Antioxidant Activity of Endophytic Fungi Isolated from Cashew (Anacardium occidentale) Leaves.

Cashew (Anacardium occidentale) is a plant used by Indonesian people a traditional medicine. The leaves are consumed as fresh vegetables and to treat various diseases. Endophytic fungi can live symbiotically in plant tissue and have the ability to produce substances called secondary metabolites. The research aims to isolate endophytic fungi from cashew leaves and identify them morphologically and molecularly as well as identify the secondary metabolite from the most active antioxidant extract. The identification of endophytic fungal species was done using morphological and molecular techniques. Both the culture and extraction processes used Potato Dextrose Broth (PDB) media and ethyl acetate as a solvent. The ethyl acetate extract, which is included in the strong antioxidant category, was continued to the stage of isolating the pure compound and then its chemical structure was analyzed using spectroscopic methods. A total of eight endophytic fungus (RDM1-RDM8) were found on cashew leaves. Ethyl acetate extract from the endophytic fungi RDM4 has the strongest antioxidant activity with an IC₅₀= 13.80 µg/mL. Morphological and molecular identification through phylogenetic analysis shows that RDM4 is Neopestalotiopsis clavispora. This endophytic fungus produces 5-isopropyl-4- methylfuran-2-one as a secondary metabolite. Ethyl acetate extract of the Neopestalotiopsis clavispora has more potential to be developed as a new source of antioxidants than the pure compound because it is thought that there is a synergistic effect between the compound components contained in the extract. [ABSTRACT FROM AUTHOR]