Abstract:The bioactivities of red and white guava fruit were compared and examined in this studied. Water and alcoholic extracts of the guava fruits were prepared, and their antioxidant activities, as well as inhibitory effects against α-glucosidase and ACE enzymes, were examined. The results revealed that the alcoholic extract of red guava exhibited the highest antioxidant activity, i.e. higher scavenging rates for ABTS+, hydroxyl, and DPPH free radicals, and higher ability of reducing Fe3+, compared with other extracts. As for the inhibitory effect against α-glucosidase, the ethanol extract of the white guava was the most effective with an inhibition rate of 93.99%. As for the ACE enzyme inhibitory activity, the water extract of the red guava was the most effective, achieving 43.03% inhibition at a mass concentration of 10 mg/mL. Qualitative analysis of the guava extracts using UPLC-QTOF-MS led to the identification of a variety of compounds, including mainly ascorbic acid, quinic acid, quinic acid, procyanidins, ellagins and catechins. The composition and contents of these compounds varied slightly with varieties and extraction methods. The results of the study showed that guava extracts possessed good bioactivities, and is expected to hold promise for promoting a healthy lifestyle. In addition, the chemical composition, content, and bioactivities of guava varied with varieties and extraction methods, which provide a reference for subsequent research.
