Bilal A. Bhat

Chemical composition, antimicrobial, cytotoxic and antioxidant activities of the essential oil of Artemisia indica Willd.

Essential oil from the aerial parts of Artemisia indica was analysed by GC-FID and GC-MS. A total of 43 compounds representing 96.8% of the oil were identified and the major components were found to be artemisia ketone (42.1%), germacrene B (8.6%), borneol (6.1%) and cis-chrysanthenyl acetate (4.8%). Antimicrobial activity of the oil was evaluated against seven clinically significant bacterial and two fungal strains. The essential oil and its major constituents exhibited moderate to potent, broad-spectrum antibacterial and antifungal activities targeting both Gram-positive and Gram-negative bacteria. In vitro cytotoxicity evaluation against four human cancer cell lines THP-1 (leukemia), A-549 (lung), HEP-2 (liver) and Caco-2 (colon) showed that the essential oil exhibited concentration dependant growth inhibition in the 10-100 μg/ml dilution range, with IC(50) values of 10 μg/ml (THP-1), 25 μg/ml (A-549), 15.5 μg/ml (HEP-2) and 19.5 μg/ml (Caco-2). It was interesting to note that the essential oil also exhibited potent antioxidant activity.

Synthesis of 3,5‐Diphenyl‐1H‐Pyrazoles

Abstract An efficient and convenient synthesis of 3,5‐diphenyl‐1H‐pyrazoles from chalcones by the action of hydrazine hydrate on chalcone‐epoxide followed by simultaneous dehydration is reported.

Chemical composition, antioxidant and antibacterial activities of the leaf essential oil of Juglans regia L. and its constituents

The essential oil from the leaves of Juglans regia L. (Juglandaceae) growing wild in Kashmir (India) was obtained by hydrodistillation and analysed by a combination of capillary GC-FID and GC-MS. A total of 38 compounds, representing 92.7% of the oil, were identified and the major components were found to be α-pinene (15.1%), β-pinene (30.5%), β-caryophyllene (15.5%) germacrene D (14.4%) and limonene (3.6%). The essential oil and the main individual constituents were screened for antibacterial activity and the essential oil evaluated for antioxidant activity. Antibacterial activity was evaluated using the disc diffusion and microdilution methods against a group of clinically significant Gram-positive (Staphylococcus epidermidis MTCC-435, Bacillus subtilis MTCC-441, Staphylococcus aureus) and Gram-negative bacteria (Proteus vulgaris MTCC-321, Pseudomonas aeruginosa MTCC-1688, Salmonella typhi, Shigella dyssenteriae, Klebsiella pneumonia and Escherichia coli). The essential oil and its major components exhibited broad spectrum inhibition against all the bacterial strains with Gram-positive being more susceptible to the oil than Gram-negative bacteria. Antioxidant activity of the oil was evaluated by the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) and hydroxyl radicals. In general, the essential oil exhibited high antioxidant activity which was comparable to the reference standards at the same dose (ascorbic acid and butylated hydroxyl toluene, BHT) with IC(50) values of 34.5 and 56.4μg/ml calculated by DPPH and hydroxyl radical scavenging assays respectively.

Synthesis and biological evaluation of ursolic acid-triazolyl derivatives as potential anti-cancer agents.

A series of ursolic acid-1-phenyl-1H-[1,2,3]triazol-4-ylmethylester congeners have been designed and synthesized in an attempt to develop potent antitumor agents. A regioselective approach using Huisgen 1,3-dipolar cycloaddition reaction of ursolic acid-alkyne derivative with various aromatic azides was employed to target an array of triazolyl derivatives in an efficient manner. Their structures were confirmed by using (1)H NMR, (13)C NMR, IR and MS analysis. All the compounds were evaluated for anti-cancer activity against a panel of four human cancer cell lines including A-549 (lung), MCF-7 (breast), HCT-116 (colon), THP-1 (leukemia) and a normal human epithelial cell line (FR-2) using sulforhodamine-B assay. The pharmacological results showed that most of the compounds displayed high level of antitumor activities against the tested cancer cell lines compared with ursolic acid. Compounds 7b, 7g, 7p and 7r were found to be the most potent compounds in this study.

Synthesis and Biological Evaluation of 4β-[(4-Substituted)-1,2,3-triazol-1-yl]podophyllotoxins as Potential Anticancer Agents

A series of novel 4β‐[(4‐substituted)‐1,2,3‐triazol‐1‐yl]podophyllotoxin derivatives were synthesized by employing CuI‐catalyzed click chemistry and evaluated for their anticancer activity against a panel of seven human cancer cell lines (HT‐29, HCT‐15, 502713, HOP‐62, A‐549, MCF‐7, and SF‐295). The compounds 9b, 9c, 9e, 9f, and 9h showed significant cytotoxic activities especially against HT‐29, HCT‐15, 502713 cell lines.

Role of substrate effects on the morphological, structural, electrical and thermoelectrical properties of V2O5 thin films

The present work focuses on the influence of different substrates on the morphological, compositional, phase purity, structural and transport properties of vanadium pentaoxide (V2O5) thin films. Thin films of V2O5 were fabricated on different substrates: glass, quartz, Si, and alumina (hereafter these films are referred to as V2O5:G, V2O5:Q, V2O5:Si and V2O5:A, respectively) using inorganic sol–gel with V2O5 powder and hydrogen peroxide (H2O2) as precursors by spin coating. Films deposited on glass substrates were found to be amorphous in nature with smooth surfaces, whereas films deposited on quartz, silicon, and alumina substrates exhibited a polycrystalline nature, having an orthorhombic structure with space group Pmmn. The crystallinity improves from quartz to silicon and the best crystalline films were fabricated on alumina. Electrical measurements as a function of temperature and substrate are investigated and characterized by measuring the resistivity, Hall and Seebeck coefficients. Negative values of Hall and Seebeck coefficients reveal that all the films are of n-type semiconductors. Electrical resistivity as well as charge carrier density decreases from the films on glass to quartz to silicon and to alumina. Carrier mobility decreases in the following order V2O5:G > V2O5:A > V2O5:Si > V2O5:Q, whereas the Seebeck coefficient varies in the reverse order. Variation of these transport parameters has been understood on the basis of scattering and trapping of charge carriers along the grain boundaries. Furthermore, a model based on thermodynamics is proposed to explain the effect of substrates on the crystallinity of thin films. Interactions between sol and substrate (adhesive forces) determine the thickness, phase purity, structural and morphological properties of thin films. As the magnitude of adhesive forces increases, both film thickness and crystallinity increase.

Organo-Manganese η2-Auxiliary Directed Reactions: A Diastereoselective Approach to 2,3-Allenols

Propargyl aldehydes underwent isomerization to allenyl aldehydes under mildly basic conditions when complexed to an organo-manganese auxiliary using methylcyclopentadienyl manganese tricarbonyl (MMT). This traceless auxiliary magnifies the axial chirality of the allene moiety, allowing for highly diastereoselective additions to the aldehyde carbonyl and subsequent access to an array of 2,3-allenols. Using this strategy, a nitrile-substituted 2,3-allenol was prepared and efficiently converted to Hagens gland lactone.

Promise of Retinoic Acid-Triazolyl Derivatives in Promoting Differentiation of Neuroblastoma Cells.

Retinoic acid induces differentiation in various types of cells including skeletal myoblasts and neuroblasts and maintains differentiation of epithelial cells. The present study demonstrates synthesis and screening of a library of retinoic acid-triazolyl derivatives for their differentiation potential on neuroblastoma cells. Click chemistry approach using copper(I)-catalyzed azide-alkyne cycloaddition was adopted for the preparation of these derivatives. The neurite outgrowth promoting potential of retinoic acid-triazolyl derivatives was studied on neuroblastoma cells. Morphological examination revealed that compounds 8a, 8e, 8f, and 8k, among the various derivatives screened, exhibited promising neurite-outgrowth inducing activity at a concentration of 10 μM compared to undifferentiated and retinoic acid treated cells. Further on, to confirm this differentiation potential of these compounds, neuroblastoma cells were probed for expression of neuronal markers such as NF-H and NeuN. The results revealed a marked increase in the NF-H and NeuN protein expression when treated with 8a, 8e, 8f, and 8k compared to undifferentiated and retinoic acid treated cells. Thus, these compounds could act as potential leads in inducing neuronal differentiation for future studies.

Two new coumarins from Euonymus hamiltonianus

Two new coumarins, euonidiol (1) and euoniside (2), and a known flavone, luteolin 7-methyl ether, were isolated from the aerial parts of the plant Euonymus hamiltanianus Wall. All the compounds were characterized on the basis of spectral analysis viz. 1H NMR, 13C NMR, DEPT, IR, UV, ESI-MS, and elemental analysis.

Regenerative γ-Lactone Annulations: A Modular, Iterative Approach to Oligo-tetrahydrofuran Molecular Stairs and Related Frameworks

A unified, stereocontrolled, regenerative γ-butyrolactone annulation approach has been conceptualized and validated through syntheses of a range of oligo-THFs. The new protocol is short (four steps), simple (table-top reagents), and efficient (50-61% overall yields). Although the scope of this approach is unlimited, it has been demonstrated up to five iterations on commercial γ-butyrolactone to assemble six fused tetrahydrofuran moieties in a staircase-like architecture. A selection of exploratory transformations is presented to exemplify the potential applications of this protocol.