Comparative study of the antioxidant and antibacterial activities of two guava (Psidium guajava) fruit varieties cultivated in Andasa Horticulture Site, Ethiopia

This investigation was carried out to evaluate the levels of phytochemicals and antioxidant potential as well as antibacterial activity of the two varieties of guava (Psidium guajava) fruit collected from Andasa horticulture site, Ethiopia. The antioxidant potential for guava fruit extracts was assessed using different in-vitro antioxidant assays, namely reducing power, Folin-Ciocalteu (F-C) assay and aluminum chloride methods. Overall, the white flesh guava fruit exhibited the highest levels of TPC, TFC and reducing power than the pink flesh guava. The mg/100g of AEAC (FRAP assay), AEAC (PMA), GAE and QE of pink and white flesh guava fruits determined in this study were 125.73, 260.28, 262.78, 377.18, 21.25, 24.61, 7.05 and 22.10, respectively. Antibacterial property of the two guava fruit variety extracts was evaluated against three gram-positive and two gram-negative bacteria using agar well diffusion technique. Ethanol extracts from both pink and white flesh guava exhibited antibacterial activity with zone of inhibition ranging from 29.50 to 30.33 and 24.33 to 29.33 mm respectively. On the other hand, only the chloroform extract from pink flesh guava showed poor antibacterial activity against MRSA and Shigella pathogens among the five tested organisms and the zone of inhibition measured was 11 and 10 mm respectively.