Isolation and Antioxidant Activity Test of Symbiotic Fungi in Pletok Beer UTA'45 Jakarta

Bir pletok is a traditional Betawi herbal beverage composed of various spices known to contain bioactive compounds. In addition to the host plants, bioactive metabolites may also be produced by symbiotic fungi associated with these natural materials. This study aimed to isolate symbiotic fungi from bir pletok, identify their macroscopic and microscopic characteristics, determine their secondary metabolite content, and evaluate the antioxidant activity of ethyl acetate extracts using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Fungal isolation was carried out on Potato Dextrose Agar (PDA), followed by cultivation on rice medium for one month. Secondary metabolites were extracted by maceration using distilled ethyl acetate with three extraction cycles, and the solvent was removed using a rotary evaporator to obtain crude extracts. Phytochemical screening and antioxidant activity assays were then performed using UV–Visible spectrophotometry. The results showed that two fungal isolates were successfully obtained and designated as J.H and J.P . Based on their macroscopic and microscopic characteristics, the J.H was presumed to belong to the genus Aspergillus, whereas the J.P was presumed to belong to the genus Mucor. Phytochemical screening revealed that both isolates contained alkaloids, flavonoids, and tannins. The J.H extract was positive for steroids, while the J.P extract was positive for triterpenoids. The maximum absorption wavelength of DPPH was observed at 516 nm with an optimum reaction time of 30 minutes. The IC₅₀ value of ascorbic acid was 6.91 ppm. The IC₅₀ values of the J.H and J.P extracts were 122.79 ppm and 123.84 ppm, respectively, indicating moderate antioxidant activity. In conclusion, symbiotic fungi isolated from bir pletok have the potential to serve as natural sources of antioxidant compounds due to the presence of secondary metabolites capable of scavenging free radicals.