Chelliah Jayabaskaran

For millennia, people have used natural herbal remedies to cure an extensive variety of illnesses. The present study evaluates the effects of differen

Endophytic fungi were isolated from the marine green alga Chaetomorpha antennina and identified as Clonostachys rosea through molecular analysis. C. rosea was grown in a tryptophan medium for 21 days and after that, the metabolites were extracted by ethyl acetate. The ethyl acetate extract showed a high cytotoxic effect on MCF-7 cells. GC–MS analysis of the ethyl acetate extract revealed the presence of many compounds, and chrysin was one of the major compounds among them. Hence, further studies were concentrated on chrysin, as it was assumed to be the major attributor to the potent cytotoxicity, based on its high anticancer efficacies reported earlier. The fungal ethyl acetate extract had been analysed for chrysin using HPTLC and compared its R_f value with authentic chrysin and it was matched. Further, the purified fungal chrysin was structurally elucidated using techniques like LC–MS and NMR analyses. Quantification revealed that C. rosea produced 1050 mg/L of chrysin. This surplus production of chrysin was the major significance of the study. The purified fungal chrysin was found to be highly cytotoxic to MCF-7 cells with a low IC₅₀ value 35.5 ± 0.6 µM. Furthermore, DNA fragmentation and apoptosis analysis indicated the selective inhibition of MCF-7 by DNA damage. Thus, the present study implies that C. rosea is an alternative source and new method for surplus production of chrysin in the tryptophan medium. All results indicate that the marine algae endophytic C. rosa produces chrysin, and for the first time, an excess amount of production was revealed by the study.

Flavonoids encompass a heterogeneous group of secondary metabolites with exceptional health benefits. Chrysin, a natural dihydroxyflavone, possesses numerous bioactive properties, such as anticancer, antioxidative, antidiabetic, anti-inflammatory, etc. However, using traditional sources of chrysin involves extracting honey from plants, which is non-scalable, unsustainable, and depends on several factors, including geography, climatic conditions, and the season, which limits its production at a larger scale. Recently, microbial production of desirable metabolites has garnered attention due to the cost-effectiveness, easy scale-up, sustainability, and low emission of waste. We previously reported for the first time the chrysin-producing marine endophytic fungus Chaetomium globosum, associated with a marine green alga. To extend our understanding of chrysin biosynthesis in C. globosum, in the present study, we have assessed the presence of flavonoid pathway intermediates in C. globosum extracts using LC-MS/MS. The presence of several key metabolites, such as dihydrokaempferol, chalcone, galangin, baicalein, chrysin, p-Coumaroyl-CoA, and p-Cinnamoyl-CoA, indicates the role of flavonoid biosynthesis machinery in the marine fungus. Further, we have aimed to enhance the production of chrysin with three different strategies: (1) optimizing the fermentation parameters, namely, growth medium, incubation time, pH, and temperature; (2) feeding key flavonoid pathway intermediates, i.e., phenylalanine and cinnamic acid; (3) elicitation with biotic elicitors, such as polysaccharide, yeast extract, and abiotic elicitors that include UV radiation, salinity, and metal stress. The combined effect of the optimized parameters resulted in a 97-fold increase in the chrysin yield, resulting in a fungal cell factory. This work reports the first approach for enhanced production of chrysin and can serve as a template for flavonoid production enhancement using marine endophytic fungi.

The Western Ghats, India, is a hotspot for lichen diversity. However, the pharmacological importance of lichen-associated metabolites remains untapped. This study aimed to evaluate the cytotoxic potential of lichens of this region. For this, sixteen macrolichens were collected and identified from two locations in the Western Ghats. The acetone extract of Usnea cornuta (UC2A) showed significant cytotoxicity towards multiple human cancer cell lines. Interestingly, co-treatment with chloroquine (CQ), an autophagy inhibitor, increased the cytotoxic potential of the UC2A extract. A gas chromatography mass spectrometry (GCMS) study revealed usnic acid (UA), atraric acid and barbatic acid as the dominant cytotoxic compounds in the UC2A extract. Further, UA was purified and identified from the UC2A extract and evaluated for cytotoxicity in HeLa cells. The monodansyl cadaverine and mitotracker red double staining revealed the autophagy-inducing activities of UA, and the inhibition of autophagy was confirmed via CQ treatment. Autophagy inhibition increased the cytotoxicity of UA by 12–16% in a concentration-dependent manner. It also increased lipid peroxidation, ROS levels and mitochondrial depolarization and decreased glutathione availability. A decrease in zeta potential and a 40% increase in caspase 3/7 activity were also noted after CQ treatment of UA-treated cells. Thus, cytotoxicity of UA can be increased by inhibiting autophagy.