Identification and evaluation of potential inhibitor molecules against TcyA from Candidatus Liberibacter asiaticus.

Of the two putative amino acid binding periplasmic receptors of ABC transporter family in Candidatus Liberibacter asiaticus (CLas), cystine binding receptor (CLasTcyA) has been shown to mainly express in phloem of citrus plant and is a target for inhibitor development. The crystal structure of CLasTcyA in complex with substrates has been reported earlier. The present work reports the identification and evaluation of potential candidates for their inhibitory potential against CLasTcyA. Among many compounds, selected through virtual screening, and MD simulation, pimozide, clidinium, sulfasalazine and folic acid showed significantly higher affinities and stability in complex with CLasTcyA. The SPR studies with CLasTcyA revealed significantly higher binding affinities for pimozide and clidinium (Kd, 2.73 nM and 70 nM, respectively) as compared to cystine (Kd, 1.26 µM). The higher binding affinities could be attributed to significantly increased number of interactions in the binding pocket as evident from the crystal structures of CLasTcyA in complex with pimozide and clidinium as compared to cystine. The CLasTcyA possess relatively large binding pocket where bulkier inhibitors fit quite well. In planta studies, carried out to assess the effect of inhibitors on HLB infected Mosambi plants, showed significant reduction in CLas titre in plants treated with inhibitors as compared to control plants. The results showed that pimozide exhibited higher efficiency as compared to clidinium in reducing CLas titre in treated plants. Our results showed that the inhibitor development against critical proteins like CLasTcyA can be an important strategy in management of HLB.

Cationic RGD peptidomimetic nanoconjugates as effective tumor targeting gene delivery vectors with antimicrobial potential.

Gene delivery combined with systemic targeting approach has shown promising potential in cancer gene therapy. Peptides are ideal functional motif for constructing biocompatible non-viral gene delivery vehicles. RGD peptides, in particular, are known to recognize the integrin αVß3, which is expressed specifically on angiogenic blood vessels and, therefore, is considered vital for anti-angiogenesis strategies and cancer treatment. In recent times, several RGD peptide-based non-viral gene delivery vectors have been utilized for targeted gene delivery, however, lack in proteolytic stability. In the current study, we have investigated a series of non-naturally modified RGD peptide mimic (MOH) nanoconjugates with low molecular weight branched polyethylenimine (bPEI 1.8 kDa). The projected peptide mimic, Fmoc-FFARKA (MOH), has already been demonstrated to have high binding efficiency for αVß3 integrins and enhanced cell adhesive ability with high stability compared to the natural RGD counterpart. The polymer-peptide, PEI-MOH (PMOH), nanoconjugate vectors have been designed to enhance the tumor targeting ability, therapeutic proficiency, transfection efficiency and proteolytic stability. The synthesized nanoconjugates showed the ability to protect the bound DNA with low cytotoxicity and their pDNA complexes displayed enhanced transfection efficiency. Furthermore, a competitive study confirmed their selective behavior towards liver cancer cells, HepG2. Lastly, PMOH nanoconjugates also exerted significant antimicrobial effects against drug-resistant pathogens. Altogether, the data suggest that nanosized non-naturally modified RGD peptide mimic-based gene vectors hold great potential as efficient biomaterials for targeted gene delivery and antimicrobial applications.

Ameliorative role of inducible nitric oxide synthase inhibitors against sodium arsenite-induced renal and hepatic dysfunction in rats.

Arsenic exposure causes immense health distress by increasing risk of cardiovascular abnormalities, diabetes mellitus, neurotoxicity, and nephrotoxicity. The present study explored the role of inducible nitric oxide synthase (iNOS) inhibitors against sodium arsenite-induced renal and hepatic dysfunction in rats. Female Sprague Dawley rats were subjected to arsenic toxicity by administering sodium arsenite (5 mg/kg/day, oral) for 4 weeks. The iNOS inhibitors, S-methylisothiourea (10 mg/kg, i.p.) and aminoguanidine (100 mg/kg, i.p.) were given one hour before sodium arsenite administration in rats for 4 weeks. Sodium arsenite led rise in serum creatinine, urea, uric acid, electrolytes (potassium, fractional excretion of sodium), microproteinuria, and decreased creatinine clearance (p < 0.001) indicated renal dysfunction in rats. Arsenic-intoxication resulted in significant oxidative stress in rat kidneys, which was measured in terms of increase in lipid peroxides, superoxide anion generation and decrease in reduced glutathione (p < 0.001) levels. A threefold increase in renal hydroxyproline level in arsenic intoxicated rats indicated fibrosis. Hematoxylin-eosin staining indicated tubular damage, whereas picrosirius red staining highlighted collagen deposition in rat kidneys. S-methylisothiourea and aminoguanidine improved renal function and attenuated arsenic led renal oxidative stress, fibrosis, and decreased the kidney injury score. Additionally, arsenite-intoxication resulted in significant rise in hepatic parameters (serum aspartate aminotransferase, alanine transferase, alkaline phosphatase, and bilirubin (p < 0.001) along with multi-fold increase in oxidative stress, fibrosis and liver injury score in rats, which was significantly (p < 0.001) attenuated by concurrent administration of iNOS inhibitors). Hence, it is concluded that iNOS inhibitors attenuate sodium arsenite-induced renal and hepatic dysfunction in rats.