In the present study, the zinc oxide nanoparticles (ZnO NPs) were synthesized from the leaf extract of Vitex trifolia L. GC and GC-MS analyses revealed that the V. trifolia contained 17 compounds. The major chemical components identified were Vitrifolin A (22.11%), 20-hydroxyecdysone (13.78%), 5-Thio D-glucose (10.32%) and 1,1-Bicyclopropyl-2-octanoic acid, 20-hexyl; methyl ester (8.33%). The synthesized ZnO NPs was characterized by UV-Vis, PL, XRD, FT-IR, SEM, FE-SEM, EDX and TEM techniques. The photodegradation of methylene blue (1 x 10 (3) M) under UV light have been tested using final ZnO products. It was found that maximum decoloration efficiency occurred by 90 min with 30 mg of ZnO NPs catalyst dose. In addition, the antimicrobial activity was evaluated by disc diffusion, MIC, MBC and MFC procedure. The results depicted that the inhibition zone is dependent on the ZnO NPs concentration and green synthesized ZnO NPs had outstanding antimicrobial activity than others (bare ZnO, leaf of V. trifolia). The possible reason may due to the Vitrifolin A (major compound of leaf extract) which binds the surface of the nanoparticles increased the antimicrobial activities. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.