Current Topics in Medicinal Chemistry - Volume 18, Issue 10, 2018

As per WHO reports, about three-quarters (65-80%) of the world's population seek plants or plant-derived natural products for various diseases. The slow discovery of new synthetic molecules and rising resistance in microbes against existing ones has triggered an alarm for speeding up the development process for new molecules. Traditional system(s) of medicine and plant resources has been foresighted again by researchers to circumvent the situation. This review represents various plant genera which, either as a whole plant or their parts, have been reported possessing antimicrobial properties during the last decade. Before 2007, literature is already well cited in various books and reviews.

Metallo-β-lactamases (MBLs) are a family of Zn(II)-dependent enzymes that can hydrolyze almost all β-lactam antibiotics. Horizontal transfer of the genes encoding MBLs among Gram-negative bacteria pathogens has led to the emergence of extensively drug-resistant pathogens, which now represent a major threat to human health. As there is not to date yet a clinically available MBL inhibitor, the discovery of new MBL inhibitors has great urgency. This review highlights the recent developments in the discovery of small-molecule MBL inhibitors.

A series of diazenyl chalcones was prepared by base catalyzed Claisen-Schmidt condensation of synthesized hydroxy substituted acetophenone azo dye with various substituted aromatic/ heteroaromatic aldehydes. The structural conformation of synthesized chalcones was done by a number of physicochemical and spectral means like FTIR, UV-visible, mass, NMR spectroscopy and CHNS/O analysis. These diazenyl chalcones were assessed for their in vitro antimicrobial potential against several Gram-negative, Gram-positive bacterial and fungal strains by serial tube dilution method. The fluconazole and cefadroxil were used as standard drugs. The target compounds were also evaluated for their antioxidant potential by DPPH assay. (2E)-3-(2,4-Dichlorophenyl)-1-(4-((2,6- dihydroxyphenyl)diazenyl)phenyl)prop-2-en-1-one (C-7) had shown very good antimicrobial potential with MIC ranges from 3.79 to 15.76 μg/ml against most of the tested microorganisms. Most of the synthesized diazenyl chalcones were found to be active against B. subtilis. The (2E)-1-(5-((2-Chloro- 4-nitrophenyl)diazenyl)-2-hydroxyphenyl)-3-(2-hydroxynaphthalen-1-yl)prop-2-en-1-one (C-10) had shown high free radical-scavenging activity when compared with the ascorbic acid as the reference antioxidant.

Conventional chemotherapeutics lack the specificity and controllability, thus may poison healthy cells while attempting to kill cancerous ones. Newly developed nano-drug delivery systems have shown promise in delivering anti-tumor agents with enhanced stability, durability and overall performance; especially when used along with targeting and triggering techniques. This work traces back the history of chemotherapy, addressing the main challenges that have encouraged the medical researchers to seek a sanctuary in nanotechnological-based drug delivery systems that are grafted with appropriate targeting techniques and drug release mechanisms. A special focus will be directed to acoustically triggered liposomes encapsulating doxorubicin.