Sabari Ghosal

Background: Crataeva nurvala is an important plant having wide application in Ayurveda and Siddha. It is extensively used in formulations for patients suffering from benign prostatic hyperplasia. Objective: Isolation, characterization, and evaluation of cytotoxic activity of bioactive fraction of C. nurvala and identification of molecular target prediction by suitable method. Materials and Methods: Gravity column chromatography followed by HPLC of the bioactive n-butanol fraction afforded compound 1. Besides cell proliferation, apoptotic index and cell migration were studied to determine the efficacy of the compound against cancer cells. Results: The cell cycle analysis revealed that the compound 1 showing apoptosis inducing property through G2/M arrest and mitotic inhibition. Besides, clonogenic assay and wound healing assay demonstrated that the compound could decrease the ability of colony formation and cell migration in a significant way. However, limited availability of the compound impelled us to undertake in silico studies to predictprobable protein targets. This resulted in the identification of IGF1R with highest docking score of −10.0 in preference to four other protein targets (EGFR, AKT1, AKT2, and BCL2) of receptor tyrosine kinase domain (RTKs). As insulin receptor R (Insulin receptor) of tyrosine kinase domain maintains high resemblance with IGF1R, molecular docking was also conducted on the same target. The insignificant docking score suggested specificity of the compound toward IGF1R. Conclusion: The study concluded that; (+)-lyoniresino1-2a-0-β-D-glucopyranoside is a promising apoptosis inducing agent. Molecular modeling of the compound against five crucial protein targets of RTKs suggested that IGF1R could be the probable protein target for the compound.

Background: Arunachal Pradesh the north-eastern state of India is a natural habitat of 550 species of orchids including 37 species of medicinal importance. Although these plants are regularly used by ethnic population, very few scientific investigations have been conducted to establish their pharmacological potential. In our previous study, we evaluated antimycobacterial and leishmanicidal activity of extracts prepared from three relatively unexplored medicinal orchids. In the present study, we conducted screening of the compounds isolated from Tropidia curculioides (Tc) for the above-mentioned activities. Furthermore, we prepared synthetic analogs of the most active compound. Objective: Evaluation of antimycobacterial and leishmanicidal activity of the isolated compounds and preparation of synthetic analogs of the most active compound followed by evaluation of biological activities. Materials and Methods: Antimycobacterial activity was evaluated by colorimetric redox indicator assay, and the leishmanicidal activity was assessed by 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide assay. The root, stem, and leaves of Tc were extracted with methanol:water (9:1) followed by fractionation with diethyl ether (Et₂O) and n-butanol solvent. All these fractions were evaluated for biological activity to identify the most active fraction. Further, chromatography of the most active fraction (Tc root Et₂O fraction) afforded three compounds, namely, 4-hydroxybenzaldehyde (1), 4,4'-dihydroxydiphenylmethane (2), and 3,5-dihydroxy-4-methoxybenzoic acid (3). Standard synthetic procedures were followed to prepare the analogs of the most active compound. Results: The screening result identified compound 2 with maximum antimycobacterial activity (minimum inhibitory concentration [MIC] – 125 μg/ml) and leishmanicidal activity (IC₅₀ 100 μg/ml). Three synthetic analogs were prepared targeting the methane linkage of compound 2. The N-benzylmethylamine derivative (6) showed the highest activity with MIC 15.62 μg/ml against Mycobacterium and IC₅₀ 31.25 μg/ml against Leishmania spp. Conclusion: The promising result of N-benzylmethylamine analog could be explored to obtain new antimycobacterial and leishmanicidal agent. Abbreviations used: MIC: Minimum inhibitory concentration; NMR: Nuclear magnetic resonance; CRI: Colorimetric redox indicator; OADC: Oleic acid, dextrose, and catalase; MDR: Multidrug Resistant; MTT: 3-(4,5-dimethylthiazol-2-Yl)-2, 5-diphenyltetrazolium bromide; Diethyl ether: Et₂O.

Purpose: To evaluate the anti-leishmanial and antibacterial activities of a relatively unexplored whole plant of Waldheimia tomentosa (Asteraceae) and the chemical profiling of its most bioactive fraction. Methods: The whole plant material was extracted with methanol - water (9 : 1) and fractionated into nhexane (C₆H₁₄ or n-Hex), dichloromethane (CH₂C_l2 or DCM), ethyl acetate (C₄H₈O₂ or EtOAc) fractions and aqueous residue. The fractions were screened for leishmanicidal activity against promastigotes and intracellular amastigotes of L. donovani, while antibacterial activity was evaluated against four multidrug resistant (MDR) clinical isolates by bioassay guided fractionation. Scanning Electron Microscopy (SEM) performed on S. aureus at the minimum inhibitory concentration (MIC). Chemical profiling of the most bioactive fraction was performed using gas chromatography-mass spectrometry (GC-MS). Results: The most significant leishmanicidal activity was exhibited by n-Hex fraction against promastigotes (DD8 strain) with half maximal inhibitory concentration (IC₅₀ of 89.85 ± 0.84 μg/mL) and intracellular amastigotes (IC₅₀ of 48.3 ± 0.40 μg/mL). The same fraction also exhibited maximum potency against S. aureus and E.coli at MIC of between 62.5 and 125 μg/mL. The fraction comprised mainly fatty acids and alkyl ketones. SEM examination performed on S. aureus at MIC revealed swelling and multiple blisters on cell surface compared to untreated control. Conclusion: The profound antibacterial activity of Waldheimia tomentosa justifies the use of the plant in traditional medicine for stomach ache and food preservation. Keywords: Waldheimia tomentosa, Antibacterial activity, Leishmanicidal activity, Stomach ache, Food preservation

The ethnic population of Arunachal Pradesh uses a number of orchids as such, or in decoction for various ailments. Three untapped orchids namely, Rhynchostylis retusa, Tropidia curculioides and Satyrium nepalense, traditionally used in tuberculosis, asthma and cold stage of malaria in folk medicine, were selected for the present study. Dried material of each plant was divided into three parts. Solvent extraction and fractionation afforded altogether 30 extracts and fractions, which were evaluated against Mycobacterium tuberculosis (H37Rv and MDR strain) for antimycobacterial activity; promastigotes and amastigotes of Leishmania donovani for leishmanicidal activity and two gram positive and three gram negative clinical isolates for antibacterial activity. The most significant antimycobacterial activity was observed with n-hexane fraction of the flower of Satyrium nepalense with MIC of 15.7 μg/mL. The most promising leishmanicidal activity was observed with diethyl ether fraction of the roots of Rhynchostylis retusa with IC50 values of 56.04 and 18.4 μg/mL against promastigotes and intracellular amastigotes respectively. Evaluation of antibacterial activity identified S. nepalense flower n-hexane and R. retusa roots diethyl ether as potential fractions with MIC values of ≤100 μg/mL against selected clinical isolates. This is the first report of the plants possessing antimycobacterial and leishmanicidal activity. The investigation resulted in identification of S. nepalense as the most promising plant, which possessed all three activities in significant proportion. This laboratory outcome could be translated to marketable pharmaceutical products and also to produce maximum benefits to the local of nearby area. Antimycobacterial and leishmanicidal activity of medicinal orchids

Visceral leishmaniasis or kala-azar is caused by the dimorphic parasite Leishmania donovani in the Indian subcontinent. Treatment options for kala-azar are currently inadequate due to various limitations. Currently, drug discovery for leishmaniases is oriented towards rational drug design; the aim is to identify specific inhibitors that target particular metabolic activities as a possible means of controlling the parasites without affecting the host. Leishmania salvages pteridin from its host and reduces it using pteridine reductase 1 (PTR1, EC 1.5.1.33), which makes this reductase an excellent drug target. Recently, we identified six alkamides and one benzenoid compound from the n-hexane fraction of the fruit of Piper longum that possess potent leishmanicidal activity against promastigotes as well as axenic amastigotes. Based on a homology model derived for recombinant pteridine reductase isolated from a clinical isolate of L. donovani, we carried out molecular modeling and docking studies with these compounds to evaluate their binding affinity. A fairly good agreement between experimental data and the results of molecular modeling investigation of the bioactive and inactive compounds was observed. The amide group in the conjugated alkamides and the 3,4-methylenedioxystyrene moiety in the benzenoid compound acts as heads and the long aliphatic chain acts as a tail, thus playing important roles in the binding of the inhibitor to the appropriate position at the active site. The remarkably high activity of a component containing piperine and piperine isomers (3.36:1) as observed by our group prompted us to study the activities of all four isomers of piperine—piperine (2E,4E), isopiperine (2Z,4E), isochavicine (2E,4Z), and chavicine (2Z,4Z)—against LdPTR1. The maximum inhibitory effect was demonstrated by isochavicine. The identification of these predicted inhibitors of LdPTR1 allowed us to build up a stereoview of the structure of the binding site in relation to activity, affording significant information that should prove useful during the structure-based design of leishmanicidal drugs.

One new alkaloid amide, piperlongumide (1) [N-isobutyl-19-(3′,4′-methylenedioxyphenyl)-2E,4E nonadecadienamide], and six known compounds with leishmanicidal activity against promastigotes and axenic amastigotes of Leishmania donovani were isolated from the n-hexane fraction of the fruits of Piper longum. The structure of 1 was elucidated by spectroscopic evidences.

Bioassay-guided fractionation of the fruits of Piper longum afforded two new minor amides, piperlongimin A (2) [2E-N-isobutyl-hexadecenamide] and piperlongimin B (4) [2E-octadecenoylpiperidine] together with five known compounds with moderate cytotoxic activity. The structures were elucidated on the basis of spectroscopic evidences. All these compounds inhibited cell proliferation of human leukemia, HL-60 cell lines, and displayed major apoptosis-inducing effects.