Antifungal activity of mangosteen pericarp and cashew leaf extract against Fusarium oxysporum in vitro

Polyphenols are secondary compounds that occur widely in plants and are highly effective in controlling plant pathogenic microorganisms. This study aimed to screen polyphenolic-rich plant extracts for their antifungal potential against Fusarium oxysporum. Several plant materials including cashew leaves, castor fruits, castor leaves, coffee husks, giant milkweed leaves, mangosteen pericarps and soapberry fruits were investigated for their total phenolic content. The results showed that cashew leaves and mangosteen pericarps contained high level of polyphenols at 108.23 and 124.14 mg GAE/g, respectively. The main phenolic compounds found in cashew leaves were gallic acid and protocatechuic acid at 377.29 mg/100 g and 56.44 mg/100 g, respectively. Mangosteen pericarps contained 16.22 mg/100 g protocatechuic acid and 55.75 mg/100 g of chlorogenic acid. The antifungal activity of cashew leaf and mangosteen pericarp extracts against F. oxysporum was 32.92 - 77.08% and 68.33 - 83.75%, respectively at the extract concentration from 2% to 10%. The combined use of cashew leaf and mangosteen pericarp extracts exhibited an additive inhibition against F. oxysporum. Cashew leaves and mangosteen pericarp are potential materials for producing bio-fungicides, which are not only effective but also safe for human and the environment.