Antifungal screening and in silico mechanistic studies of an in-house azole library

Antibacterial azole derivatives: Antibacterial activity, cytotoxicity, and in silico mechanistic studies

Azole antifungal drugs are commonly used in antifungal chemotherapy. Antibacterial effects of some topical antifungals, such as miconazole and econazole, have lately been revealed, which suggests a promising venue in antimicrobial chemotherapy. In this study, we tested an in-house azole collection with antifungal properties for their antibacterial activity to identify dual-acting hits using the broth microdilution method. The in vitro screen yielded a number of potent derivatives against gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus. Compound 73's minimum inhibitory concentration (MIC) value less than 1 μg/ml against S. aureus; however, none of the compounds showed noteworthy activity against methicillin-resistant S. aureus (MRSA). All the active compounds were found safe at their MIC values against the healthy fibroblast cells in the in vitro cytotoxicity test. Molecular docking studies of the most active compounds using a set of docking programs with flavohemoglobin (flavoHb) structure, the proposed target of the azole antifungals with antibacterial activity, presented striking similarities regarding the binding modes and interactions between the tested compounds and the antifungal drugs with crystallographic data. In addition to being noncytotoxic, the library was predicted to be drug-like and free of pan-assay interference compounds (PAINS). As a result, the current study revealed several potential azole derivatives with both antifungal and antibacterial activities. Inhibition of bacterial flavoHb was suggested as a possible mechanism of action for the title compounds.

Discovery of potent α-glucosidase inhibitors through structure-based virtual screening of an in-house azole collection

Diabetes mellitus, a chronic disorder characterized by hyperglycemia, is considered a pandemic of modern times. α-Glucosidase inhibitors emerged as a promising class of antidiabetic drugs with better tolerability compared with its alternatives. Azoles, although widely preferred in drug design, have scarcely been investigated for their potential against α-glucosidase. In this study, we evaluated α-glucosidase inhibitory effects 20 azole derivatives selected out of an in-house collection via structure-based virtual screening (VS) with consensus scoring approach. Seven compounds were identified with better IC₅₀ values than acarbose (IC₅₀  = 68.18 ± 1.01 µM), a well-known α-glucosidase inhibitor drug, which meant 35% success for our VS methodology. Compound 52, 54, 56, 59, and 81 proved highly potent with IC₅₀ values in the range of 40-60 µM. According to the enzyme kinetics study, four of them were competitive, 56 was non-competitive inhibitor. Structure-activity relationships, quantum mechanical, and docking analyses showed that azole rings at ionized state may be key to the potency observed for the active compounds and modifications to shift the balance between the neutral and ionized states further to the latter could yield more potent derivatives.