Isolation and identification of active antioxidant compound derived from endophytic fungus BoCiClD-2 in turmeric (Curcuma longa) plant

The turmeric plant serves as a botanical origin of antioxidant compounds. One potential approach to expedite the generation of antioxidant compounds from turmeric involves the utilization of its endophytic fungi. Endophytic fungi, identified as microorganisms that inhabit plant tissues, demonstrate an ability to produce chemical compounds derived from host plants, thereby exhibiting potential as pharmaceutical agents. This study aims to isolate and characterize antioxidant compounds derived from turmeric endophytic fungus BoCiClD-2 extract. The chemical compounds originating from the fungus were obtained via a dynamic liquid fermentation process in a solution comprised of potato dextrose broth (PDB) on a rotary shaker over 12 days at ambient temperature. The crude extract was purified using column chromatography followed by 2-dimensional thin-layer chromatography. The antioxidant activities of the extract and fraction were assessed through the implementation of the DPPH free radical scavenging method. The active compounds were characterized by FTIR spectrophotometry, proton spectrophotometry, carbon, and DEPT NMR. EtOAc crude extract and fraction II from endophytic fungus have antioxidant activity with IC₅₀ values of 96.08±0.06 and 96.23±0.09μg/mL, respectively. Then, fraction II.2, obtained from the second purification from fraction II, had the highest antioxidant activity of 51.85%. Interpretation of NMR spectrophotometer data from fraction II.2 showed that the compound suspected to have antioxidant activity was 3-hydroxy-4-methyl benzoic acid. Therefore, the endophytic fungus BoCiClD-2 has the potential for development as a generator of naturally occurring active compounds that possess antioxidant properties.