Comparative analysis of antioxidant and antimelanogenesis properties of three local guava (Psidium guajava L.) varieties of Thailand, via different extraction solvents

The antioxidant and antimelanogenesis potentials of three local varieties of guava ( Psidium guajava L.) from Thailand namely: Pansithong, Thai original and Kimju were studied. The extracts were made with water, 40 % ethanol and simulated gastrointestinal digestion (SGD). Antioxidant properties were determined by total polyphenolic compounds, DPPH assay, superoxide anion assay and hydroxyl radical assay. Antimelanogenesis properties were determined by anti-tyrosinase assay, total phenolic acid and total vitamin C contents. The results for antioxidant analysis revealed that Pansithong, when extracted by 40 % ethanol and SGD showed the presence of highest polyphenol compounds, and DPPH antioxidant activity respectively. Kimju exhibited the highest hydroxyl radical antioxidant activity among all extracts and highest superoxide anion antioxidant activity, when extracted by 40 % ethanol. The results for antimelanogenesis determination presented that Kimju showed highest tyrosinase inhibition, total phenolic acid and total vitamin C contents. It was concluded that Pansithong showed highest antioxidant potential while the highest antimelanogenesis potential was found in Kimju. Over all water has been found as the best solvent for antioxidant extraction followed by 40 % ethanol and SGD.