Marine Algicolous Endophytic Fungi - A Promising Drug Resource of the Era

Endophytic fungi have currently been acknowledged as the most promising source of bioactive compounds for drug discovery, and considerable progress has been made in exploring their diversity, species richness, and bioprospecting. Fungal endophytes from unique environmental settings offer a pool of potentially useful medicinal entities. Owing to the constant stresses imposed on macroalgae by marine environments, it is believed that algae and their associated endophytic symbionts represent a good source of structurally diverse bioactive secondary metabolites. Despite the proven significance of active metabolites of algal endophytes, little have been exploited. This review highlights the latest discoveries in algicolous endophytic research, with particular focus on the bioactive metabolites from algal endophytes. Compounds are classified according to their reported biological activities, like anticancer, antibacterial, antifungal, and antioxidant properties. Present experimental evidence suggests that a majority of the bioactive metabolites were reported from Phaeophyceae followed by Rhodophyceae and Chlorophyceae. An intensive search for newer and more effective bioactive metabolites has generated a treasure trove of publications, and this review partially covers the literature published up to 2016.

Exploration and profiling of hidden endophytic mycota of marine macroalgae with potential drug leads

Diversity studies of endophytic assemblages are emerging challenges, which unveil novel phenotypes producing interesting chemical entities and a better understanding of their ecological significance. In the present investigation, we selected an extremely complex and unique environment supporting unexplored endophytes, 'Macroalgae of Kerala coast, India'. Unlike terrestrial flora and mangroves, reports displaying endophytic assemblages of marine flora remain limited, especially from India. The main goal of this study was to expose hidden endophytic fungi from macroalgae and examination of their bioactive potential. An ecological investigation of four red, four green and three brown algae resulted in 133 fungal taxa with 29 distinct morphospecies. Aspergillus and Penicillium were found to be the dominant genera. Penicillium chrysogenum was the sole fungi that contributed 11% of the entire endophytic community. Antimicrobial activity against various aquaculture/human pathogens revealed that around 59% of endophytes inhibited at least one of the pathogens screened. The maximum number of isolates (37%) inhibited Escherichia coli tailed by Aspergillus fumigatus (27%). Antimicrobial profile of fungal endophytes endorses them as a potential source of bioactive molecules that can be explored to find a solution for drug resistance in microbial pathogens.

Mangrove-associated endomycota: diversity and functional significance as a source of novel drug leads

Endophytic fungi are known for their unprecedented ability to produce novel lead compounds of clinical and pharmaceutical importance. This review focuses on the unexplored fungal diversity associated with mangroves, emphasizing their biodiversity, distribution, and methodological approaches targeting isolation, and identification. Also highlights the bioactive compounds reported from the mangrove fungal endophytes. The compounds are categorized according to their reported biological activities including antimicrobial, antioxidant and cytotoxic property. In addition, protein kinase, α-glucosidase, acetylcholinesterase, tyrosinase inhibition, antiangiogenic, DNA-binding affinity, and calcium/potassium channel blocking activity are also reported. Exploration of these endophytes as a source of pharmacologically important compounds will be highly promising in the wake of emerging antibiotic resistance among pathogens. Thus, the aim of this review is to present a detailed report of mangrove derived endophytic fungi and to open an avenue for researchers to discover the possibilities of exploring these hidden mycota in developing novel drug leads.

L-asparaginase from the mangrove endophyte Penicillium citrinum MEF 455: a focus on cancer surveillance gene expression in tumor cell lines HL-60 and NCI-H 460

Marine endophytic fungi serve as a valuable source of bioactive molecules, with growing applications in enzyme production. This study investigates the therapeutic potential of glutaminase- and urease-free Type II L-asparaginase derived from the mangrove endophyte Penicillium citrinum MEF 455 against neoplastic cells. Extracellular L-asparaginase production was done using Czapek Dox broth amended with L-asparagine and a 66 kDa molecular mass asparaginase could be observed. The specific activity of 41.6 U/mg with 5.8-fold purification was attained using DEAE cellulose and Sephacryl S-200 column. The kinetic study showed that the Km, Vmax, and Kcat were 1.370 mM, 161.29 U/mL/min, and 1240.69/min, respectively. Purified L-asparaginase displayed optimal activity at 40 °C and pH 8, with a substrate concentration of 2.5 mM L-asparagine. Metallic ions like Na+, K+, Mg2+, Co2+, and Li+, improved asparaginase activity. The enzyme displayed strong anticancer potential with considerable reduction in the growth of HL-60, and NCI-H 460 cells with IC50 values of 0.37 ± 0.225 U/mL and 0.39 ± 0.176 U/mL, respectively. Major cancer-controlling genes i.e. p53, caspase-3, caspase-9, NF-kB, Bax, and Rb1 were up-regulated. In contrast, anti-apoptotic i.e. Cox-2 and Bcl-2 were down-regulated on asparaginase treatment in Human cancer cell lines HL-60 and NCI-H 460. The experimental study demonstrates that Type II L-asparaginase produced from an endophytic fungal source, P. citrinum MEF 455, was free from glutaminase and urease activity, thereby minimizing associated immunogenic complications. In general, understanding the physicochemical properties and functionality of the enzyme highlights its potential as a promising antitumor candidate for therapeutic development and clinical applications.