Moganavelli Singh

Novel 2-(1-(substitutedbenzyl)-1H-tetrazol-5-yl)-3-phenylacrylonitrile derivatives: synthesis, in vitro antitumor activity and computational studies

This work describes the two-step synthesis of new series of 2-(1-(substitutedbenzyl)-1H-tetrazol-5-yl)-3-phenylacrylonitrile derivatives (6a–k) starting from substituted benzyl halides (5a–k) and 3-phenyl-2-(1H-tetrazol-5-yl)acrylonitrile (4). Initially, compound 4 was synthesized using benzaldehyde, malononitrile and sodium azide. All the synthesized compounds were obtained in good yields and were characterized using 1H NMR, 13C NMR, FTIR and HRMS spectral data. The new compounds (6a–k) were evaluated for their potential in vitro antitumor activity against four human cancer cell lines (MCF-7, CaCO2, HeLa and SkBr3) by MTT assay. The most potent compounds 6b, 6h and 6j show good activity (IC50 values) relative to 5-fluorouracil, with potential to be antitumor agents. Compounds 6a, 6c, 6g, 6f and 6k showed moderate activity. The best performing three compounds (6b, 6h and 6j) were evaluated for in silico analysis on the PharmMapper web server, and the human mitogen-activated protein kinase 1 (MEK-1) enzyme was recognized as the main target protein. MEK-1 inhibition by these compounds was further confirmed by the docking study to corroborate the target.Graphical Abstract

Anti-Plasmodial Activity of Some Zulu Medicinal Plants and of Some Triterpenes Isolated from Them

Mimusops caffra E. Mey. ex A.DC and Mimusops obtusifolia Lam (both members of the Sapotaceae family), and Hypoxis colchicifolia Bak (family Hypoxidaceae) are used by traditional healers in Zululand to manage malaria. Anti-plasmodial investigation of the crude extracts and some triterpenes isolated from the plants showed activity against a chloroquine sensitive (CQS) strain of Plasmodium falciparum (D10). Among the crude extracts the leaves of M. caffra exhibited the highest activity, with an IC50 of 2.14 μg/mL. The pentacyclic tritepenoid ursolic acid (1), isolated from the leaves of M. caffra was the most active compound (IC50 6.8 μg/mL) as compared to taraxerol (2) and sawamilletin (3) isolated from the stem bark of M. obtusifolia (IC50 > 100). Chemical modification of the ursolic acid (1) to 3β-acetylursolic acid (4) greatly enhanced its anti-plasmodial activity. Compound 4 reduced parasitaemia against Plasmodium berghei by 94.01% in in vivo studies in mice. The cytotoxicity of 3β-acetylursolic acid (IC50) to two human cell lines (HEK293 and HepG2) was 366.00 μg/mL and 566.09 μg/mL, respectively. The results validate the use of these plants in folk medicine.

Silver salts of carboxylic acid terminated generation 1 poly (propyl ether imine) (PETIM) dendron and dendrimers as antimicrobial agents against S. aureus and MRSA

Novel therapeutic strategies are essential to address the current global antimicrobial resistance crisis. Branched molecules with multiple peripheral functionalities, known as dendrimers, have gained interest as antimicrobials and have varying levels of toxicity. Silver displays activity against several micro-organisms only in its positively charged form. In this study, silver salts of generation 1 (G1) poly (propyl ether imine) (PETIM) dendron and dendrimers were synthesised and evaluated for their antimicrobial potential against sensitive and resistant bacteria. The purpose was to exploit the multiple peripheral functionalities of G1 PETIM dendron and dendrimers for the formation of silver salts containing multiple silver ions in a single molecule for enhanced antimicrobial activity at the lowest possible concentration. G1 PETIM dendron, dendrimers and their silver salts were synthesised and characterised by FT-IR, 1H NMR and 13C NMR. PETIM silver salts were evaluated against Hep G2, SKBR-3 and HT-29 cell lines for their cytotoxicity using the MTT assay. The G1 PETIM dendron/dendrimers, silver nitrate and silver salts of the G1 dendron (compound 13), G1 dendrimer with an aromatic core (compound 14) and an oxygen core (compound 15) were evaluated for activity against S. aureus and methicillin-resistant S. aureus (MRSA) by the broth dilution method. PETIM silver salts were found to be non-cytotoxic even up to 100 μg ml−1. Minimum inhibitory concentration values of compounds 13, 14 and 15 against S. aureus were 52.1, 41.7 and 20.8 μg ml−1 while against MRSA they were 125.0, 26.0 and 62.5 μg ml−1, respectively. The calculated fractional inhibitory concentration index further indicated that compound 14 specifically displayed additive effects against S. aureus and synergism against MRSA. The enhanced antimicrobial activities of the PETIM dendron/dendrimer-silver salts against both sensitive and resistant bacterial strains widen the pool of available pharmaceutical materials for optimizing treatment of bacterial infections.

Synthesis and Characterization of Layered Double Hydroxides and Their Potential as Nonviral Gene Delivery Vehicles

Layered double hydroxides (LDHs) exhibit characteristic anion-exchange chemistry making them ideal carriers of negatively charged molecules like deoxyribonucleic acid (DNA). In this study, hydrotalcite (Mg−Al) and hydrotalcite-like compounds (Mg−Fe, Zn−Al, and Zn−Fe), also known as LDHs, were evaluated for their potential application as a carrier of DNA. LDHs were prepared by coprecipitation at low supersaturation and characterized by Powder X-ray diffraction (XRD), infrared (IR), Raman, and inductively coupled plasma—optical emission spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD patterns showed strong and sharp diffraction peaks for the (003) and (006) planes indicating well-ordered crystalline materials. TEM images yielded irregular circular to hexagonal-shaped particles of 50–250 nm in size. Varying degrees of DNA binding was observed for all the compounds, and nuclease digestion studies revealed that the LDHs afford some degree of protection to the bound DNA. Minimal toxicity was observed in human embryonic kidney (HEK293), cervical cancer (HeLa) and hepatocellular carcinoma (HepG2) cell lines with most showing a cell viability in excess of 80 %. All LDH complexes promoted significant levels of luciferase gene expression, with the DNA:Mg−Al LDHs proving to be the most efficient in all cell lines.

Novel serum-tolerant lipoplexes target the folate receptor efficiently

Gene transfer using non-viral vectors is a promising approach for the safe delivery of nucleic acid therapeutics. In this study, we investigate a lipid-based system for targeted gene delivery to malignant cells overexpressing the folate receptor (FR). Cationic liposomes were formulated with and without the targeting ligand folate conjugated to distearoylphosphatidyl ethanolamine polyethylene glycol 2000 (DSPE-PEG2000), the novel cytofectin 3β[N(N(1),N(1)-dimethlaminopropylsuccinamidoethane)-carbamoyl]cholesterol (SGO4), which contains a 13atom, 15Å spacer element, and the helper lipid, dioleoylphosphatidylethanolamine (DOPE). Physicochemical parameters of the liposomes and lipoplexes were obtained by zeta sizing, zeta potential measurement and cryo-TEM. DNA-binding and protection capabilities of liposomes were confirmed by gel retardation assays, EtBr intercalation and nuclease protection assays. The complexes were assessed in an in vitro system for their effect on cell viability using the MTT assay, and gene transfection activity using the luciferase assay in three cell lines; HEK293 (FR-negative), HeLa (FR(+)-positive), KB (FR(++)-positive). Low cytotoxicities were observed in all cell lines, while transgene activity promoted by folate-tagged lipoplexes in FR-positive lines was tenfold greater than that by untargeted constructs and cell entry by folate complexes was demonstrably by FR mediation. These liposome formulations have the design capacity for in vivo application and may therefore be promising candidates for further development.

Cytotoxicity, Antioxidant and Apoptosis Studies of Quercetin-3-O Glucoside and 4-(β-D-Glucopyranosyl-1→4-α-L-Rhamnopyranosyloxy)-Benzyl Isothiocyanate from Moringa oleifera

Moringa oleifera, from the family Moringaceae, is used as a source of vegetable and herbal medicine and in the treatment of various cancers in many African countries, including Kenya. The present study involved the phytochemical analyses of the crude extracts of M.oleifera and biological activities (antioxidant, cytotoxicity and induction of apoptosis in-vitro) of selected isolated compounds. The compounds isolated from the leaves and seeds of the plant were quercetin-3-O-glucoside (1), 4-(β-D-glucopyranosyl-1→4-α-L-rhamnopyranosyloxy)-benzyl isothiocyanate (2), lutein (3), and sitosterol (4). Antioxidant activity of compound 1 was significant when compared to that of the control, while compound 2 showed moderate activity. The cytotoxicity of compounds 1 and 2 were tested in three cell lines, viz. liver hepatocellular carcinoma (HepG2), colon carcinoma (Caco-2) and a non-cancer cell line Human Embryonic Kidney (HEK293), using the MTT cell viability assay and compared against a standard anticancer drug, 5-fluorouracil. Apoptosis studies were carried out using the acridine orange/ethidium bromide dual staining method. The isolated compounds showed selective in vitro cytotoxic and apoptotic activity against human cancer and non-cancer cell lines, respectively. Compound 1 showed significant cytotoxicity against the Caco-2 cell line with an IC50 of 79 μg mL(-1) and moderate cytotoxicity against the HepG2 cell line with an IC50 of 150 μg mL(-1), while compound 2 showed significant cytotoxicity against the Caco- 2 and HepG2 cell lines with an IC50 of 45 μg mL(-1) and 60 μg mL(-1), respectively. Comparatively both compounds showed much lower cytotoxicity against the HEK293 cell line with IC50 values of 186 μg mL(-1) and 224 μg mL(-1), respectively.

Synthesis, characterization, and cytotoxic and antimicrobial activities of ruthenium(II) arene complexes with N,N-bidentate ligands

Abstract Three new complexes, [(η6-C6H6)RuCl(C5H4N-2-CH=N-Ar)]PF6 (Ar = phenylmethylene (1), (4-methoxyphenyl)methylene (2), and phenylhydrazone (3)), were prepared by reacting [(η6-C6H6)Ru(μ-Cl)Cl]2 with N,N′-bidentate ligands in a 1 : 2 ratio. Full characterization of the complexes was accomplished using 1H and 13C NMR, elemental and thermal analyses, UV–vis and IR spectroscopy and single crystal X-ray structures. Single crystal structures confirmed a pseudo-octahedral three-legged, piano-stool geometry around Ru(II), with the ligand coordinated to the ruthenium(II) through two N atoms. The cytotoxicity of the mononuclear complexes was established against three human cancer cell lines and selectivity was also tested against non-cancerous human epithelial kidney (HEK 293) cells. The compounds were selective toward the tumor cells in contrast to the known anti-cancer drug 5-fluoro uracil which was not selective between the tumor cells and non-tumor cells. All the compounds showed moderate activity against MCF7 (human breast adenocarcinoma), but showed low antiproliferative activity against Caco-2 and HepG2. Also, antimicrobial activities of the complexes were tested against a panel of antimicrobial-susceptible and -resistant Gram-negative and Gram-positive bacteria. Of special interest is the anti-mycobacterial activity of all three synthesized complexes against Mycobacterium smegmatis, and bactericidal activity against resistant Enterococcus faecalis and methicillin-resistant Staphylococcus aureus ATCC 43300.

Novel Targeted Liposomes Deliver siRNA to Hepatocellular Carcinoma Cells in vitro

Liposomes form a major class of non‐viral vectors for short interfering RNA delivery, however tissue and cell‐specific targeting are additional requirements in the design of short interfering RNA delivery systems with a therapeutic potential. Selective delivery of liposomes to hepatocytes may be achieved by directing complexes to the asialoglycoprotein receptor, which is expressed on hepatocytes, and which displays high affinity for the β‐d‐galactopyranosyl moiety. We aimed to show that the d‐galactopyranosyl ring in direct β‐glycosidic link to cholesterol, when formulated into liposomes with 3β[N‐(N′,N′‐dimethylaminopropane) carbamoyl] cholesterol (Chol‐T) or its quaternary trimethylammonium analogue (Chol‐Q), may promote targeted delivery of cytotoxic short interfering RNA to the human hepatoma cell line HepG2 via the asialoglycoprotein receptor. Liposome‐short interfering RNA interactions were characterized by electron microscopy, dye displacement, gel retardation and nuclease assays. Stable short interfering RNA‐protective lipoplexes were formed at N/P ratios in the range 5:1–7:1. Targeted lipoplex 4 achieved high transfection efficiencies at 50 nm short interfering RNA (70%) and <10% in a competition assay, whilst untargeted complexes reached low levels at the same concentration (<25%). Transfection efficiencies of all lipoplexes in the asialoglycoprotein receptor‐negative cell line HEK293 under the same conditions were low. Lipoplexes containing cholesteryl‐β‐d‐galactopyranoside may therefore form the basis for the development of useful hepatotropic short interfering RNA delivery vectors.

The electrokinetic characterization of gold nanoparticles, functionalized with cationic functional groups, and its' interaction with DNA.

Gold nanoparticles have attracted strong biomedical interest for drug delivery due to their low toxic nature, surface plasmon resonance and capability of increasing the stability of the payload. However, gene transfection represents another important biological application. Considering that cellular barriers keep enclosed their secret to deliver genes using nanoparticles, an important step can be achieved by studying the functionalization of nanoparticles with DNA. In the present contribution the synthesis of nanoparticles consisting of a gold core coated with one or more layers of amino acid (l-lysine), and cationic polyelectrolytes (poly-ethyleneimine and poly-l-lysine) is reported. All nanoparticles were subjected to dynamic light scattering, electrophoretic mobility measurements, UV-vis optical spectrophotometry analysis and transmission electron microscopy imaging. In addition, the adsorption of DNA plasmid (pSGS) with linear and supercoiled configurations was studied for those gold nanoparticles under the most suitable surface modifications. Preliminary results showed that the gold nanoparticles functionalized with poly-ethyleneimine and poly-l-lysine, respectively, and bound to linear DNA configurations, present in absolute value a higher electrophoretic mobility irrespective of the pH of the media, compared to the supercoiled and nicked configuration. The findings from this study suggest that poly-ethyleneimine and poly-l-lysine functionalized gold nanoparticles are biocompatible and may be promising in the chemical design and future optimization of nanostructures for biomedical applications such as gene and drug delivery.

The Effects of Syzygium aromaticum-Derived Oleanolic Acid on Kidney Function of Male Sprague–Dawley Rats and on Kidney and Liver Cell Lines

Studies indicate that Syzygium spp-derived oleanolic acid (OA) enhances renal function of streptozotocin (STZ)-induced diabetic rats as evidenced by its reversal of the previously reported inability of the kidney to excrete Na+ in these animals. We postulated that OA influences Na+ excretion in the proximal tubule, the site where two-thirds of filtered NaCl is reabsorbed through a process mediated by transport proteins. Therefore, the study investigated the effects of OA on proximal tubular Na+ handling in male Sprague–Dawley rats using renal lithium clearance (CLi). Renal CLi has been used widely in animal and clinical studies to assess proximal tubular function. Sub-chronic doses of OA were administered to rats twice every third day for 5 weeks. Rats treated with deionized water served as control animals. Cytotoxicity of OA on kidney and liver cell lines was assessed by the MTT and comet assays. OA increased Na+ excretion of conscious male Sprague–Dawley rats from week 3 to week 5. By the end of the 5-week experimental period, OA treatment significantly reduced (p < 0.05) plasma creatinine concentration of STZ-induced diabetic rats with a concomitant elevation in glomerular filtration rate (GFR). Acute OA infusion was also associated with increases in fractional excretion of sodium (FENa) and lithium (FELi) in anesthetized rats in the absence of significant changes in GFR. The MTT assay studies demonstrated that OA increased the metabolic activity of kidney and liver cell lines. Taken together with previous observations, this study implicates the proximal tubule in OA-evoked increases in urinary Na+ output.