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Mitogenic and anti-proliferative activity of a lectin from the tubers of Voodoo lily (Sauromatum venosum)
No full textA new lectin with the potent mitogenic and in vitro anti-proliferative activity was isolated from the tubers of a wild monocotyledonous plant Sauromatum venosum (Schott), from the family Araceae, by affinity chromatography on the asialofetuin linked amino-activated silica beads. The apparent native molecular mass of S. venosum lectin (SVL), as determined by gel filtration chromatography, was 54 kDa.
In HPLC, size exclusion and cation exchange chromatography, SVL gave a single peak and also a single band of 13.5 kDa in SDS-PAGE,pH 8.3, under reducing and non-reducing conditions, indicating that the lectin is composed of four identical subunits. S. venosum lectin agglutinated rabbit, rat, sheep and guinea pig erythrocytes but reacted with goat erythrocytes after the neuraminidase treatment. However,SVL was unable to agglutinate human ABO blood group erythrocytes even after treatment with neuraminidase. SVL was inhibited by Nacetyl-d-Lactosamine (LacNAc), which is an important marker in various carcinomas and a complex desialylated glycoprotein,asialofetuin. The amino acid composition showed that lectin contained a high amount of aspartic acid and glycine but totally devoid of cysteine. However, trace amounts of methionine was present. The lectin showed a potent mitogenic response towards BALB/c splenocytes and human lymphocytes. As the mitogenic stimulation was more than that of Con A, a standard well-known plant mitogen and the response of this lectin was almost double than that of Con A. This lectin is endowed with proliferation of T cells as revealed by IL-2
bioassay but showed no production of immunoglobulins thus indicating the non-stimulation of B cells. SVL significantly inhibited the proliferation of murine cancer cell-lines, i.e., WEHI-279 to 84.6%, J774 to 81%, P388D1 to 74% and A-20 to 47%. In addition, the in vitro anti-proliferative activity of SVL was also evaluated against nine human cancer cell lines representing different organs and tissues namely, T-47D (breast), SiHa (cervix), SK-N-MC (CNS), SK-N-SH (CNS), SW-620 (colon), HT-29 (colon), HEP-2 (liver), OVCAR-5(ovary) and PC-3 (prostate). SVL showed a significant inhibition towards the entire cell lines except the cell lines from CNS, which showed partial response in comparison to a standard anticancer drug adriamycin which was used at a concentration of 5�10�5 M. Thus the anti-proliferative ability of SVL may be helpful in identification of new lectin probes that can lead to better understanding in the detection and study of certain types of cancer
Synthesis of β-adrenergic blockers (R)-(−)-nifenalol and (S)-(+)-sotalol via a highly efficient resolution of a bromohydrin precursor
No full textAbstract—(R)- and (S)-2-bromo-1-(4-nitrophenyl)ethanol are precursors of important b-adrenergic receptor blocking drugs (R)-nifenalol and (S)-sotalol, respectively. Both were obtained in enantiomeric pure forms via a single highly efficient enzymatic transesterification reaction of (±)-2-bromo-1-(4-nitrophenyl)ethanol using immobilized lipase PS-C-II (E >1000; concn 200 g/L), while PS
lipase completely failed to react. On the other hand, the hydrolytic method also produced enantiorich precursors though relatively less efficient (PS-C-II, E = 5.1). Out of all the approaches employed the transesterification method proved to be the most efficient
Isolation of a Novel N-acetyl-d-lactosamine Specific Lectin from Alocasia cucullata (Schott.)
No full textAn N-acetyl-D-lactosamine (LacNAc) specific lectin from tubers of Alocasia cucullata was purified by affinity chromatography on asialofetuin-linked amino activated silica. The pure lectin showed a single band in SDS-PAGE at pH 8.8 and was a homotetramer with a subunit molecular mass of 13.5 kDa and native molecular mass of 53 kDa. It was heat stable up to 55 �C for 15 min and showed optimum hemagglutination activity from pH 2 to 11. The lectin was affected by denaturing agents such as urea (2 M), thiourea
(2 M) and guanidine�HCl (0.5 M) and did not require Ca2+ and Mn2+ for its activity. It was a potent mitogen at 10 lg/ml towards human peripheral blood mononuclear cells with 50% growth inhibitory potential towards SiHa (human cervix ) cancer cell line at 100 lg/ml
Heterochromatic Silencing and HP1 Localization in Drosophila Are Dependent on the RNAi Machinery
No full textGenes normally resident in euchromatic domains are silenced when packaged into heterochromatin, as exemplified in Drosophila melanogaster by position effect variegation (PEV).Loss-of-function mutations resulting in suppression of PEV have identified critical components of heterochromatin, including proteins HP1, HP2, and histone H3 lysine 9 methyltransferase.Here, we demonstrate that this silencing is dependent on the RNA interference machinery, using tandem mini-white arrays and white transgenes in heterochromatin to show loss of silencing as a result of mutations in piwi, aubergine, or spindle-E (homeless), which encode RNAi components. These mutations result in reduction of H3 Lys9 methylation and delocalization of HP1 and HP2, most dramatically in spindle-E mutants
Separation, identification, and quantification of selected withanolides in plant extracts ofWithania somnifera by HPLC-UV(DAD) - Positive ion electrospray ionisation-mass spectrometry
No full textThis paper describes a method for separation, identification, and quantification of selected withanolides in Withania somnifera plant extracts by HPLC-UV(DAD)–Mass
Spectrometry (HPLC-MS). Withaferin-A (WS-3), 12-deoxywithastramonolide (WS-12DS), Withanolide A (WS-1), and Withanone (WS-2) were used as external standards.
The compounds were isolated from Withania somnifera by repeated column chromatography of the root extract and their identity was established by 1H- and 13CNMR
and mass spectral data. The compounds were chromatographed on a Merck(25064.6 mm ID, 5 lm) column and analyzed by Electrospray Ionization on a mass spectrometer in Selected Ion Mode (SIM). For quantification, [M + Na]+ ions were
monitored. Linear calibration curves were obtained in the concentration range of 1.50 lg/mL to 6.5 lg/mL. The method was applied successfully to the detection and
quantification of the said withanolides in a number of samples
Pyrrolo[2,1-c][1,4]benzodiazepine–anthraquinone conjugates. Synthesis, DNA binding and cytotoxicity
No full textNew pyrrolobenzodiazepine–anthraquinone hybrids have been designed and synthesized, found to effectively bind to
DNA and also exhibit cytotoxicity against many cancer cell lines
Enzyme directed diastereoselectivity in chemical reductions: studies towards the preparation of all four isomers of 1-phenyl-1,3-butanediol
No full textEnzymes play an important role in guiding the diastereoselectivity of the final products during the chemical reduction of the intermediates (R)- and (S)-3-hydroxy-1-phenyl-1-butanone, prepared by bioreduction of 1-phenyl-1,3-butadione. For example,the presence of an oxidoreductase such as Pichia capsulata during a one pot, two step, enzymo-chemical reduction of 1-phenyl-1,3-
butadione produced corresponding (1R,3S)-1-phenyl-1,3-butanediol (de�98%), similarly Zygosaccharomyces rouxii furnished(1S,3R)-1-phenyl-1,3-butanediol (de�98%). On the other hand chemical reduction of (R)- and (S)-3-hydroxy-1-phenyl-1-butanone after the exclusion of the enzymes resulted in complete loss of diastereoselectivity, leading to the formation of all four isomers of
1-phenyl-1,3-butanediol. Moreover the yields of the final products are higher in the one-pot transformations than in the two step sequential reactions
Chemoenzymatic approach to optically active phenylglycidates: resolution of bromo- and iodohydrins
No full textEnantiomerically enriched phenylglycidates, precursors of the taxol C-13 phenylisoserine side chain and diltiazem, were prepared by kinetic resolution of anti-2-bromo-3-hydroxy- and anti-3-hydroxy-2-iodophenylpropanoates to provide enantioriched(2R,3R)- and (2S,3S)-halohydrins. The bulkiness and inflexibility of bromo and iodo groups in halohydrins have made them inaccessible to the active site of most of the lipases utilized for the hydrolysis of their acyloxy derivatives. In a set of 22 hydrolases screened herein,including native as well as commercial enzymes, only Aspergillus niger (Lipase AS, AMANO) could catalyze the hydrolysis with high enantioselectivity (E = 176). The resolved halohydrins easily underwent transformation to the corresponding (2S,3R)- and (2R,3S)-phenylglycidates
Enzymatic resolution of naproxen
No full textTrichosporon sp. (TSL), a newly found strain isolated from a locally fermented cottage cheese has been found to be
highly stereoselective in the resolution of(S)-(+)-naproxen (ee >99%, E�500) from the corresponding racemic methyl ester. The process of resolution using whole cells has been scaled up to multi-kg level. Optimization of experimental conditions including downstream processing at 80–100 g/L substrate concentration with >90% recovery has been achieved. Changes in the physical parameters such as the particle size of the substrate play an important role in the resolution kinetics. A new strain of Trichosporon
sp. having high cell density in cultivation (>60 g dry cell mass L−1 in 14–16 h) is found to be sufficiently stable for two years in dry powder form at 5–8°C. The viability of the resolution process has been further improved by the development of a simple racemization process for the enriched (R)-(−)-ester