Antioxidative activity and catechin content of four kinds of Uncaria gambir extracts from West Sumatra, Indonesia

Abstract

Gambir cubadak (GC), gambir udang (GU), gambir riau mancik (GRm) and gambir riau gadang (GRg) are popular cultivars of Uncaria gambir in Siguntur, West Sumatra, Indonesia. The aqueous extract of gambir has been used as traditional medicine to treat diarrhea, sore throat and some studies have attributed it to the presence of antioxidant properties. The purpose of this study was to characterize the antioxidative activity and properties of four kinds of gambir extract. The antioxidative activity and properties were determined using 1,1-diphenyl-2picrylhydrazyl (DPPH) radical scavenging activity and HPLC. Reaction times of 2 min and 30 min were used to compare the measurement of DPPH. Cell viability was determined using a cytotoxicity assay. Results indicated that the four kinds of U. gambir provided antioxidants that were effective and safe. Total polyphenol contents of GC, GU, GRm, and GRg were 13.86, 13.60, 13.58 and 13.90 g 100 g-1, respectively. Catechin is a major component of gambir extracts. GC and GRm contain caffeic acid (0.99 and 0.98 μg ml-1), while in GU and GRg, it is not detected. The catechin contents of GC, GU, GRm and GRg was 104.5, 101.2, 99.4 and 108.5, 104.5 μg ml-1. In conclusion, the results indicated that GC, GU, GRm and GRg, showed similar tendencies as antioxidants. The presence of catechin influences the antioxidant properties and the reaction time of 30 min was recommended for the measurement of DPPH scavenging activity because of slow acting antioxidant material in gambir.   Key words: Antioxidant, catechin, DPPH, Uncaria gambir.