Cytotoxic and Infection-Controlled Investigations of Novel Dihydropyridine Hybrids: An Efficient Synthesis and Molecular-Docking Studies

A sequence of novel 1,4-dihydropyridines (DHP) and their hybrids was developed using a multicomponent strategy under environmentally benign conditions. In addition, computational studies were performed, and the ligand-protein interactions calculated in different bacteria and two fungal strains. Para-hydroxy-linked DHP (5f) showed the best binding energies of 3.591, 3.916, 8.499 and 6.895 kcal/mol against various pathogens used and other substances received a good docking score. The pathogen resistance potential of the synthesized targets against four bacteria and two fungi showed that whole DHP substances exhibit different levels of resistance to each microorganism. Gram-positive bacteria, which are highly sensitive to all molecules, and the MTCC-1884-encoded fungus strongly rejected the studied compounds compared to comparator drugs. In particular, the 5f candidate showed remarkable antimicrobial activity, followed by the substances 5a, 5b, 5j, 5k and 5l. Furthermore, MIC and MBC/MFC properties showed that 5f had a minimum bacterial concentration of 12.5 μg/mL against E. coli and against two fungal pathogens, with its killing activity being effective even at low concentrations. On the other hand, whole motifs were tested for their cytotoxic activity, revealing that the methoxy and hydroxy-linked compounds (5h) showed greater cytotoxic potency, followed by the two hydroxy linked compounds (5d and 5f). Overall, this synthetic approach used represents a prototype for future nature-favored synthesis methods and these biological results serve as a guide for future therapeutic drug research. However, the computer results play an important role in the further development of biological experiments.

Extracellular metabolites of endophytic fungi from Azadirachta indica inhibit multidrug-resistant bacteria and phytopathogens

Aim: To evaluate antimicrobial activity of extracellular metabolites (EMs) of endophytic fungal isolates (EFIs) from Azadirachta indica. Materials & methods: EFIs were identified by internal transcribed spacer (ITS) sequencing. Antimicrobial activity, and minimum inhibitor concentration (MIC) and minimum bactericidal concentration (MBC) were determined using agar diffusion and microdilution method, respectively. Results: Seventeen EFIs were isolated from different organs of A. indica. Eight of them were identified based on ITS sequencing. The EMs of EFIs inhibited the growth of six multidrug-resistant (MDR) bacterial superbugs and three phytopathogenic fungi. The MDR bacterial superbugs are resistant to six commercial antibiotics of different generations but susceptible to EMs of EFIs. The MIC (0.125-1.0 μg/μl), MBC (0.5-4.0 μg/μl) and minimum fungicidal concentration (1.0-4.0 μg/μl) of the EMs from EFIs are lower enough. Conclusion: The EMs of the EFIs have promising antimicrobial activity against MDR bacteria and phytopathogenic fungi.

Phytochemical analysis and antimicrobial activity of some medicinal plants against selected pathogenic microorganisms

The aim of the present study is to investigate the antimicrobial potency of leaves from various extracts of Capparis zeylanica, Streblus asper and Tribulus terrestris were evaluated. In addition, this is the first report on MIC, MBC/MFC antimicrobial activities of above mentioned plants and also identify the phytochemical, functional groups by GC-MS and FT-IR respectively. Soxhlet extraction method was used for preparation of different extracts viz., aqueous, petroleum ether, ethyl acetate and methanol. The extracts were examined against Staphylococcus epidermidis, Enterococcus faecallis, Salmonella paratyphi, Shigella dysenteriae, Candida albicans and Mycobacterium tuberculosis by agar well diffusion method, and Minimum Inhibitory Concentratioon (MIC), Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) values were determined through micro dilution method. Phytochemical analysis of compounds was carried out by GC-MS analysis and functional groups were identified by FT-IR. Based on the outcome of our results, Ethyl acetate extract Showed significant antimicrobial activity against the tested pathogens especially, for C. albicans (40 mm) followed by ethyl acetate of S. asper against S. paratyphi (38 mm). While, the least inhibition was observed with aqueous extract of T. terrestris against S. paratyphi (10 mm). The MIC ranged from 3.21 mg/ml to 50 mg/ml and MBC/MFC 6.25 mg/ml to 50 mg/ml was recorded. Ethyl acetate extracts of almost all samples showed better activity than other extracts in inhibition growth of pathogens. Phytochemical analysis exhibited the presence of Steroids, tannins and cardiac glycosides were found only in ethyl acetate extract of C. zeylanica. Functional group of leaf extract was confirmed by FT-IR spectrum and GC-MS analysis of the ethyl acetate extract revealed the presence of 20 compounds. The results revealed that ethyl acetate extract of C. zeylanica leaves has potential activity than the other extracts as well as standard drugs (Gentamycin and Ketocozole). Hence, this plant may be recommended for further studies in isolation of active compounds and related pharmacological activities.

Synthesis, antimicrobial activity and advances in structure-activity relationships (SARs) of novel tri-substituted thiazole derivatives

Trisubstituted thiazoles were synthesized and studied for their antimicrobial activity and supported by theoretical calculations. In addition, MIC, MBC and MFC were also tested. Moreover, the present study was analyzed to scrutinize comprehensive structure-activity relationships. In fact, LUMO orbital energy and orbital orientation was reliable to explain their antibacterial and antifungal assay. Amongst the tested compounds, tri-methyl-substituted thiazole compound showed higher antimicrobial activity and low MIC value due to highest LUMO energy.

Chemical composition and in vitro antifungal activity screening of the Allium ursinum L. (Liliaceae)

The objective of the study was to summarize the methods for isolating and identifying natural sulfur compounds from Allium ursinum (ramson) and to discuss the active constituents with regard to antifungal action. Using chromatographic techniques, the active constituents were isolated and subsequently identified. Analyses by high-performance liquid chromatography (HPLC) suggested that these compounds were sulfur constituents, with a characteristic absorbance at 250 nm. Gas chromatography-mass spectrometry (GC-MS) analyses allowed the chemical structures of the isolated constituents to be postulated. We adopted the same methods to identify the health-giving profiling of ramsons and the effects are thought to be primarily derived from the presence and breakdown of the alk(en)ylcysteine sulphoxide, alliin and its subsequent breakdown to allicin (sulfur-compounds of ramson) in connection with antifungal action. The aim of the study was the characterization of the chemical composition of ramsons and the testing of the action of the in vitro extracts, on different strains of Candida albicans. The main goal was to highlight the most efficient extracts of Allium ursinum that can provide long-term antifungal activity without remissions. The extracts from Allium ursinum plants, inhibited growth of Candida spp. cells at concentrations ranging from 0.5 to 4.0 mg/mL, while that of adherent cells at concentrations ranging from 1.0 to > 4.0 mg/mL, depending on the yeast and plant species.

Bioefficacy of Lantana camara L. against Some Human Pathogens

Antimicrobial efficacy of flavonoids (free and bound) and crude alkaloids of Lantana camara L. was determined by disc diffusion assay against three bacteria (Escherichia coli, Proteus mirabilis, and Staphylococcus aureus) and two fungi (Candida albicans and Trichophyton mentagrophytes). Minimum inhibitory concentration, minimum bactericidal/fungicidal concentration and total activity were also studied. Most susceptible microorganism in the present study was C. albicans followed by P. mirabilis, S. aureus, E. coli, and T. mentagrophytes. The range of minimum inhibitory concentration of tested extracts was 0.039-0.625 mg/ml while minimum bactericidal/fungicidal concentration ranged from 0.078-1.25 mg/ml. Six extracts out of eleven tested showed same values of minimum inhibitory concentration and minimum bactericidal/fungicidal concentration, while rest showed higher values of minimum bactericidal/fungicidal concentration. Highest total activity (120.51 ml/g) was observed for bound flavonoids of root against Candida albicans and Staphylococcus aureus. Results of the present investigation indicate that Lantana camara has good antimicrobial activity with low range of minimum inhibitory concentration hence can be exploited for future plant based antimicrobial drugs.