Bioactive potential of endophytic Myrothecium sp. isolate M1-CA-102, associated with Calophyllum apetalum

Context: Endophytes colonizing medicinal plants are diverse, constituting a rich bioresource for novel natural products.

Objective: Myrothecium sp. isolate M1-CA-102 was the most promising among the 16 Myrothecium isolates screened. The bioactive potential of the crude extract from the Calophyllum apetalum Willd. endophytic Myrothecium sp. (Alb. &; Schwein.) Ditmar (Incertae sedis) isolate M1-CA-102 and its thin layer chromatography (TLC) fractions were screened based on antioxidant, anti-inflammatory, antimicrobial activities, and cytotoxicity.

Materials and methods: The antioxidant activity was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging capacities. Further, 15-lipoxygenase (15-LOX) and human cyclooxygenase-2 (COX-2) inhibition were assessed at different concentrations (25, 50, and 100?μg/mL for the crude extract, 5, 25, and 50?μg/mL for the TLC fractions). DNA-nicking assay as an indicator of the capacity of extracts to scavenge hydroxyl radical was recorded at a concentration of 50?μg/mL. Cell cytotoxicity was recorded by colorimetric 3-(4,5-dimethylthylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Antibacterial (Bacillus subtilis) and anti-Candida (Candida albicans) assays were performed by the microdilution method.

Results: The DPPH and ABTS IC₅₀ values of M1-CA-102 extract were 10 and 6?μg/mL compared with 6.1 and 7.03?μg/mL for the positive control quercetin. The cytotoxicity IC₅₀ value of M1-CA-102 extract was 37?μg/mL, while the M-I TLC fraction was 21?μg/mL. The M1-CA-102 extract gave an IC₅₀ value of 58 and 8?μg/mL for 15-LOX and COX-2, respectively. The MIC values for antimicrobial activity for M1-CA-102 extract ranged from 35 to 54?μg/mL, while for the TLC fractions, it ranged from 91 to 515?μg/mL.

Conclusion: The results indicate that Myrothecium M1-CA-102 isolated from C. apetalum is a potential source of natural metabolites of pharmaceutical importance.