Browsing by Author "Braj R. Singh"

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Coating with Microbial Hydrophobins: A Novel Approach to Develop Smart Drug Nanoparticles
(Elsevier Ltd, 2018) Brahma N. Singh; Braj R. Singh; Vijai K. Gupta; Ravindra N. Kharwar; Lorenzo Pecoraro
Microbial hydrophobin (MH)-based surface coating is emerging as a novel protein engineering approach for drug nanoparticles to enhance the solubility and stability of therapeutic agents. These hydrophobins are amphiphilic proteins that can form self-assembled monolayers on hydrophobic materials and can coat nanoparticles for efficient drug delivery. © 2018 Elsevier Ltd
Lagerstroemia speciosa fruit extract modulates quorum sensing-controlled virulence factor Production and biofilm formation in Pseudomonas aeruginosa
(2012) Brahma N. Singh; H.B. Singh; Akanksha Singh; Braj R. Singh; Aradhana Mishra; C.S. Nautiyal
Lagerstroemia speciosa (Lythraceae) is a south-east Asian tree more commonly known as 'Jarul'. Research on health benefits suggests that the L. speciosa plant contains phytomolecules that may have antioxidant, anti-diabetic and anti-obesity properties. However, antimicrobial activities have not been reported for this plant. The ability of L. speciosa fruit extract (LSFE) to antagonize cell-tocell communication, expression of virulence genes and factors, and biofilm formation was evaluated in Pseudomonas aeruginosa strain PAO1. Our results suggested that LSFE caused downregulation of quorum sensing (QS)-related genes (las and rhl) and their respective signalling molecules, N-acylhomoserine lactones, without affecting the growth of P. aeruginosa PAO1. Significant inhibition of virulence factors: LasA protease, LasB elastase, and pyoverdin production, was also recorded. Application of LSFE to P. aeruginosa PAO1 biofilms increased bacterial susceptibility to tobramycin. These data suggest a possible role for quorum-quenching mechanisms unrelated to static or cidal effects, and also suggest that L. speciosa could serve as a cost-effective source in the development of new QS-based antibacterial drugs. © 2012 SGM Printed in Great Britain.
Mycofabricated biosilver nanoparticles interrupt Pseudomonas aeruginosa quorum sensing systems
(Nature Publishing Group, 2015) Braj R. Singh; Brahma N. Singh; Akanksha Singh; Wasi Khan; Alim H. Naqvi; Harikesh B. Singh
Quorum sensing (QS) is a chemical communication process that Pseudomonas aeruginosa uses to regulate virulence and biofilm formation. Disabling of QS is an emerging approach for combating its pathogenicity. Silver nanoparticles (AgNPs) have been widely applied as antimicrobial agents against human pathogenic bacteria and fungi, but not for the attenuation of bacterial QS. Here we mycofabricated AgNPs (mfAgNPs) using metabolites of soil fungus Rhizopus arrhizus BRS-07 and tested their effect on QS-regulated virulence and biofilm formation of P. aeruginosa. Transcriptional studies demonstrated that mfAgNPs reduced the levels of LasIR-RhlIR. Treatment of mfAgNPs inhibited biofilm formation, production of several virulence factors (e.g. LasA protease, LasB elastrase, pyocyanin, pyoverdin, pyochelin, rhamnolipid, and alginate) and reduced AHLs production. Further genes quantification analyses revealed that mfAgNPs significantly down-regulated QS-regulated genes, specifically those encoded to the secretion of virulence factors. The results clearly indicated the anti-virulence property of mfAgNPs by inhibiting P. aeruginosa QS signaling.
Plant polyphenols for prevention and therapy of liver cancer
(Nova Science Publishers, Inc., 2011) Brahma N. Singh; Braj R. Singh; Shi W. Jiang; Harikesh B. Singh
Primary liver cancer, mainly hepatocellular carcinoma (HCC), is the third leading cause of cancer-related deaths worldwide. The incidence of HCC is increasing worldwide; the overall survival of patients with HCC is grim because most patients are diagnosed late, when curative treatment is not possible and is the direct cause of about 1 million deaths annually. Chronic infection with hepatitis B viruses, toxic industrial chemicals, food additives (N-nitrosodiethylamine; NDEA), fungal toxins (aflatoxins), air, water pollutants and chronic heavy alcohol use leading to cirrhosis of the liver remain the most important causes. The great challenge in cancer prevention and control is how to manage those who have already been exposed to carcinogens, such as individuals who are HBsAg carriers and have long-term aflatoxin and NDEA exposure. The development of tumor markers that can detect HCC at even earlier stages is essential. In recent years, clinically useful tumor markers for HCC diagnosis have included α-fetoprotein (AFP), a fucosylated variant of the AFP glycoprotein which has a high affinity to the sugar chain of lens culinaris (AFPL3), des- γ-carboxy prothrombin (DCP), carcinoembryonic antigen (CEA) glypican-3 (GPC3) golgi protein 73 (GP73), growth factors or cytokines, insulin-like growth factor (IGF), interleukin (IL)-6 and IL-10, γ-glutamyl transferase (GGT) and α-L -fucosidase (AFU) etc. Chemoprevention has been proposed as the good tool to target these high-risk populations. Among various identified chemopreventive agents, plant polyphenols have been shown to be safe and high effective in inhibition of carcinogen-induced mutagenesis and tumorigenesis in bioassays and animal models for different target organ sites. The compounds derived from the plants are of considerable interest among oncologists. Many plant-derived, plant polyphenols have been studied for their chemopreventive and chemotherapeutic properties against human HCC, including green tea polyphenols, genistein (found in soy), apigenin (celery, parsley), luteolin (broccoli), quercetin (onions), kaempferol (broccoli, grapefruits), curcumin (turmeric), etc. The more we will discuss their involved molecular mechanisms and cellular targets, the better we could utilize these "natural gifts" for the prevention and treatment of HCC. Furthermore, better understanding of their structure-activity relationships will guide synthesis of analog compounds with improved bio-availability, stability, potency and specificity. In this article, for the sake of better understanding, the effective plant polyphenols against HCC will also be discussed, with more emphases on the basic conceptions of phenolics with strong antioxidant activity. ©2011 Nova Science Publishers, Inc. All rights reserved.
Potential chemoprevention of N-nitrosodiethylamine-induced hepatocarcinogenesis by polyphenolics from Acacia nilotica bark
(2009) Brahma N. Singh; Braj R. Singh; B.K. Sarma; H.B. Singh
Chemopreventive potential of Acacia nilotica bark extract (ANBE) against single intraperitoneal injection of N-nitrosodiethylamine (NDEA, 200 mg/kg) followed by weekly subcutaneous injections of carbon tetrachloride (CCl4, 3 ml/kg) for 6 weeks induced hepatocellular carcinoma (HCC) in rats was studied. At 45 day after administration of NDEA, 100 and 200 mg/kg of ANBE were administered orally once daily for 10 weeks. The levels of liver injury and liver cancer markers such as alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT), total bilirubin level (TBL), α-feto protein (AFP) and carcinoembryonic antigen (CEA) were substantially increased following NDEA treatment. However, ANBE treatment reduced liver injury and restored liver cancer markers. ANBE also significantly prevented hepatic malondialdehyde (MDA) formation and reduced glutathione (GSH) in NDEA-treated rats which was dose dependent. Additionally, ANBE also increased the activities of antioxidant enzymes viz., catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) in the liver of NDEA-administered rats. Eventually, ANBE also significantly improved body weight and prevented increase of relative liver weight due to NDEA treatment. Histological observations of liver tissues too correlated with the biochemical observations. HPLC analysis of ANBE showed the presence of gallic, protocatechuic, caffeic and ellagic acids, and also quercetin in ANBE. The results strongly support that A. nilotica bark prevents lipid peroxidation (LPO) and promote the enzymatic and non-enzymatic antioxidant defense system during NDEA-induced hepatocarcinogenesis which might be due to activities like scavenging of oxy radicals by the phytomolecules in ANBE. © 2009 Elsevier Ireland Ltd. All rights reserved.
ROS-dependent anticandidal activity of zinc oxide nanoparticles synthesized by using egg albumen as a biotemplate
(IOP Publishing Ltd, 2013) M. Shoeb; Braj R. Singh; Javed A. Khan; Wasi Khan; Brahma N Singh; Harikesh B. Singh; Alim H. Naqvi
Zinc oxide nanoparticles (ZnO NPs) have attracted great attention because of their superior optical properties and wide application in biomedical science. However, little is known about the anticandidal activity of ZnO NPs against Candida albicans (C. albicans). This study was designed to develop the green approach to synthesize ZnO NPs using egg white (denoted as EtZnO NPs) and investigated its possible mechanism of antimicrobial activity against C. albicans 077. It was also notable that anticandidal activity of EtZnO NPs is correlated with reactive oxygen species (ROS) production in a dose dependent manner. Protection of histidine against ROS clearly suggests the implication of ROS in anticandidal activity of EtZnO NPs. This green approach based on egg white-mediated synthesis of ZnO NPs paves the way for developing cost effective, eco-friendly and promising antimicrobial nanomaterial for applications in medicine. © 2013 Vietnam Academy of Science & Technology.
ROS-mediated apoptotic cell death in prostate cancer LNCaP cells induced by biosurfactant stabilized CdS quantum dots
(2012) Braj R. Singh; Brahma N. Singh; W. Khan; H.B. Singh; A.H. Naqvi
Cadmium sulfide (CdS) quantum dots (QDs) have raised great attention because of their superior optical properties and wide utilization in biological and biomedical studies. However, little is known about the cell death mechanisms of CdS QDs in human cancer cells. This study was designed to investigate the possible mechanisms of apoptosis induced by biosurfactant stabilized CdS QDs (denoted as " bsCdS QDs" ) in human prostate cancer LNCaP cells. It was also noteworthy that apoptosis correlated with reactive oxygen species (ROS) production, mitochondrial damage, oxidative stress and chromatin condensation in a dose- and time-dependent manner. Results also showed involvement of caspases, Bcl-2 family proteins, heat shock protein 70, and a cell-cycle checkpoint protein p53 in apoptosis induction by bsCdS QDs in LNCaP cells. Moreover, pro-apoptotic protein Bax was upregulated and the anti-apoptotic proteins, survivin and NF-κB were downregulated in bsCdS QDs exposed cells. Protection of N-acetyl cysteine (NAC) against ROS clearly suggested the implication of ROS in hyper-activation of apoptosis and cell death. It is encouraging to conclude that biologically stabilized CdS QDs bear the potential of its applications in biomedicine, such as tumor therapy specifically by inducing caspase-dependent apoptotic cell death of human prostate cancer LNCaP cells. © 2012.