Antibacterial properties of Persicaria minor (Huds.) ethanolic and aqueous-ethanolic leaf extracts.

Persicaria minor known as small water-pepper is used traditionally for the treatment of dandruffs and stomach indigestion. Therefore, this study was designed to evaluate the antibacterial activity of plant leaf material. 30% aqueous-ethanol and 100% aqueous were used for solvent extraction. Both extracts were evaluated for total protein and polysaccharide contents and results were compared. The extracts were then tested against four strains of bacteria; Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 11229, Staphylococcus aureus ATCC 6538and Pseudomonas aeruginosa ATCC 1544,at different concentrations using disc-diffusion and microplate dilution assays with penicillin being used as a positive control standard. Both extracts showed antibacterial activity against S. aureus, E. faecalis, and E. coli, respectively with aqueous-ethanolic extract being more potent. However, none of the extracts were active against P. aeruginosa. Results from this study truly illustrated high potential of P. minor leaves to be used topically as antibacterial agent for controlling of tested colony.

Antioxidant and tyrosinase inhibition activities of α- mangostin and Garcinia mangostana Linn. pericarp extracts.

The methanol, ethyl acetate and petroleum ether crude extracts of mangosteen pericarp and α- mangostin were evaluated for the antioxidant capacity and tyrosinase inhibition properties. The ferric reducing antioxidant power (FRAP) assay was used to investigate their antioxidant capacity. Tyrosinase inhibition effect was evaluated using mushroom tyrosinase inhibition assay. Methanol extract has higher antioxidant reducing capacity (m= 1.621), compared to the rest of the extracts. Meanwhile, ethyl acetate extract and α- mangostin showed potent tyrosinase inhibition activities as compared to Kojic acid, a well- known tyrosinase inhibitor. It is observed that tyrosinase inhibition effect is antioxidant independent as ethyl acetate extract possessed low antioxidant capacity. This study suggests direct tyrosinase inhibition by ethyl acetate extract of Garcinia mangostana.

Antioxidant and tyrosinase inhibition activities of Eurycoma longifolia and Swietenia macrophylla.

Extract from plants have been reported to contain valuable bioactive compounds that have potential in promoting antioxidant activity. The present study was aimed to investigate the extracts of two plants available in Southeast Asia, Eurycoma longifolia and Swietenia macrophylla for their primary metabolite contents, phenolic contents, antioxidant and anti- tyrosinase activity. Two types of solvents were utilised in the extraction process of both plants. Ethyl acetate found to be a better solvent for isolation of primary metabolite compound compared to methanol. For Folin-Ciocalteu assay, methanol extract of Swietenia macrophylla possed higher phenolic content while for Eurycoma longifolia, ethyl acetate extract had higher phenolic content. In DPPH assay, the radical scavenging activity of extracts were strongly correlated to the total phenolic content based on the percentage of DPPH radical scavenging of each extracts (p<0.05). In tyrosinase inhibition assay, the activity of each extracts were very low compared to standard Kojic acid. It was assumed that, the ability of plant extracts to inhibit tyrosinase are partly contributed by antioxidant potential of the extracts (p<0.01).