Ashoke K. Nandy

Bio: Ashoke K. Nandy is an academic researcher from Indian Institute of Chemical Biology. The author has contributed to research in topic(s): Triterpene & Orthorhombic crystal system. The author has an hindex of 8, co-authored 9 publication(s) receiving 368 citation(s).

Review article number 67Triterpenoids

Abstract: Triterpenoids isolated and characterized from various sources are reviewed. The newer techniques used in their isolation and structure elucidation, the newer skeleton triterpenoids characterized, chemical modifications and synthetic studies reported are discussed. A compilation of the triterpenoids isolated during the period 1982–1989 along with their occurrence, available physical data, spectroscopy and X-ray analysis used for their characterization, is included. The biological activities of the triterpenoids are also described.

Triterpenoids and their glucosides from Terminalia bellerica

Abstract: In addition to the isolation and identification of arjungenin and its glucoside, the structures of a new triterpene, belleric acid and its glucoside, bellericoside have been defined as 2α,3β,23,24-tetrahydroxyolean-12-en-28-oic acid and its β- d -glucopyranosyl ester.

Triterpenoid saponins discovered between 1987 and 1989.

Abstract: Triterpenoid saponins isolated and characterized from various sources are reviewed. The recent techniques used in their isolation and structure elucidation are discussed. A compilation of the triterpenoid saponins isolated during the period from 1987 to mid-1989, together with their occurrence, available physical data and spectroscopy used for their characterization is included. The biological activities of the triterpenoid saponins are also covered.

Targeted delivery of arjunglucoside I using surface hydrophilic and hydrophobic nanocarriers to combat experimental leishmaniasis

Abstract: The purpose of the present study was to investigate the therapeutic efficacy of the indigenous drug arjunglucoside I (AG) against in vivo models of experimental leishmaniasis by incorporating it in surface hydrophilic co-polymeric nanogel particles of size less than 100 nm diameter and to compare its efficacy with that of the free drug as well as the drug encapsulated in hydrophobic poly-dl-lactide (PLA) nanoparticles. The drug AG, having glucose at the terminal end of the glycosidic chain, was isolated from an indigenous source. Drug-incorporated ultra-low-sized nanogels (∼90 nm in diameter) composed of cross-linked random co-polymer of N-isopropylacrylamide (NIPAAM) and N-vinyl pyrrolidone(VP) were prepared, characterized and used as delivery vehicles to combat experimental leishmaniasis in hamster models. For comparison, drug-encapsulated hydrophobic nanoparticles (∼250 nm in diameter) made from PLA were used as a control. The drug AG was incorporated in these nanocarriers and these drug-nanocarrier co...

Structure elucidation of two acylated triterpenoid bisglycosides from acacia auriculiformis cunn.

Abstract: Acaciasides A and B, two novel acylated triterpenoid bisglycosides isolated from the fruits of Acacia auriculiformis, were respectively defined to be 3- O -[β-D-glucopyranosyl (1→6) &{;α-L-arabinopyranosyl (1→2)&};- β-D-glucopyranosyl]-21- O -&{;6′S)-2′-trans-2′,6′-dimethyl-6′- O -β-D-glucopyranosyl-2′,7′-octadienoyl&}; acacic acid 28- O -α-L-rhamnopyranosyl (1→6) [β-D-xylopyranosyl (1→6) &{;α-L-arabinopyranosyl (1→2)&};-β-D-glucopyranosyl]-21- 0 -[(6′S)-2′-trans-2′,6′- O -&{;β-D-xylopyranosyl (1→2)-β-D-glucopyranosyl&};- 2′,7′-octadienoyl] acacic acid 28- O -α-L-rhamnopyranosyl (1→6) [β-D-xylopyranosyl (1→2)]-β-D-glucopyranoside (2). The structural details were elucidated by a combination of fast-atom-bombardment mass spectrometry, 1H-, and 13C NMR spectroscopy, and some chemical transformations.

Hydrogel Nanoparticles in Drug Delivery

Abstract: Hydrogel nanoparticles have gained considerable attention in recent years as one of the most promising nanoparticulate drug delivery systems owing to their unique potentials via combining the characteristics of a hydrogel system (e.g., hydrophilicity and extremely high water content) with a nanoparticle (e.g., very small size). Several polymeric hydrogel nanoparticulate systems have been prepared and characterized in recent years, based on both natural and synthetic polymers, each with its own advantages and drawbacks. Among the natural polymers, chitosan and alginate have been studied extensively for preparation of hydrogel nanoparticles and from synthetic group, hydrogel nanoparticles based on poly (vinyl alcohol), poly (ethylene oxide), poly (ethyleneimine), poly (vinyl pyrrolidone), and poly-N-isopropylacrylamide have been reported with different characteristics and features with respect to drug delivery. Regardless of the type of polymer used, the release mechanism of the loaded agent from hydrogel nanoparticles is complex, while resulting from three main vectors, i.e., drug diffusion, hydrogel matrix swelling, and chemical reactivity of the drug/matrix. Several crosslinking methods have been used in the way to form the hydrogel matix structures, which can be classified in two major groups of chemically- and physically-induced crosslinking.

Nanocarriers’ entry into the cell: relevance to drug delivery

Abstract: Nanocarriers offer unique possibilities to overcome cellular barriers in order to improve the delivery of various drugs and drug candidates, including the promising therapeutic biomacromolecules (i.e., nucleic acids, proteins). There are various mechanisms of nanocarrier cell internalization that are dramatically influenced by nanoparticles' physicochemical properties. Depending on the cellular uptake and intracellular trafficking, different pharmacological applications may be considered. This review will discuss these opportunities, starting with the phagocytosis pathway, which, being increasingly well characterized and understood, has allowed several successes in the treatment of certain cancers and infectious diseases. On the other hand, the non-phagocytic pathways encompass various complicated mechanisms, such as clathrin-mediated endocytosis, caveolae-mediated endocytosis and macropinocytosis, which are more challenging to control for pharmaceutical drug delivery applications. Nevertheless, various strategies are being actively investigated in order to tailor nanocarriers able to deliver anticancer agents, nucleic acids, proteins and peptides for therapeutic applications by these non-phagocytic routes.

NMR spectroscopy in the structural elucidation of oligosaccharides and glycosides.

Abstract: The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group, in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.

13C NMR spectra of pentacyclic triterpenoids--a compilation and some salient features

Abstract: A compilation of the13C NMR data of a selected variety of naturally occurring pentacyclic triterpenoids, arranged skeletonwise, is provided. A bri

Polymeric nanoparticle-encapsulated curcumin ("nanocurcumin"): a novel strategy for human cancer therapy

Abstract: Curcumin, a yellow polyphenol extracted from the rhizome of turmeric (Curcuma longa), has potent anti-cancer properties as demonstrated in a plethora of human cancer cell line and animal carcinogenesis models. Nevertheless, widespread clinical application of this relatively efficacious agent in cancer and other diseases has been limited due to poor aqueous solubility, and consequently, minimal systemic bioavailability. Nanoparticle-based drug delivery approaches have the potential for rendering hydrophobic agents like curcumin dispersible in aqueous media, thus circumventing the pitfalls of poor solubility. We have synthesized polymeric nanoparticle encapsulated formulation of curcumin – nanocurcumin – utilizing the micellar aggregates of cross-linked and random copolymers of N-isopropylacrylamide (NIPAAM), with N-vinyl-2-pyrrolidone (VP) and poly(ethyleneglycol)monoacrylate (PEG-A). Physico-chemical characterization of the polymeric nanoparticles by dynamic laser light scattering and transmission electron microscopy confirms a narrow size distribution in the 50 nm range. Nanocurcumin, unlike free curcumin, is readily dispersed in aqueous media. Nanocurcumin demonstrates comparable in vitro therapeutic efficacy to free curcumin against a panel of human pancreatic cancer cell lines, as assessed by cell viability and clonogenicity assays in soft agar. Further, nanocurcumin's mechanisms of action on pancreatic cancer cells mirror that of free curcumin, including induction of cellular apoptosis, blockade of nuclear factor kappa B (NFκB) activation, and downregulation of steady state levels of multiple pro-inflammatory cytokines (IL-6, IL-8, and TNFα). Nanocurcumin provides an opportunity to expand the clinical repertoire of this efficacious agent by enabling ready aqueous dispersion. Future studies utilizing nanocurcumin are warranted in pre-clinical in vivo models of cancer and other diseases that might benefit from the effects of curcumin.