Evaluation of flavonoid compound in coconut waste and its antioxidant activity

Abstract The coconut tree, Cocos nucifera L., is planted for a variety of purposes. According to the Malaysian Agricultural Research and Development Institute (MARDI), rising coconut production has resulted in an increase in agricultural waste (coconut husk) in Malaysia (536,606 million coconuts in 2018 compared to 22,167 million coconuts in 2016). More than 60% of solid waste degradation in the environment is caused by the manufacture of coconut husks each year. Recycling coconut waste, particularly coconut husk, as a source of natural compounds offers environmental and economic benefits. The objectives of this study are to extract the flavonoid compounds from coconut husk from three different types of coconut fruit (Pandan Coconut, MAWA Coconut and Yellow Coconut) by using ethanolic solvent and compare them. Secondly, the antioxidant activity of coconut husk was determined by using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Thirdly, the alkaline reagent test was used to determine the presence of flavonoid compounds. The flavonoid compounds are existed in the coconut husk ethanolic extract and it have the antioxidant activity. IC50 of the standard compounds, ascorbic acid was 9.2 μg/ml. The most powerful radical scavenging effect was seen in Yellow Coconut husk extract, which had an IC50 value of 8.4 μg/ml. Flavonoids found in the husk of coconuts are known to have antioxidant properties. This shows that coconut husk extract has enormous potential as a natural preservative and a good bioresource of antioxidants.