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Indian Journal of Pharmacology, Vol. 36, No. 4, August, 2004, pp. 244-245 Research Letter Pharmacological investigation of prunin-6"-O-p-coumarate: A flavonoid glycoside Harikrishna D, Appa Rao AVN, Prabhakar MC Departments of Chemistry, University College of Pharmaceutical Sciences, Kakatiya University, Warangal - 506 009 Code Number: ph04079 Sir, Flavonoids possess a wide variety of biological activities and in recent items this group of natural products has gained much interest as bioactive compounds[1]. Prunin-6"-O-p-coumarate a flavonoid glycoside was isolated first from the nut shells of Anacardium occidentale (Anacardiaceae) in 1978 by Wasiur Rahman and co-workers[2] and later in 1999 in our natural products laboratory. This glycoside is peculiar in that it is esterified by p-coumaric acid in glucose part. Literature survey reveals that this compound has not been screened for its pharmacological activity. We herewith report for the first time its antinociceptive, antiinflammatory, antioxidant and antibacterial activities. Prunin-6"-O-p-coumarate was isolated from the nut shells of Anacardium occidentale and it identity was established by spectroscopy (Mass, 1H-NMR and 13C NMR). Melting point was found to be 154-156°C and it coincides with the earlier report[2]. Its structure is shown in [Figure - 1]. Male Wistar rats (150-200 g) and Swiss albino mice of either sex (22-25 g) were used in the study. The animals were maintained under standard environmental conditions during quarantine period. Unless mentioned otherwise the test compound was administered as a suspension in distilled water containing 0.1% w/v of sodium carboxy methyl cellulose as suspending agent. Blank consisted of distilled water and 0.1%w/v of the suspending agent. For antinociceptive activity writhings were induced by acetic acid (1.0% v/v, 0.1 ml/10 g, i.p.) in mice[3]. Diclofenac (20 mg/kg, i.p.) was used as reference substance. Two doses of anacardium occidentale-1 (AO-1) (30 and 100 mg/kg, i.p.) were used. Antiinflammatory activity was tested by carrageenin induced rat paw edema[4]. Ibuprofen (50 mg/kg, i.p.) was used as a reference, and the doses of AO-1 tested were same as above. For the in vitro study of antioxidant activity of AO-1, a stable free radical a, a -diphenyl-b-picryl hydrazyl (DPPH) was used at a concentration of 0.2 mM in methanol[5]. in a set of clean, dry test tubes 1 ml of different concentration of AO-1 solution were taken (10,30,100,300 mg and 1 and 3 mg). To each of these tubes 2.4 ml of methanol and 0.5 ml of DPPH were added and mixed thoroughly. Immediately the absorbance due to DPPH reagent solution was read at 517 nm. It was read against a blank prepared identically without the drug (i.e., only DPPH in methanol). Blank readings were recorded for each concentration. The antibacterial activity of the test compound was investigated by an agar-well diffusion method against two gram positive (Bacillus subtilis and Staphylococcus albus) and two gram negative (Escherichia coli and Proteus vulgaris) bacteria[6]. AO-1 was dissolved in a mixture of water and dimethyl formamide (1:4). Streptomycin Sulphate was employed as the reference drug. All the investigations were carried out in duplicate. Simultaneous control investigations were done to observe the solvent effect. Results are expressed as mean+SD. The differences between experimental groups were compared by one-way ANOVA (control Vs treatment) followed by Student-Neuman-Keuls test and were considered statistically significant at P<0.05. The number of acetic acid induced writhings were significantly reduced by treatment with AO-1 in both the doses. The effect was found to be more than that of the standard, diclofenac (20 mg/kg) at a dose of 100 mg/kg [Table - 1]. AO-1 pretreatment significantly reduced the paw edema in rats. The effect was dose-dependent and at a dose of 100 mg/kg was comparable with that of Ibuprofen 50 mg/kg [Table - 1]. AO-1 has not shown any absorbance per se (without DPPH). The absorbance value of DPPH blank was found to be 0.175. AO-1 exhibited a dose dependent antioxidant activity in the DPPH assay. At 3 mg/0.1 ml concentration the absorbance value was 0.06. An antibacterial activity against both gram positive and gram negative organisms was also evident. MIC values of E. coli and B. subtilis was found to be 100 mg/ml (0.172 mM) and for P. vulgaris and S. albus it was 90 mg/ml (0.154 mM). AO-1 exhibited antinociceptive activity against acetic acid - induced writhings in mice. At the highest tested dose it was found to be more effective than diclofenac. AO-1 also possesses significant antiinflammatory, antioxidant and antibacterial activities. ACKNOWLEDGEMENTS The first author wishes to thank the University Grants Commission, New Delhi, for the financial support. Thanks are also due to Dr. B. Ravi Kumar for the supply of Prunin-6-O-p-coumarate. REFERENCES
Copyright 2004 - Indian Journal of Pharmacology The following images related to this document are available:Photo images[ph04079t1.jpg] [ph04079f1.jpg] |
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