Generation of reactive oxygen has been implicated in the pathogenesis of cancer and other diseases (Halliwell and Gutterigde, 1999). Four endophytic fungi PGS1, NLS2 and PGL3, NLL3 were isolated using standard methods from the stem and leaf of Psiduim guajava and Newbouldia laevis respectively. The fungal secondary metabolites were extracted with ethyl acetate after solid state fermentation of the isolated fungi on rice media for 21 days at 220C. The antioxidant activity of the extracts were evaluated in vitro using 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging assay and their IC50 were calculated using quercetin as the standard. The immunomodulatory activity of the extracts were also evaluated by cyclophospahamide induced myelosuppression. The extracts were subjected to High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) analysis for the detection bioactive components. Two of the endophytic fungi (PGS1 and NLL3) at 100 mg/ml significantly reduced the total White Blood Cells count of the mice after five days treatment of the mice with the extracts p < 0.005. The crude extracts of PGS1 and NLL3 scavenged the DPPH with percentage inhibition of 69.84 and 76.58 % and gave the highest observed antioxidant activity in this study with IC50 of 44.1 and 41.1 ug/ml respectively. The significant antioxidant activity of these extracts explain the strong suppressive activity of the extract. There was a perfect correlation between antioxidant and immunosuppressive activities. The HPLC-DAD analysis revealed the presence of Protocatechuic acid, beauvericin, catechin and asteric acid previously reported to have antioxidant and immunosuppressant properties.Extracts of endophytic fungi isolated from these P.guajava and N.laevis possesses antioxidant and immunosuppressive activities supporting a great therapeutic potential and a wide range of clinical applications.
Reference:
Halliwell, B. and Gutteridge, J.M.C. (1999) "Free radicals in biology and Medicine", Oxford University Press, UK.