Abstract

          The research objective was to evaluate the antioxidant activity, the allelopathic potentialon germination growth of Neptunia javanica Miq. seeds and the total phenolic content (TPC) of crude extracts and fractions from Lippia nodiflora(L.) Michx. In this research, the ethanol crude extracts of leaves (LE), stems (SE) and roots (RE) from L. nodiflorawere subjectedto study the antioxidant activity by using DPPH free radical scavenging assayand the allelopathic potential on germination seeds of N. javanica. The RE extractshad the highest antioxidant activity with IC₅₀ value of 136.87 ppm. The allelopathic effect of LE extracts at a concentration of20 mg/mL completely inhibited the seed germination of N. javanica. The LE fractions were separated by liquid-liquid partitionwith hexane and ethyl acetate system to afford the leaf hexane fraction (LH), leaf ethyl acetate fraction (LEtOAc) and leaf hydroethanolic fraction (LW). The antioxidant, TPC andallelopathic activities of all fractions were investigated. The antioxidant activity of LW (158.21)and LEtOAc (175.45) fractions werebetter than those of LE (296.87) extracts, whileLH fraction showed the lowest antioxidant activity at 722.08 ppm. The active allelopathic compounds in LEtOAc at a concentration of 10 mg/mL showed complete inhibition of radicle and hypocotyl on germination seed growth and50 % of seed growth inhibition (IC₅₀) was 3.14 mg/mL. Crude extracts and fractions showed more inhibited radicle growththan hypocotyl growth of N. javanica seeds. The TPC of leaves crude extracts andfractions werethe highest. Interestingly,the total phenolic content of LEtOAc fraction, was the highest (0.072 mg GAE/g) that was related to the good allelopathic properties, compared with other fractions and crude extracts. Our resultsindicate that the ethanolic crude extracts and an ethyl acetate fraction of L. nodiflora leaves can be applied to weed control, especially for N. javanica.

Keywords:Lippia nodiflora (L.) Michx., Neptunia javanica Miq.,Antioxidant Activity, Allelopathic Potential