Abstract Book - 3rd International Symposium on Medicinal Plants ...

1.81 Antioxidant Activity and Scavenging Effect of Oregano and Tea
Aqueous Extracts.
Senator Abderrahmane, Belambri, S.A, Kaabour, F., and Bouriche, H.
Laboratory of Applied Biochemistry, University Ferhat Abbas, Setif, Algeria.
<strong>Abstract</strong>: Antioxidant activity and free radical-scavenging capacity of aqueous extracts obtained
by decoction and infusion from oregano and tea leaves were determined by four different assays
(DPPH radical scavenging activity, antioxidant activity with β-carotene/linoleic acid assay, total
antioxidant activity and metal chelating activity). Leaves of oregano were collected from Setif
region, whereas Chinese green tea (disma) was purchased from local supermarket (Setif, Algeria).
Tea and oregano extracts were prepared from 10g of dried leaves steeped in 200 ml of boiled
water or boiled in the same volume for 20 min, respectively. After filtration and centrifugation, the
residue was lyophilized. Results indicated that the four extracts of oregano and tea exhibited
significant and similar DPPH radical scavenging activity, but slowly lower than the activity of
ascorbic acid used as standard antioxidant. This activity was concentration-dependent and
became stable when it riches the maximum values of 86% and 88 % for oregano and tea
respectively. The four extracts also inhibited similarly and strongly lipid peroxidation; at the same
concentration (130 µg/ml) similar inhibition was obtained with BHT, used as positive control. The
absorbance of β-carotene solution remained stable in presence of each extract during all the
incubation period (120 min). The total antioxidant activity was measured using ferric thiocyanate
test which determines the amount of peroxides produced at the initial stage of lipid peroxidation.
Lower absorbance indicates a higher level of antioxidant activity. The extend of inhibition of lipid
oxidation is very important with all the samples tested, which is in agreement with results obtained
in β-carotene/linoleic acid assay system. In fact, in the presence of both extracts of tea and
oregano, absorbance remained very low during all the incubation time. After 96 h, inhibition of lipid
peroxidation was about 88-90%. Moreover, both extracts of tea exhibited a considerable Fe 2+ -
chelating activity (80% maximum), with IC 50 of 1.73 mg/ml and 1.55 mg/ml respectively. However,
oregano extracts showed a moderate chelating activity (65% maximum) with IC 50 of 2.50 mg/ml
and 2.80 mg/ml, respectively. Leave infusion or decoction extracts of oregano and tea can be used
potentially as a readily accessible source of natural antioxidants principles and a possible
pharmaceutical supplement.
Key words: Antioxidant, decoction, tea extract, infusion, oregano extract, scavenging.
1.82 Study of Tyrosinase Inhibitory Activity of Major Fractions of Quercus
infectoria Galls
Sharififar , Fariba 1 , Purhemati, Amin 2,3 , Moshrefi , Mandana 2,3 , Raeiat ,
Zeinab 1
1 Traditional and Herbal Medicines research Center, Department of Pharmacognosy, Faculty of
Pharmacy, Kerman University of Mediacl Sciences, Kerman, Iran. 2 Department of Plant Protection,
Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran. 3 American Chemical
Society, Washington, DC 20036, USA.
<strong>Abstract</strong>: Our previous studies have poven the high tyrosinase inhibitory effects of Quercus
infectoria galls, an endemic plant to Iran. Considering the potency of tyrosinase inhibitors in
cosmetic as a skin depigmentation and lightening agent, we have studied the galls of Quercus
infectoria, and its major fractions for tyrosinase-inhibitory activity. Methanolic extract of Q.
infectoria galls was evaporated in vaccum. The resulting residue was suspended in water and
extracted successively with increasing orders of a combination of petroleum ether, chloroform,
ethyl acetate and methanol in increasing order of polarity. As a result, fractions 1–18 were
obtained. The fractions were initially screened for the O-diphenolase inhibitory activity of
tyrosinase using L-tyrosine as substrate on TLC plate by bioautography method. All the active
inhibitors from the first test were dissolved in methanol to give at least 5 concentrations. 80
microliter of L-tyrosine (0.5mM) was added to wells containing 50 microlitre sample, incubated for
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