ArticlePDF Available

Screening for Antioxidant and Antibacterial potential of common medicinal plants in the treatment of Acne

Authors:
  • SP College of Pharmacy

Abstract

In the present study, sequential extracts of Camellia sinensis, Glycyrrhiza glabra, Calendula officinalis and Linum usitatissimum were analyzed for their antioxidant activity in different test systems. Phytochemical analysis indicated that amongst twelve test extracts, methanolic extract of Camellia sinensis was found to have the highest total phenolic content (104.93 ± 1.630 mg GAE /g) and FRAP value (1046.330±1.948 mg TE/g). flavonoid content (115.503±2.984 mg RuE /g dry extract) of methanolic extract of Glycyrrhiza glabra was found to be superior among all the extracts. Highest DPPH scavenging (IC50=44.03 ±1.784 μg/ml) effect was also observed in methanolic extracts of Camellia sinensis. In vitro antimicrobial screening indicated that methanolic extracts showed promising antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis and Propionibacterium acnes.
Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Nand Pratibha
1*
, Drabu Sushma
1
, Gupta Rajinder K
2*
1
Maharaja Surajmal Institute of Pharmacy, Janakpuri, New Delhi, India
2
University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India.
Key words:
Acne, Antioxidant assay, Free radicals, Medicinal
plants.
How to Cite this Paper:
Nand Pratibha, Drabu Sushma, Gupta
Rajinder K
*
“Screening for Antioxidant and
Antibacterial potential of common medicinal plants
in the treatment of Acne”, Int. J. Drug Dev. & Res.,
Jan-March 2012, 4(1): 65-71
Copyright © 2010 IJDDR, Gupta Rajinder K et
al. This is an open access paper distributed under the
copyright agreement with Serials Publication, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
work is properly cited.
Introduction
Acne vulgaris is the most common skin disorder of
pilosebaceous unit caused by hormonal,
microbiological and immunological factors. It affects
all age groups i.e. teenagers (85%), 25-34 year (8%)
and 35-44 year (3%) and is characterized by the
presence of bacteria namely Staphylococcus aureus,
Staphylococcus epidermidis and Propionibacterium
acnes in the follicular canal [
1
]. The severity of this
skin disorder generally increases with age and time.
Propionibacterium acnes evokes mild local
inflammation by producing neutrophil chemotactic
factors. Consequently, neutrophils get attracted to
International Journal of Drug Development & Research
| January-March 2012 | Vol. 4 | Issue 1 | ISSN 0975-9344 |
Available online http://www.ijddr.in
Covered in Official Product of Elsevier, The Netherlands
SJR Impact Value 0.03,& H index 2
©2010 IJDDR
Abstract
In the present study, sequential extracts of
Camellia sinensis, Glycyrrhiza glabra, Calendula
officinalis and Linum usitatissimum were analyzed for
their antioxidant activity in different test systems.
Phytochemical analysis indicated that amongst twelve
test extracts, methanolic extract of Camellia sinensis
was found to have the highest total phenolic content
(104.93 ± 1.630 mg GAE /g) and FRAP value
(1046.330±1.948 mg TE/g). Flavonoid content
(115.503±2.984 mg RuE /g dry extract) of methanolic
extract of Glycyrrhiza glabra was found to be superior
among all the extracts. Highest DPPH scavenging
(IC
50
=44.03 ±1.784 µg/ml) effect was also observed in
methanolic extracts of Camellia sinensis. In vitro anti-
microbial screening indicated that methanolic extracts
showed promising antimicrobial activity against
Staphylococcus aureus, Staphylococcus epidermidis
and Propionibacterium acnes.
*Corresponding author, Mailing address:
Gupta Rajinder K
Email Id: rkg67ap@yahoo.com
Article History:------------------------
Date of Submission: 22-08-2011
Date of Acceptance: 08-10-2011
Source of Support
: All India Council
of Technical Education & University
Grant Commission
F U LL L en g t h R e s e a rc h P a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
65
the acne lesions and constantly release inflammatory
mediators such as reactive oxygen species (ROS) [
2
].
Reactive oxygen species (ROS) namely hydroxyl
(
OH) and super oxide (O
2•-
) and reactive nitrogen
species (RNS) like nitrous oxide (N
2
O) nitroxyl anion
(NO
-
) are the most common free radicals. These toxic
ROS can also act as a messenger in the induction of
several biological responses such as NF-kB and AP-1.
These radicals are formed with the reduction of
oxygen to water. Normally, the production of these
radicals is slow and they are removed naturally by the
antioxidant enzymes like superoxide dismutase
(SOD), catalase (CAT) and glucose-6-phosphate
dehydrogenase (G6PD) existing in the cell, but due to
depletion of immune system and natural antioxidants
in different ailments, it becomes necessary to use
antioxidants as free radical scavengers for removal of
ROS to reduce cell damage that occurs during acne
inflammation [
3
]. Antioxidant compounds have the
ability to capture, deactivate and repair the damage
caused by free radicals (Alonso et al., 2002) [
4
].
Hence, the objective of the present study was to
investigate antioxidant potential of the following four
medicinal plants viz: Camellia sinensis [
5
]
Glycyrrhiza glabra [
6
] Calendula officinalis [
7
,
8
] and
Linum usitatissimum possessing antimicrobial and
anti-inflammatory potential also.
Materials and Methods
Plant materials and chemicals
Fresh and dried plant materials were collected from
medicinal gardens and authorized herbal stores in
Delhi. Their botanical identities were determined and
authenticated at the National Institute of Science
Communication and Information Resources
(NISCAIR), New Delhi, India vide voucher specimen
NISCAIR/RHM/consult/2007-08/936/120 and
NISCAIR/RHM/consult/2008-09/978/09.
Clindamycin phosphate was procured from Sri Ram
Institute of Industrial Research, New Delhi. All other
chemicals used were of analytical grade and obtained
from either Sigma-Aldrich or Merck.
Preparation of Extracts and Phytochemical
Screening
The air dried leaves, flowers, stolons, roots and seeds
were pulverized and used for extraction in soxhlet
apparatus at room temperature. Sequential
extraction of 200 g was done with solvents of
increasing polarity i.e. petroleum ether (PE),
dichloromethane (DCM) and methanol (ME) and the
extracts were abbreviated as: Camellia sinensis
(CSPE, CSDCM, CSME), Glycyrrhiza glabra (GGPE,
GGDCM, GGME), Calendula officinalis (COPE,
CODCM, COME) and Linum usitatissimum (LUPE,
LUDCM, LUME). The extracts were evaporated
under vacuum conditions using a rotary evaporator
and stored at 4˚C in air tight containers for further
studies. Preliminary phytochemical screening and
percentage yield of the twelve extracts was recorded
[
9
].
Determination of total phenolic content
The total phenolic content of the thirteen extracts
was determined using McDonald method with
modifications [
10
]. 100 µl of the diluted extracts
containing 500 µg and standard phenolic compound
gallic acid (10-50µg/ml) were mixed separately with
(62.5µl) Folin-Ciocalteu reagent and diluted with
0.287 ml distilled water and 0.375 ml of 20%
aqueous Na
2
CO
3.
The mixtures were then allowed to
stand for 2 hrs and the total phenolic content was
determined using spectrophotometer at 765 nm. The
concentration of the total phenolic compounds was
calculated using the equation (y = 0.02769x +
0.0103: r
2
= 0.9984) and the total phenolic content
was expressed as mg of Gallic acid equivalents (GAE)
/ g of dried extract (Table 1).
Table 1: Total phenolic and flavonoid content of test
extracts
F U LL L en g t h R e s e a rc h P a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Gupta Rajinder K et al: Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
66
Scientific name
(GAE) PhenolicContent (mg/g) (RuE) Flavonoid content (mg/g)
PE DCM ME PE DCM ME
Camellia sinensis (le) 14.16 ± 0.91 17.88 ± 1.85 104.93 ± 1.63 19.29 ± 2.56 24.29 ± 0.90 28.87 ±0.51
Glycyrrhiza
Glabra (ro& st) 60.52 ± 1.94 73.51 ± 1.45 95.38 ± 2.49 41.14 ± 0.56 115.48 ± 3.69 115.5 ±2.98
Calendula
officinalis(fl) ND 52.26 ± 1.28 91.00 ± 1.66 2.49 ± 1.66 62.35 ± 2.40 73.42 ±2.68
Linum
Usitatissimum (se) 1.62 ± 0.69 2.69 ± 0.25 15.14 ±0.12 14.39 ± 1.03 27.25 ± 0.19 7.59 ±0.21
le ( leaves) ; ro& st (roots and stolons); fl (flowers); se (seeds);PE (petroleum ether extract); DCM
(dichloromethane extract); ME (methanolic extract); ND (not detected).
Results were mean ± standard deviation
Determination of total flavonoid
The total flavonoid content of all the extracts and
TTO was determined using existing Chang et al.
method with some modifications [
11
]. 100µl of the
extract containing 500 µg was mixed with 300 µl of
distilled water and 30 µl of 5% NaNO
2
. The mixture
was kept at room temperature for 5 min followed by
addition of 30µl of 10% AlCl
3
, 0.2 ml of 1mM NaOH
and 1ml distilled water. The absorbance of the
reaction mixture was measured at 415 nm with UV
spectrophotometer. The concentration of the
flavonoid compounds was calculated using the
equation (y = 0.01083x - 0.00476: r
2
= 0.9945)
obtained from the rutin (20-100 µg/ml) calibration
curve and the flavonoid content was expressed as
mg of rutin equivalents (RuE) / g of dried extract
(Table 1).
Scavenging effect on 1, 1-diphenyl-2-
picrylhydrazyl (DPPH)
The free radical scavenging activity was estimated by
1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay using
Blois method with some modifications [
12
]. The
reaction mixture contained 100µl of test extracts
(100-500 µg/ml) and 1 ml of methanolic solution of
0.1mM DPPH radical. The mixture was then shaken
vigorously and incubated at 37
0
C for 30 min. The
absorbance was measured at 517 nm using ascorbic
acid (100-500 µg/ml) as positive control. Lower
absorbance of the reaction mixture indicated higher
free radical scavenging activity which was calculated
using the following equation:
DPPH scavenging effects (%) = 100 x (A
o
- A
1
)/(A
o
)
where A
o
is the absorbance of the control reaction
and A
1
is the absorbance of reaction mixture
containing DPPH and extract at 517 nm. The
antioxidant activity of the extract was expressed as
IC
50
value which is defined as the concentration
(µg/ml) of extract that inhibits the formation of
DPPH radicals by 50%. It was obtained from linear
regression analysis (Figure 1).
Ferric reducing antioxidant power (FRAP)
assay
Freshly prepared FRAP reagent contained 5 mL of a
10mM TPTZ (2, 4, 6 -tripyridyl- 2- triazine) solution
in 40 mM HCl, 5 mL of 20mM FeCl
3
.6H
2
0 and 50ml
of 300 mM acetate buffer (pH 3.6) and was heated
at 37
0
C. 100 µl of various extracts (10mg/ml) was
mixed with 900 µl of FRAP reagent and the mixture
was then incubated at 37
0
C for 6 min. Ferric
reducing antioxidant power of the extracts was
determined by modified Benzie and Strain method
[
13
]. The absorbance of the coloured reaction
mixture (ferrous tripyridyltriazine complex) was
measured at 595 nm using standard trolox (1
mg/ml) to estimate the percentage of iron reduced.
The results were calculated as mg of trolox
equivalent (TE) per g of dried extract using the
F U LL L en g t h R e s e a rc h P a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Gupta Rajinder K et al: Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
67
equation: (y = 0.0749 + 0.003X, r
2
= 0.9888)
(Figure 2).
0 100 200 300 400 500
0
20
40
60
80
100
DPPH scavenging effect (%)
Concentration g/ml)
Ascorbic acid
CSME
GGME
COME
LUPE
LUME
Figure 1: DPPH scavenging effect (%) of active
plant extracts and ascorbic acid
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
Camellia sinensis Glycyrrhiza glabra Calendula officinalis Linum
usitatissimum
T r ol ox E q u iv a le n t (m g /g )
PE DCM ME
Figure 2: Ferric reducing antioxidant power of test
extracts
Antimicrobial screening
Microorganism and media
Aerobic bacteria: Staphylococcus aureus (MTCC
96), Staphylococcus epidermidis (MTCC 2639) and
anaerobic bacteria: Propionibacterium acnes
(MTCC *1951) were obtained from the Microbial
Type Culture Collection Centre, Institute of
Microbial Technology, Chandigarh. Fresh cultures of
the isolates of aerobic and anaerobic bacteria were
suspended in nutrient broth and reinforced
clostridium medium respectively. S. aureus and S.
epidermidis cultures were incubated for 24 h at 37°C
and 30°C, respectively. P. acnes culture was
incubated in an anaerobic chamber at 37°C
consisting of 10% CO
2,
10% H
2
and 80% N
2
for 48 h.
Antimicrobial screening using disc diffusion
method
Antibacterial activity of the extracts was tested using
agar disc diffusion method
[
14
]. 100 µl of fresh
culture suspension of the test bacteria was evenly
spread on nutrient agar and reinforced clostridial
agar plates. The concentration of cultures was 5x10
5
CFU/ml. For screening, 6 mm diameter filter paper
disc, impregnated with 20 µl of extract solution
equivalent to 0.2 mg of extract was placed on the
surface of inoculated media agar plates. Incubation
was done at 37°C or 30°C for 24 h and 48 h
depending upon the type of bacteria under optimum
conditions. Clear zones of inhibition were measured
in mm, including the diameter of the disc. Zone
measuring 10 mm or more was considered as
effective against test organisms. Clindamycin (10
µg/disc) was used as positive control and the
respective solvents, which were used for extraction,
served as negative control.
Statistical analysis
All the samples were run in triplicate and mean
values were used for the result analysis. The
statistical significance between the antioxidant
activity of extracts and standards was evaluated
using SPSS version 10.0.1 and the comparison was
done using Mann-Whitney U test.
Results and Discussion
In the present study, the percentage yield of test
extracts indicated that GGME showed the highest
percentage yield (20.11) followed by COME (11.22)
and CSME (9.55). Preliminary phytochemical
screening indicated the presence of the following
phytoconstituents in selected medicinal plants: C.
F U LL L en g t h R e s e a rc h P a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Gupta Rajinder K et al: Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
68
sinensis (alkaloids, flavonoids, terpenoids and
tannins), G. glabra (carbohydrate, glycosides,
flavonoids, saponins, terpenes and sterol), C.
officinalis (flavonoids, saponins and terpenoids) and
Linum usitatissimum (terpenes, proteins and fatty
acids). In recent years, attention has been focused
on the oxidative stress while treating acne vulgaris
because the rate of generation of ROS is more than
the rate of its removal. Though the biological system
tries to protect with the help of enzymes like SOD
and CAT in case the activity of CAT gets reduced, yet
it leads to the accumulation of superoxide radicals
and hydrogen peroxide [
15
].
In the present
investigation, results clearly indicated (Table 1) that
amongst all test extracts, CSME showed the highest
amount of GAE of phenolic compounds (104.934 ±
1.630 mg/g) and the lowest was observed in LUPE
(1.620 ± 0.692 mg/g). COPE didn’t show any
phenolic content. Total phenolic content of the
extracts was found to be significant (P< 0.05).
Camellia sinensis is well known to be rich in
polyphenolic content and possesses antioxidant
activity. The constituents of C. sinensis include large
amounts of (-)-epigallocatechin, (-)-epicatechin, (+)-
gallocatechin, (+)-catechin, their derivatives [
16
],
rutin and myricetin which have been shown to
possess high antioxidant and free radical scavenging
activity and have a positive effect on the human
health. Phenols are the simplest bioactive
phytochemicals having free radical scavenging
ability due to the presence of hydroxyl groups. The
site and the number of hydroxyl groups present are
related to their relative toxicity to microorganisms,
showing that increased hydroxylation results in
increased toxicity [
17
].
Flavonoids are polyphenolic
compounds which play an important role in
stabilizing lipid oxidation and are also associated
with antioxidative action.
Flavonoid content of the
extracts in terms of (mg/g) rutin equivalents was
recorded (Table 1). Highest and lowest flavonoid
content was observed in GGME (115.503 ± 2.984
mg/g) and COPE (2.488 ± 1.659 mg/g) respectively.
This could be due to the licorice flavonoid
constituents possessing free radical scavenging
effect and antioxidant potential. Licorice flavonoids
contain mainly flavones, flavonols, isoflavones,
chalcones, dihydroflavones and dihydrochalcones
[
18
].
The in-vitro antioxidant activity of test extracts was
estimated using DPPH assay. All methanolic extracts
except LSME exhibited potent antioxidant activity
when DPPH radical was used as a substrate
to
evaluate the free radical scavenging activity. The
antioxidants reacted with DPPH, a purple coloured
stable free radical which accepts an electron or
hydrogen radical to become a stable diamagnetic
molecule. The amount of DPPH reduced was
estimated by measuring the decrease in absorbance
at 517 nm. A lower IC
50
value indicated a greater
antioxidant activity [
19
]. Our experimental data
indicated that though all the test extracts
demonstrate H-donor activity, still the highest
DPPH radical scavenging activity was observed in
CSME (IC
50
= 44.03 ± 1.784 µg/ml) followed by
GGME (IC
50
= 51.07 ± 3.050 µg/ml) and COME
(IC
50
= 111.96 ± 1.129 µg/ml) presented in (Fig. 1)
whereas LUME (IC
50
= 687.79 µg/ml) didn’t show
much radical scavenging activity. Mann-Whitney U
test showed comparison of ascorbic acid and active
methanolic extracts. P value < 0.05 was observed in
COME indicating data to be significantly different
whereas CSME and GGME showed P value > 0.05.
FRAP on the other hand gives a direct measure of
antioxidants or reductants in a sample which react
with ferric tripyridyltriazine (Fe
3+
TPTZ) complex
and produce a coloured product, ferrous
tripyridyltriazine (Fe
2+
TPTZ) [
20
].
All the plant
extracts showed a dose-dependent reducing activity
(Fig. 2). None of the plant extracts exhibited
absorbance higher than the standard Trolox.
Reducing activity of the extracts in terms of mg/g of
F U LL L en g t h R e s e a rc h P a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Gupta Rajinder K et al: Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
69
TE (y = 0.003x + 0.0749: r
2
= 0.98824) was between
(1046.330 ± 1.948 and 86.248 ± 2.329). The
highest FRAP activity was observed in GGME
(946.330 ± 1.948) followed by CSME (901.506 ±
2.044) and COME (460.089 ± 1.943) whereas the
lowest value was recorded in COPE (86.248 ±
2.091).
Screening for In vitro antimicrobial activity using
clindamycin phosphate as a positive control clearly
indicated that CSME, GGME and COME showed
promising antimicrobial activity against all the three
organisms. Furthermore, LUPE was found to be
more effective than LUME against aerobic and
anaerobic test strains. Highest zone of inhibition,
17.8 ± 0.016 mm, was observed for CSME against S.
epidermidis. Literature revealed strong relationship
between the total phenolic content and antioxidant
activity in many plant species because phenolic
compounds not only attack cell walls and cell
membranes by affecting their permeability but also
interfere with membrane functions like electron
transport, protein synthesis and enzyme activity.
Hence, active phenolic compounds could lead to the
destruction of pathogens [
21
].
Conclusion
The results of this study indicated that a higher
concentration of phenolic compounds in methanolic
extracts makes them a strong free radical scavenger,
which further indicates that these plants can be a
good source of natural antioxidants to prevent free
radical mediated oxidative stress in case of acne.
Therefore, further investigation is needed to explore
the parameters essential for formulation so that the
antioxidant and antibacterial potential of these
medicinal plants can be utilized to provide safe and
effective topical herbal formulation for the
treatment of acne.
Acknowledgments
We acknowledge the financial support from All India
Council for Technical Education
8023/BOR/RID/RPS-27/2008-09 & UGC-SAP-3-
23/2011. We also would like to thank Professor
Rama Choudhary, HOD, Microbiology, All India
Institute of Medical Sciences for providing the
anaerobic microbial facility to carry out antibacterial
activity of plant extracts.
References
1) Leyden JJ. Current issues in antimicrobial therapy
for the treatment of acne. J Eur Dermatol Venereol
2001; 3: 51-55.
2) Leyden JJ. Therapy for acne vulgaris. N Engl J
Med 1997; 336: 1156-1160.
3) Halliwell B. Reactive oxygen species in living
systems: Source, biochemistry, and role in human
disease. Am J Med 1991; 91: 14-22.
4) Alonso AM, Guillen DA, Barroso CG, Puertas B,
Garcia A. Determination of antioxidant activity of
wine by products and its correlation with
polyphenolic content. Journal of agriculture and
food chemistry 2002; 50: 5832-5836.
5) Stapleton PD, Shah S, Anderson JC, Hara Y,
Hamilton-Miller JMT, Taylor PW. Modulation of
β-lactam resistance in Staphylococcus aureus by
catechins and gallates. Int J Antimicrob Agents
2004; 23: 462-467.
6) Saeedi M, Morteza-Semnani, Ghoreishi MR. The
treatment of atopic dermatitis with licorice gel. J
Dermatolog Treat 2003; 14: 153-157.
7) Zitterl-Eglseer K, Sosa S, Jurenitsch J, Schubert-
Zsilavecz M, Della LR, Tubaro A et al. Anti-
oedematous activities of the main triterpendiol
esters of marigold (Calendula officinalis). J
Ethnopharmacol 1997; 57: 139-144.
8) Della LR ,Tubaro S, Sosa S, Becker H, Saar St,
Isaac O. The role of triterpenoids in the topical
anti-inflammatory activity of Calendula officinalis
flowers. Planta Med 1994; 60: 516-520.
9) Harborne JB. Phytochemcial methods. (London):
Chapman and Hall, Ltd. 1973.
F U LL L en g t h R e s e a rc h P a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Gupta Rajinder K et al: Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
70
10) McDonald S, Prenzler PD, Autolovich M, Robards
K. Phenolic content and antioxidant activity of
olive extracts. Food Chem 2001; 73: 73-84.
11) Chang C, Yang M, Wen H, Chern J, Estimation of
total flavonoids content in propolis by two
complementary colorimetric methods. J Food Drug
Anal 2002; 10: 178-182.
12) Blois MS. Antioxidant determinations by the use of
a stable free radical. Nature 1958; 26: 1199-1200.
13) Benzie IF, Strain JJ. The ferric reducing ability of
plasma (FRAP) as a measure of antioxidant power,
the FRAP assay. Anal Biochem 1996; 239: 70-76.
14) Bauer AW, Kirby WMM, Sherris JC and Turck M
(1966) Antibiotic susceptibility testing by a
standardized single disk method. American
Journal of Clinical Pathology 45:493-496.
15) Srinivasa R, Chandrasekar MJN, Nanjan MJ,
Suresh B. Antioxidant activity of Caesalpinia
digyna root. Journal of Ethnopharmacology 2007;
113: 284-291.
16) Mitscher L, Jung M, Shankel D, Dou J, Steele L,
Pillai S. Chemoprotection: A review of the potential
therapeutic antioxidant properties of green tea
(Camellia sinensis) and certain of its constituents.
Med Res Rev 1997; 17: 327-365.
17) Fujiki H, Yoshizawa S, Horiuchi T, SuganumaM,
Yatsunami J, Nishiwaki S et al. Anticarcinogenic
effects of (-)-epigallocatechin gallate. Prev Med
1992; 21: 503-509.
18) Guoxiu X, Nan L, Tong W, Meiyan Y. Advances in
studies on flavonoids of Licorice. Zhongguo Zhong
Yao Za Zhi 2003; 28: 593-597.
19) Yamaguchi T, Takamura H, Matoba T, Terao J.
HPLC method for evaluation of the free radical-
scavenging activity of foods by using 1, 1-diphenyl-
2-picrylhydrazyl. Biosci Biotechnol Biochem 1998;
62: 1201-1204.
20) Li Y, Guo C, Yang J, Wei J, Xu J, Cheng S.
Evaluation of antioxidant properties of
pomegranate peel extract in comparison with
pomegranate pulp extract. Food Chem 2006; 96:
254-260.
21)
Oktay M, Culcin I, Kufrevioglu OI. Determination
of in vitro antioxidant activity of fennel
(Foenniculum vulgare) seed extracts. Lebensm
Wiss Technol 2003; 36: 263-271.
F U LL L en g t h R e s e a rc h P
a p e r
C o v e re d in I n d e x C o pe r n ic u s w i th I C V a l u e 4 .6 8 fo r 2 0 1 0
Gupta Rajinder K et al: Screening for Antioxidant and Antibacterial potential of common
medicinal plants in the treatment of Acne
Int. J. Drug Dev. & Res., Jan-March 2012, 4 (1): 65-71
Covered in Scopus & Embase, Elsevier
71
... In this regard various extracts of G. glabra was screened and it was found that all the extracts contain sufficient amount of total phenols which are at par with the study of Cakmak et al., (2012) who determined considerable amount of total phenolic content (114.33 mg GAE g -1 ) in methanol root extract of G. echinata [21]. Likewise, Pratibha et al. (2012) reported that dichloro methane (DCM) fraction of root and stolon of G. glabra possessed notable amount of total phenolic contents (73.51 mg GAE g -1 ), which justifies our findings [22]. ...
... In this regard various extracts of G. glabra was screened and it was found that all the extracts contain sufficient amount of total phenols which are at par with the study of Cakmak et al., (2012) who determined considerable amount of total phenolic content (114.33 mg GAE g -1 ) in methanol root extract of G. echinata [21]. Likewise, Pratibha et al. (2012) reported that dichloro methane (DCM) fraction of root and stolon of G. glabra possessed notable amount of total phenolic contents (73.51 mg GAE g -1 ), which justifies our findings [22]. ...
... Our finding in this regards was also supported by Cakmak et al. (2012) who observed that methanol extract obtained from the root of G. echinata have remarkable antioxidant property with IC50 value of 184.99 µg ml -1 respectively [21]. Pratibha et al. (2012) examined that methanol extract of root and stolon of G. glabra have promising antioxidant activity with IC50 value of 51.07 µg ml -1 [22] whereas Tohma and Gulçin (2010) reported 52.20% and 54.40% of antioxidant activity of aqueous and ethanol root fractions of G. glabrai [35]. ...
Article
Full-text available
The ethnobotanical important wild medicinal plant Glycyrrhiza glabra (linn) was evaluated to determine various phytochemical constituents, antiox-idant activity, elemental composition and antibacte-rial activity. The stem, roots and leaves were screened to obtained crude methanol (MeOH), chlo-roform (CHCl3), ethyl acetate (EtOAc), n-butanol (BtOH) and aqueous (AQ) fractions. Results of phy-tochemical analysis divulged the presence of promising amount of total phenolic (159.56 mg GAE 100 g-1), total tannins (95.42 mg GAE 100 g-1), total fla-vonoids content (94.96 mg QE 100 g-1) in MeOH extract of root and leaves while lowest value was observed in CHCl3 fraction of stem (57.76 mg GAE 100 g-1), leaves (46.73 mg GAE 100 g-1) and root (44.60 mg QE 100 g-1). Remarkable antioxidant potential was observed in MeOH extract (80.58%) of root and trivial amount was found in CHCl3 fraction (56.77%) of leaves. Micro-minerals analysis reveals that lead (0.291 mg Kg-1), cadmium (0.780 mg Kg-1), chromium (0.172 mg Kg-1) and cobalt was found maximum in root parts whereas iron (414.0 mg Kg-1), zinc (68.33 mg Kg-1) and copper (60.33 mg Kg-1) was recorded in leaves. The antibacterial activity determine by well diffusion method divulges that all the extracts shows notable inhibitory activity against Proteus mirabilis, Escherichia coli and Agrobacte-rium tumefaciens.
... In vitro (48) Ex vivo (48) Human (68,69) Total extract Animal (33) Human (32,34) In vitro (36)(37)(38)(39)(40)(41)(42) In vitro (51) In vitro (51,62,63) In vitro (71) ...
... Licorice extract has demonstrated potent antioxidant and free-radical-scavenging effects in topical preparations (51,62,63). Glycyrrhizin (43), glabridin (54, 58-60), hispaglabridins A and B (58), licochalcone A (4, 31), and licochalcones B and D (61) have been reported with antioxidant activities. ...
Article
Full-text available
Clinical advantages of licorice (Glycyrrhiza spp.) have been investigated for several years. It has been traditionally used for a variety of disorders. Different constituents with various characteristics have been isolated from Glycyrrhiza spp. extracts. This review aimed to summarize the current knowledge on the pharmacological efficacy and safety of licorice extract constituents to treat the pathophysiology of acne vulgaris (AV) and the associated postinflammatory hyperpigmentation (PIH). Anti-androgenic, antimicrobial, anti-inflammatory, antioxidant, depigmenting, and skinturnover-accelerating properties have been identified for licorice extract which could be effective against AV and PIH through multiple pharmacological mechanisms. The active compounds responsible for these pharmacological activities, molecular mechanisms, safety profile, as well as the in vitro, in vivo, animal, and clinical studies are discussed. Licorice extract possesses broadspectrum activity and could be considered as an effective and safe option in the treatment of AV and its associated PIH. However, evidence-based clinical trials are required to prove its efficacy as well as safety. We hope this paper can provide new insights for further studies, particularly large controlled clinical trials.
... Granulation tissue undergoing maturation starting from the epidermis to the muscular layer is found in excision. In our study, we observed a remission of the inflammatory event after the third day for all the experimental models used in this study, confirming the data presented in the literature [17]. Marigold flowers have been widely used as an anti-inflammatory agent for the treatment of wounds, first degree burns, bruises, and skin eruption. ...
... Several pharmacological studies have confirmed the healing of wounds treated with Calendula officinalis [18,19]. A previously published study regarding the effect of a 1% aqueous solution of ethanol extract obtained from marigold flowers on skin wounds of Wistar rats showed that wound epithelialization in the group treated with marigold extract has started on day 7 of treatment, and full recovery was observed within 14 days [17]. Our results with regard to both wound contraction and healing time are significantly better. ...
Article
Full-text available
The present paper aims to formulate and characterize four phytotherapeutic ointments based on Hippophae fructus, Calendulae flos, Bardanae folium, and Millefolii herba, which are included in a novel ointment base. In order to investigate the healing properties of the ointments, in vivo experimental wound models of linear incision, circular excision, and thermal burn were performed on Wistar rats. Topical treatment was performed daily for 21 days. Determination of the wound contraction rate (WCR), the period of reepithelization, and histopathological examination were achieved. Additionally, for the tested ointments, oscillatory and rotational rheological tests were carried out, and for the extracts, HPLC analysis was performed. The results demonstrate that the tested novel ointments are safe for use and the most effective ointment proved to be the one based on Arctium lappa, followed by that of Calendulae flos.
... critical role in initiating and prolonging inflammation [18,19]. Phytochemicals exert their antioxidant properties by scavenging free radicals generated during the process of inflammation, thereby reducing oxidative stress and cell damage. ...
... In fact, one of the mechanisms underlying the anti-inflammatory effects of herbal extracts may be due, in part, to the antioxidant compounds they contain. It is widely recognized that excessive production of free radicals, such as hydroxyl, superoxide and nitrous oxide in sebum produced by C. acnes-infected sebaceous glands, and their uncontrolled regulation play a critical role in initiating and prolonging inflammation [18,19]. Phytochemicals exert their antioxidant properties by scavenging free radicals generated during the process of inflammation, thereby reducing oxidative stress and cell damage. ...
Article
Full-text available
Cutibacterium acnes (formerly Propionibacterium acnes) is a key pathogen involved in the development and progression of acne inflammation. The numerous bioactive properties of wild bitter melon (WBM) leaf extract and their medicinal applications have been recognized for many years. In this study, we examined the suppressive effect of a methanolic extract (ME) of WBM leaf and fractionated components thereof on live C. acnes-induced in vitro and in vivo inflammation. Following methanol extraction of WBM leaves, we confirmed anti-inflammatory properties of ME in C. acnes-treated human THP-1 monocyte and mouse ear edema models. Using a bioassay-monitored isolation approach and a combination of liquid-liquid extraction and column chromatography, the ME was then separated into n-hexane, ethyl acetate, n-butanol and water-soluble fractions. The hexane fraction exerted the most potent anti-inflammatory effect, suppressing C. acnes-induced interleukin-8 (IL-8) production by 36%. The ethanol-soluble fraction (ESF), which was separated from the n-hexane fraction, significantly inhibited C. acnes-induced activation of mitogen-activated protein kinase (MAPK)-mediated cellular IL-8 production. Similarly, the ESF protected against C. acnes-stimulated mouse ear swelling, as measured by ear thickness (20%) and biopsy weight (23%). Twenty-four compounds in the ESF were identified using gas chromatograph-mass spectrum (GC/MS) analysis. Using co-cultures of C. acnes and THP-1 cells, β-ionone, a compound of the ESF, reduced the production of IL-1β and IL-8 up to 40% and 18%, respectively. β-ionone also reduced epidermal microabscess, neutrophilic infiltration and IL-1β expression in mouse ear. We also found evidence of the presence of anti-inflammatory substances in an unfractionated phenolic extract of WBM leaf, and demonstrated that the ESF is a potential anti-inflammatory agent for modulating in vitro and in vivo C. acnes-induced inflammatory responses.
... [14] In our past work, we had screened methanolic extracts for phytochemical, antibacterial, and antioxidant potential. [15,16] The fundamental goal of the current investigation is to plan and evaluate herbal ethosomal gel formulations loaded with methanolic extracts of G. glabra and to assess for in vitro permeation studies that were carried out using modified Franz diffusion cell to study. The release of drug from the prepared vesicles and drug released from a hydroethanolic solution. ...
Article
Full-text available
Anti-acne herbal formulations are utilized for the treatment of acne vulgaris with the additional benefit of not creating adverse effects, unlike synthetic drugs. Phytoconstituents present in methanolic extracts of Glycyrrhiza glabra have antibacterial and antioxidant properties. An approved UV spectrophotometer confirmed the presence of glycyrrhizin in these extracts. Extracts loaded with Carbopol  940 were utilized for the preparation of herbal drug-loaded ethosomal gel formulations (EF1, EF2, and EF3) at various times and followed the assessment of ethosomal gel formulation. The evaluation of ethosomal gel formulation done by pH, viscosity, spreadability, texture analysis, differential scanning calorimetry, FT-IR spectral analysis, in vitro drug release study, and antioxidant activity against Propionibacterium acnes. Herbal ethosomal gel formulation demonstrated antibacterial potential and was additionally assessed for skin permeation by gamma scintigraphy utilizing hydrophilic radiotracer 99mTc-DTPA and lipophilic radiotracer 99mTc-MIBI. Significant permeation (1.3 μg/mg) was seen with a hydrophilic radiotracer named 99mTc-DTPA-PHF and this proposed that the formulation was equipped with sustained drug delivery for the treatment of moderate to an extreme type of acne.
... Glycyrrhiza glabra showed a remarkable antibacterial activity against P. acnes [19]. The methanol extracts of C. sinensis, G. glabra and C. officinalis can be a good source of natural antioxidants to prevent free radical mediated oxidative stress in acne [20]. In another study the extracts showed significant antibacterial activities against two gram-positive (Bacillus subtili and Stapphylococcus aureus) and two gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria [21]. ...
Article
Full-text available
ABSTRACT Background: Yuvana pidaka or the Mukha dhushika is the disease mentioned in Ayurveda which can be compared with the acne vulgaris in modern medicine. The young age is most vulnerable period for the disease but sometimes it is a problem in other age also. Ayurveda mainly emphasized external treatment for its management but some internal remedies especially Shodana treatment are also prescribed. Aims: The aim of this study was to study the effect of Vaynaya Yoga powder and Cream on Yuvana Pidaka. The target was the overcome the disease as well as the side effects like blackish spots. Methodology: Total 60 diagnosed patients were randomly allocated for three groups and Group I treated with Varnyayoga powder and Group II treated with Varnayayoga cream and Group III treated with both drugs. Treatment period was two months and assessment was done by the self prepared grading scale for 12 criteria. Results: The results show that Group III (combine treatment) was the most effective (over all relief was 77.29%) than the other two groups. The Group I and II over all relief was 54.15% and 25.19% respectively. Conclusions: By concluding combine as well as local application is more effective than the internal/oral treatment for Yuvana Pidaka.
... Glycyrrhiza glabra showed a remarkable antibacterial activity against P. acnes [19]. The methanol extracts of C. sinensis, G. glabra and C. officinalis can be a good source of natural antioxidants to prevent free radical mediated oxidative stress in acne [20]. In another study the extracts showed significant antibacterial activities against two gram-positive (Bacillus subtili and Stapphylococcus aureus) and two gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria [21]. ...
Article
Full-text available
Background: Yuvana pidaka or the Mukha dhushika is the disease mentioned in Ayurveda which can be compared with the acne vulgaris in modern medicine. The young age is most vulnerable period for the disease but sometimes it is a problem in other age also. Ayurveda mainly emphasized external treatment for its management but some internal remedies especially Shodana treatment are also prescribed. Aims: The aim of this study was to study the effect of Vaynaya Yoga powder and Cream on Yuvana Pidaka. The target was the overcome the disease as well as the side effects like blackish spots. Methodology: Total 60 diagnosed patients were randomly allocated for three groups and Group I treated with Varnyayoga powder and Group II treated with Varnayayoga cream and Group III treated with both drugs. Treatment period was two months and assessment was done by the self-prepared grading scale for 12 criteria. Results: The results show that Group III (combine treatment) was the most effective (over all relief was 77.29%) than the other two groups. The Group I and II over all relief was 54.15% and 25.19% respectively. Conclusions: By concluding combine as well as local application is more effective than the internal/oral treatment for Yuvana Pidaka.
... Flavonoids is able chelate trace metals through interaction with the catechol moiety in the B-ring, 3-hydroxyl, 4-oxo groups in the heterocyclic ring, and 4-oxo, 5-hydroxyl groups between the heterocyclic and the A-rings, decreasing the availability of these metals to participate in the generation of free radicals (25,29). According to the decline in the immune system and natural antioxidants in various diseases, the use of antioxidants as free radical scans is essential to eliminate ROS to reduce the cellular damage caused by acne inflammation (30). ...
... Flavonoids is able chelate trace metals through interaction with the catechol moiety in the B-ring, 3-hydroxyl, 4-oxo groups in the heterocyclic ring, and 4-oxo, 5-hydroxyl groups between the heterocyclic and the A-rings, decreasing the availability of these metals to participate in the generation of free radicals (25,29). According to the decline in the immune system and natural antioxidants in various diseases, the use of antioxidants as free radical scans is essential to eliminate ROS to reduce the cellular damage caused by acne inflammation (30). ...
Article
Full-text available
Background: Acne is the most prevalent skin disease in the world and antibiotics as its standard treatments have limited and also adverse effects. Cedar (Ziziphus spina-christi) has medicinal properties like antibacterial activity and is used topically for treatment of some kinds of skin problems in Persian medicine. The aim of this study was to evaluation the efficacy of topical cedar solution of acne vulgaris. Methods: Eighty patients aged between 15–45 years with mild to moderate acne vulgaris were conducted in this randomized, double blind trial. The participants were allocated to receive the topical cedar solution plus clindamycin 1% or topical placebo plus 1% clindamycin solution for six weeks. Patients were evaluated at the beginning of the study, second, sixth and eighth weeks after intervention for the acne severity index (ASI) and total acne lesions counting (TLC). Data was analyzed by SPSS software with Mann–Whitney U test. Results: From 105 subjects 68 people completed the study (33 persons in cedar group and 35 persons in placebo group). The mean and standard deviation of the age was 26.1 ± 7.5 years and 22 subjects (32.4%) were male. TLC and ASI in the sixth and eighth weeks in cedar group were significantly less than in placebo group (p < 0.001). Topical cedar solution had no serious side effects. Conclusion: The topical cedar solution plus clindamycin 1% was more effective and safe than placebo plus 1% clindamycin for the treatment of acne vulgaris.
... The study, however, only compared the activity of L. usitatissimum oil to petroleum, which is not as suitable a control, as petroleum has been shown to retard the rate of wound healing [63]. Investigation regarding the antimicrobial activity of S. aureus and Staphylococcus epidermidis is limited to the extract [170,171]. ...
Article
Full-text available
Wounds are a common medical infliction. With the increase in microbial resistance and a shift of interest towards complementary medicines, essential oils have been shown to be beneficial in suppressing microbial growth. However, in practice, essential oils are more often diluted into a base due to the risk of topical adverse effects, such as dermatitis. There is a lack of collated evidence-based information on toxicity and efficacy of carrier oils. The current information on the subject matter is restricted to generic, aroma-therapeutic books and pamphlets, based on anecdotal evidence rather than an experimental approach. Therefore, this review aimed at identifying the recommended carrier oils used in dermatology and thereafter collating the scientific evidence to support the use of carrier oils together with essential oils recommended for dermatological use. Aloe vera gel had multiple studies demonstrating the ability to enhance wound healing; however, several other carrier oils have been largely neglected. It was observed that the extracts for certain plant species had been used to justify the use of the carrier oils of the same plant species. This is an inaccurate cross assumption due to the difference in chemical composition and biological activities. Lastly, despite these carrier oils being recommended as a base for essential oils, very little data was found on the interactive profile of the carrier oil with the essential oil. This review provides a platform for further studies, especially if essential oils are to receive credence in the scientific field.
Article
Full-text available
Pomegranate is an important source of bioactive compounds and has been used for folk medicine for many centuries. Pomegranate juice has been demonstrated to be high in antioxidant activity and is effective in the prevention of atherosclerosis. In a previous study, we found that pomegranate peel had the highest antioxidant activity among the peel, pulp and seed fractions of 28 kinds of fruits commonly consumed in China as determined by FRAP (ferric reducing antioxidant power) assay. In this study, we extracted antioxidants from pomegranate peel, using a mixture of ethanol, methanol and acetone, and the antioxidant properties of the extract were further investigated as compared with the pulp extract. The contents of total phenolics, flavonoids, proathocyanidins and ascorbic acid were also measured. The results showed that pomegranate peel extract had markedly higher antioxidant capacity than the pulp extract in scavenging or preventive capacity against superoxide anion, hydroxyl and peroxyl radicals as well as inhibiting CuSO4-induced LDL oxidation. The contents of total phenolics, flavonoids and proathocyanidins were also higher in peel extract than in pulp extract. The large amount of phenolics contained in peel extract may cause its strong antioxidant ability. We concluded that pomegranate peel extract appeared to have more potential as a health supplement rich in natural antioxidants than the pulp extract and merits further intensive study.
Article
Flavonoids, with various biological activities, are considered as key compounds in propolis. In this study, quantitative determinations of flavonoids in propolis were conducted by two complementary colorimetric methods, aluminum chloride method and 2,4-dinitrophenylhydrazine method. Results suggested that the sum of flavonoid contents determined by the above two individual methods may represent the real content of total flavonoids. In this work, six raw propolis samples were investigated and the total contents of flavonoids ranged from 10.38 ± 0.14% to 24.91 ± 0.53%. As for the 12 commercial propolis products examined, the levels of total flavonoids in tinctures were all below 7% and those in powdery products varied from 2.97 ± 0.05% to 22.73 ± 0.72%.
Article
METHODS for measuring antioxidants and appraising antioxidant activity appear to be of two general types. If the chemical nature of the antioxidant is known, one may strive for a test specific for the compound or group of interest; for example, the nitroprusside test for sulphydryl groups. Alternatively one may observe the inhibition of some natural oxidative process such as the β-oxidation of fats, as a function of the added antioxidant.
Article
The phenolic component of freeze-dried olive fruit was fractionated by high-performance liquid chromatography using ultraviolet, atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI) detection. The fractions together with several standards were tested for antioxidant activity in an aqueous and a lipid system. The negative ion mode of APCI and ESI showed less fragmentation than positive ion mode. The latter was generally more useful in obtaining fragmentation data and hence structural information. Some olive phenolics notably tyrosol exhibited a low ionisation efficiency in both APCI and ESI. There was no simple relationship between antioxidant activity and chemical structure. The ranking of antioxidant activity was strongly dependent on both the test system and on the substrate demonstrating the need to examine activity in both aqueous and lipid systems. Significant antioxidant activity was seen in most olive fractions and this was related to phenolic content. The kinetics of the oxidation process are complex and suggest that multiple pathways may be involved at different antioxidant concentrations.
Article
In this study, the antioxidant activity of water and ethanol extracts of fennel (Foeniculum vulgare) seed (FS) was evaluated by various antioxidant assay, including total antioxidant, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, metal chelating activities and reducing power. Those various antioxidant activities were compared to standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α-tocopherol. The water and ethanol extracts of FS seeds showed strong antioxidant activity. 100 μg of water and ethanol extracts exhibited 99.1% and 77.5% inhibition of peroxidation in linoleic acid system, respectively, and greater than the same dose of α-tocopherol (36.1%). The both extracts of FS have effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. This antioxidant property depends on concentration and increasing with increased amount of sample. In addition, total phenolic compounds in the water and ethanol extracts of fennel seeds were determined as gallic acid equivalents. The results obtained in the present study indicated that the fennel (F. vulgare) seed is a potential source of natural antioxidant. Although, the tests presented here show the usefulness of FS extracts as in vitro antioxidants it still needs to be that this extracts show their activity in emulsions, biological systems, health implications or dry foods.
Article
Our research objective is to develop nontoxic cancer chemopreventive agents and to apply these agents in treating humans. We are identifying agents that inhibit the process of tumor promotion in two-stage carcinogenesis experiments on mouse skin. We review (a) the inhibitory effect of penta-O-galloyl-beta-D-glucose (5GG) on tumor promotion by teleocidin, one of the 12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters (5GG is structurally similar to (-)-epigallocatechin gallate (EGCG) and is isolated from hydrolyzed tannic acid); (b) the inhibitory effects of EGCG, the main constituent of Japanese green tea, on tumor promotion with two tumor promoters, teleocidin and okadaic acid, a non-TPA-type tumor promoter; (c) the mechanisms of action of EGCG, a single application of which reduced the specific binding of [3H]TPA and [3H]okadaic acid to a particulate fraction of mouse skin; and (d) the anticarcinogenic effects of EGCG on duodenal carcinogenesis induced by N-ethyl-N'-nitro-N-nitrosoguanidine in male C57BL/6 mice. EGCG is a nontoxic compound. We believe that the main constituent of Japanese green tea, EGCG, is a practical cancer chemopreventive agent available in everyday life.
Article
Reactive oxygen species are constantly formed in the human body and removed by antioxidant defenses. An antioxidant is a substance that, when present at low concentrations compared to that of an oxidizable substrate, significantly delays or prevents oxidation of that substrate. Antioxidants can act by scavenging biologically important reactive oxygen species (O2-., H2O2.OH, HOCl, ferryl, peroxyl, and alkyl), by preventing their formation, or by repairing the damage that they do. One problem with scavenging-type antioxidants is that secondary radicals derived from them can often themselves do biologic damage. These various principles will be illustrated by considering several thiol compounds.