Lead Optimization Resources in Drug Discovery for Diabetes

Endophytic Fungi: Key Insights, Emerging Prospects, and Challenges in Natural Product Drug Discovery

Plant-associated endophytes define an important symbiotic association in nature and are established bio-reservoirs of plant-derived natural products. Endophytes colonize the internal tissues of a plant without causing any disease symptoms or apparent changes. Recently, there has been a growing interest in endophytes because of their beneficial effects on the production of novel metabolites of pharmacological significance. Studies have highlighted the socio-economic implications of endophytic fungi in agriculture, medicine, and the environment, with considerable success. Endophytic fungi-mediated biosynthesis of well-known metabolites includes taxol from Taxomyces andreanae, azadirachtin A and B from Eupenicillium parvum, vincristine from Fusarium oxysporum, and quinine from Phomopsis sp. The discovery of the billion-dollar anticancer drug taxol was a landmark in endophyte biology/research and established new paradigms for the metabolic potential of plant-associated endophytes. In addition, endophytic fungi have emerged as potential prolific producers of antimicrobials, antiseptics, and antibiotics of plant origin. Although extensively studied as a “production platform” of novel pharmacological metabolites, the molecular mechanisms of plant–endophyte dynamics remain less understood/explored for their efficient utilization in drug discovery. The emerging trends in endophytic fungi-mediated biosynthesis of novel bioactive metabolites, success stories of key pharmacological metabolites, strategies to overcome the existing challenges in endophyte biology, and future direction in endophytic fungi-based drug discovery forms the underlying theme of this article.

Dexmedetomidine reversed hypoxia/reoxygenation injury-induced oxidative stress and endoplasmic reticulum stress-dependent apoptosis of cardiomyocytes via SIRT1/CHOP signaling pathway

We aimed to investigate the protective role and mechanism of dexmedetomidine (DEX) on H9c2 cardiomyocytes after hypoxia/reoxygenation (H/R) injury. Six experimental groups were designed as follows: normal control group (group C), H/R group, H/R + DEX group, H/R + gastrodin group, H/R + Ex527 (SIRT1 inhibitor) group, and H/R + DEX + Ex527 group. Lactate dehydrogenase (LDH) activity and the levels of oxidative stress-related enzymes such as malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) were measured using corresponding commercial kits. Cell counting kit (CCK)-8 assay was used to detect cell survival rate while flow cytometry and caspase 3/7 activity were used to determine cell apoptosis, respectively. Western blot was used to detect the expression of silent information regulator 1 (SIRT1), C/EBP homologous protein (CHOP), cleaved-caspase-12/3 and pro-caspase-12/3 in each group. From our findings, when compared with H/R, H/R + Ex527 and H/R + DEX + Ex527 groups, DEX pretreatment of cells in H/R + DEX group significantly increased cell survival rate, and simultaneously reduced LDH activity, oxidative stress and the apoptosis rate of H9c2 cells with H/R injury. Moreover, DEX up-regulated SIRT1 expression level and down-regulated the levels of endoplasmic reticulum (ER) stress-related markers such as CHOP, cleaved-caspase-12 and cleaved-caspase-3, respectively. Ex527 could completely block DEX-induced upregulated expression of SIRT1, and partially blocked the DEX-induced downregulated expression levels of CHOP, cleaved-caspase-12 and cleaved-caspase-3. These results proved that DEX reversed H/R injury-induced oxidative stress and ER stress-dependent apoptosis of cardiomyocytes via SIRT1/CHOP signaling pathway.