Browsing by Author "Om Prakash Tiwari"

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Antioxidant properties of different fractions of Vitex negundo Linn.
(2007) Om Prakash Tiwari; Yamini B. Tripathi
Vitex negundo Linn. (VN), belonging to family Verbenaceae, is an aromatic shrub distributed throughout India. In the ayurvedic system of medicine it is used as a drug of choice to manage pain, inflammation and other related diseases. It contains many polyphenolic compounds, terpenoids, glycosidic iridoids and alkaloids. Since polyphenolic compounds have high antioxidant potential, the antioxidant potency of V. negundo was investigated by employing various established in vitro systems, such as 2,2′-azino-bis 3-ethyl benzothiazoline-6-sulfuric acid (ABTS*+)/Lipid Peroxides (LPO)/Superoxide/Hydroxyl radical scavenging and iron ion chelation. Total antioxidant capacity was determined by the assay based on the preformed radical monocation ABTS*+. Lipid peroxidation was assessed in terms of thiobarbituric acid reactive substances by using egg yolk homogenates as lipid rich media. Superoxide radical scavenging assay was based on the riboflavin-light-Nitro blue tetrazolium (NBT) system. Hydroxyl radical trapping potential was determined by evaluating hydroxyl radical induced deoxyribose degradation using the thiobarbituric acid method. In order to assess the metal chelation properties, hydroxyl radical induced deoxyribose degradation was evaluated in the absence of Ethylenediamine tetra acetic acid (EDTA). All the polar fractions significantly showed trapping of free radicals, and thereby inhibition of lipid peroxidation, and also chelated the iron ion. Interestingly, the hexane fraction did not show any activity against superoxides radicals and it had minimum trapping potential for other free radical (FR) species also. Thus, it may be concluded that the polar fractions of VN possess potent antioxidant properties, which may be mediated through direct trapping of the free radicals and also through metal chelation. Therefore its reported anti-inflammatory properties, could be through the down regulation of the free radical mediated pathway of inflammation. © 2005 Elsevier Ltd. All rights reserved.
Pharmacokinetic-interaction of Vitex negundo Linn. & paracetamol
(2009) Yamini Bhusan Tripathi; Om Prakash Tiwari; Santosh Nagwani; Brahmeshwar Mishra
Background & objectives: Currently, herbal preparations are clinically used as functional food, food supplements or as add on therapy, which affects the bioavailability and also the net therapeutic potential of co-administered allopathic drugs. Therefore, it is important to assess the interaction among these two classes of drugs. Here we studied the interaction between orally-administered ethanolic extract of leaves of Vitex negundo Linn. (Verbenaceae) (VN extract) and paracetamol in albino rats. Method: Solvent free dried extract of VN leaves was orally given to experimental rats in different doses (62.5-1000 mg/kg/b.wt.), daily for six consecutive days. On days 3 and 6, paracetamol (100 mg/kg/b.wt.) was orally administered to these extract treated rats and control rats (drug vector). At various time intervals (5 min - 120 min), blood was collected from each animal and paracetamol concentration was determined in plasma by using HPLC with UV detector at 249 nm. Various pharmacokinetic parameters were calculated by non compartmental model. Results: A significant decline in plasma concentration of paracetamol with time-gap was recorded with the increasing dose of VN extract, without affecting its Tmax (maximum time to achieve peak plasma concentration). There was a significant decrease in the extent of absorption and decline in intensity of therapeutic response (as evidenced by reduced AUC value and decline in Cmax). Further, compared to control, the relative bioavailability of paracetamol, in presence of VN extract, decreased significantly. Interpretation & conclusions: VN extract or its ayurvedic formulation if co-administered with allopathic drug like paracetamol, the dose of allopathic drug needs to be adjusted in order to achieve desired therapeutic response of paracetamol.
Synthesis, characterization, antimicrobial and cytotoxicity evaluation of quaternary cadmium (II)-quercetin complexes with 1,10-phenanthroline or 2,2’-bipyridine ligands
(Taylor and Francis Ltd., 2020) Tanu Srivastava; Sunil Kumar Mishra; Om Prakash Tiwari; Avinash Kumar; Kavindra Nath Tiwari; Pradeep Kumar; Jyoti Dixit; Jitendra Kumar; Amit Kumar Singh; Pooja Verma; Rajesh Saini; Angaraj Singh; Ashutosh Kumar Dwivedi
This study reports the synthesis and antibacterial evaluation of two novel complexes, [Cd (Q) (Bpy) (CH3COO)2, complex 1] and [Cd (Q) (Phen) (CH3COO)2, complex 2], based on quercetin ligand. The method of synthesis was by reacting natural flavonoid quercetin (Q) with a good chelator (Bpy = 2,2’-bipyridine, Phen= 1,10-phenanthroline and Q = quercetin) and metal ions. The produced metal complexes were studied in the solid state by Fourier-transform infrared (FTIR) spectroscopy and in solution by UV-Vis absorption. Further analysis included high resolution mass spectrometry (HRMS) for confirmation. To understand the nature and coordination of quercetin and its metal complexes, density functional theory (DFT) calculation was performed. The scavenging (DPPH radical), antibacterial, MTT, enzymatic and non-enzymatic antioxidant activity assay, cytotoxicity assay (fluorescence study) were done and quercetin was used for comparison. Both complex 1 and complex 2 induced loss of cell viability via impairment of metabolic activity, leakage of intracellular proteins, and increased oxidative stress. The free-radical scavenging activity of complex 2 (IC50 340.175 µg/mL) was statistically significantly more potent than that of complex 1. The MIC values of complex 2 (7.80 µg/mL Escherichia coli, 15.62 µg/mL Staphylococcus aureus) were higher as compared to complex 1 and quercetin in both test microorganisms. There was inhibition of cell proliferation in Escherichia coli treated with 2 µg/mL of complex 2, whereas Staphylococcus aureus did not show inhibition at this concentration. The cytotoxicity screening on MG 63 cell line showed that the compounds were safe up to 500 mg/L. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.