Passiflora suberosa L. belonging to the family Passifloraceae is an important medicinal plant used in traditional medicinal system in Sri Lanka to treat diabetes, hypertension and skin diseases. We extracted P. suberosa leaves under reflux conditions using different solvents (hexane, chloroform, methanol and water), then subjected to phytochemical screening. Alkaloids, flavonoids and saponins and saponins and anthraquinones were present in hexane and chloroform extracts. Alkaloids, unsaturated sterols, triterpenes, saponins, flavonoids and tannins were observed in both methanol and aqueous extracts. Proanthocyanidins were observed only in the aqueous extract. Hence, aqueous and methanol extracts with most classes of phytochemicals present were subjected to antimicrobial, antioxidant, antihaemolytic activities and Brine shrimp lethality studies. Antibacterial activity and minimum inhibition concentrations were evaluated using three Gram-positive (Bacillus subtilis, Staphylococcus aureus and Enterococcus faecium) and three Gram-negative bacteria (Pseudumonas aeruginosa, Salmonella typhimuriam and Escherichia coli). The results indicated that only the methanol extract of P. suberosa exhibited antibacterial activities against all the strains of Gram-negative and Gram-positive bacterial with stronger activity against Gram-negative bacteria. DPHH (2,2-diphenyl-1-picrylhydrazy) scavenging assay was adopted to evaluate antioxidant properties while antihaemolytic and toxic activities were studied respectively using cow blood and Brine shrimp lethality assay. The IC50 values of the aqueous extract in both antioxidant and antihaemolytic assays were significantly lower than the standard ascorbic acid. Similar results were observed in the Brine shrimp lethality assay. In conclusion both aqueous and methanol extracts of P. suberosa leaves showed the presence of majority of phytochemicals including proanthocyanidins. Antibacterial activity was obtained only for methanol extract with better activity against Gram-negative bacteria. The aqueous extract showed better antioxidant, antihaemolytic and toxic activities than the methanol extract and their respective standards. Further investigations on the chemical composition and possible isolation of active ingredients is warranted.

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Plants are the basis of traditional medicine system and have been the source of many of novel drug components. Passiflora suberosa is used in Sri Lankan Ayurvedic system to treat many diseases including diabetes. The objective of the present study was to evaluate phytochemical constituent of different extracts and antimicrobial effect of methanol and aqueous extracts of leaves of P. suberosa. Aqueous, methanol, chloroform and hexane extracts of leaves of P. suberosa obtained under reflux conditions were subjected for phytochemical screening according to previously established methods. Aqueous and methanol extracts of P. suberosa leaves possessed more phytochemicals, thus those extracts were subjected for antimicrobial study which was obtained using minimum inhibition assay as determined by agar well diffusion method. Both methanol and aqueous extracts ranging from 6 μg/ml -800 μg/ml were tested against both gram positive (Bacillus subtilis, Staphylococcus aureus and Enterococcus faecium) and gram negative bacteria (Pseudumonas aeruginosa, Salmonella typhimuriam and Escherichia cloi) while Gentamicin was used as the standarded drug. The phytochemical screening revealed the presence of saponins and anthraquinones in the chloroform extract, alkaloids, saponins, and flavonoids in the hexane extract and alkaloids, unsaturated sterols, triterpenes, saponins, flavonoids and tannins in both methanol and aqueous extracts. Proanthocyanidin, which is a potent free radical scavenger, was observed only in the aqueous extract. Further, only methanol extract was found to possess moderate activity against all the tested bacterial strains. Highest concentration (800 μg/ml) of methanol extract showed widest zone of inhibition (7 mm), indicating moderate activity against tested bacterial strains. In contrast, the aqueous extract showed poor activity against tested bacterial strains. In conclusion, results revealed the presence of bioactive natural compounds in aqueous and mehtanolic extracts that may be used in the development of pharmaceutical products. Similarly, preliminary studies on antimicrobial activity exhibited antimicrobial potential of methanol extract, which could be used as future antimicrobial sources for natural therapies, food industry.