Phytochemical Screening and Antioxidant Potential of Endophytic Fungi Isolated From Hibiscus sabdariffa

Fungal endophytes are friendly microbes colonizing in plants and play an effective role in plant-environment interactions. They produce valuable secondary metabolites that both plants and human beings can benefit from such products. Diverse compounds are biosynthesized by endophytes to promote plant growth and prevent pathogen attacks. Some of these compounds can be used for human drugs as antibiotics. Thirteen endophytic fungal species were isolated from root, stem and leaves of Hibiscus sabdariffa. The assessment of the antioxidants activity, total phenolic content (TPC), total flavonoids content and total antioxidant capacity (TAC), hydrogen peroxide scavenging and reducing power assays of 26 ethyl acetate and 13 methanol crude fungal extracts has been carried out. Qualitative assay of bioactive compounds for 39 endophytic fungal extracts have been checked by standard procedures. Quantitative estimation of TPC and flavonoids content was done. The DPPH free radical scavenging was estimated using DPPH (1,1-diphenyl-2-picrylhydrazyl), and hydrogen peroxide scavenging and reducing power assays were used to evaluate the antioxidants activity. Qualitative detection of secondary metabolites revealed that endophytic fungal extracts from Aspergillus terreus isolated from the leaves of Hibiscus sabdariffa was found to be able to produce all the tested functional metabolites with the highest total phenolic contents (204.5±0.4 mg GAE/g) and antioxidant activity for DPPH radical scavenging assay (91.88 ± 0.17 μg/mL). The present study revealed that metabolites produced by some endophytic fungi isolated from the medicinal plant, Hibiscus sabdariffa could be a potential source of novel natural antioxidant compounds.