Synthesis and antibacterial study of eugenol derivatives

Article abstract of DOI:10.14233/ajchem.2017.20100

A series of eugenol derivatives (2-14) were synthesized and evaluated for their antibacterial activity against five bacterial test strains; three Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis) and two Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) using well-diffusion method. Among the compounds tested, compounds 2-4 displayed susceptible activity toward S. epidermidis with 16-18 mm whereas compounds 12 exhibited susceptible inhibition towards S. aureus only with inhibition diameter of 16 mm, respectively. Other compounds possessed varied antibacterial activities classified as intermediate or resistance indicating that eugenol derivatives have narrow spectrum activity and specifically to Gram-positive bacteria.

Full text of DOI:10.14233/ajchem.2017.20100

Asian Journal of Chemistry; Vol. 29, No. 1 (2017), 22-26
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2017.20100
Synthesis and Antibacterial Study of Eugenol Derivatives
1
2
3
NURUL HAZWANI CHE ABDUL RAHIM , ASNUZILAWATI ASARI1,2,*, NORAZNAWATI ISMAIL and HASNAH OSMAN
1School of Fundamental Science, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
2Institute of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
3School of Chemical Sciences, 11800, Universiti Sains Malaysia, Pulau Pinang, Malaysia
*Corresponding author: E-mail: asnu@umt.edu.my; n.hazwani_91@ymail.com
Received: 25 May 2016;
Accepted: 15 September 2016;
Published online: 29 October 2016;
AJC-18091
A series of eugenol derivatives (2-14) were synthesized and evaluated for their antibacterial activity against five bacterial test strains; three
Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis) and two Gram-negative bacteria
(Escherichia coli and Salmonella typhimurium) using well-diffusion method. Among the compounds tested, compounds 2-4 displayed
susceptible activity toward S. epidermidis with 16-18 mm whereas compounds 12 exhibited susceptible inhibition towards S. aureus only
with inhibition diameter of 16 mm, respectively. Other compounds possessed varied antibacterial activities classified as intermediate or
resistance indicating that eugenol derivatives have narrow spectrum activity and specifically to Gram-positive bacteria.
Keywords: Eugenol derivatives, Well-diffusion method, Antibacterial activities.
Eugenol itself is believed to be toxic in high dose [23,24],
which was subsidized to central nervous system depression
and hepatic failure [25-28] Apart from that, the free radicals
formations by this phenolic compound was act as prooxidant
and lead to cytotoxic that causes tissue damages [29-31].
Therefore, the modification of eugenol structure were done
as reported in literatures to evaluate the biological activities
such as antioxidant, antimicrobial, antiproliferative and pro-
apoptotic activity.
Hence, as part of our ongoing effort to search for pro-
mising antibacterial agent from natural product, in this present
study, we report a series of eugenol ethers and eugenol esters
(2-14) and their antibacterial activity.
INTRODUCTION
Eugenol (4-allyl-2-methoxyphenol) is a major component
of the essential oil extracted from the dried flower buds of the
clove tree (Eugenia caryophyllata). Recently, much attention
has been paid to eugenol derivatives due to their diverse
biological activities [1-6]. Eugenol has been shown to possess
many medicinal properties such as antiseptic and analgesic
[7,8], anesthetic [9], antispasmodic [10], antipyretic [11] and
antioxidant [9,11-13]. Despites, eugenol analogues have also
been synthesized due to their variety of applications. Among
the other derivatives, eugenol ethers and eugenol esters are two
types of eugenol derivatives commonly studied due to their
simple synthesis, stability and broad spectrum of biological
activity [14-17]. In previous report, the synthetic pathway
for the preparation of eugenol esters has been described [18].
These derivatives were synthesized from the reaction between
eugenol with long chain acyl chloride such as palmitoyl,
myristoyl and lauroyl chloride in comparison to many other
aromatic eugenol ethers and eugenol esters commonly reported
[19-21]. Besides, several derivatives of eugenol esters and
eugenol ethers have been evaluated for antispasmodic activity
and have promising antispasmodic activity of eugenol esters
derivatives [10]. Derivatives like eugenol-related biphenyl were
also believed to enhance the activity of antiproliferative and
pro-apoptotic activity against malignant melanoma activity
[22].
EXPERIMENTAL
All reagents used were obtained from Sigma-Aldrich Co.,
Merck Chemical Co.,Acros Organics Co. and R&M Chemical
without further additional purification. All reactions were
performed under nitrogen atmosphere. The reactions were
monitored by thin layer chromatography (TLC) and were
visualized under UV 254 nm without treatment. Column
chromatography was performed by using silica gel 60 (230-
400 mesh, Merck). Infrared spectra were recorded in KBr disc
on Perkin Elmer 100 FT-IR spectrometer. UV-visible spectra
were recorded on Shimadzu UV-1601 PC spectrophotometer.
1H (400 MHz) and 13C (100 MHz) NMR were recorded by

Vol. 29, No. 1 (2017)
Synthesis and Antibacterial Study of Eugenol Derivatives 23
using Bruker Spectrospin-400 Spectrometer. Elemental analyses
were performed on CHNS Analyzer FlashEA 1112 series. All
compounds obtained were evaluated against three Gram-
positive bacterial strains (B. subtilis ATCC 11774, S. aureus
ATCC 25983 and S. epidermidisATCC 13528) and two Gram-
negative bacteria (E. coli ATCC11775 and S. typhimurium
ATCC 14128) respectively for antibacterial activity by using
standard well-diffusion method [32].
General procedure: The preparation of compounds 2-5
was done by known method [33]. Potassium carbonate (1.5
equiv) was added to a solution of eugenol (1) (1.0 equiv) and
benzyl halide (1.5 equiv) in anhydrous acetone (20 mL) under
an inert atmosphere. The mixture was refluxed upon completion
(TLC monitoring). The reaction crude was diluted with water
(30 mL) and extracted with CH2Cl2 (3 × 30 mL). The organic
layer was dried over anhydrous MgSO4 and the solvent was
removed by rotary evaporator. The residue was purified by
column chromatography to give compounds 2 to 5 in various
yields (57 to 72 %).
4-Allyl-1-benzyloxy-2-methoxybenzene (2) [34]:Yield:
72 %; IR (KBr, νmax, cm-1) 2934, 2907, 1637, 1590, 1512, 1454,
1261; UV (MeOH) λmax (log ε) 205.0 (4.65), 234.5 (4.00),
276.0 (4.18) nm; 1H NMR (400 MHz) δ 3.20 (d, J = 5.4 Hz,
2H, H-3), 3.77 (s, 3H, OCH3), 4.94-5.02 (m, 2H, CH2, H-1),
5.02 (s, 2H, H-8), 5.80-5.88 (m, 1H, H-2), 6.54 (d, J = 5.5 Hz,
1H, CHar), 6.62 (s, 1H, CHar), 6.70 (d, J = 6.5 Hz, 1H, CHar),
7.24 (d, J = 6.1 Hz, 3H, CHar), 7.33 (d, J = 6.3 Hz, 2H CHar);
13C NMR (100 MHz, (CD3)2CO) δ 39.7, 40.0, 55.9, 71.1, 76.8,
77.2, 112.4, 114.3, 115.7, 120.5, 127.5, 127.9, 128.3, 128.5,
133.3, 137.7, 146.5 ppm; EIMS m/z [M + Na]+ 277.11 (m.f.
C17H18O2, m.w. 254.10).
4-Allyl-1-(4-isopropyl-benzyloxy)-2-methoxybenzene
(3):Yield: 61 %; IR (KBr, νmax, cm-1) 2960, 2935, 1638, 1588,
1513, 1426, 1232; UV (MeOH) λmax (log ε) 205.2 (4.69), 233.8
(4.05), 277.8 (3.99) nm; 1H NMR (400 MHz) δ 1.30 (s, 6H,
H-12), 2.92-2.95 (m, 1H, H-11), 3.36 (d, J = 5.6 Hz, 2H, H-3),
3.90 (s, 3H, OCH3), 5.08-5.13 (m, 2H, CH2, H-1), 5.12 (s, 2H,
H-8), 5.96-6.01 (m, 1H, H-2), 6.70 (d, J = 6.5 Hz, 1H, CHar),
6.76 (s, 1H, CHar), 6.87 (d, J = 6.5 Hz, 1H, CHar), 7.35 (d, J =
5.7 Hz, 2H, CHar), 7.40 (d, J 6.7 Hz, 2H, CHar);13C NMR (100
MHz, (CD3)2CO) δ 24.0, 33.9, 39.8, 46.2, 55.9, 71.1, 76.8,
112.4, 114.2, 115.6, 120.4, 126.9, 127.5, 128.7, 133.2, 134.8,
137.8, 146.7, 148.5 ppm; EIMS m/z [M + Na]+ 319.16 (m.f.
C20H24O2, m.w. 296.10).
4-Allyl-2-methoxy-1-(4-nitrobenzyloxy)benzene (5)
[35]:Yield: 57 %; IR (KBr, νmax, cm-1) 2934, 2907, 1637, 1590,
1512, 1454, 1261; UV (MeOH) λmax (log ε) 205.0 (4.75), 233.5
(3.03), 278.0 (4.12) nm; 1H NMR (400 MHz) δ, 3.33 (d, J =
6.8 Hz, 2H, H-3), 3.83 (s, 3H, OCH3), 4.98-5.09 (m, 2H, CH2,
H-1), 5.24 (s, 2H, H-8), 5.90-6.00 (m, 1H, H-2), 6.68 (d, J =
2.0 Hz, 1H, CHar), 6.76 (s, 1H, CHar), 6.95 (d, J = 8.0 Hz, 1H,
CHar), 7.75 (d, J = 7.8 Hz, 2H, CHar), 8.25 (d, J = 9.0 Hz, 2H,
CHar);13C NMR (100 MHz, (CD3)2CO) δ 40.3, 56.1, 70.6,
113.7, 115.6, 115.9, 121.2, 124.2, 128.8, 134.9, 138.7, 146.6,
147.2, 148.3, 150.9 ppm. EIMS m/z [M + 2H]+ 300.14 (m.f.
C17H17NO4, m.w. 322.10); Anal. Calcd. for C17H17NO4: C,
68.22; H, 5.72; N, 4.68; found: C, 69.22; H, 6.42; N, 4.70 %.
General procedure for the preparation of compounds
6-14 [36]: Eugenol (1) (1.0 equiv) was dissolved in dichloro-
methane (30 mL) and was added with triethylamine (9.3 mL).
The solution was stirred for 0.5 h in 0 °C. Then, an excess of
acyl chloride was added dropwise in 15 min periods. The
solution was stirred for another 0.5 h at 0 °C before removed
to room temperature and continued stirring for another 24 h.
The progress of the reaction was monitored by thin layer
chromatography (TLC). After the completion of the reaction,
the residue was purified with column chromatography using
hexane and ethyl acetate (3:1 ethyl acetate in hexane) and
yielded products of various colours of compounds 6 to 14 with
yields varied from 49 to 99 %.
4-Allyl-2-methoxyphenyl propanoate (6) [37]: Yield:
75 %; IR (KBr, νmax, cm-1) 3079, 2980, 2940, 1761, 1637, 1422,
1269; UV (MeOH) λmax (log ε) 203.5 (3.45), 221.0 (3.81) nm;
1H NMR (400 MHz) δ 1.18 (t, J = 7.4 Hz, 3H, CH3), 2.52-
2.58 (q, J = 7.5 Hz, 2H, CH2), 3.37 (d, J = 6.8 Hz, 2H, CH2,
H-3), 3.77 (s, 3H, OCH3), 5.01-5.12 (m, 2H, CH2, H-1), 5.09
(d, J = 3.4 Hz, 2H, CH2, H-1), 5.92-6.02 (m, 1H, CH, H-2),
6.76 (d, J = 8.0 Hz, 1H, CHar), 6.92 (d, J = 3.2 Hz, 1H, CHar),
6.95 (s, 1H, CHar); 13C NMR (100 MHz, (CD3)2CO) δ 9.4,
27.4, 40.4, 56.0, 112.8, 113.7, 115.5, 121.2, 123.3, 137.9,
145.7, 152.0, 172.4 ppm; EIMS m/z [M + N]+ 243.09 (m.f.
C13H16O3, m.w. 220.10).
4-Allyl-2-methoxyphenyl butyrate (7) [38]:Yield: 69 %;
IR (KBr, νmax, cm-1) 3077, 2966, 2937, 1726, 1638, 1418, 1268;
UV (MeOH) λmax (log ε) 270 (5.5), 322.5 (4.0) nm; 1H NMR
(400 MHz) δ 1.00 (t, J = 7.4 Hz, 3H, CH3), 1.67-1.76 (m, 2H,
CH2), 2.49 (t, J = 7.2 Hz, 2H, CH2), 3.36 (d, J = 6.8 Hz, 2H,
CH2, H-3), 3.75 (s, 3H, OCH3), 5.02-5.12 (m, 2H, CH2, H-1),
5.91-6.01 (m, 1H, CH, H-2), 6.75 (d, J = 8.0 Hz, 1H, CHar),
6.91 (d, J = 4.0 Hz, 1H, CHar), 6.93 (s, 1H, CHar); 13C NMR
(100 MHz, (CD3)2CO) δ 13.7, 19.0, 36.1, 56.0, 113.5, 116.0,
121.0, 123.3, 138.3, 139.1, 139.6, 152.0, 171.6 ppm; EIMS
m/z [M + Na]+ 257.12 (m.f. C14H18O3, m.w. 234.10).
4-Allyl-2-methoxyphenyl 4-methylbenzoate (8) [19,38]:
Yield: 74 %; IR (KBr, νmax, cm-1) 3067, 2974, 2936, 1730,
1608, 1420, 1268; UV (MeOH) λmax (log ε) 203.5 (4.8), 240.50
(4.3), 273.5 (3.8) nm; 1H NMR (400 MHz) δ 2.44 (s, 3H,CH3),
3.41 (d, J = 6.8 Hz, 2H, CH2, H-3), 3.78 (s, 3H, OCH3), 5.04-
5.15 (m, 2H, CH2, H-1), 5.96-6.06 (m, 1H, CH, H-2), 6.83 (d,
J = 8.0 Hz, 1H, CHar), 6.99 (s, 1H, CHar), 7.10 (d, J = 8.0 Hz,
1H, CHar), 7.39 (d, J = 8.0 Hz, 2H, CHar), 8.05 (d, J = 8.4 Hz,
2H, CHar); 13C NMR (100 MHz, (CD3)2CO) δ 21.6, 40.5, 56.1,
4-Allyl-2-methoxy-1-(4-trifluoromethyl-benzyloxy)-
benzene (4): Yield: 57 %; IR (KBr, νmax, cm-1) 2961, 2935,
1641, 1588, 1515, 1420, 1232; UV (MeOH) λmax (log ε) 205.6
(4.90), 232.6 (4.28), 275.6 (4.22) nm; 1H NMR (400 MHz) δ,
3.36 (d, J = 5.4 Hz, 2H, H-3), 3.91 (s, 3H, OCH3), 5.08-5.13
(m, 2H, CH2, H-1), 5.21 (s, 2H, H-8), 5.94-6.02 (m, 1H, H-2),
6.70 (d, J = 6.5 Hz, 1H, CHar), 6.79 (d, J = 5.7 Hz, 1H, CHar),
6.81 (s, 1H, CHar), 7.58 (d, J = 6.4 Hz, 2H, CHar), 7.65 (d, J =
6.5 Hz, 2H, CHar);13C NMR (100 MHz, (CD3)2CO) δ 39.8,
55.9, 70.4, 77.9, 112.5, 114.3, 115.8, 120.4, 123.0, 125.2,
125.5, 127.3, 129.7, 133.9, 137.5, 141.5, 146.1, 149.7 ppm.
EIMS m/z [M + He]+ 327.07 (m.f. C18H17F3O2, m.w. 322.32);
Anal. Calcd. for C18H17O2F3: C, 67.07; H, 5.32; found: C, 68.14;
H, 6.30 %.

24 Abdul Rahim et al.
Asian J. Chem.
113.7, 116.1, 121.2, 123.6, 127.7, 130.2, 130.6, 131.2, 138.4,
139.2, 139.9, 145.2, 152.2, 165.0 ppm; EIMS m/z [M + H]+
283.13, EIMS m/z [M + Na]+ 305.11, (m.f. C18H18O3, m.w.
282.10); Anal. Calcd. for C18H18O3: C, 76.57; H, 6.43; found:
C, 72.09; H, 6.02 %.
2H, CH2, H-3), 3.81 (s, 3H, OCH3), 5.05-5.16 (m, 2H, CH2,
H-1), 5.96-6.09 (m, 1H, CH, H-2), 6.86 (d, J = 8.0 Hz, 1H,
CHar), 7.03 (s, 1H, CHar), 7.17 (d, J = 8.0 Hz, 1H, CHar), 8.41-
8.42 (m, 4H, CHar); 13C NMR (100 MHz, (CD3)2CO) δ 40.3,
56.1, 70.6, 113.7, 115.6, 115.9, 121.2, 124.2, 128.8, 134.8,
146.5, 147.2, 148.3 ppm;Anal. Calcd. for C17H15NO5: C, 65.17;
H, 4.83; N, 4.47; found: C, 64.34; H, 5.257; N, 4.66 %.
4-Allyl-2-methoxyphenyl 4-methoxybenzoate (14)
[18,19,38]:Yield: 97 %; IR (KBr, νmax, cm-1) 3010, 2976, 2941,
1728, 1606, 1421, 1264; UV (MeOH) λmax (log ε) 203.0 (4.7),
4-Allyl-2-methoxyphenyl 4-ethylbenzoate (9): Yield:
63 %; IR (KBr, νmax, cm-1)3067, 2971, 2937, 1732, 1608, 1418,
1268; UV (MeOH) λmax (log ε) 203.0 (4.8), 242.5 (4.4), nm;
1H NMR (400 MHz) δ 1.26 (t, J = 7.6 Hz, 3H, CH3), 2.73-
2.79 (q, J = 7.6 Hz, 2H, CH2), 3.42 (d, J = 6.8 Hz, 2H, CH2,
H-3), 3.78 (s, 3H, OCH3), 5.04-5.15 (m, 2H, CH2, H-1), 5.96-
6.06 (m, 1H, CH, H-2), 6.83 (d, J = 8.0 Hz, 1H, CHar), 7.00 (s,
1H, CHar), 7.10 (d, J = 8.0 Hz, 1H, CHar), 7.43 (d, J = 8.4 Hz,
2H, CHar), 8.08 (d, J = 8.0 Hz, 2H, CHar); 13C NMR (100 MHz,
(CD3)2CO) δ 40.5, 51.9, 56.0, 56.1, 113.8, 114.8, 116.1, 121.2,
122.7, 123.7, 132.1, 132.8, 138.4, 139.8, 152.3, 164.7, 164.9
ppm; EIMS m/z [M + Na]+ 319.13 (m.f. C19 H20 O3, m.w.
296.10); Anal. Calcd. for C19H20O3: C, 73.60; H, 6.79; found:
C, 76.45; H, 7.61 %.
4-Allyl-2-methoxyphenyl 4-fluorobenzoate (10) [19,38]:
Yield: 49 %; IR (KBr, νmax, cm-1) 3085, 2981, 2939, 1736,
1603, 1412, 1265; UV (MeOH) λmax (log ε) 202.0 (4.5), 227.0
(4.4), 263.0 (3.2) nm; 1H NMR (400 MHz) δ 3.42 (d, J = 6.8
Hz, 2H, CH2, H-3), 3.79 (s, 3H, OCH3), 5.05-5.15 (m, 2H,
CH2, H-1), 5.98-6.05 (m, 1H, CH, H-2), 6.84 (d, J = 8.4 Hz,
1H, CHar), 7.01 (s, 1H, CHar), 7.12 (d, J = 8.0 Hz, 1H, CHar),
7.35 (t, J = 9.0 Hz, 2H, CHar), 8.23 (d, J = 8.8 Hz, 2H, CHar);
13C NMR (100 MHz, (CD3)2CO) δ 40.5, 56.1, 113.8, 116.1,
116.5, 116.7, 121.3, 123.5, 127.0, 127.1, 133.5, 138.3, 139.1,
140.2, 152.2, 164.1, 165.6 ppm.
4-Allyl-2-methoxyphenyl 4-chlorobenzoate (11) [19,21]:
Yield: 90 %; IR (KBr, νmax, cm-1) 2914, 1739, 1591, 1463,
1265, 1068, 848; UV (MeOH) λmax (log ε) 203.0 (4.7), 248.0
(4.3), 273.5 (3.5) nm; 1H NMR (400 MHz) δ 3.42 (d, J = 6.8
Hz, 2H, CH2, H-3), 3.79 (s, 3H, OCH3), 5.05-5.15 (m, 2H,
CH2, H-1), 5.96-6.04 (m, 1H, CH, H-2), 6.84 (d, J = 8.0 Hz,
1H, CHar), 7.01 (s, 1H, CHar), 7.12 (d, J = 8.0 Hz, 1H, CHar),
7.63 (d, J = 8.8 Hz, 2H, CHar), 8.16 (d, J = 8.8 Hz, 2H, CHar);
13C NMR (100 MHz, (CD3)2CO) δ 40.6, 52.5, 56.2, 116.2,
121.3, 121.5, 129.2, 129.6, 129.9, 131.9, 132.7, 133.0, 138.3,
139.1, 152.1, 164.2 ppm.
4-Allyl-2-methoxyphenyl 4-bromobenzoate (12):Yield:
79 %; IR (KBr, νmax, cm-1) 3075, 2968, 2935, 1738, 1588, 1420,
1263; UV (MeOH) λmax (log ε) 203.0 (4.7), 245.5 (4.3) nm;
1H NMR (400 MHz) δ 3.42 (d, J = 6.8 Hz, 2H, CH2, H-3),
3.79 (s, 3H, OCH3), 5.05-5.15 (m, 2H, CH2, H-1), 5.96-6.06
(m, 1H, CH, H-2), 6.84 (d, J = 8.0 Hz, 1H, CHar), 7.01 (s, 1H,
CHar), 7.12 (d, J = 8.0 Hz, 1H, CHar), 7.79 (d, J = 8.8 Hz, 2H,
CHar), 8.09 (d, J = 8.8 Hz, 2H, CHar); 13C NMR (100 MHz,
(CD3)2CO) δ 40.5, 52.5, 56.2, 113.8, 116.1, 121.3,123.5, 128.9,
129.2, 130.3, 132.5, 132.6, 133.9, 138.3, 139.1, 140.2, 152.1,
164.2, 166.5 ppm; EIMS m/z [M + N]+ 360.19 (m.f.
C17H15BrO3, m.w. 346.10); Anal. Calcd. for C17H15BrO3: C,
58.81; H, 4.35; found: C, 53.10; H, 4.02 %.
1
259.0 (4.4) nm; H NMR (400 MHz) δ 3.42 (d, J = 6.8 Hz,
2H, CH2, H-3), 3.78 (s, 3H, OCH3), 3.92 (s, 3H, OCH3), 5.04-
5.15 (m, 2H, CH2, H-1), 5.96-6.06 (m, 1H, CH, H-2), 6.83 (d,
J = 8.0 Hz, 1H, CHar), 6.99 (s, 1H, CHar), 7.09 (d, J = 9.0 Hz,
2H, CHar), 7.11 (s, 1H, CHar), 8.11 (d, J = 8.8 Hz, 2H, CHar);
13C NMR (100 MHz, (CD3)2CO) δ 40.6, 52.5, 56.2, 116.2,
121.3, 121.5, 129.2, 129.6, 129.9, 131.9, 132.7, 133.0, 138.3,
139.1, 152.1, 164.2 ppm; EIMS m/z [M + H]+ 299.12, EIMS
m/z [M + Na]+ 321.11 (m.f. C18H18O4, m.w. 298.10); Anal.
Calcd. for C18H18O4: C, 72.47; H, 6.08; found: C, 70.84; H,
6.67 %.
Antibacterial assay:All eugenol derivatives synthesized
were tested for their antibacterial activity against five bacterial
strains of Gram-positive and Gram-negative bacteria; three
Gram-positive bacteria (B. subtilis, S. aureus and S. epidermidis)
and two Gram-negative bacteria (E. coli and S. typhimurium)
using standard well-diffusion method [32]. The Mueller-
Hinton agar (MHA) plates were seeded with cultured bacterial
strains using cotton swab. Wells of 6.0 mm diameter were cut
on the media using sterile cork borer and was loaded with 60
µL of diluted compounds. 1 mg/mL of synthesized compounds
were prepared by using methanol as solvent. Streptomycin
(Abtek Biologicals Ltd) was used as positive control.All plates
were incubated at 37 °C for overnight before evaluating the
antibacterial activity by measuring the diameter of inhibition
zones against bacteria.
RESULTS AND DISCUSSION
A series of eugenol derivatives were synthesized according
to the pathways described in Scheme-I. The treatment of eugenol
(1), with various benzyl halides and potassium carbonate by
following published method [33] to furnish (2-5) in moderate
isolated yields. Eugenol esters (6-14) have been synthesized
following the reported method [36] by the reaction of eugenol
(1), with various acyl chlorides in the presence of triethylamine.
Antibacterial evaluation of synthesized compounds:
All the synthesized compounds 2-14 were subjected to antibac-
terial study using standard well-diffusion method [32]. The
diameters of inhibition zone of all compounds were represented
in Table-1. The results showed that most compounds are active
against S. epidermidis. Notably, compounds 2-4 exhibited
susceptible activity against S. epidermidis whereas compounds
12 displayed susceptible activity towards S. aureus. Compounds
5-6, 8-10, 12 and 14 were intermediately active in inhibiting
the growth of S. epidermidis, respectively. Compounds 7, 9
and 12 exhibited moderate activity against S. typhimurium, S.
aureus and E. coli.
4-Allyl-2-methoxyphenyl 4-nitrobenzoate (13) [38]:
Yield: 57 %; IR (KBr, νmax, cm-1) 2940, 1746, 1605,1530, 1344,
1264, 1076; UV (MeOH) λmax (log ε) 203.5 (4.7), 258.0 (4.4),
1
273.5 (4.3) nm; H NMR (400 MHz) δ 3.43 (d, J = 6.8 Hz,

Vol. 29, No. 1 (2017)
Synthesis and Antibacterial Study of Eugenol Derivatives 25
2, R = H, X = Br (72%)
K2CO3,
Acetone anhy.
O
3, R = CH(CH3)2, X = Cl (61%)
4, R =CHF3, X = Cl (57%)
5, R = NO2, X = Cl (57%)
O
X
R
R
O
6, R = CH2CH3 (77 %)
7, R = CH2CH2CH3 (69 %)
HO
Et3N
DCM anhy.
8, R =
9, R =
10, R =
11, R =
12, R =
13, R =
14, R =
p
-C6H4CH3 (74 %)
1
, Eugenol
O
O
p-C6H4CH2CH3 (63 %)
O
p
p
p
p
p
-C6H4F (49 %)
O
-C6H4Cl (85 %)
-C6H4Br (79 %)
-C6H4NO2 (99 %)
-C6H4OCH3 (97 %)
R
R
Cl
Scheme-I: Synthesis of compounds 2-14
TABLE-1
Conclusion
ANTIBACTERIAL ACTIVITY FOR EUGENOL (1)
AND ITS DERIVATIVES (2-14)
In conclusion, 13 derivatives of eugenol were successfully
synthesized from the reaction of eugenol with benzyl halides
and acyl chloride. Antibacterial screening revealed that com-
pounds 12 as the most potential antibacterial agent with broad
spectrum of activity against Gram-positive and Gram-negative
bacteria.
Zone of inhibition (mm)
Compounds
Gram-positive bacteria
Gram-negative bacteria
BS
6
7
6
7
NI
9
7
SA
6
SE
12
18
16
16
10
11
7
11
14
10
9
EC
6
7
6
6
8
9
NI
7
7
ST
NI
6
6
NI
6
8
10
7
7
8
1
2
3
4
5
6
7
8
9
10
11
12
13
14
6
6
6
NI
7
ACKNOWLEDGEMENTS
This research was supported financially by Research
Acculturation Collaborative Effort (RACE) grant (56008). The
authors thank the School of Fundamental Science, Institute of
Marine Biotechnology and Horseshoe Crab Laboratory of
Universiti Malaysia Terengganu for facilities and research
supports.
7
8
NI
10
7
NI
NI
7
8
8
7
6
7
7
9
6
16
NI
9
10
9
10
8
NI
NI
15
REFERENCES
14
24
8
17
1. F.M.Abdel Bar, M.A. Khanfar,A.Y. Elnagar, F.A. Badria,A.M. Zaghloul,
K.F. Ahmad, P.W. Sylvester and K.A. El Sayed, Bioorg. Med. Chem.,
18, 496 (2010).
2. H. Carrasco A, L. Espinoza C, V. Cardile, C. Gallardo, W. Cardona, L.
Lombardo, K. Catalán M, M. Cuellar F and A. Russo, J. Braz. Chem.
Soc., 19, 543 (2008).
Streptomycin
16
17
BS = B. subtilis; SA = S. aureus; SE = S. epidermidis; EC = E. coli;
ST = S. typhimurium; NI = No Inhibition.
Previous study demonstrated that the compounds with the
presence of nitro group as substituent showed good antimicro-
bial activity [39]. However, the result obtained in this study
revealed that compound 13 employing nitro substituent dis-
played intermediate to resistance activity towards tested strains.
This might be attributed to substituent position which is para
directing that deactivate the molecules. This is in accordance
with the previous study [40] that showed the nitro substituent
at para position displayed no activity towards the bacterial
strains. Apart from that, the modification of eugenol structure
in the presence of bromine as substituent has led to the increase
in antibacterial activity as shown by compound 12. This finding
is in agreement with previous work [40,41]that showed potent
activity against S. aureus in the presence of bromine substituent.
Compound 12 emerges as the best antibacterial agent and
susceptible to both Gram-positive and negative bacteria strains,
indicating broad-spectrum activity.
3. M.E. Hidalgo, C. De la Rosa, H. Carrasco, W. Cardona, C. Gallardo
and L. Espinoza, Quim. Nova, 32, 1467 (2009).
4. K.G. Lee and T. Shibamoto, Food Chem., 74, 443 (2001).
5. S.E. Moon, H.Y. Kim and J.D. Cha, Arch. Oral Biol., 56, 907 (2011).
6. Y. Huang, S.H. Ho, H.C. Lee and Y.L. Yap, J. Stored Prod. Res., 38,
403 (2002).
7. W.R. Hume, J. Dent. Res., 62, 1013 (1983).
8. K. Markowitz, M. Moynihan, M. Liu and S. Kim, Oral Surg. Oral Med.
Oral Pathol., 73, 729 (1992).
9. L. Jirovetz, G. Buchbauer, I. Stoilova, A. Stoyanova, A. Krastanov and
E. Schmidt, J. Agric. Food Chem., 54, 6303 (2006).
10. H. Wagner, K. Jurcic and R. Deininger, Planta Med., 37, 9 (1979).
11. J. Feng and J.M. Lipton, Neuropharmacology, 26, 1775 (1987).
12. M.I. Nassar, A.H. Gaara, A.H. El-Ghorab, A.R.H. Farrag, H. Shen, E.
Huq and T.J. Mabry, Rev. Latinoamer. Quim., 35, 47 (2007).
13. A. Alqareer, A. Alyahya and L. Andersson, J. Dent., 34, 747 (2006).
14. D. Rico-Molina, G. Aparicio-Ozores, L. Dorantes-Alvarez and H.
Hernandez-Sanchez, Am. J. Food Technol., 7, 289 (2012).
15. K.P. Devi, S.A. Nisha, R. Sakthivel and S.K. Pandian, J. Ethnopharmacol.,
130, 107 (2010).

26 Abdul Rahim et al.
Asian J. Chem.
16. S.T. Chang, P.F. Chen and S.C. Chang, J. Ethnopharmacol., 77, 123
(2001).
30. T. Atsumi, I. Iwakura, S. Fujisawa and T. Ueha, Biomaterials, 22, 1459
(2001).
17. C.W. Gayoso, E.O. Lima, V.T. Oliveira, F.O. Pereira, E.L. Souza, I.O.
Lima and D.F. Navarro, Fitoterapia, 76, 247 (2005).
31. S. Fujisawa, T. Atsumi, Y. Kadoma and H. Sakagami, Toxicology, 177,
39 (2002).
18. P.K. Awasthi, S.C. Dixit and A.K. Sinha, J. Pharm. Res., 1, 218 (2008).
19. H. Sadeghian, S.M. Seyedi, M.R. Saberi, Z. Arghiani and M. Riazi,
Bioorg. Med. Chem., 16, 890 (2008).
20. T. Koeduka, K. Sugimoto, B. Watanabe, N. Someya, D. Kawanishi, T.
Gotoh, R. Ozawa, J. Takabayashi, K. Matsui and J. Hiratake, Plant
Biol., 16, 451 (2014).
21. P.H.O. Abrão, R.B. Pizi, T.B. de Souza, N.C. Silva, A.M. Fregnan,
F.N. Silva, L.F.L. Coelho, L.C.C. Malaquias, A.L.T. Dias, D.F. Dias,
M.P. Veloso and D.T. Carvalho, Chem. Biol. Drug Des., 86, 459 (2015).
22. M. Pisano, G. Pagnan, M. Loi, M.E. Mura, M.G. Tilocca, G. Palmieri,
D. Fabbri, M.A. Dettori, G. Delogu, M. Ponzoni and C. Rozzo, Mol.
Cancer, 6, 8 (2007).
23. B.Alpar, H. Gunay, W. Geurtsen and G. Leyhausen, Clin. Oral Investig.,
3, 41 (1999).
24. G. Kozam and G.M. Mantell, J. Dent. Res., 57, 954 (1978).
25. B.W. Lane, M.J. Ellenhorn, T.V. Hulbert and M. McCarron, Hum. Exp.
Toxicol., 10, 291 (1991).
26. G. Hartnoll, D. Moore and D. Douek, Arch. Dis. Child., 69, 392 (1993).
27. J.S. Eisen, G. Koren, D. Juurlink and V.L. Ng, J. Toxicol. Clin. Toxicol.,
42, 89 (2004).
32. N. Raman, S. Thalamuthu, J.D. Raja, M.A. Neelakandan and S.
Banerjee, J. Chil. Chem. Soc., 53, 1450 (2008).
33. S. García-Muñoz, M. Álvarez-Corral, L. Jiménez-González, C. López-
Sánchez, A. Rosales, M. Muñoz-Dorado and I. Rodríguez-García,
Tetrahedron, 62, 12182 (2006).
34. R. Maurya, A. Ahmad, P. Gupta, K. Chand, M. Kumar, Jayendra, P.
Rawat, N. Rasheed and G. Palit, Med. Chem. Res., 20, 139 (2011).
35. E.E. Reid, J. Am. Chem. Soc., 39, 304 (1917).
36. W. Gul, N.L. Hammond, M. Yousaf, J.J. Bowling, R.F. Schinazi, S.S.
Wirtz, G. de Castro Andrews, C. Cuevas and M.T. Hamann, Bioorg. Med.
Chem., 14, 8495 (2006).
37. J.D.F. Barbosa, V.B. Silva, P.B. Alves, G. Gumina, R.L.C. Santos, D.P.
Sousa and S.C.H. Cavalcanti, Pest Manag. Sci., 68, 1478 (2012).
38. M. d’ Avila Farias, P.S. Oliveira, F.S.P. Dutra, T.J. Fernandes, C.M.P.
de Pereira, S.Q. de Oliveira, F.M. Stefanello, C.L. Lencina and A.G.
Barschak, J. Pharm. Pharmacol., 66, 733 (2014).
39. H. Carrasco, M. Raimondi, L. Svetaz, M.D. Liberto, M.V. Rodriguez,
L. Espinoza, A. Madrid and S. Zacchino, Molecules, 17, 1002 (2012).
40. S. Muratovic, K. Duric, E. Veljovic, A. Osmanovic, D. Softic and D.
Zavrsnik, Asian J. Pharm. Clin. Res., 6, 134 (2013).
28. S.E. Janes, C.S. Price and D. Thomas, Eur. J. Pediatr., 164, 520 (2005).
29. J.W. McDonald and J.E. Heffner, Am. Rev. Respir. Dis., 143, 806 (1991).
41. G. Eyambe, L. Canales and B.K. Banik, Heterocycl. Lett., 2, 154 (2011).