Antioxidant potential, content of phenolic and flavonoidscompounds in the aqueous and ethanolic extracts ofClincanthus nutans (Sabah snake grass)

The compounds of total phenolic content, total flavonoid content and antioxidant activity using ethanolic and hot aqueous extracts of Clinacanthus nutans (Sabah Snake Grass) was conducted at the School of Sustainable Agriculture in Universiti Malaysia Sabah, Sandakan, Sabah. The objectives of this study were to determine and evaluate the total phenolic content, total flavonoids content and antioxidant activity present in ethanol and hot aqueous extracts of Clinacanthus nutans plant, in order to elucidate the underlying relationship between potential antioxidant activity with the compounds of phenolic acids and flavonoid acids. The total phenolic content and total flavonoid content were estimated through the oxidation by molybdotungstate reagent (Folin-Ciocalteu) and total flavonoid test respectively. Meanwhile, the antioxidant activity was assessed through 2,2-diphenyl-1-picrylhydrazyl free scavenging radical assay. Datas were analyzed using one-way ANOVA. It was found; highest total phenolic content (1979.67 ± 126.93 mg GAE/100 g) was observed in ethanolic extract followed by (815.97 ± 20.52 mg GAE/100 g). There was a significant difference between these two extracts. Meanwhile, in total flavonoid content test, the ethanol extract (1716.01 ± 11.63 mg QE/100 g) had higher total flavonoid content as compared to hot aqueous extract (617.34 ± 4.42 mg QE/100 g) and they were significantly different (p<0.05). Present study showed that stronger antioxidant activity was observed in the ethanolic extract with the lowest IC50 value (34.11 ± 3.78µg/mL), whereas aqueous extract with high IC50 value (99.46 ± 0.79 µg/mL). Both of the total phenolic content and total flavonoid content exhibited strong negative correlation (r=0.99) with antioxidant activity in Clinacanthus nutans plant extracts.