In vitro and in vivo bioactivities of leptocarpus disjunctus ethanolic extract

Abstract

Leptocarpus disjunctus Mast. is edible plant in the Southern region of Thailand. Although there is the indigenous warning about its side effects for dizziness and intoxicated symptoms. It has been eaten as side dish of the local food for a long time. This study aimed to investigate the secondary metabolites and biological activities of L. disjunctus. Determination of the secondary metabolites presented coumarin glycoside, tannin, steroid and sugar. Whole fresh plant was extracted with ethanol and performed in vitro and in vivo tests. This study found that L. disjunctus ethanolic extract had no antimicrobial property againstMicrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Bacillus cereus, Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa, Salmonella typhi, Salmonella typhimurium,Shigella sp., Candida albicans and Saccharomyces cerevisiae.Furthermore the ethanolic extract showed antioxidant propertieson various types of radicals. DPPH radical scavenging assay showed radical scavenging activity with EC50 of 0.8 mg/ml and positive control (BHT) showed EC50 of 5.96 mg/ml. Ferric reducing antioxidant power (FRAP) assay indicated that the ethanolic extract at the concentration of 25 mg/ml had a reducing power value equivalent to ferrous sulphate 6μmol/ml and ascorbic acid at the concentration of 0.031 mg/ml had a reducing power value equivalent to ferrous sulphate 3 μmol/ml. Nitric oxide radical inhibitory assay showed scavenging activity with EC50 of 2.32 mg/ml and quercetin activity was more pronounced with EC50 of 0.29 mg/ml. Betacarotene bleaching assay indicated that the ethanolic extract presented antioxidant activity only 4% compared to the positive control (BHT) which showed antioxidant capacity of 74%. Brine shrimp lethality and phototoxic activity tests indicated thatthe ethanolic extract of L. disjunctus had no cytotoxicity and genotoxicity against brine shrimp (LD50>500 mg/ml) and microorganisms respectively. Tyrosinase inhibitory assay indicated L. disjunctus was able to inhibit the enzyme with EC50 of 15.15 mg/ml while positive control (glutathione) had EC50 of 0.02 mg/ml. Alpha-glucosidase inhibitory assay indicated that ethanolic extract was able to inhibit enzyme with the EC50 of 6.13 mg/ml.The positive control (1- deoxynojirimycin) had EC50 of 0.0124 mg/ml. Furthermore, the ethanolic extracts of L. disjunctus whole fresh plant exhibited dose relationship of hypnotic effect in pentobarbitone induced sleeping time in mice. This study revealed the bioactive potentials of L. disjunctusfor antioxidation, anti tyrosinase, anti glucosidase and hypnotic agents.