Optimization of Anthocyanin Extraction from Rhodomyrtus tomentosa (ait.) Hassk. Fruits and their Antioxidant Potentials

Fruits of Rhodomyrtus tomentosa (sim fruits) are comprised of high amount of anthocyanin content. They are among the richest sources of anthocyanins, an indication that the plant is endowed with potential bioactive agents. Anthocyanins are plant pigments that play important roles in plant physiology, as well as, beneficial health effects to humans. In this study, optimal conditions for extraction of total anthocyanins of R. tomentosa fruits and their antioxidant activity were investigated. Parameters, such as solvent, acid concentration, solid-to-solvent, ultrasound, temperature, and time were applied for investigation of extraction efficiency of anthocyanins of the plant. Total anthocyanin content was determined via the pH differential method. Antioxidant activity of the anthocyanin-rich extract was then examined using DPPH and ABTS+ radical-scavenging assays and DCFH-DA method. The results showed that total anthocyanin content of up to 123.9 mg/kg was obtained from the sim fruits under the extraction conditions of acidified 50% aqueous ethanol by hydrochloric acid solution 0.1 M at a solid-to-solvent ratio of 1:4 with the assistance of ultrasound for 60 min before being processed at a temperature of 60oC for 60 min. The anthocyanins-rich extract was able to scavenge DPPH and ABTS+ radicals with IC50 values of 0.0173 ± 0.001 μg/mL and 0.0238 ± 0.0002 μg/mL, respectively. Moreover, the inhibitory activity of the anthocyanin-rich extract on intracellular reactive oxygen species production from macrophage RAW 264.7 cells was also evidenced. As a result, anthocyanins from R. tomentosa fruits might be a useful source of ingredients for the prevention of oxidant-induced disorders.