Comparative Analysis of Antioxidant Activity, Flavonoid and Phenolic Contents, and Secondary Metabolite Profiles in Broth and Mycelium Extracts of <em>Coniochaeta dendrobiicola</em>

Background: Endophytic fungi are known for diverse bioactive compounds with immense potential for agriculture and medicinal applications. Coniochaeta dendrobiicola isolated from root of the Dedrobium longicornu was investigated for its antioxidant and metabolite composition. The present study compares the antioxidant properties, flavonoid and phenolic contents and metabolic profiles of broth and mycelium extracts. Methanolic broth and mycelium extracts were tested for antioxidant potential using DPPH, while total flavonoid and phenolic content were measured using a UV-VIS spectrophotometer High-resolution mass spectrometry (HRMS) revealed a markedly richer and more diverse metabolite profile in the broth extract compared to the mycelium fraction. The broth extract exhibited significantly higher antioxidant activity, flavonoid, and phenolic contents, correlating with the presence of diverse bioactive compounds, including indole derivatives, flavonoids, phenolic acids, quinoline derivatives, and antifungal metabolites. Notably, several indole-related and phenolic compounds detected predominantly in the broth are known for antioxidant, antimicrobial, and plant growth–promoting properties. These findings indicate that C. dendrobiicola actively secretes biologically relevant secondary metabolites into the extracellular medium, highlighting its potential for agricultural and pharmaceutical applications.