Microbial transformation of capsaicin by several human intestinal fungi and their inhibitory effects against lysine-specific demethylase 1

Discovery and isolation of novel capsaicinoids and their TRPV1-related activity

Chilis contain capsaicin and other structurally related molecules known as capsaicinoids. Capsaicin's target protein, the transient receptor potential cation channel subfamily V member 1 (TRPV1), has been linked to many post-activation effects, including changes in metabolism and pain sensation. Capsaicinoids also bind to TRPV1, but current studies often disregard non-capsaicin interactions. To fill in these gaps, we screened 40 different chili varieties derived from four Capsicum species by means of untargeted metabolomics and a rat TRPV1 (rTRPV1) calcium influx activation assay. The resulting capsaicinoid profiles were specific to each variety but only partially corresponded with species delimitations. Based on rTRPV1 activation elicited by crude chili extracts, capsaicinoids act in an additive manner and a capsaicinoid profile can serve as a gauge of this activation. In addition, we isolated eighteen capsaicinoids, including five previously unreported ones, and confirmed their structure by NMR and MS/MS. We then tested rTRPV1 activation by 23 capsaicinoids and three related compounds. This testing revealed that even slight deviations from the structure of capsaicin reduce the ability to activate the target, with a mere single hydroxylation on the acyl tail reducing potency towards rTRPV1 by more than 100-fold. In addition, we tested how rTRPV1 activity changes in the presence of capsaicin together with non-activating capsaicin analogs and weakly activating capsaicinoids and found both classes of molecules to positively modulate the effects of capsaicin. This demonstrates that even such compounds have measurable pharmacological effects, making a case for the use and study of natural chili extracts.

Modification of natural compounds through biotransformation process by microorganisms and their pharmacological properties

The biotransformation of natural compounds by fungal microorganisms is a complex biochemical process. Tandem whole-cell biotransformation offers a promising, alternative, and cost-effective method for modifying of bioactive novel compounds. This approach is particularly beneficial for structurally complex natural products that are difficult to be synthesized through traditional synthetic methods. Biotransformation also provides significant regio- and stereoselectivity, making it a valuable tool for the chemical modification of natural compounds. By utilizing microbial conversion reactions, the biological activity and structural diversity of natural products can be enhanced. In this review, we have summarized 282 novel metabolites resulting from microbial transformation by various microorganisms. We discussed the chemical structures and pharmacological properties of these novel biotransformation products. The review would assist scientists working in the fields of biotechnology, organic chemistry, medicinal chemistry, and pharmacology.

Biotransformation of chenodeoxycholic acid by human intestinal fungi and the agonistic effects on FXR

Bile acids play a vital role in modulating host metabolism, with chenodeoxycholic acid (CDCA) standing out as a primary bile acid that naturally activates farnesoid X receptor (FXR). In this study, we investigated the microbial transformations of CDCA by seven human intestinal fungal species. Our findings revealed that hydroxylation and dehydrogenation were the most prevalent metabolic pathways. Incubation of CDCA with Rhizopus microspores (PT2906) afforded eight undescribed compounds (6-13) alongside five known analogs (1-5) which were elucidated by HRESI-MS and NMR data. Notably, compounds 8, 12 and 13 exhibited an inhibitory effect on FXR in contrast to the FXR activation observed with CDCA in vitro assays. This study shone a light on the diverse transformations of CDCA by intestinal fungi, unveiling potential modulators of FXR activity with implications for host metabolism.

Recent advances of LSD1/KDM1A inhibitors for disease therapy

Lysine-specific demethylase 1 (LSD1/KDM1A) dysregulation is closely associated with the pathological processes of various diseases, especially hematologic malignancies. Significant progresses have been made in the field of LSD1-targeted drug discovery. Nine LSD1 inhibitors including tranylcypromine, ORY-1001, ORY-2001, GSK-2879552, IMG-7289, INCB059872, TAK-418, CC-90011 and SP-2577 have entered clinical stage for disease treatment as either mono- or combinational therapy. This review updates LSD1 inhibitors reported during 2022. Design strategies, structure-activity relationship studies, binding model analysis and modes of action are highlighted. In particular, the unique multiple-copies binding mode of quinazoline derivatives paves new ways for the development of reversible LSD1 inhibitors by blocking the substrate entrance. The design strategy of clinical candidate TAK-418 also provides directions for further optimization of novel irreversible LSD1 inhibitors with low hematological side effects. The influence of the stereochemistry on the potency against LSD1 and its homolog LSD2 is briefly discussed. Finally, the challenges and prospects of LSD1-targeted drug discovery are also given.

Membrane-Active Nonivamide Derivatives as Effective Broad-Spectrum Antimicrobials: Rational Design, Synthesis, and Biological Evaluation

Antibiotic resistance is emerging as a "global public health concern". To address the growing epidemic of multidrug-resistant pathogens, the development of novel antimicrobials is urgently needed. In this study, by biomimicking cationic antibacterial peptides, we designed and synthesized a series of new membrane-active nonivamide and capsaicin derivatives as peptidomimetic antimicrobials. Through modulating charge/hydrophobicity balance and rationalizing structure-activity relationships of these peptidomimetics, compound 51 was identified as the lead compound. Compound 51 exhibited potent antibacterial activity against both Gram-positive bacteria (MICs = 0.39-0.78 μg/mL) and Gram-negative bacteria (MICs = 1.56-6.25 μg/mL), with low hemolytic activity and low cytotoxicity. Compound 51 displayed a faster bactericidal action through a membrane-disruptive mechanism and avoided bacterial resistance development. Furthermore, compound 51 significantly reduced the microbial burden in a murine model of keratitis infected by Staphylococcus aureus or Pseudomonas aeruginosa. Hence, this design strategy can provide a promising and effective solution to overcome antibiotic resistance.

Biotransformation of dihydrocapsaicin by human intestinal fungi and the inhibitory effects of metabolites against LSD1

Dihydrocapsaicin is the main bioactive component in Capsicum plants, which is widely used in China and India as a food drug and additive. In this study, the biotransformation of dihydrocapsaicin was performed using four cultivated human intestinal fungal strains in vitro. Eight metabolites, including seven previously undescribed metabolites (1 and 3-8) and one known analog (2), were obtained. Numerous spectroscopic data, such as NMR and HRESIMS, were collected to determine their structures. Based on the structures of the dihydrocapsaicin metabolites, the main biotransformation reactions were revealed to be hydroxylation, alcohol oxidation, and lactylation. In particular, the lactylation of hydroxyl groups is mainly mediated by Rhizopus oryzae R2701. In addition, metabolite 1 showed significant inhibitory effect on lysine-specific demethylase 1 (LSD1) (IC₅₀ 1.99 μM). Therefore, the biotransformation of dihydrocapsaicin by intestinal fungi afforded various derivatives, which were important resources for developing LSD1 inhibitors and potential application in cancer treatment.