Endofit merupakan mikroba yang hidup di dalam jaringan tanaman dan merupakan hubungan simbiosis mutualisme. Senyawa metabolit hasil fermentasi kapang endofit dapat digunakan sebagai sistem pertahanan bagi tumbuhan terhadap bakteri dan jamur patogen. Beberapa senyawa bioaktif yang dihasilkannya juga berfungsi sebagai sumber potensial obat baru.Tujuan penelitian ini adalah untuk mencari sumber potensial antimikroba dan antioksidan kapang endofit yang diisolasi dari ranting dan daun tanaman Garcinia mangostana. Fermentasi dilakukan terhadap kapang endofit yang telah diisolasi. Hasil fermentasi kapang endofit diekstraksi dengan menggunakan pelarut organik etil asetat, n-butanol, dan methanol.Hasil ekstraksi yang diperpoleh berupa fraksi-fraksi dari masing-masing pelarut organik . Ekstrak yang diperoleh diuji aktivitasnya sebagai antimikroba dan antioksidan. Uji aktivitas antimikroba dilakukan dengan metode cakram dan uji aktivitas antioksidan dilakukan dengan menggunakan radikal 1,1-difenilikrilhidrazil (DPPH). Uji aktivitas antimikroba dilakukan terhadap bakteri Escherichia coli, Staphylococcus aureus, Salmonella typhosa, Bacillus subtilis, Pseudomonas aeruginosa, Khamir Candida albicans, dan kapang Aspergillus niger.Hasil menunjukkan zona hambat terbesar dihasilkan oleh ekstrak R2.M terhadap Bacillus subtilis (12,85 mm) dan terhadap Staphylococcus aureus (11,90 mm). Aktivitas antioksidan terbaik diperoleh dari ekstrak n-butanol R18.B dengan nilai IC50 107,71 μg/ml.Endophytes are microbial entities that live within living tissue of plants and have symbiotic mutualism relationship. Metabolite compounds as a result of fermentation of endophytic fungi are useful as a defense against pathogenic fungi and bacteria. Some of bioactive compounds that are produced by endophytic fungi are also useful for novel drug discovery.

This research was done to screen new potential sources for antimicrobial and antioxidant agent from endophytic fungi that were isolated from twigs and leaves of Garcinia mangostana. Fermentation was done to endophytic fungi which had been isolated from sample. The fermentation products of endophytic fungi were extracted by using organic solvent ethyl acetate, nbuthanol, and methanol.

The result was some fractions from each solvent that was used. The extracts then were tested as antimicrobial and antioxidant activity. Antimicrobial assay was done by using the disc method and antioxidant was tested by using free radical 1,1-diphenylpicrylhydrazyl (DPPH). Antimicrobial assay was done against Escherichia coli, Staphylococcus aureus, Salmonella typhosa, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, dan Aspergillus niger.

The result showed that the largest zone of inhibition was performed by R2.M extract against Bacillus subtilis (12.85 mm) and against Staphylococcus aureus (11.90 mm). The best antioxidant activity was resulted from R18.B extract with IC50 107.71 μg/ml.