, 53.3, 36.0, 31.9, 31.4, 29.7,
29.5, 29.4, 22.7, 14.1.
1-(4-(4-Nitrophenyl)piperazin-1-yl)-3-(3-pentadecyl-
phenoxy)propan-2-ol (2e)
1
Yield: 53%; yellow solid; mp 49-50 °C; H NMR
1-(3-Pentadecylphenoxy)-3-(o-tolylamino)propan-2-ol (2i)
Yield: 67%; light yellow solid; mp 42-43 °C; 1H NMR
(300 MHz, CDCl3) d 7.23-7.07 (m, 3H), 6.92-6.68 (m, 5H),
4.75-4.27 (m, 3H), 3.55-3.30 (m, 2H), 2.59 (t, J 7.60 Hz,
2H), 2.25 (s, 3H), 1.62 (quintet, J 7.16 Hz, 2H), 1.41-1.22
(m, 24H), 0.91 (t, J 6.87 Hz, 3H); 13C NMR (75 MHz,
CDCl3) d 158.3, 144.79, 143.8, 130.5, 129.2, 127.2, 121.4,
119.8, 114.7, 111.4, 70.0, 68.0, 48.5, 36.0, 31.9, 31.4, 29.7,
29.6, 29.5, 29.3, 22.7, 17.4, 14.1. HRMS (ESI): C31H49NO2
calcd. 468.3833; m/z [M + H]+ found 468.3836.
(300 MHz, CDCl3) d 8.13 (d, J 9.35 Hz, 2H), 7.20 (t,
J 7.45 Hz, 1H), 6.86-6.66 (m, 5H), 4.15 (quintet, J 4.09 Hz,
1H), 4.04-3.99 (d, J 4.97 Hz, 2H), 3.51-3.41 (m, 4H),
3.24 (bs, 1H), 2.88-2.78 (m, 2H), 2.73-2.53 (m, 6H),
1.60 (quintet, J 7.02 Hz, 2H), 1.40-1.21 (m, 24H), 0.88
13
(t, J 6.72 Hz, 3H); C NMR (75 MHz, CDCl3) d 158.6,
154.7, 144.7, 138.7, 129.2, 125.9, 121.3, 114.8, 112.8,
111.4, 70.0, 66.0, 60.6, 36.0, 31.9, 31.4, 29.7, 29.6, 29.5,
29.3, 22.7, 14.1.
1-(Diisopropylamino)-3-(3-pentadecylphenoxy)propan-2-ol
1-((4-Bromophenyl)amino)-3-(3-pentadecylphenoxy)
propan-2-ol (2j)
(2f)
1
Yield: 91%; light yellow liquid; H NMR (300 MHz,
Yield: 69%; light yellow solid; mp 66-68 °C; 1H NMR
(300 MHz, CDCl3) d 7.28-7.14 (m, 3H), 6.82-6.68 (m, 3H),
6.53 (d, J 8.77 Hz, 2H), 4.26-4.17 (m, 1H), 4.09-3.96 (m,
2H), 3.37 (dd, J 12.72 and 4.02 Hz, 1H), 3.24 (dd, J 12.72
and 7.16 Hz, 1H), 2.55 (t, J 7.60 Hz, 2H), 1.58 (quintet,
CDCl3) d 7.17 (t, J 7.89 Hz, 1H), 6.80-6.70 (m, 3H),
4.05-3.88 (m, 3H), 3.09 (sept, J 6.58 Hz, 2H), 2.74 (d,
J 3.51 Hz, 1H), 2.60-2.42 (m, 3H), 1.59 (quintet, J 6.56 Hz,
2H), 1.35-1.17 (m, 24H), 1.09 (d, J 6.58 Hz, 6H), 1.03 (d,

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Synthesis, Antibacterial and Antitubercular Evaluation of Cardanol and Glycerol-Based β-Amino Alcohol Derivatives J. Braz. Chem. Soc.
J 6.72 Hz, 2H), 1.34-1.14 (m, 24H), 0.86 (t, J 7.31 Hz, 3H);
13C NMR (75 MHz, CDCl3) d 158.3, 147.1, 144.9, 131.9,
129.3, 121.6, 114.8, 111.5, 109.6, 69.9, 68.7, 46.5, 36.0,
31.9, 31.4, 29.7, 29.6, 29.5, 29.3, 22.7, 14.1. HRMS (ESI):
C30H46BrNO2 calcd. 532.2785; m/z [M + H]+ found 532.2613.
(m, 6H), 4.31-4.22 (m, 1H), 4.11-4.02 (m, 2H), 3.45 (dd,
J 12.0 and 4.39 Hz, 1H), 3.30 (dd, J 12.0 and 7.02 Hz,
1H), 3.04 (bs, 1H), 2.58 (t, J 7.75 Hz, 2H), 1.61 (quintet,
J 7.02 Hz, 2H), 1.38-1.22 (m, 24H), 0.89 (t, J 6.87 Hz,
13
3H); C NMR (75 MHz, CDCl3) d 158.4, 148.0, 144.8,
129.3, 129.2, 121.5, 118.0, 114.7, 113.3, 111.5, 70.0, 68.8,
46.6, 36.0, 31.9, 31.4, 29.7, 29.6, 29.5, 29.3, 22.7, 14.1.
HRMS (ESI): C30H47NO2 calcd. 454.36818; m/z [M + H]+
found 454.36818.
1-((2-Bromophenyl)amino)-3-(3-pentadecylphenoxy)
propan-2-ol (2k)
Yield: 70%; light yellow solid; mp 39-40 °C; 1H NMR
(300 MHz, CDCl3) d 7.45 (dd, J 7.9 and 1.30 Hz, 1H),
7.25-7.15 (m, 2H), 6.86-6.69 (m, 4H), 6.61 (td, J 7.85 and
1.30 Hz, 1H), 4.77 (bs, 1H), 4.32-4.25 (m, 1H), 4.13-4.04
(m, 2H), 3.54-3.32 (m, 2H), 2.64 (bs, 1H), 2.59 (t,
J 7.60 Hz, 2H), 1.62 (quintet, J 7.02 Hz, 2H), 1.40-1.22 (m,
24H), 0.90 (t, J 6.87 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d 158.3, 144.8, 132.5, 129.2, 128.5, 121.5, 118.3, 114.7,
111.5, 111.4, 110.2, 69.8, 68.6, 46.4, 35.9, 31.8, 29.7, 29.6,
29.5, 29.3, 22.7, 14.1. HRMS (ESI): C30H46BrNO2 calcd.
532.27870; m/z [M + H]+ found 532.27847.
1-(3-Pentadecylphenoxy)-3-(pyridin-2-ylamino)propan-2-ol
(2o)
1
Yield: 82%; light yellow oil; H NMR (300 MHz,
CDCl3) d 8.90-8.80 (m, 1H), 7.62-7.49 (m, 3H), 7.10 (t,
J 7.45 Hz, 1H), 6.77-6.57 (m, 3H), 4.62-4.02 (m, 7H),
2.51 (t, J 7.31 Hz, 2H), 1.61-1.49 (m, 2H), 1.35-1.17 (m,
24H), 0.86 (t, J 6.87 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d 157.9, 155.3, 144.7, 141.2, 139.5, 129.2, 121.4, 116.6,
114.7, 112.7, 111.4, 67.8, 66.8, 56.5, 35.9, 31.8, 31.3, 29.6,
29.5, 29.4, 29.3, 29.2, 22.6, 14.0. HRMS (ESI): C29H46N2O2
calcd. 455.36330; m/z [M + H]+ found 455.36312.
1-((4-Chlorophenyl)amino)-3-(3-pentadecylphenoxy)
propan-2-ol (2l)
Yield: 78%; light yellow solid; mp 69-70 °C; 1H NMR
(300 MHz, CDCl3) d 7.20 (t, J 7.75 Hz, 1H), 7.13 (d,
J 8.48 Hz, 2H), 6.84-6.70 (m, 3H), 6.59 (d, J 8.62 Hz, 2H),
4.29-3.99 (m, 3H), 3.40 (dd, J 12.79 and 4.20 Hz, 1H),
3.26 (dd, J 12.79 and 7.02 Hz, 1H), 2.58 (t, J 7.75 Hz, 2H),
1.60 (quintet, J 7.02 Hz, 2H), 1.38-1.21 (m, 24H), 0.88 (t,
J 6.87 Hz, 3H); 13C NMR (75 MHz, CDCl3) d 158.3, 146.7,
144.9, 129.3, 129.1, 121.6, 114.7, 114.3, 111.5, 69.9, 68.8,
46.7, 36.0, 31.9, 31.4, 29.7, 29.6, 29.5, 29.3, 22.7, 14.1.
HRMS (ESI): C30H46ClNO2 calcd. 488.3289; m/z [M + H]+
found 488.3293.
Antimicrobial assays
S. aureus and E. coli
The 96-well plates were prepared by dispensing
100 µL Mueller-Hinton broth (Sigma-Aldrich) into each
well. A stock solution was prepared at a concentration of
2 mg mL-1 and serial dilutions were performed to reach a
final concentration within 1 to 1000 µg mL-1 range, with
a 100 µL final volume in each well. For gentamicin, final
concentration ranged from 64 to 0.5 µg mL-1. The test
organisms used in this study were S. aureus (ATCC 25923
and clinical isolates of oxacillin and penicillin G resistant
S. aureus) and E. coli (ATCC 25922). Clinical strain was
donated by the Laboratory of Bacteriology of the Center
for Clinical Analysis of the UFMS Teaching Hospital,
in Campo Grande, Brazil, and assays were performed at
Sintmol (Biotechnology Lab of Institute of Chemistry,
UFMS). The inoculum was an overnight culture of each
bacterial species in Mueller-Hinton agar (Sigma-Aldrich)
diluted in saline sterile solution (0.45%) to a concentration
of approximately 108 CFU mL-1. This solution was diluted
1/10 in saline solution (0.45%) and 5 µL (104 CFU mL-1)
were added to each well containing the test samples.
All experiments were performed in triplicate and the
microdilution trays were incubated at 36 °C for 18 h.
Then, 20 µL of an aqueous solution (0.5%) of triphenyl
tetrazolium chloride (TTC) were added to each well and
the trays were again incubated at 36 °C for 2 h.Afterwards,
in those wells where bacterial growth did occur, TTC
1-((2-Chlorophenyl)amino)-3-(3-pentadecylphenoxy)
propan-2-ol (2m)
1
Yield: 66%; light yellow solid; 40-41 °C; H NMR
(300 MHz, CDCl3) d 7.31-7.11 (m, 3H), 6.86-6.64 (m,
5H), 4.33-4.17 (m, 1H), 4.14-4.04 (m, 2H), 3.83-3.70 (m,
1H), 3.48 (dd, J 13.0 and 4.60 Hz, 1H), 3.36 (dd, J 13.0
and 6.75 Hz, 1H), 2.71 (bs, 1H), 2.60 (t, J 7.89 Hz, 2H),
1.63 (quintet, J 7.75 Hz, 2H), 1.42-1.21 (m, 24H), 0.91 (t,
J 6.87 Hz, 3H); 13C NMR (75 MHz, CDCl3) d 158.3, 158.2,
144.8, 143.9, 129.2, 127.8, 121.6, 121.5, 119.6, 117.7, 114.8,
111.4, 69.9, 68.6, 68.4, 46.3, 45.9, 36.0, 31.9, 31.4, 29.7,
29.6, 29.5, 29.3, 22.7, 14.1. HRMS (ESI): C30H46ClNO2
calcd. 488.32921; m/z [M + H]+ found 488.32898.
1-(3-Pentadecylphenoxy)-3-(phenylamino)propan-2-ol (2n)
Yield: 73%; light yellow solid; mp 44-45 °C; 1H NMR
(75 MHz, CDCl3) d 7.20 (t, J 7.60 Hz, 3H), 6.84-6.66

Vol. 29, No. 3, 2018
Manda et al.
643
changed from colorless to red. MIC was defined as the
lowest concentration of each substance at which no color
change occurred, and was expressed in µg mL-1.
out. To check our hypothesis, initially, we attempted the
amination of cardanol epoxide 1 (1 mmol) with morpholine
(1.5 mmol) in ethanol (1.5 mL) at room temperature as a
model reaction.As anticipated, the reaction did not proceed
well and the starting materials were fully recovered.
Subsequently, the same reaction was performed at 80 °C
and it was observed that a new spot appeared on the TLC.
The work-up followed by purification of the product and
analysis by 1H, 13C NMR and ESI mass revealed that the
product is amino alcohol derivative of cardanol. To our
delight, we observed a clean formation of the desired
product towards amino alcohol, which was attained in
excellent yield (87%, Table 1, entry 1) after simple work
up. This method did not require any additives or catalysts
to promote the reaction. The reaction was quite general
and efficient.
Having successfully identified the desired product, the
generality of the method was investigated by elaborating the
same reaction protocol for the construction of various other
aminated cardanol-glycerol analogues. The reaction of
cardanol-epoxide 1 with aliphatic and aromatic amines such
as piperidine, pyrrolidine, piperazine, 1-(4-nitrophenyl)
piperazine, di-isopropylamine, 4-methoxyaniline,
4-methylaniline, 2-methylaniline, 4-bromoaniline,
2-bromoaniline, 4-chloroaniline, 2-chloroaniline, aniline
and 2-aminopyridine were carried out (Scheme 2).
Interestingly, reactions of most of the substrates with amines
having electron-neutral, -donating and -withdrawing groups
were executed smoothly and the corresponding aminated
cardano-glycerols were obtained in good to excellent yields
and are illustrated in Table 1. However, the reactions of
cardanol-epoxide 1 with deactivated 4-nitroaniline and
2-nitroaniline were not successful (Table 1, entries 16,
17). Usually, it is necessary a catalyst to perform epoxide
aminolysis with poor nucleophiles.61 The new compounds
synthesized were completely characterized by their spectral
data before proceeding for antimicrobial evaluation.
The β-amino alcohols 2a-2o were examined for
antibacterial and antitubercular activities using methods
previously reported.59 The results are shown in Table 2.
From the results, it was observed that compounds 2b, 2c
and 2f showed good to moderate activity63 for both standard
and clinical strains of S. aureus; the amino alcohol 2o was
Mycobacterium tuberculosis
The antitubercular activity of all compounds was
determined through the resazurin microtiter assay (REMA)
methodology according to the procedures described by
Palomino et al.59 Stock solutions of the tested compounds
were prepared in dimethyl sulfoxide (DMSO) and diluted
in Middlebrook 7H9 broth (Difco) supplemented with
10% OADC enrichment (oleic acid, albumin, dextrose and
catalase) and using a Precision XS™ (BioTek®), to obtain
final drug concentration ranging from 0.09 to 25 µg mL-1.
Rifampicin was used as a control drugs. A suspension of
the MTB H37RvATCC 27294 was cultured in Middlebrook
7H9 broth supplemented with 10% OADC and 0.05%
Tween 80. The culture was frozen at –80 °C in aliquots.
The concentration was adjusted to 2 × 105 CFU mL-1 and
100 µL of the inoculum was added to each well of a 96-well
microtiter plate together with 100 µL of the compounds.
Samples were set up in three independent assays. The
plate was incubated for 7 days at 37 °C. After 24 h, 30 µL
of 0.01% resazurin in distilled water was added. The
fluorescence of the wells was read using a Cytation™ 3
(BioTek®) in which excitations and emissions filters were
used at wavelengths of 530 and 590 nm, respectively. The
MIC90 value was defined as the lowest drug concentration at
which 90% of the cells are infeasible relative to the control.
Results and Discussion
The cardanol-ene mixture was isolated from technical
CNSL by vacuum distillation, and subsequently, it was
subjected to catalytic hydrogenation with Pd/C (5%),
according to our previously reported method.19 The
key starting material cardanol epoxide 1 was attained
in excellent yield (85%) by the reaction of cardanol
(3-pentadecylphenol) with epichlorohydrin (obtained from
glycerol)60 in the presence of 4-dimethylaminopyridine
(DMAP) under reflux conditions (Scheme 1).9,19
After having the crucial precursor in hand, reactions
with various amines with cardanol-epoxide 1 were carried
Scheme 1. Synthesis of cardanol epoxide 1.

644
Synthesis, Antibacterial and Antitubercular Evaluation of Cardanol and Glycerol-Based β-Amino Alcohol Derivatives J. Braz. Chem. Soc.
Scheme 2. Synthesis of cardanol based amino alcohols by using various amines.
Table 1. Synthesis of amino alcohol derivatives based on cardanol and glycerola
entry
1
Compound
Amine
Product
time / h
8
Yieldb / %
87
2a
2
3
2b
2c
8.5
8.5
83
85
4
5
2d
2e
9
64
54
10
6
7
8
9
2f
2g
2h
2i
8
91
64
76
67
8.5
8.5
9

Vol. 29, No. 3, 2018
Manda et al.
645
Table 1. Synthesis of amino alcohol derivatives based on cardanol and glycerola (cont.)
entry
10
Compound
Amine
Product
time / h
8
Yieldb / %
69
2j
11
12
2k
2l
8.5
8.5
70
78
13
14
2m
2n
9.5
8
66
73
15
16
17
2o
2p
2q
8
82
–
–
–
12
12
3
aReaction conditions: cardanol epoxide (1 mmol), amine (1.5 mmol) and solvent (1.5 mL), unless otherwise mentioned, stirred at 80 °C for an appropriate
time; bisolated yields.
active only against the standard strain. The lipophilicity
(reported as log P) of the amino alcohols 2a-2o is shown in
Table 2. Interestingly, except for the compound 2f, the log P
values of the most active compounds 2a, 2b, 2c and 2o are
lower than 9, whereas for the other compounds (with low
or no activity) the log P value is higher than 9. None of the
compounds had any effect on E. coli, which is in accordance
with the fact that the outer membrane of Gram-negative
bacteria seems to act as a barrier to lipophilic compounds.
Also, this membrane protects enteric bacterial cells from
the action of detergents, amphiphilic compounds like the
derivatives presented here.64,65
For antitubercular activity a similar profile was
observed, and compounds 2a-2c, 2e, 2f and 2o showed
good to moderate activity, with MIC90 ranging from 3.18
to 16.54 µg mL-1. Previous studies have reported that the
outer layer functions as an exclusion barrier for hydrophilic
compounds,66 and highly hydrophobic drugs are the most
active antitubercular compounds because they could
easily dissolve in the lipids of the outer cell wall layer and
interact with bacterial amphiphilic surface. Therefore,
it is assumed that the lipophilic compounds could cross
the cell wall through the lipophilic periplasmic space of
the mycobacterial cell wall leading to antimycobacterial
efficacy.66,67
The more active compounds against S. aureus and
M. tuberculosis were heterocyclic aliphatic amines (2a,
2b, and 2c) or those possessing a pyridine moiety (2o)
or aliphatic chains bonded to the nitrogen atom in their
structures (2f). This set of structural features could be
responsible for the antibacterial activity of these amino
alcohols. In addition, the presence of separate hydrophilic
and hydrophobic regions indicates a potentially strong
amphiphilic character of the synthesized amino alcohols. The
ability of these type of compounds to inhibit bacterial growth
appears to depend on their interaction with proteins and/or

646
Synthesis, Antibacterial and Antitubercular Evaluation of Cardanol and Glycerol-Based β-Amino Alcohol Derivatives J. Braz. Chem. Soc.
Table 2. MIC and MIC90 values for synthesized compounds against bacterial strains and log P
S. aureus
S. aureus
E. coli
M. tuberculosis
(ATCC 25923)
(clinical)
(ATCC 25922)
H37Rv (ATCC 27294)
Compound
log Pa
MIC /
MIC /
MIC /
(µg mL-1)
MIC /
MIC90 / µM
MIC90 / µM
MIC90 / µM
MIC90 / µM
(µg mL-1)
(µg mL-1)
(µg mL-1)
2a
8.48
8.99
8.78
10.31
9.20
9.14
9.19
9.30
9.29
9.40
9.38
9.36
9.35
9.17
8.85
na
125.0
279.41
17.51
36.16
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
3.18
3.27
7.36
> 25
16.54
4.37
nd
7.12
7.34
2b
7.81
17.53
36.23
7.80
2c
15.63
15.60
17.07
> 30.97
39.15
9.46
2d
na
na
na
na
2e
2f
3.90
8.45
7.80
16.90
2g
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
2h
> 25
> 25
> 25
> 25
> 25
> 25
> 25
5.22
–
> 53.59
> 53.49
> 47.06
> 47.06
> 51.30
> 51.30
> 55.14
11.51
2i
2j
2k
2l
2m
2n
2o
3.90
1.86
8.45
3.89
Gentamicin
Rifampicin
> 64
3.75
7.84
–
–
–
0.08
0.01
clinical: clinical isolates of oxacillin and penicillin G resistant S. aureus; na: not active at the tested concentrations; nd: not determined. aThe theoretical
log P was calculated using the MolInspiration algorithm.62
their membrane disrupting properties.64,68 It is important to
highlight that phenolic lipids, for example, are highly active
for Gram-positive bacteria, Mycobacterium smegmatis and
Mycobacterium tuberculosis, as well as for phytopathogenic
bacteria,68,69 matching the results obtained in this work.
Acknowledgments
We are grateful to the FUNDECT (PRONEM No.
054/12), CNPq, CAPES and Kardol Ind. Química Ltda. for
supporting our studies in this field of research. B. R. M.,
A. N. P. and N. R. T. would like to acknowledge the support
from PNPD-CAPES and CNPq, Brazil for the fellowship.
Conclusions
In conclusion, we have demonstrated that a simple and
efficient protocol for synthesis of cardanol-based amino
alcohols by using cardanol and glycerol frameworks
with diverse amines in good to excellent yields. The
advantages of this procedure involved readily available
starting materials, good substrate generality and catalyst-
free under mild conditions. The goal of this investigation
was to transform renewable materials into a new class of
amphiphilic compounds and to evaluate their antibacterial
activities. Our results show that this strategy can be an
effective way for the discovery of new antimicrobial agents.
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