Anti-oxidant activity, phenolic and flavonoid constituents of Crude extracts from Piper ribesioides and Zanthoxylum limonella traditional herbal medicine in Northern Thailand

Abstract

The objective of current study was to evaluate an anti-oxidant activity with different solvent polarities (methanol, ethyl acetate, dichloromethane, and hexane) derived from stem of Piper ribesioides together with stalk and seed of Zanthoxylum limonella traditional herbal medicine in Northern Thailand.  Natural antioxidant in medicinal plants were defined for provide antioxidant activity by DPPH scavenging assay together with quantification of the phenolic and flavonoid constituents using Folin Ciocalteau and Aluminium chloride method, respectively.  The polar methanol extract showed greatest antioxidant effect, while ethyl acetate was the second order reaction both in P. ribesioides and Z. limonella.  The ability of methanol extract from stem of P. ribesioides exhibited strongest antioxidant DPPH radical scavenging with IC₅₀ values as 0.2 mg/ml, which was correlated with maximum value of total phenolic acid (68.83  0.38   mg equivalent of gallic acid per gram, mgGAE/g) and flavonoid content (37.13  0.47 mg equivalent of quercetin per gram, mgQE/g).  Similarly, the highest anti-oxidant activity of Z. limonella stalk and seed extract on methanol extract showed IC₅₀ values as 0.26 and 0.37 mg/ml, respectively.  Stalk showed higher phenolic content (53.67  0.45 mgGAE/g) than seed (24.15  0.48 mgGAE/g) as well as total flavonoid content of stalk (25.76  0.43 mgQE/g) and seed (10.25  0.63 mgQE/g).  A relationship between antioxidant activities and increasing levels of total phenolic compounds -or flavonoids was found to be active based on solvent polarities in the extraction of these medicinal plants.  Our findings revealed the preliminary scientific evidence for develop traditional herbal medicine into a valuable source for the future of human health care.