Application of Microwave and Ultrasonication for Anthocyanin Extraction Process from Garcinia indica Choisy Fruit Waste and Assessment of Antioxidant Activity using Caenorhabditis elegans Model

Abstract: Garcinia indica (also known as kokum) is a small evergreen tree that has been used in a variety of culinary, industrial, and pharmacological products, as well as fruit juices and food. In the present study, the antioxidant capacity of anthocyanin extracted from Garcinia indica fruit waste was assessed using DPPH, ABTS assay, and a Caenorhabditis elegans infection model. The independent variables, such as temperature, solvent concentration, microwave exposure, and exposure to ultrasonication were integrated as independent variables in a five-level central composite design using response surface methodology. Based on statistical analysis, the generated models were successfully utilised to analyse the experimental data and determine the best extraction conditions. The rescue effect of anthocyanin was further studied using a paralysis and killing assay in a C. elegans infection model. The extraction yield was 21.0 mg/g under these conditions, with antioxidant activity of 9.9 µg/ml by ABTS assay and 6.6 µg/ml by DPPH assay, respectively. Furthermore, as compared to ethanol leaching extraction, this experimental design increased anthocyanin yield by more than 15 fold. The treatment of anthocyanin with C. elegans from E. coli and Pseudomonas aeruginosa PAO1 infection resulted in a significantly longer lifetime. Garcinia indica fruit waste extracts high in anthocyanins might be employed as natural food colorants and antioxidant additives in food products.