Anti-encystment and amoebicidal activity of Lonicera japonica Thunb. and its major constituent Chlorogenic acid in vitro

Objective:To examine the acanthamoebicidal effects of ethyl acetate,aqueous and butanol fractions of dried flower buds of Lonicera japonica(L.japonica) Thunb.(Flos Lonicerae) in vitro.Methods:Acanthamoeba triangularis isolates were obtained from environmental water samples and identified by PCR.They were exposed to ethyl acetate,water and butanol fractions of L.japonica Thunb.at concentrations ranging from 0.5 mg/m L to 1.5 mg/m L.The extracts were evaluated for growth inhibition at 24,48 and 72 h,respectively.Chlorogenic acid at a concentration of 1 mg/mL was examined for inhibition of encystment.Results:Ethyl acetate fraction at a concentration of 1.5 mg/mL evoked a significant reduction of trophozoite viability by 48.9% after 24 h,49.2% after 48 h and 33.7% after 72 h Chlorogenic acid,the major active constituent of L.japonica Thunb.at the concentration of 1 mg/mL reduced the cysts/trophozoite ratio by 100% after 24 h,84.0% after 48 h and 72.3% after 72 h.This phenolic compound at concentration of 1 mg/mL concurrent with 0.6% hydrogen peroxide inhibited hydrogen peroxide-induced encystment by 92.8% at 72 h.Conclusions:Results obtained from this study show that ethyl acetate fraction at 1.5 mg/m L is the most potent fraction of L.japonica Thunb.and its major constituent chlorogenic acid showed the remarkable inhibition of encystment at a concentration of 1 mg/mL.

Phytochemical Analysis and Antioxidant Activity Determination on Crude Extracts of <i>Melodinus eugeniifolus</i>Barks and Leaves from Malaysia

Six different extracts of Melodinus eugeniifolus (a very rare medical plant belonging to Apocynaceae) leaves and barks were screened for their phytochemical composition, and free radical scavenging activities. Three different methods were used to test the antioxidant activity for extracts which include FRAP assay (Ferric reducing antioxidant potential), DPPH radical scavenging assay (1,1-diphenyl-2-picryl hydrazyl radical reducing power methods), and β-carotene bleaching assay. Among the different extracts tested, the ethanol extract of barks showed significant radical scavenging activities. Phytochemical analysis of the extracts revealed that the radical scavenging activities are mainly due to the presence of alkaloids, cardiac glycosides, sterols, steroids and flavonoids. The results obtained suggest that Melodinus eugeniifolus could be exploited in the management of various diseases like cancer, cardiovascular diseases and infection diseases. Highlights: Melodinus eugeniifolus, a very rare medical plant from South Asian rain forest which may be a potential drug for many diseases is first reported about its phytochemical characteristics and antioxidant activity by different methods.