Optimization of PhysicoChemical Parameters for Production of Cytotoxic Secondary Metabolites and Apoptosis Induction Activities in the Culture Extract of a Marine Algal–Derived Endophytic Fungus Aspergillus sp.

Abstract

The endophytic fungal community in the marine ecosystem has been demonstrated to be relevant source of novel and pharmacologically active secondary metabolites. The current study focused on the evaluation of cytotoxic and apoptosis induction potential in the culture extracts of endophytic fungi associated with Sargassum muticum, a marine brown alga. The cytotoxicity of the four marine endophytes, Aspergillus sp., Nigrospora sphaerica, Talaromyces purpureogenus, and Talaromyces stipitatus, was evaluated by the MTT assay on HeLa cells. Further, several physicochemical parameters, including growth curve, culture media, and organic solvents, were optimized for enhanced cytotoxic activity of the selected extract. The Aspergillus sp. ethyl acetate extract (ASE) showed maximum cytotoxicity on multiple cancer cell lines. Chemical investigation of the metabolites by gas chromatography–mass spectroscopy (GC-MS) showed the presence of several compounds, including quinoline, indole, 2,4-bis(1,1-dimethylethyl) phenol, and hexadecenoic acid, known to be cytotoxic in ASE. The ASE was then tested for cytotoxicity in vitro on a panel of six human cancer cell lines, namely, HeLa (cervical adenocarcinoma), MCF-7 (breast adenocarcinoma), Hep G2 (hepatocellular carcinoma), A-549 (lung carcinoma), A-431 (skin/epidermis carcinoma), and LN-229 (glioblastoma). HeLa cells were most vulnerable to ASE treatment with an IC50 value of 24 ± 2 μg/ml. The mechanism of cytotoxicity exhibited by the ASE was further investigated on Hela cells. The results showed that the ASE was capable of inducing apoptosis in HeLa cells through production of reactive oxygen species, depolarization of mitochondrial membrane, and activation of the caspase-3 pathway, which shows a possible activation of the intrinsic apoptosis pathway. It also arrested the HeLa cells at the G2/M phase of the cell cycle, eventually leading to apoptosis. Through this study, we add to the knowledge about the marine algae associated with fungal endophytes and report its potential for purifying specific compounds responsible for cytotoxicity.

Ethyl Acetate Extract of Colletotrichum gloeosporioides Promotes Cytotoxicity and Apoptosis in Human Breast Cancer Cells

“…Previous studies have also demonstrated similar findings using marine algal-derived endophytic fungus Aspergillus sp. and apoptotic events in HeLa cells after treatment with fungal extract was evidenced using Annexin V-FITC/PI staining . A study performed using Annexin V-FITC and PI dual staining also showed that the fungal endophyte Cladosporium cladosporioides derived bioactive compound cladosporol A significantly induces apoptosis in MCF-7 cells …”

“…and apoptotic events in HeLa cells after treatment with fungal extract was evidenced using Annexin V-FITC/PI staining. 57 A study performed using Annexin V-FITC and PI dual staining also showed that the fungal endophyte Cladosporium cladosporioides derived bioactive compound cladosporol A significantly induces apoptosis in MCF-7 cells. 55 EA Extract of C. gloeosporioides Induces ROS Production and Depolarizes the Mitochondrial Membrane Potential in Breast Cancer Cells.…”

Deciphering the role of endophytic microbiome in postharvest diseases management of fruits: Opportunity areas in commercial up-scale production

“…The commercialization of secondary metabolites and VOCs derived from endophytes faces hurdles in sustainable release and economic upscale production. Media optimization, selection of potent microbial strains, and metabolic engineering are some of the parameters that can be employed (Sah et al, 2020;Kamat et al, 2020;Taritla et al, 2021) for the sustained production of desired antimicrobial secondary metabolites from endophytes. The addition of some of the precursors from the host system has also been studied during media optimization for continuous upscale production of the antimicrobial metabolites from endophytes during the fermentation process.…”

Metabolites Produced by Fungi against Fungal Phytopathogens: Review, Implementation and Perspectives

“…Thus, as an example, secondary metabolites obtained from Fusarium equiseti isolated from marine seaweed have shown activity against cancer cells [ 75 ]. Taritla et al [ 76 ] also reported compounds isolated from the extracts of the marine endophyte Aspergillus sp. that produced cytotoxicity and apoptosis in human cancer lines.…”