Sunil K. Chattopadhyay

Development of QSAR model for immunomodulatory activity of natural coumarinolignoids

Immunomodulation is the process of alteration in immune response due to foreign intrusion of molecules inside the body. Along with the available drugs, a large number of herbal drugs are promoted in traditional Indian treatments, for their immunomodulating activity. Natural coumarinolignoids isolated from the seeds of Cleome viscose have been recognized as having hepatoprotective action and have recently been tested preclinically for their immunomodulatory activity affecting both cell-mediated and humoral immune response. To explore the immunomodulatory compound from derivatives of coumarinolignoids, a quantitative structure activity relationship (QSAR) and molecular docking studies were performed. Theoretical results are in accord with the in vivo experimental data studied on Swiss albino mice. Immunostimulatory activity was predicted through QSAR model, developed by forward feed multiple linear regression method with leave-one-out approach. Relationship correlating measure of QSAR model was 99% (R2 = 0.99) and predictive accuracy was 96% (RCV2 = 0.96). QSAR studies indicate that dipole moment, steric energy, amide group count, lambda max (UV-visible), and molar refractivity correlates well with biological activity, while decrease in dipole moment, steric energy, and molar refractivity has negative correlation. Docking studies also showed strong binding affinity to immunomodulatory receptors.

Analysis of hairy root culture of Rauvolfia serpentina using direct analysis in real time mass spectrometric technique.

The applicability of a new mass spectrometric technique, DART (direct analysis in real time) has been studied in the analysis of the hairy root culture of Rauvolfia serpentina. The intact hairy roots were analyzed by holding them in the gap between the DART source and the mass spectrometer for measurements. Two nitrogen-containing compounds, vomilenine and reserpine, were characterized from the analysis of the hairy roots almost instantaneously. The confirmation of the structures of the identified compounds was made through their accurate molecular formula determinations. This is the first report of the application of DART technique for the characterization of compounds that are expressed in the hairy root cultures of Rauvolfia serpentina. Moreover, this also constitutes the first report of expression of reserpine in the hairy root culture of Rauvolfia serpentina.

The potential health benefit of polyisoprenylated benzophenones from Garcinia and related genera: Ethnobotanical and therapeutic importance

The diversity present in biological activities and the medicinal significance of natural products provide a renewed interest in the use of natural compounds and, more importantly, their role as a basis for drug development. Advancements in the field of natural product chemistry provide valuable information on Garcinia fruits which revealed the presence of biologically important secondary metabolites named as polyisoprenylated benzophenones (PIBs). They are mainly present in the genus Garcinia (Guttiferae) which occupies a prominent position in the history of natural products. Compared to the long history of medicinal uses and widespread research on Garcinia, the study of polyisoprenylated benzophenones was relatively limited. During recent years, these PIBs have been recognized as interesting and valuable biologically active secondary metabolites as many of the isolated polyisoprenylated benzophenones exhibited significant cytotoxic activity in in vitro and in vivo assay. During past decades, some promising advances had been achieved in understanding the chemistry and pharmacology of polyisoprenylated benzophenones. However, there has been not any systematic review on the ethnobotanical importance, chemistry, isolation techniques, structure activity relationships and the biological activities of polyisoprenylated benzophenones. In this review, the biological activity of different structures of polyisoprenylated benzophenones isolated from genus Clusia, Garcinia, Vismia, Allanblackia, Moronobea, Symphonia, Hypericum, Tovomita, Tovomiptosis and Ochrocarpus have been described. Therefore, the goal of this review article would be a valuable reference for the natural product chemists and biologists working on these PIBs. Furthermore, the review article on polyisoprenylated benzophenones would also be useful from the drug discovery point of view as cytotoxic agents in near future. This review focuses our understanding about the specific biological effects of Garcinia fruits, which may be useful for predicting other medicinal uses, potential drug or food interactions and may benefit people where the fruits are prevalent and healthcare resources are scarce.

In silico exploration of anti-inflammatory activity of natural coumarinolignoids.

Natural coumarinolignoids isolated from the seeds of Cleome viscosa consist of a racemic mixture of cleomiscosins A, B and C. To screen out potential lead, anti‐inflammatory activity of the isolated compounds was evaluated through molecular docking and QSAR studies by using reported in vivo activity of Swiss albino mice. Based on docking binding affinity, a possible mechanism of action has been hypothesized which constitute toll‐like receptors (TLR‐4), cluster of differentiation molecules (CDs), iNOS, COX‐2 and STAT‐6 proteins. It was very interesting to find that the 3D topology of the active site of COX‐2 from the docking was in good agreement with QSAR model and in silico ADME/T parameters. A forward feed multiple linear regression model was developed with r2 = 0.92 and rCV2 = 0.87. This study showed that chemical descriptors, for example dipole vector‐X, dipole vector‐Y, steric energy, LUMO energy, size of smallest ring, size of largest ring and carboxyl group count, correlate reasonably well with experimental in vivo activity (logLD50). QSAR study indicates that dipole vector‐Y and carboxyl group count have negative correlation with activity. Cleomiscosins also showed compliance with 95% of in silico ADME/T properties of available drugs, e.g. serum protein binding, blood–brain barrier, CNS activity, HERG K+ channel activity, apparent Caco‐2 permeability, apparent MDCK permeability, skin permeability and human oral absorption in GI. Besides, toxicity screening study suggests that cleomiscosin molecules possess no toxicity risk parameters. This study offer useful references for understanding and molecular design of inhibitors with improved anti‐inflammatory activity.

A taxane from the himalayan yew, Taxus wallichiana

The stem bark of Taxus wallichiana gave the new taxane 2-deacetoxydecinnamoyl taxinine J, whose structure was established by spectroscopic data.

A rearranged taxane from the Himalayan yew

The needles of Taxus wallichiana gave an abeobaccatin IV derivative, whose structure was established by spectroscopical data.

QSAR, docking and in vitro studies for anti-inflammatory activity of cleomiscosin A methyl ether derivatives

A series of five (6a-8b) novel polyhalogenated derivatives and an interesting ester (9a) derivative have been synthesized from cleomiscosin A methyl ether. All the six derivatives were subjected to in silico QSAR modeling and docking studies and later the predicted results were confirmed through in vitro experiments. QSAR modeling results showed that compounds 6a and 9a possessed anti-inflammatory activity comparable or even higher than diclofenac sodium. Docking results revealed that compounds 9a and 6a showed very good anti-inflammatory activity due to low docking energies of viz., IL6 (-92.45 and -81.993 kcal mol(-1)), TNF-α (-94.992 and -69.235 kcal mol(-1)) and IL1β (-67.462 and -65.985 kcal mol(-1)). Further all the six novel derivatives were subjected for in vitro anti-inflammatory activity using primary macrophages cell culture bioassay system. At the initial doses of 1 μg/ml and 10 μg/ml, the pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) were quantified from cell culture supernatant using enzyme linked immunosorbent assay (ELISA). The in vitro effect of 6a-9a on cell viability in mouse peritoneal macrophage cells isolated from mice was evaluated using MTT assay. The in silico and in vitro data suggested that all the derivatives might be considered as potential anti-inflammatory drug-like molecules.

High-performance liquid chromatography and LC-ESI-MS method for identification and quantification of two isomeric polyisoprenylated benzophenones isoxanthochymol and camboginol in different extracts of Garcinia species

A rapid, sensitive and simple reverse-phase high-performance liquid chromatography-electrospray ionization mass spectrometric method has been developed for the identification and quantification of two isomeric polyisoprenylated benzophenones, isoxanthochymol and camboginol, in the extracts of the stem bark, seeds and seed pericarps of Garcinia indica and in the fruit rinds of Garcinia cambogia. The separation of isoxanthochymol and camboginol was achieved on a Perkin Elmer RP(8) column (10 x 2.1 mm with 5.0 microm particle size) using a solvent system consisting of a mixture of acetonitrile-water (80:20, v/v) and methanol-acetic acid (99.0:1.0, v/v) as a mobile phase in a gradient elution mode. The limits of detection and quantification were 5 and 10 microg/mL for isoxanthochymol and 50 and 100 microg/mL for camboginol, respectively. The intra- and inter-day precisions were 2.34 and 3.41% for isoxanthochymol and 3.35 and 3.66% for camboginol. The identity of the two isomeric compounds in the samples was determined on a triple quadrupole mass spectrometer with ESI interface operating in the negative ion mode. The method was used to identify and quantify isoxanthochymol and camboginol in the different extracts of two Garcinia species, Garcinia indica and Garcinia cambogia.

A rearranged taxane from the Himalayan yew Taxus wallichiana

The stem bark of Taxus wallichiana gave an abeobaccatin IV derivative, whose structure was established by spectral data and derivatization.

Novel chemical constituents with anti-inflammatory activity from the leaves of Sesbania aculeata

From the hexane and ethyl acetate extracts of the leaves of Sesbania aculeata, three novel chemical compounds were isolated and fully characterized as compound 1, (ceramide type); compound 2, (cerebroside type) and compound 3 as a triterpene acid 3-O-α-L-rhamnopyranoside along with nine known compounds (Tricontanol, Lauric acid, Palmitic acid, Heptadecanoyl-1-tridecanoic acid, β-sitosterol, stigmasterol, poriferasterol glucoside, ononitol and pinitol). The anti-inflammatory potential of all three compounds were evaluated using in vitro target based anti-inflammatory activity in LPS-stimulated macrophages. TNF-α is one of the mediators of various chronic inflammatory disorders and treatment of hexane leaf extract (HL), Ethyl acetate leaf extract (EAL) and compounds 1, 2 and 3 at a dose of 10 μg/mL showed significant (P<0.001) inhibition of TNF-α, a pro-inflammatory cytokine. IL-6 was significantly (P<0.05) inhibited by compound 1 and HL at a dose of 10 μg/mL as compared with vehicle treatment. In-vitro cell cytotoxicity study using MTT assay revealed that these compounds were non toxic to the normal cells.