Rajib Majumder

Dr. Rajib Majumder

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Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 February 2024 in Gut
Verified
Journal Article
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Kurtis Francis BuddenKurtis Francis Budden
Kurtis Francis Budden
SSShakti Shukla
Shakti Shukla
KBKate L Bowerman
Kate L Bowerman
AVAnnalicia Vaughan
Annalicia Vaughan
SGShaan L Gellatly
Shaan L Gellatly
PHPhilip M. Hansbro
Philip M. Hansbro
Objective: Chronic obstructive pulmonary disease (COPD) is a major cause of global illness and death, most commonly caused by cigarette smoke. The mechanisms of pathogenesis remain poorly understood, limiting the development of effective therapies. The gastrointestinal microbiome has been implicated in chronic lung diseases via the gut-lung axis, but its role is unclear. Design: Using an in vivo mouse model of cigarette smoke (CS)-induced COPD and faecal microbial transfer (FMT), we characterised the faecal microbiota using metagenomics, proteomics and metabolomics. Findings were correlated with airway and systemic inflammation, lung and gut histopathology and lung function. Complex carbohydrates were assessed in mice using a high resistant starch diet, and in 16 patients with COPD using a randomised, double-blind, placebo-controlled pilot study of inulin supplementation. Results: FMT alleviated hallmark features of COPD (inflammation, alveolar destruction, impaired lung function), gastrointestinal pathology and systemic immune changes. Protective effects were additive to smoking cessation, and transfer of CS-associated microbiota after antibiotic-induced microbiome depletion was sufficient to increase lung inflammation while suppressing colonic immunity in the absence of CS exposure. Disease features correlated with the relative abundance of Muribaculaceae, Desulfovibrionaceae and Lachnospiraceae family members. Proteomics and metabolomics identified downregulation of glucose and starch metabolism in CS-associated microbiota, and supplementation of mice or human patients with complex carbohydrates improved disease outcomes. Conclusion: The gut microbiome contributes to COPD pathogenesis and can be targeted therapeutically.

5 April 2017 in Scientific Reports
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Journal Article
Open access
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VBVivek K. Bajpai
Vivek K. Bajpai
BABadrul Alam
Badrul Alam
KQKhong Trong Quan
Khong Trong Quan
KKKyoo-Ri Kwon
Kyoo-Ri Kwon
MJMi-Kyoung Ju
Mi-Kyoung Ju
MNMinKyun Na
MinKyun Na
The aim of the present study was to examine the antioxidative activity of (+)-lariciresinol (LRSL), an optically active lignan isolated from Rubia philippinensis in several in vitro assays. LRSL was also subjected to evaluate its inhibitory effect against the generation of reactive oxygen species (ROS) in murine macrophage (RAW 264.7) cells. The results showed that LRSL possessed very strong radical scavenging activity and reducing power, as well as inhibited ROS generation in a dose-dependent manner without showing any cytotoxicity. The transcriptional and translational levels of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were markedly higher in the sample treated group. LRSL treatment also increased the transcriptional and translational activities of NF-E2-related factor-2 (Nrf-2) with a corresponding increase in the transcriptional and translational activities of the heme oxygenase-1 (HO-1). LRSL activated p38 and treatments with SB239063 (a p38 inhibitor) suppressed the LRSL-induced activation of Nrf2, resulting in a decrease in HO-1 expression. Collectively, the data demonstrated that LRSL has potent antioxidative activity, decreasing ROS generation in RAW 264.7 cells and increasing the transcriptional and translational levels of antioxidant enzymes by activating Nrf2-mediated HO-1 induction via p38 signaling.

15 June 2018 in Scientific Reports
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Journal Article
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VBVivek K. Bajpai
Vivek K. Bajpai
BABadrul Alam
Badrul Alam
KQKhong Trong Quan
Khong Trong Quan
MJMi-Kyoung Ju
Mi-Kyoung Ju
RMRajib Majumder
Rajib Majumder
Young-Kyu HanYoung-Kyu Han
Young-Kyu Han
We examined the anti-inflammatory effects of (+)-syringaresinol (SGRS), a lignan isolated from Rubia philippinensis, in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells using enzyme-based immuno assay, Western blotting, and RT-PCR analyses. Additionally, in vivo effects of SGRS in the acute inflammatory state were examined by using the carrageenan-induced hind paw edema assay in experimental mice. As a result, treatment with SGRS (25, 50, and 100 μM) inhibited protein expression of lipopolysaccharide-stimulated inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor kappa B (NF-κB) as well as production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-6 (IL-6) induced by LPS. Moreover, SGRS also reduced LPS-induced mRNA expression levels of iNOS and COX-2, including NO, PGE2, TNF-α, IL-1β, and IL-6 cytokines in a dose-dependent fashion. Furthermore, carrageenan-induced paw edema assay validated the in vivo anti-edema effect of SGRS. Interestingly, SGRS (30 mg/kg) suppressed carrageenan-induced elevation of iNOS, COX-2, TNF-α, IL-1β, and IL-6 mRNA levels as well as COX-2 and NF-κB protein levels, suggesting SGRS may possess anti-inflammatory activities.

1 October 2016 in Bangladesh Journal of Pharmacology
Verified
Journal Article
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Vivek K. BajpaiVivek K. Bajpai
Vivek K. Bajpai
RMRajib Majumder
Rajib Majumder
JPJae Gyu Park
Jae Gyu Park
Chromatographic techniques have significant role in natural products chemistry as well as contribute dramatically in the discovery of novel and innovative compounds of pharmaceutical and biomedical importance. This study focused on step-by-step visual demonstration of fractionation and isolation of biologically active plant secondary metabolites using column-chromatographic techniques. Isolation of bioactive compounds using column-chromatographic involves: a) Preparation of sample; b) Packing of column; c) Pouring of sample into the column; d) Elution of fractions; and e) Analysis of each fractions using thin layer chromatography. However, depending on nature of research, compounds can be further purified using high performance liquid chromatography (HPLC), and nuclear magnetic resonance (NMR) spectral analyses.Video ClipsPart 1: 3 min 45 secPart 2: 6 min 21 secPart 3: 4 min 45 sec

10 April 2017 in Scientific Reports
Verified
Journal Article
Open access
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BABadrul Alam
Badrul Alam
VBVivek K. Bajpai
Vivek K. Bajpai
JLJungIn Lee
JungIn Lee
PZPeijun Zhao
Peijun Zhao
JBJung-Hee Byeon
Jung-Hee Byeon
Sang-Han LeeSang-Han Lee
Sang-Han Lee
In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.

1 June 2016 in Bangladesh Journal of Pharmacology
Verified
Journal Article
Open access
PDF file
Vivek K. BajpaiVivek K. Bajpai
Vivek K. Bajpai
RMRajib Majumder
Rajib Majumder
Irfan A. RatherIrfan A. Rather
Irfan A. Rather
KKKangmin Kim
Kangmin Kim
Lactic acid bacteria are classified ‘Generally Recognized As Safe’ (GRAS) with most effective potential to divert significant amount of fermentable sugars towards the biosynthesis of functional exopolysaccharide. Exopolysaccharides from lactic acid bacteria are receiving a renewed interest due to the claims of human health benefits, such as modulation of immune response system and more importantly in food and pharma industries as a texturizer, viscosifer, emulsifier and syneresis-lowering agent. Its purification methodology involves: a) Extraction of cell-free supernatant from lactic acid bacteria; b) Denature of protein using trichloroacetic acid; c) Ethanol precipitation; d) Dialysis; and e) Freeze drying. However, depending on nature of research, compounds can be further purified using scanning electron microscopy (SEM), infrared spectrum (IR); and nuclear magnetic resonance (NMR) spectral analyses.Video ClipsPart 1: 7 min 42 secPart 2: 3 min 36 sec