Can Small Chemical Modifications of Natural Pan-inhibitors Modulate the Biological Selectivity? The Case of Curcumin Prenylated Derivatives Acting as HDAC or mPGES-1 Inhibitors.

Curcumin, or diferuloylmethane, a polyphenolic molecule isolated from the rhizome of Curcuma longa, is reported to modulate multiple molecular targets involved in cancer and inflammatory processes. On the basis of its pan-inhibitory characteristics, here we show that simple chemical modifications of the curcumin scaffold can regulate its biological selectivity. In particular, the curcumin scaffold was modified with three types of substituents at positions C-1, C-8, and/or C-8' [C5 (isopentenyl, 5-8), C10 (geranyl, 9-12), and C15 (farnesyl, 13, 14)] in order to make these molecules more selective than the parent compound toward two specific targets: histone deacetylase (HDAC) and microsomal prostaglandin E2 synthase-1 (mPGES-1). From combined in silico and in vitro analyses, three selective inhibitors by proper substitution at position 8 were revealed. Compound 13 has improved HDAC inhibitory activity and selectivity with respect to the parent compound, while 5 and 9 block the mPGES-1 enzyme. We hypothesize about the covalent interaction of curcumin, 5, and 9 with the mPGES-1 binding site.

Design, synthesis and evaluation of cytotoxicity of novel chromeno[4,3-b]quinoline derivatives.

In the present work 15 new 1,4-dihydropyridines (DHPs) bearing a coumarin ring were synthesized and assessed on 4 different human cancer cell lines (HeLa, K562, LS180, and MCF-7). Although, all the derivatives were inactive on LS180 cell line, the results on other cells showed that these compounds had weak to moderate antitumoral activities and their IC(50) ranged from 25 to >100 µM. Among the synthesized compounds, 7-(2-nitrophenyl)-8,9,10,12-tetrahydro-7H-chromeno[4,3-b]quinoline-6,8-dione (6a) demonstrated the highest activity (IC(50) range in different cell lines: 25.4-58.6 µM). Furthermore, the calcium channel antagonist activity of the derivatives, an undesired effect when these compounds are used as antitumoral agents, was much lower than nifedipine, a reference antagonist. In conclusion, this group of compounds seems to have promising biological properties and further investigation on this group could potentially lead to the discovery of cytotoxic agents with low calcium channel blocking activity.

Synthesis and antibacterial activity of levofloxacin derivatives with certain bulky residues on piperazine ring.

A number of levofloxacin analogues carrying a 2-aryl-2-oxoethyl or a 2-aryl-2-oxyiminoethyl moiety attached to the piperazine ring at C-10 position have been prepared and evaluated as antibacterial agents against a series of Gram-positive and Gram-negative bacteria. Some of them exhibited significant inhibitory activity against Gram-positive bacteria.