Public Defense of a Ph.D Research Scholar at Department of Pharmacy
- 10:00 am
- Department of Pharmacy, UoP
This Ph.D dissertation is based on the biological screenings and phytochemical investigations of Hypericum oblongifolium, in which, the powdered material (12 kg) of the plant was extracted with 30 L of methanol. 2.4 kg of the methanolic extract was fractionated with different solvents (n-hexane, chloroform, ethyl acetate, n-butanol and water) according to their polarity. While 38 g of the methanolic extract was used for different biological activities. In in-vitro biological activities, various crude extracts of the plant have shown significant phytotoxic activity, except the chloroform extract. The methanolic extract showed 20, 20 and 0 % insecticidal activity against R. dominica, C. analis and T. castaneum respectively. Similarly aqueous fraction exhibited 20 % mortality against R. dominica. All the extracts except ethyl acetate were effective against Microsporum canis while no antibacterial activity was observed for any of the extracts.
The methanolic extract of H. oblongifolium (HOME) at doses of 100,200 and 300 mg/kg exhibited anti-nociceptive activity by outstanding reduction (p < 0.001) in the acetic acid induced writhing. However, no significant effect was observed in the hot plate test. Likewise substantial protection (p < 0.001) from carrageenan induced inflammation was exhibited by HOME at doses of 100, 200 and 300 in the four hours testing paradigm. Similarly, outstanding attenuation (p < 0.001) of hyperthermia induced by yeast was observed with 100, 200 and 300 doses of HOME and remained substantial up to 4 hours of administration. The methanolic extract at doses of 200 and 300 mg/kg produced a remarkable reduction (P < 0.001) in the locomotor activity. Moreover, significant reduction in the immobility time of anti-depressant activity was represented by HOME at 200 mg/kg (P < 0.01) and 300 mg/kg (p < 0.001).
Phytochemical investigation of the ethyl acetate soluble fraction of Hypericum oblongifolium (H. oblongifolium) has led to the isolation of two new compounds, folenolide and folicitin, and three known natural products, quercitin, 4- hydroxyphenylacetate and 4-dihydroxybenzoic acid . Structures of the compounds were determined with aid of NMR and Mass spectroscopic techniques.
4-Hydroxyphenylacetate has been isolated for the first time from a natural source while quercitin and 4-dihydroxybenzoic acid have been reported first time from this plant. These metabolites were characterized on the basis of detailed spectroscopic analyses. In- vitro anti-oxidant potential of the new compounds was evaluated by the DPPH radical scavenging assay. Folicitin exhibited promising antioxidant activity ((IC50 (p.g/10pL) SEM = 25.5 0.26)) while folenolide was found inactive.