Antioxidant and immunosuppressive activities of extracts of endophytic fungi isolated from Psidium guajava and Newbouldia laevis

Abstract

BackgroundPlant endophytic fungi have been recognized as an important and novel resource of natural bioactive products with potential application in different fields of life. PurposeThe present work evaluated the antioxidant and immunosuppressive activities of the extracts of endophytic fungi isolated from Psidium guajava and Newbouldia laevis. Study design/methodsEndophytic fungi were isolated from the selected plants and their secondary metabolites extracted with ethyl acetate after solid state fermentation on rice media for 21 days at 22°C. Free radical scavenging activity (DPPH assay) was used to determine the antioxidant capacity of the extracts and their IC50 were calculated, using quercetin as the standard. Immunomodulatory activities of the extracts were evaluated using cyclophosphamide induced myelosuppression model. Bioactive components of the extracts were examined using High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) analysis, ResultsTwo endophytic fungi (PGS1 and NLL3) were isolated from P. guajava and N. laevis, respectively. The fungal extract at 200 and 100 mg/mL significantly (p<0.05) reduced the total white blood cell count of the mice after ten days treatment. The crude extracts of PGS1 and NLL3 exhibited potent inhibition of DPPH free radical activity with IC50 values of 44.1 and 41.1 µg/mL, respectively. HPLC-DAD analysis revealed the presence of protocatechuic acid, asteric acid, citrinin, nidulalin, citreohybridinol, p-hydroxybenzoic acid, cyclopenin, nakijinol previously reported to have antioxidant and immunosuppressant properties. ConclusionExtracts of endophytic fungi isolated from P. guajava and N. laevis possess antioxidant and immunosuppressive activities, which could be attributed to the presence of the secondary metabolites identified by dereplication.