Bioprospecting of katang-katang leaves (Ipomoea pes-caprae) from Sumba Island, East Nusa Tenggara: antimicrobial, antioxidant and secondary metabolites content

Abstract

Ipomoea pes-caprae (Katang-katang) is one of the vegetations that grows in coastal area. Previous studies have proven that I. pes-caprae showed antibacterial, anti-inflammatory, and antioxidant properties. This research was conducted to characterize secondary metabolites content, antimicrobial activity and antioxidant activity of I. pes-caprae crude extract from Sumba, East Nusa Tenggara. The extraction was carried out using consecutive extraction method using n-hexane, ethyl acetate, and methanol with agitation (115 r.p.m for 24 hours). Phytochemical test and thin layer chromatography were performed to analyse the secondary metabolites in I. pes-caprae. In addition, total phenolic content (TPC) was calculated using Folin-Ciocalteu method. The antimicrobial activity was conducted using paper disc diffusion method against Bacillus cereus, Salmonella typhi, Escherichia coli, Micrococcus luteus, Candida albicans, and C. tropicalis. Phytochemical test and TLC analysis showed that n-hexane extract contained flavonoid, tannin, and steroid; ethyl acetate extract contained alkaloid, flavonoid, and terpenoid; while methanol extract contained alkaloid, tannin, and steroid. The antimicrobial activity gave negative results against all microbial pathogen. The ethyl acetate and methanol extracts were noted as a strong antioxidant agent with IC50 values of 65.7 ppm and 81.8 ppm. Moreover, TPC in each extract was 3.7 mg GAE/g in n-hexane extract, 6.4 mg GAE/g in ethyl acetate extract and 8.9 mg GAE/g in methanol extract.