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81.
82.
Nardostachys jatamansi DC. is a highly reputed Medhya and Nootropic (Learning and Memory) Ayurvedic medicinal plant. Its use as herbal medicine singly and as an ingredient of multi‐herbal formulations is fast increasing. In order to authenticate and evaluate it quantitatively, its standardization is highly warranted with respect to a reliable marker. In this connection a rapid and highly sensitive UPLC‐QTOF MS method has been developed. The analysis was carried out on an Acquity BEH C18 column with gradient elution of methanol–water and 3 mm ammonium acetate using QTOF mass detector in negative ionization mode. The method was validated over a concentration range of 9.76–156.25 ng/mL nardin. The calibration curve is linear with the correlation coefficient (r) and coefficient of determination (R2) were 0.9997 and 0.9995 respectively. The LOD and LOQ were 3.050 and 9.277 ng/mL respectively. The recovery of nardin in the range 96.36–111.13% achieved from spiked samples was consistent and reproducible. The inter‐day and intra‐day assay precision of the analytes over the entire concentration range was less than 5%. The developed method required only 4 min for chromatography to authenticate and quantify the marker, viz. nardin in N. jatamansi samples, in addition to the sample preparation time. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
83.
Sanjay Kumar Venkata Dasu Veeranki Kannan Pakshirajan 《Applied biochemistry and biotechnology》2011,163(3):327-337
Statistically based experimental design was applied to maximize the production of glutaminase-free L-asparaginase from Pectobacterium carotovorum MTCC 1428. The effect of physical process parameters (initial pH of the medium, temperature, rpm of the shaking incubator,
and inoculum size) on the production of L-asparaginase from P. carotovorum MTCC 1428 was studied using central composite design technique. The individual optimum levels of initial pH of the medium,
temperature, rpm of shaking incubator, and inoculum size were found to be 6.90, 29.8 °C, 157 rpm, and 2.61% (v/v), respectively, for the production of L-asparaginase. After physical process parameters optimization, the production and
productivity of L-asparaginase was enhanced by 26.39% (specific activity) and 10.19%, respectively. Maximization of L-asparaginase
production was achieved at 12 h under optimal levels of physical process parameters in shake flask level. 相似文献
84.
Li M Ishihara S Akada M Liao M Sang L Hill JP Krishnan V Ma Y Ariga K 《Journal of the American Chemical Society》2011,133(19):7348-7351
Electrochemical-coupling layer-by-layer (ECC-LbL) assembly is introduced as a novel fabrication methodology for preparing layered thin films. This method allows us to covalently immobilize functional units (e.g., porphyrin, fullerene, and fluorene) into thin films having desired thicknesses and designable sequences for both homo- and heteroassemblies while ensuring efficient layer-to-layer electronic interactions. Films were prepared using a conventional electrochemical setup by a simple and inexpensive process from which various layering sequences can be obtained, and the photovoltaic functions of a prototype p/n heterojunction device were demonstrated. 相似文献
85.
Three novel diterpene glycosides were isolated for the first time from the commercial extract of the leaves of Stevia rebaudiana, along with several known steviol glycosides, namely stevioside, rebaudiosides A-F, rubusoside and dulcoside A. The new compounds were identified as 13-[(2-O-β-D-glucopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-15-en-19-oic acid, 13-[(2-O-β-D-glucopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-16β-hydroxy-ent-kauran-19-oic acid and 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid-β-D-glucopyranosyl ester on the basis of extensive 2D NMR and MS spectroscopic data as well as chemical studies. 相似文献
86.
An efficient alumina-supported CuO-catalyzed O-arylation of phenols and aliphatic alcohols with various aryl as well as heteroaryl halides under ligand-free conditions are reported. This protocol provides a variety of diaryl ether and bis-diaryl ether motifs by reacting different aryl/aliphatic halides with differently substituted phenols and saturated alcohols in the presence of a catalytic amount of CuO on alumina and KOH as a base at moderate temperature under nitrogen atmosphere. The described methodology is simple, straightforward and efficient to afford the cross-coupled products in high yields under ligand-free conditions. The explored catalyst is inexpensive, air-stable and recyclable up to three cycles. 相似文献
87.
Konkala Karnakar Jilla Shankar Sabbavarapu Narayana Murthy Yadavalli Venkata Durga Nageswar 《Helvetica chimica acta》2011,94(5):875-880
Various phenyl and p‐tolyl allyl sulfone derivatives were prepared stereoselectively by reacting Baylis? Hillman acetates with sodium 4‐R‐benzenesulfinate (R=H, Me) in H2O. The reaction was very efficient in providing the corresponding sulfone derivatives in good to excellent yields (Table). 相似文献
88.
Lingam Venkata Reddy Mamatha Nakka Alishetty Suman Soumen Ghosh Madeleine Helliwell Khagga Mukkanti Alok Kumar Mukherjee Sarbani Pal 《Journal of heterocyclic chemistry》2011,48(3):555-562
Reduction of nimesulide followed by treating the N‐acyl derivative of resulting arylamine with Vilsmeier‐Haack reagent provided novel 2‐chloro‐3‐formylquinoline derivatives. The construction of quinoline ring using Vilsmeier‐Haack reagent afforded an unexpected compound, N‐(2‐chloro‐3‐formyl‐7‐phenoxy quinolin‐6‐yl)formamide, in addition to the expected product. The structure of this unexpected quinoline derivative was established via single‐crystal X‐ray analysis and its formation could be explained by an unprecedented N‐S bond cleavage under Vilsmeier‐Haack reaction conditions. The 2‐chloro‐3‐formylquinoline derivatives obtained were converted to a number of corresponding Schiff bases with potential pharmacological importance. J. Heterocyclic Chem., 2011. 相似文献
89.
Kokatla HP Thomson PF Bae S Doddi VR Lakshman MK 《The Journal of organic chemistry》2011,76(19):7842-7848
Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis(pinacolato)- and in some cases bis(catecholato)diboron [(pinB)(2) and (catB)(2), respectively]. Reductions occur upon simply mixing the amine N-oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N'-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)(2) was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)(2), triethylborane reduced alkylamino-N-oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)(2) has been probed by (1)H and (11)B NMR. 相似文献
90.