Leishmania donovani: assessment of leishmanicidal effects of herbal extracts obtained from plants in the visceral leishmaniasis endemic area of Bihar, India.

One obstacle faced in the effective control of visceral leishmaniasis (VL) is the limited number of available treatment options. Furthermore, control efforts have been hindered further by the emergence of Leishmania resistance to many of the available drugs. In this study, we investigated the anti-leishmanial properties of 30 medicinally important plants from the VL endemic area of Bihar, India and compared them to two available anti-leishmanial drugs (sodium antimony gluconate and amphotericin B) and two plant lectins (phytohemagglutinin and concanavalin A) on Leishmania donovani promastigotes in vitro at 24 and 48 h after initiation of culture. We identified eight plant extracts in addition to phytohemagglutinin and amphotericin B that significantly inhibited the growth of promastigotes (p < 0.03). We further studied the minimum effective concentrations as well as the effect on axenic amastigotes viability and the cell cytotoxicity on human peripheral blood of four (Agave americana, Azadirachta indica, Eclipta alba and Piper longum) of the eight plant extracts that induced significant promastigotes killing (p = 0.00098). Effect-based dose finding analysis revealed that the threshold concentration of A. americana required to eliminate L. donovani after 24h was 0.05 mg/ml. A. indica and P. longum plant extracts eliminated L. donovani promastigotes after 48 h at concentrations of 0.1 and 0.5mg/ml, respectively. E. alba eliminated the promastigotes at a concentration of 0.5mg/ml within 24h. The axenic amastigote killing response was 1.90-, 2.52- and 1.3-fold higher than the promastigote killing response with A. indica, A. americana and E. alba plant extracts, respectively. A. americana and A. indica, respectively, led to approximate 2.5- and 1.3-fold declines in mitochondrial dehydrogenase activity compared with control. E. alba stimulation resulted in an up-regulation of dehydrogenase activity (p = 0.00329). The CSA from P. longum was found to be least cytotoxic; the observed difference in mitochondrial activity was insignificant (p = 0.16314). Further studies may reveal the pharmacological significance of many of the plants with anti-leishmanial properties identified in the present study.

Synthesis, Self-Assembly, and Biological Activities of Pyrimidine-Based Cationic Amphiphiles.

Pyrimidine-based cationic amphiphiles (PCAms), i.e., di-trifluoroacetic acid salts of N1-[1'-(1″,3″-diglycinatoxy-propane-2″-yl)-1',2',3'-triazole-4'-yl]methyl-N3-alkylpyrimidines have been synthesized utilizing naturally occurring biocompatible precursors, like glycerol, glycine, and uracil/ thymine in good yields. Synthesized PCAms consist of a hydrophilic head group comprising TFA salt of glyceryl 1,3-diglycinate and hydrophobic tail comprising of C-7 and C-12 N3-alkylated uracil or thymine conjugated via a 4-methylene-1,2,3-triazolyl linker. The physicochemical properties of all PCAms, such as critical aggregation concentration, hydrodynamic diameter, shape, and zeta potential (surface charge) were analyzed. These PCAms were also evaluated for their anti-proliferative and anti-tubercular activities. One of the synthesized PCAm exhibited 4- to 75-fold more activity than first-line anti-tubercular drugs streptomycin and isoniazid, respectively, against the multidrug resistant clinical isolate 591 of Mycobacterium tuberculosis.

Synthesis and antimycobacterial activity of 1-(ß-d-Ribofuranosyl)-4-coumarinyloxymethyl- / -coumarinyl-1,2,3-triazole.

A series of ß-d-ribofuranosyl coumarinyl-1,2,3-triazoles have been synthesized by Cu-catalyzed cycloaddition reaction between azidosugar and 7-O-/7-alkynylated coumarins in 62-70% overall yields. The in vitro antimycobacterial activity evaluation of the synthesized triazolo-conjugates against Mycobacterium tuberculosis revealed that compounds were bactericidal in nature and some of them were found to be more active than one of the first line antimycobacterial drug ethambutol against sensitive reference strain H37Rv, and 7 to 420 times more active than all four first line antimycobacterial drugs (isoniazid, rifampicin, ethambutol and streptomycin) against multidrug resistant clinical isolate 591. Study of in silico pharmacokinetic profile indicated the drug like characters for the test molecules. Further, transmission electron microscopic experiments revealed that these compounds interfere with the constitution of bacterial cell wall possibly by targeting mycobacterial InhA and DNA gyrase enzymes. Study conducted on the activities of the test compounds on bacterial InhA and DNA gyrase revealed that the most bactericidal test compound, N1-(ß-d-ribofuranosyl)-C4-(4-methylcoumarin-7-oxymethyl)-1,2,3-triazole (6b) and its corresponding directly linked conjugate N1-(ß-d-ribofuranosyl)-C4-(4-methylcoumarin-7-yl)-1,2,3-triazole (11b) significantly inhibited the activity of both the enzymes. The results were further supported by molecular docking studies of the compound 6b and 11b with bacterial InhA and DNA gyrase B enzymes. Further, the cytotoxicity study of some of the better active compounds on THP-1 macrophage cell line using MTT assay showed that the synthesized compounds were non-cytotoxic.

Study of the mechanism of interaction of antibody (IgG) on two mixed mode sorbents.

Purification of target proteins from a crude biological mixture containing proteins, peptides and other biomolecules is the chromatographic challenge. Mixed mode chromatography offers additional selectivities to improve the overall productivity of commercial bioprocesses with novel chromatographic sorbents being introduced to overcome the problem. HEA HyperCel (n-hexyl amine) and PPA HyperCel (phenyl propyl amine) are industry scalable mixed mode chromatography sorbents where both hydrophobic and electrostatic interactions are predominant. Our study focuses on understanding the underlying mechanism of interaction of protein with the sorbent. Parameters like buffer conditions, pH and temperature were tuned to study the adsorption and desorption conditions of the protein. Dynamic binding capacity of HEA HyperCel and PPA HyperCel sorbents was studied with human IgG as a model protein. Our study shows that, in HEA the interaction of IgG to the sorbent is predominantly hydrophobic as the binding is enhanced (50-60 mg/ml of sorbent) by presence of salt in buffer and increase in temperature. Binding capacity of PPA is 50-60 mg/ml of sorbent irrespective of temperature effect and/or the presence of salt. The chromatographic experiments show that the interaction could be hydrophobic or ionic or some charge transfer mechanism depending upon the buffer conditions.