Synthesis and Biological Profiles of Some Benzimidazolyl-chalcones as Anti-leishmanial and Trypanocidal Agents

Background: Benzimidazole constitutes a starting point for the development of new antiprotozoal agents since this nucleus exists in several pharmacologically significant molecules, in particular possessing antifungal, antiviral, antibacterial, and antiparasitic properties. Objective: The present study aimed to identify a molecular hit likely to be developed as an anti-leishmanial and antitrypanosomal drug candidate. Methods: Thus, 12 hybrids of chalcone or benzimidazolyl-arylpropenones were synthesized and screened in vitro for anti-leishmanial activity against promastigotes of Leishmania donovani. The microculture tetrazolium assay was used to determine their potential to inhibit 50% of a parasite growth (IC50). Results: Two compounds among 5-chlorobenzimidazole-chalcones (4a and 4c), which exhibited potent activity (IC50<1 μM) against L. donovani and one derivative (4d) poorly effective against L. donovani (IC50>50 μM) were selected to check their trypanocidal activity. Lethal concentration (LC100) values of these compounds were estimated by using observations on the viability of trypomastigotes of Trypanosoma brucei brucei in MEM medium with Earle’s salts and L-glutamine. Seven of the tested compounds (4a, 4b, 4c, 4e, 4g, 4h, and 4j) showed particularly higher inhibitory activity than pentamidine (IC50= 7.6 μM) against L. donovani promastigotes with IC50 values in a range from 0.5 to 1.8 μM. In addition, the 2’-chlorine derivative (4c), displayed potent anti-trypanosomal activity comparable to those of melarsoprol, used as reference drug. Conclusion: These results support this series of benzimidazole holding arylpropenone group in position 2 as a starting point for future optimization to get novel agents active against leishmaniasis and trypanosomiasis.

Colochiroside E, an Unusual Non-holostane Triterpene Sulfated Trioside from the Sea Cucumber Colochirus Robustus and Evidence of the Impossibility of a 7(8)-Double Bond Migration in Lanostane Derivatives having an 18(16)-Lactone

The unusual non-holostane triterpene glycoside, colochiroside E (1) was isolated from the sea cucumber Colochirus robustus (Cucumariidae, Dendrochirotida). The structure of 1 was established by analysis of ID, 2D NMR and HRESI MS data. Colochiroside E (1) belongs to a rare group of glycosylated 9β-H-lanosta-18(16)-lactones and has an unprecedented sulfated trisaccharide carbohydrate chain consisting of two glucose and one xylose units. In contrast with (9β-H)-7(8)-unsaturated holostane glycosides, the 7(8)-double bond in the having (9β-H)-configuration aglycone of colochiroside E is not capable of migration into the 8(9)- and then into the 9(11)-position on treatment with HC1. The formation of a chlorine derivative of 1 was observed under these conditions.

Studies on photodynamic mechanism of a novel chlorine derivative (TDPC) and its antitumor effect for photodynamic therapy in vitro and in vivo

Photodynamic therapy (PDT) represents a promising method for treatment of cancerous tumors. The chemical and physical properties of used photosensitizer (PS) play key roles in the treatment efficacy. In this study, a novel PS, 5,10,15,20-tetrakis((5-dipropylamino)pentyl)-chlorin (TDPC) which displayed a characteristic long wavelength absorption peak at 650 nm were synthesized. It also shows a singlet oxygen generation rate of 4.257 min-1. Generally, TDPC is localized in mitochondria and nucleus of cell. After light irradiation with 650 nm laser, it can kill many types of cell, in addition, TDPC–PDT can destroy ECA-109 tumor in nude mice and a necrotic scab was formed eventually. The expression levels of many genes which regulated cell growth and apoptosis were determined by RT-PCR following TDPC–PDT. The results showed that it either increased or decreased, among which, the expression level of TNFSF13, a member of tumor necrosis factor superfamily, increased significantly. In general, TDPC is an effective antitumor PS in vitro and in vivo and is worthy of further study as a new drug candidate. TNFSF13 will be an important molecular target for the discovery of new PSs.

Complexes of Zn, Cd and Hg Halides with S and N Polydentate Schiff-Base. Metal Template Effect in the Synthesis of Analogous Oxygenated Base. Crystal Structure of [Zn(btsc)2Cl2] and [Cd(btsc)2Br2]

Zinc, cadmiun and mercury dihalide react with 4-acetylpyridinthiosemicarbazone (4-aptsc) to give complexes with 1:1 and 2:1 ligand/metal stoichiometric ratios. These metals are effective templates for the Schiff-base condensation of 4-acetylpyridine with semicarbazide to give the complexes [M(4-apsc)X2] and [M(4-apsc)2X2] where M = Zn, Cd or Hg and X = Cl, Br or I. These compounds were characterized by elemental analyses, conductivities measurements, IR and 13C, 1H NMR spectra.The zinc chloride and bromide complexes of benzalthiosemicarbazone (btsc) have been prepared and characterized by X-ray measurements.The compounds Zn(btsc)2Cl2 and Cd(btsc)2Br2 are isostructural and crystallize in the space group P21/n. The crystal structure of the chlorine derivative has been resolved by single-crystal X-ray diffraction. The zinc centre is in a slightly distorted tetrahedral environment. There are intra and intermolecular hydrogen bonds.