Green synthesis of silver nanoparticles using Fagopyrum esculentum starch: antifungal, antibacterial activity and its cytotoxicity

52-63Silver nanoparticles (AgNPs) have been synthesized using Fagopyrum esculentum starch as a stabilizing and reducing agent. This reaction was carried out in an autoclave at 15 psi, 121°C for 20 min. UV-visible spectrum of the colloidal nanoparticles showed the surface plasmon absorption band with maximum absorbance at 418 nm. Interaction between functional groups present in the starch and nanoparticles were analyzed by Fourier-transform infrared spectroscopy (FTIR). Size of the synthesized nanoparticles was found to be in the range of 20-30 nm, as revealed from transmission electron microscopy (TEM). The X-ray diffraction analysis revealed the face-centred cubic (fcc) geometry of silver nanoparticles. The nanoparticles were found to be good antifungal agents against Aspergillus niger. The antibacterial activity of the nanoparticles was also studied. The nanoparticles showed higher inhibitory activity against Gram-negative bacteria (Escherichia coli) than the Gram-positive bacteria (Staphylococcus aureus). These results thus show that F. esculentum starch stabilized AgNPs could be used as a promising antimicrobial agent against bacteria the fungi In vitro cytotoxicity assessment of starch stabilized AgNPs has shown no significant cytotoxic effect on human cervical carcinoma cells lines (HeLa) by MTT assay and AgNPs concentration at 200 ug/ml of showed 86% cell viability

Low temperature co-fired ceramic (LTCC)- based biosensor for detection of vanadium using immobilized Arachis hypogaea alkaline phosphatase on multi walled carbon nanotubes ethyl cellulose sponge matrix

Studies on enzyme based thermometric biosensor are limited. Here, we report on fabrication of an alkaline phosphate based thermometric biosensor. We designed alkaline phosphatase inhibition based biosensor for detection of vanadium using immobilized alkaline phosphatase on multi walled carbon nano tubes (MWCTs) ethyl cellulose sponge matrix. We isolated protein from plant source, partially purified and fabricated a miniature ceramic viz. LTCC (low temperature co-fired ceramics technology) based biosensor for detection of vanadium. This biosensor consists of a microreaction chamber with buried heaters. Alkaline phosphatase has been isolated from the seeds of ‘Arachis hypoghaea’ was studied for its biochemical properties viz. optimum pH and temperature. The partially purified enzyme was immobilized using carboxyl-functionalised carbon nanotubes (CNTs) by cross linking with epichlorohydrin (ECH) along with a matrix of ethyl cellulose. The developed LTCC based biosensor on testing indicated its linear response to vanadium concentration up to 9 mM with a relatively high sensitivity of about 147 nA/mM. Thus, we have demonstrated a LTCC based biosensor using immobilized alkaline phosphatase for detection of vanadium

Low temperature co-fired ceramic (LTCC)based biosensor for detection of vanadium using immobilized Arachis hypogaea alkaline phosphatase on multi walled carbon nanotubes ethyl cellulose sponge matrix

916-920Studies on enzyme based thermometric biosensor are limited. Here, we report on fabrication of an alkaline phosphate based thermometric biosensor. We designed alkaline phosphatase inhibition based biosensor for detection of vanadium using immobilized alkaline phosphatase on multi walled carbon nano tubes (MWCTs) ethyl cellulose sponge matrix. We isolated protein from plant source, partially purified and fabricated a miniature ceramic viz. LTCC (low temperature co-fired ceramics technology) based biosensor for detection of vanadium. This biosensor consists of a microreaction chamber with buried heaters. Alkaline phosphatase has been isolated from the seeds of ‘Arachis hypoghaea’ was studied for its biochemical properties viz. optimum pH and temperature. The partially purified enzyme was immobilized using carboxyl-functionalised carbon nanotubes (CNTs) by cross linking with epichlorohydrin (ECH) along with a matrix of ethyl cellulose. The developed LTCC based biosensor on testing indicated its linear response to vanadium concentration up to 9 mM with a relatively high sensitivity of about 147 nA/mM. Thus, we have demonstrated a LTCC based biosensor using immobilized alkaline phosphatase for detection of vanadium

1-Aza-sugars from D-glucose. preparation of 1-deoxy-5-dehydroxymethyl-nojirimycin, its analogues and evaluation of glycosidase inhibitory activity

D-Glucose derived pentodialdoses 11a-c on reduction followed by tosylation, azide displacement, hydrogenation and protection with -Cbz group gave N-Cbz protected compounds 14a-c, respectively, which on removal of 1,2-acetonide functionality and hydrogenation afforded corresponding 1-aza-sugars 3, 9 and 10 in good overall yields. The glycosidase inhibition activity of these 1-aza-sugars was tested with sweet almond as a rich source of different glycosidases

synthesis and evaluation of glycosidase inhibitory activity of octahydro-2H-pyrido[1,2-a]pyrimidine and octahydro-imidazo[1,2-a]pyridine bicyclic diazasugars

An efficient chiron approach for the synthesis of bicyclic diazasugars 4a and 4b having both -CH<SUB>2</SUB>OH and -OH functionality at the same carbon atom (C-6) is reported. Thus, easily available &#945;-D-xylo-pentodialdo-1,4-furanose 5, obtained from D-glucose, on aldol-crossed Cannizzaro reaction followed by hydrogenolysis afforded 7. The regio-selective &#946;- and &#945;-sulfonylation of hydroxymethyl groups in 7 afforded 8a (&#946;-sulfonylation) and 11 (&#945;-sulfonylation) in good yields. The cleavage of the 1,2-acetonide functionality, individually in 8a and 11, followed by reaction with ethylenediamine gave in situ formation of sugar aminals that undergo concomitant nucleophilic displacement of the sulfonyloxy group, by amino functionality, to give hitherto unknown bicyclic diazasugars 4a and 4b, respectively. The inhibitory potency of the earlier reported bicyclic diazasugars 3a,b and 4a,b was evaluated against &#945;- and &#946;-glycosidases and they were found to be potent and specific against the &#946;-glycosidases with IC<SUB>50</SUB> and K<SUB>i </SUB>values in the micro molar range

Synthesis and evaluation of the glycosidase inhibitory activity of 5-hydroxy substituted isofagomine analogues

An efficient strategy for the synthesis of 5-hydroxy substituted isofagomine analogues 4a, 4b and 4c, having both -CH<SUB>2</SUB>OH/CH<SUB>3</SUB> and -OH functionality at the C-5 position, and evaluation of their inhibitory potency is reported. The synthetic methodology involves the aldol-Cannizzaro reaction of easily available &#945;-D-xylopentodialdose followed by hydrogenolysis to afford the triol 5. Selective amidation of the &#945;- and &#946; -hydroxymethyl group at C-4, deprotection of the 1,2-acetonide group and hydrogenation gave the target molecules, which were found to be potent against &#946;-glycosidases with IC<SUB>50 </SUB>values in the micro molar range. Compound 4c showed excellent potency against glycosidases and human salivary amylase

N-hydroxyethyl-piperidine and -pyrrolidine homoazasugars: preparation and evaluation of glycosidase inhibitory activity

An efficient and practical strategy for the synthesis of N-hydroxyethyl-1-deoxy-homonojirimycins 4 and 5 and N-hydroxyethyl-pyrrolidine homoazasugars 6 and 7 with full stereocontrol is being reported. The key step involved is the intermolecular Michael addition of benzylamine to D-glucose derived &#945;,&#946;-unsaturated ester 8 followed by N-alkylation with ethyl bromoacetate. Reduction with LAH, acetylation, hydrogenation and protection with -Cbz group afforded compounds 14a and 14b. Removal of 1,2-acetonide functionality, hydrogenation and deacetylation afforded N-hydroxyethyl-D-gluco-1-deoxyhomonojirimycin (4) and N-hydroxyethyl-L-ido-1-deoxyhomonojirimycin (5), respectively. Compounds 14a and 14b on acetylation followed by removal of 1,2-acetonide functionality, sodium metaperiodate oxidation, hydrogenation and deacetylation gave1,4,5-trideoxy-1,4-imino-N-hydroxyethyl-D-arabino-hexitol (6) and 1,4,5-trideoxy-1,4-imino-N-hydroxyethyl-L-xylo-hexitol (7), respectively. The glycosidase inhibition activity of compounds 4, 5, 6, 7, 16a and 16b was evaluated using sweet almond seed as a rich source of different glycosidases

A versatile access to calystegine analogues as potential glycosidases inhibitors

An efficient metathetic strategy and nitrone chemistry have been suitably tethered to construct 8-azabicyclo[3.2.1]octanes as versatile precursors for the synthesis of several calystegine analogues. This synthetic strategy relies on the ability of mannose-derived nitrone to undergo a highly stereoselective nucleophilic addition of various Grignard reagents to access syn orientation of alkenes, which then smoothly undergo ring-closing metathesis (RCM) to provide this framework. These RCM products 18 and 20 have been successfully used as advance precursors to synthesize many calystegine analogues (27, 36, 38, 40, 43, and 44) either by syn-dihydroxylation or by hydrogenation and followed by global deprotection. Interestingly, both compounds 36 and 40 exhibited significant noncompetitive inhibition against &#945;-mannosidase and N-acetyl-&#946;-D-glucosaminidase