Abdul Rahman Khan

Simultaneous Quantification of Bergenin, Epicatechin, (+)-Catechin, and Gallicin in Bergenia ciliata Using High Performance Liquid Chromatography

γBergenia ciliata (Paashanbheda, Saxifragraceae) has been used for centuries in Ayurvedic formulations for a number of ailments related to antiurolithiasis, as an anti-inflamatory, for antitussive activity, and as an antioxidant. In the present communication, four samples of Bergenia ciliata were collected from varying altitudes of Uttrakhand, India, and an analytical HPLC method was developed and validated for the separation and quantification of Bergenin, Epicatechin, (+)-Catechin, and Gallicin (A-D) in Bergenia ciliata. HPLC analysis was carried out onto a reverse phase column (Reodein; RP-C18; size 4.5 × 250 mm, 5.0 µm) with mobile phase started with gradient composition prepared from water:phosphoric acid 99.6:0.3 (component A) and acetonitrile:water:phosphoric acid 79.6:20:0.3 (component B). Scanning wavelength λmax 280 nm was used in the determination of compounds using HPLC. The contents of targeted compounds A–D were found positively correlated with the altitudes of collecting site. However, good correlation was only found in compound A and B contents (r = 0.6892, 0.6398) compared to compound C and D contents (r = 0.1297, 0.3245).

Simultaneous Quantification of Syringic Acid and Kaempferol in Extracts of Bergenia Species Using Validated High-Performance Thin-Layer Chromatographic-Densitometric Method

A rapid, sensitive, selective and robust quantitative densitometric high-performance thin-layer chromatographic method was developed and validated for separation and quantification of syringic acid (SYA) and kaempferol (KML) in the hydrolyzed extracts of Bergenia ciliata and Bergenia stracheyi. The separation was performed on silica gel 60F254 high-performance thin-layer chromatography plates using toluene : ethyl acetate : formic acid (5 : 4: 1, v/v/v) as the mobile phase. The quantification of SYA and KML was carried out using a densitometric reflection/absorption mode at 290 nm. A dense spot of SYA and KML appeared on the developed plate at a retention factor value of 0.61 ± 0.02 and 0.70 ± 0.01. A precise and accurate quantification was performed using linear regression analysis by plotting the peak area vs concentration 100-600 ng/band (correlation coefficient: r = 0.997, regression coefficient: R(2) = 0.996) for SYA and 100-600 ng/band (correlation coefficient: r = 0.995, regression coefficient: R(2) = 0.991) for KML. The developed method was validated in terms of accuracy, recovery and inter- and intraday study as per International Conference on Harmonisation guidelines. The limit of detection and limit of quantification of SYA and KML were determined, respectively, as 91.63, 142.26 and 277.67, 431.09 ng. The statistical data analysis showed that the method is reproducible and selective for the estimation of SYA and KML in extracts of B. ciliata and B. stracheyi.

Computer-aided drug design and virtual screening of targeted combinatorial libraries of mixed-ligand transition metal complexes of 2-butanone thiosemicarbazone

The present paper deals with in silico evaluation of 32 virtually designed transition metal complexes of 2-butanone thiosemicarbazone and N,S,O containing donor hetero-ligands namely py, bpy, furan, thiophene, 2-picoline, 1,10-phenanthroline, piperazine and liquid ammonia. The complexes were designed with a view to assess their potential anticancer, antioxidant and antibacterial activity. The absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of the chosen ligands were calculated by admetSAR software. Metabolic sites of different ligands likely to undergo metabolism were predicted using Metaprint 2D. The proposed complexes were also evaluated for their drug-like quality based on Lipinskis, Veber, Ghose and leadlikeness filters. Druglikeness and toxicity potential were predicted by OSIRIS property explorer. The pharmacokinetic properties and bioactivity scores were calculated by Molinspiration tool. Bioactivity scores of the complexes were predicted for drug targets including enzymes, nuclear receptors, kinase inhibitors, G-protein coupled receptor ligands and ion channel modulators. Molecular docking of selected Fe(II) mixed-ligand complexes was performed using AutoDock version 4.2.6 and i-GEMDOCK version 2.1 with two target proteins namely Ribonucleotide reductase (RR) and Topoisomerase II (Topo II). The results were compared with three standard reference drugs viz. Doxorubicin HCl, Letrozole (anticancer) and Tetracycline (antibiotic). Multivariate data obtained were analyzed using principal component analysis (PCA) for visualization and projection as scatter and 3D plots. Positive results obtained for hetero-ligands using admetSAR version 1.0 indicated good absorption and transport kinetics of the hetero-ligand complexes through the human intestine and blood-brain barrier. The hetero-ligands were predicted to have no associated mutagenic effect(s) also. However, none of the hetero-ligands was predicted to be Caco-2 (human colon cancer cell line) permeable. Most of the hetero-ligands and the parent ligand (2-butanone thiosemicarbazone) were predicted to undergo Phase-I metabolism prior to excretion using MetaPrint2D software. Pharmacokinetic evaluation of the proposed complexes revealed that all complexes displayed drug-like character and were predicted to have no apparent toxic side-effects. All the proposed complexes showed moderate to good biological activity scores (-5.0 to 0.0). Mixed complexes with bpy, 2-picoline and 1,10-phenanthroline showed significant bioactivity scores (as enzyme inhibitors) in the range 0.02-0.13. Likewise, good docking scores were obtained for Fe (II) complexes with the same ligands. [FeL(2-pic)2] displayed the lowest binding energy (-6.47 kcal/mol) with respect to Topo II followed by [FeL(py)2] (-6.14 kcal/mol) as calculated by AutoDock version 4.2.6. With respect to binding with RR, [FeL(2--pic)2] again displayed the lowest binding energy (-7.21 kcal/mol) followed by [FeL(py)2] (-5.96 kcal/mol). On the basis of docking predictions and various other computational evaluations, four mixed-ligand complexes of Fe in +2 oxidation state with py, bpy, 2--picoline and 1,10-phenanthroline were synthesized with 2-butanone thiosemicarbazone. All the synthesized Fe complexes were characterized using various spectroscopic techniques and tested for their potential anticancer activity in vitro against human breast carcinoma cell line MDA-MB 231 and human lung carcinoma cell line A549 cell line using MTT assay. [FeL(2-pic)2], [FeL(bpy)], and [FeL(py)2] were found to exhibit significant antiproliferative activity with IC50 values in the range of 80-100 μM against breast and lung cancer cells. The synthesized Fe complexes also displayed mild antioxidant activities. The synthesized and studied Fe complexes have the potential for development into future anticancer agents if analyzed and modified further for improvement of their ADMET, solubility and permeability criteria set for potential drug-candidates.

Anticancer, antioxidant potential and profiling of polyphenolic compounds of Wrightia tinctoria Roxb. (R.Br.) bark

Wrightia tinctoria Roxb. (R.Br.) is an Ayurvedic remedy, ethnomedically used in the treatment of various ailments. The present work was carried out to evaluate the anticancer and antioxidant activity as well as total phenolic and phytochemical contents of W. tinctoria bark methanolic extract (WTBM) by high-performance liquid chromatography (HPLC)-diode array detector. Antiproliferative activity of WTBM was evaluated against MDA-MB-231 and MCF-7 cancer cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony formation, and Hoechst staining. In addition, the antioxidant potential was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and 2,2- azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation decolorization assay. Total phenolic content was assessed by Folin-Ciocalteu method. The results demonstrated that WTBM exhibited significant antiproliferative effect against MDA-MB-231 (IC 50 = 88.9 ± 1.27 μg/ml) and MCF-7 (IC 50 = 45.71 ± 7.74 μg/ml) cancer cells in time- and dose-dependent manner. WTBM significantly suppresses colony formation and induces apoptosis in both MDA-MB-231 and MCF-7 cells as evident by morphological assessment, clonogenic assay, and Hoechst staining. The total phenolic content of WTBM was found to be 30.3 gallic acid equivalent mg/g dry weight of bark extract while IC 50 value for DPPH and ABTS radical scavenging activity was 72.2 ± 2.8 μg/ml and 45.16 ± 1.95 μg/ml, respectively. HPLC analysis showed the presence of gallic acid, rutin, and quercetin in WTBM. These findings demonstrated that WTBM significantly inhibited proliferation of breast cancer cells and induced apoptosis, suggesting the potential chemopreventive activity of W. tinctoria bark.