Phytochemical and Biological Activity Studies of Cosmos Caudatus and Curcuma Mangga and the Online Characterization of Bioactive Fractions from Melicope ptelefolia

Twelve species of Malay traditional vegetables were screened for antioxidant and nitric oxide (NO) inhibitory activities. Ferric thiocyanate (FTC), thiobarbituric acid (TBA) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) methods were used for the antioxidant activity measurements, and the Griess assay on elicited murine peritoneal macrophages was used to assess NO inhibitory activity of the extracts. Melicope ptelefolia, Cosmos caudatus, and Curcuma mangga were selected for further study, based on the results of their biological activity evaluations. Characterization of the NO inhibitory fractions of the Melicope ptelefolia using on-line high performance liquid chromatography (HPLC)-diode array detector (DAD)-mass spectrometry (MS), identified seven main constituents. The compounds were identified as kokusaginine (1), either kokusagine (2a) or 5- methoxymaculine (2b), 3-prenyl-2,4, 6-trihydroxyacetophenone (3), 3 (4), 3-geranylgeranyl- 2,4,6-trihydroxyaceto-phenone (5), 3-[4-O-(3,7-dimethyl-2, 6-octadienyl)phenyl]-2-propenoic acid (6),and 3- farnesylgeranyl-2,4,6-trihydroxyacetophenone (7). Phytochemical investigation of the methanolic extract of Cosmos caudatus led to the isolation of four known compounds namely, quercetin 3-O-β- arabinofuranoside (17), quercetin 3-O-α-rhamnoside (18), quercetin 3-O-β-glucoside (19), and quercetin (20). All four compounds isolated from C. caudatus showed strong antioxidant activity. The activity was in the order of 20 > 17 > 18 > 19 > α-tocopherol (standard).

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