Positive effects of Cordyceps cateniannulata colonization in tobacco: Growth promotion and resistance to abiotic stress.

Background: Entomopathogenic fungi can live in insects to cause disease and death and are the largest group of entomopathogenic microorganisms. Therefore, these fungi are best known for their microbial control potential. Importantly, they also have other beneficial effects, including promoting plant growth and development by colonizing plant. Here, the study sought to identify specific strains of the entomopathogenic fungus, Cordyceps cateniannulata that would form endophytic associations with tobacco, thus benefiting plant growth and resistance to abiotic stresses, thereby highlighting the application of entomopathogenic fungi in tobacco. Methods: The C. cateniannulata-tobacco symbiont was constructed by root irrigation. The effects of C. cateniannulata on tobacco growth were evaluated by measuring the maximum leaf length, maximum leaf width, number of leaves, plant height, stem thickness, stem circumference, dry and fresh shoot weight 7, 14, 21, and 28 days after colonization. The peroxidase, catalase, superoxide dismutase, and malondialdehyde were measured to observe the impact of C. cateniannulata on tobacco defense enzyme activity. Finally, high-throughput sequencing was used to access microbial communities in the rhizosphere, with data subsequently linked to growth indicators. Results: After tobacco was inoculated with C. cateniannulata X8, which significantly promoted growth and related enzyme activity, malondialdehyde was decreased. The most significant impact was on peroxidase, with its activity being upregulated by 98.20, 154.42, 180.65, and 170.38% in the four time periods, respectively. The high throughput sequencing results indicated that C. cateniannulata had changed the rhizosphere microbial relative abundances, such as increasing Acidobacteria and Ascomycetes, and decreasing Actinomycetes and Basidiomycetes. The redundancy analysis showed that C. cateniannulata significantly boosted tobacco growth by reducing the abundance of specific dominant genera such as Stachybotrys, Cephalotrichum, Streptomyces, Isoptericola, and Microbacterium. Conclusion: Specific strains of C. cateniannulata can be introduced into host plants as endophytes, resulting in promotion of host plant growth and increased resistance to abiotic stress and microbial pathogens. The study provides a foundation for future studies of C. cateniannulata as an ecological agent.

Cyclic pentapeptides with anti-inflammatory, cytotoxic or α-glucosidase inhibitory activities from Basidiobolus meristosporus.

Basidiobolus meristosporus is an opportunistic pathogen of mammals with unique habitats, but its metabolites have not been extensively studied. Through semi-preparative HPLC, nine undescribed cyclic pentapeptides were isolated from mycelia of B. meristosporus RCEF4516. The structure of the compounds 1-9 were identified with MS/MS and NMR data and designated as basidiosin D-L respectively. The absolute configurations were determined according to the advanced Marfey's method after compound hydrolysis. Bioactivity testing showed that compounds 1, 2, 3, 4 and 8 decreased NO production in LPS-activated RAW264.7 cells in a concentration-dependent manner. The nine compounds showed cytotoxicity against RAW264.7, 293 T and HepG2 cells. All the compounds except compound 7 showed stronger inhibitory effects on α-glucosidase than acarbose.

Two Alkaloids From Delphinium brunonianum Royle, Their Anti-inflammatory and Anti-oxidative Stress Activity via NF-κB Signaling Pathway.

In this study, we isolated and identified four compounds in Delphinium brunonianum Royle, and they were Delbrunine (1), 4-O-α-D-Glucosyl benzoic acid (2), Kaempferol 3-O-ß-D-glucopyranoside 7-O-α-L-rhamnopyranoside (3) and Eldeline (4). Furthermore, the anti-inflammatory activity of these compounds was screened in RAW264.7 cells. The results showed that the anti-inflammatory activities of compounds 2 and 3 were weak, and 1, 4 had good anti-inflammatory activity. The macrophage inflammation model was established by lipopolysaccharide (LPS). Then, the anti-inflammatory activity was evaluated by ELISA kits, qRT-PCR experiment and western blot experiment. And the anti-oxidative stress activity was assessed by flow cytometry. The results showed that compounds 1, 4 could significantly inhibit the elevation of inflammatory factors nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and also had obvious inhibitory effects on the production of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2). In addition, compounds 1 and 4 could effectively inhibit the overexpression of reactive oxygen species (ROS) in RAW264.7 cells that activated by LPS. These results indicated that compounds 1 and 4 may exert anti-inflammatory and anti-oxidative stress effects through the NF-κB signaling pathway.

A Peptide Stapling Strategy with Built-In Fluorescence by Direct Late-Stage C(sp2 )-H Olefination of Tryptophan.

Fluorescent stapled peptides are important chemical tools for detecting intracellular distribution, protein-protein interactions, and localization of target proteins. These peptides are usually labeled with bulky sized fluorophores through reactive functional groups, which may alter the physical properties and biological activities of peptides. Herein, a unique strategy is developed for synthesizing new stapled peptides with built-in fluorescence. The stapled peptides were prepared through Rh-catalyzed C(sp2 )-H olefination in tryptophan (Trp) residues by using pyridine/pyrimidine as the directing groups under mild conditions. This method displays good regioselectivity and high efficiency. Furthermore, as a proof of concept for its biological applications, stapled peptides without additional fluorophore 9 a and 9 b were constructed for a cell imaging study. These peptides displayed strong binding affinity toward integrin αvß3 in A549 cells by cell imaging experiments. Notably they demonstrated even better anticancer activity than commercial antagonist cyclic (RGDfK). The method will provide robust tools for the peptide macrocyclization field.