Anticholinesterase, Antioxidant and Nitric Oxide Scavenging Activity of the Aqueous Extract of Some Medicinal Plants.

Aims: Enhancement of cholinergic activity and reduction of oxidative stress by scavenging free radicals such as nitric oxide are well recognized therapeutic approaches in several pathological conditions. We evaluated the anticholinesterase, antioxidant and nitric oxide scavenging activity of the aqueous extracts of Ocimum basilicum, Curcuma longa and Solanum nigrum. Study Design: Experimental. Place and Duration of Study: Delhi Institute of Pharmaceutical Sciences & Research, Delhi University, New Delhi, India between January 2008 and December 2008. Methodology: The aqueous extracts of the rhizome of Curcuma longa, berries of Solanum nigrum and seeds of Ocimum basilicum were authenticated by HPTLC fingerprinting. The anticholinesterase activity of these extracts was estimated spectrophotometrically as described by Ellman in 1961 and IC50 was calculated. Total antioxidant capacity of extracts was also estimated spectrophotometrically based on the reduction of molybdenum (Mo) (VI) to Mo(V) by the sample and the subsequent formation of a green phosphate/Mo(V) complex at acidic pH. Ascorbic acid was used as standard. Estimation of nitric oxide scavenging activity of extracts was based on the diazotization reaction. Results: The anticholinesterase activity (IC50) was observed at the concentrations of 2.73 ± 0.09, 3.38 ± 0.05 and 3.88 ± 0.11 gram/l for Solanum nigrum, Curcuma longa, and Ocimum basilicum respectively. At these concentrations, maximum antioxidant capacity equivalent to 4.36 ± 0.14 mM of ascorbic acid was shown by Curcuma longa, followed by Solanum nigrum, and Ocimum basilicum. Curcuma longa showed the maximum nitric oxide scavenging activity equivalent to 29.78 ± 1.28 mM of sodium nitrite followed by Solanum nigrum and Ocimum basilicum. Conclusion: Plant derived pharmacological agents may provide an attractive therapeutic option in future for several pathological conditions especially the neurodegenerative diseases due to their anticholinesterase, antioxidant and nitric oxide scavenging properties.

In vitro antioxidant activity of Hedyotis corymbosa (L.) Lam. aerial parts.

The methanolic extract of the aerial part of Hedyotis corymbosa (L.) Lam. (Rubiaceae) was screened for antioxidant activity using 1,1-diphenyl-2-picryl hydroxyl (DPPH) quenching assay, 2,2’-azinobis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) cation decolorization test, ferric reducing power (FRP), scavenging capacity towards hydroxyl ion (OH·) radicals and nitric oxide (NO) radical inhibition activity using established assay procedures. Total phenolics and total flavonoid contents were also determined. The plant yielded 210 mg gallic acid equivalent/100 g phenolic content and 55 mg quercetin equivalent/100 g flavonoid content. The extract exhibited high antiradical activity against DPPH, ABTS, nitric oxide and hydroxyl radicals with EC50 value of 82, 150, 130, and 170 µg/ml, respectively. The FRP increased with increasing concentration of the sample. The antioxidant activity of the extract was comparable with that of the standard butylated hydroxyl toluene (BHT). High correlation between total phenolic/flavonoid contents and scavenging potential of different reactive oxygen species (R2 = 0.785-0.998) indicated the polyphenols as the main antioxidants.