Jualang Azlan Gansau

Yeasts in sustainable bioethanol production: a review

Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

Design, characterization, in vitro antibacterial, antitubercular evaluation and structure–activity relationships of new hydrazinyl thiazolyl coumarin derivatives

Herein, we describe the synthesis of 11new thiazolyl coumarin derivatives and evaluation of their potential role as antibacterial and antituberculosis agents. The structures of the synthesized compounds were established by extensive spectroscopic studies (Fourier transform infrared spectroscopy, 1H-nuclear magnetic resonance, 13C-nuclear magnetic resonance, 2D-nuclear magnetic resonance and liquid chromatography–mass spectrometry) and elemental analysis. All synthesized compounds were assayed for their in vitro antibacterial activity against a few gram positive and gram negative bacteria and antituberculosis activity against Mycobacterium tuberculosis H37Rv ATCC 25618 by using colorimetric microdilution assay method. Nine derivatives showed moderate anti-bacterial and anti-tuberculosis activities against all the tested strains. The highest activity against all the pathogens including Mycobacterium tuberculosis was observed by compound 7c with MIC values ranging between 31.25–62.5 μg/mL, indicating that coumarin skeleton could indeed provide useful scaffold for the development of new anti-microbial drugs.

Synthesis, X-ray crystallographic study, pharmacology and docking of hydrazinyl thiazolyl coumarins as dengue virus NS2B/NS3 serine protease inhibitors

A series of total twenty-one thiazole-coumarin derivatives 7a-u, linked via hydrazine linkage were synthesized through Hantzsch cyclisation. Out of twenty-one derivatives, fourteen derivatives viz. 7b-d, 7g, 7i-k, 7n and 7p-u are the novel derivatives. The structures of the synthesized compounds were established by extensive spectroscopic studies (FTIR, 1H NMR, 13C NMR, 2D NMR, LC-MS) and elemental analysis. The structure of (E)-6-methoxy-3-(1-(2-(4-p-tolylthiazol-2-yl)hydrazono)ethyl)-2H-chromen-2-one (7d) was unambiguously confirmed by X-ray crystallography analysis. Hybrid molecules were evaluated for their potential as anti-tubercular agents against Mycobacterium tuberculosis H37Rv ATCC 25618, and anti-bacterial agents against Eschericia coli, Enterobacter aerogenes, Salmonella typhi, Streptococcus pneumoniae and Staphylococcus aureus. All the compounds displayed considerable potency against all the pathogens with MIC values ranging from 31.25 to 250 μg/mL, therein compounds 7i, 7j, 7k, 7q and 7t displayed superior inhibitory activities compared to standard drugs streptomycin, kanamycin, vancomycin and isoniazid. Molecular docking studies were performed to check the potential as dengue virus NS2B/NS3 serine protease inhibitors, by comparing to standards 4-hydroxypanduratin, panduratin and ethyl 3-(4-(hydroxymethyl)-2-methoxy-5-nitrophenoxy)propanoate with DS of −3.379, −3.189 and −3.381, respectively. All the compounds were found to exhibit potency against the DENV virus. In particular, compound 7c (DS –5.141) and 7l (DS –3.894) were found to be even better than the standards followed by compounds 7j (DS –3.113) and 7q (DS –3.561).