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1.
A highly sensitive and stable amperometric tyrosinase biosensor has been developed based on multiwalled carbon nanotube (MWCNT) dispersed in mesoporous composite films of sol–gel‐derived titania and perfluorosulfonated ionomer (Nafion). Tyrosinase was immobilized within a thin film of MWCNT–titania–Nafion composite film coated on a glassy carbon electrode. Phenolic compounds were determined by the direct reduction of biocatalytically‐liberated quinone species at ?100 mV versus Ag/AgCl (3 M NaCl) without a mediator. The present tyrosinase biosensor showed good analytical performances in terms of response time, sensitivity, and stability compared to those obtained with other biosensors based on different sol–gel matrices. Due to the large pore size of the MWCNT–titania–Nafion composite, the present biosensor showed remarkably fast response time with less than 3 s. The present biosensor responds linearly to phenol from 1.0×10?7 M to 5.0×10?5 M with an excellent sensitivity of 417 mA/M and a detection limit of 9.5×10?8 M (S/N=3). The enzyme electrode retained 89% of its initial activity after 2 weeks of storage in 50 mM phosphate buffer at pH 7.0. 相似文献
2.
Bingyou Yang Qiuhong Wang Yonggang Xia Weisheng Feng Haixue Kuang 《Helvetica chimica acta》2008,91(5):964-971
Three new withanolide compounds, named baimantuoluolines D–F, along with three known withanolides and a lignan were isolated from the flower of Datura metel L., the parts effective against psoriasis. The structures of the new compounds were elucidated as (5α,6β,12β,20R,22R,24R,25S)‐21,24‐epoxy‐5,6,12‐trihydroxy‐27‐methoxy‐1‐oxowith‐2‐enolide ( 1 ), (5α,6β,12β,20R,22R,24R,25S)‐21,24‐epoxy‐5,6,12,27‐tetrahydroxy‐1‐oxowith‐2‐enolide ( 2 ), and (5α,6β,12β,22R)‐5,6,12,21‐tetrahydroxy‐1‐oxowith‐24‐enolide( 3 ) on the basis of physicochemical evidence. 相似文献
3.
Yu Zhang Ying‐Tong Di Hai‐Yang Liu Chun‐Shun Li Cheng‐Jian Tan Qiang Zhang Xin Fang Shun‐Lin Li Xiao‐Jiang Hao 《Helvetica chimica acta》2008,91(11):2153-2158
Nine Daphniphyllum alkaloids, including three new ones, paxiphyllines C–E ( 1 – 3 , resp.), were isolated from the twigs and the leaves of Daphniphyllum paxianum. Paxiphylline C ( 1 ) represents the first example of Daphniphyllum alkaloids with a carbonyldioxy group. Their structures were elucidated on the basis of spectroscopic data. 相似文献
4.
Four new polyketides, botryosphaerones A–D ( 1 – 4 , resp.), were obtained from the fermentation culture of Botryosphaeria australis strain ZJ12‐1A, together with four known compounds, O‐methylasparvenone ( 5 ), 6‐ethyl‐2,7‐dimethoxyjuglon ( 6 ) and its monoacetyl derivative 7 , and O‐methylaspmenone ( 8 ). Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments, and HR‐Q‐TOF mass spectrometry, and by comparison with reported data. All compounds were evaluated for their cytotoxic and antimicrobial activities in vitro. Only compounds 6 and 7 showed cytotoxic and antimicrobial activities, as already reported. 相似文献
5.
Xing‐Ping Zheng Qiong‐Fang Cui Jing‐Feng Zhao Li‐Juan Yang Hong‐Bin Zhang Xiao‐Dong Yang Liang Li 《Helvetica chimica acta》2014,97(12):1638-1643
Three new phthalides, gnaphalides A–C ( 1 – 3 , resp.), together with three known phthalides, were isolated from the aerial part of Gnaphalium adnatum. The structures of the new compounds were elucidated as 6‐(1,1‐dimethylprop‐2‐en‐1‐yl)‐5,7‐dihydroxy‐2‐benzofuran‐1(3H)‐one ( 1 ), 5‐hydroxy‐7‐[(2‐hydroxy‐3‐methylbut‐3‐en‐1‐yl)oxy]‐2‐benzofuran‐1(3H)‐one ( 2 ), and 1,3‐dihydro‐7‐[(3‐methylbut‐2‐en‐1‐yl)oxy]‐1‐oxo‐2‐benzofuran‐5‐yl β‐D ‐glucopyranoside ( 3 ) on the basis of spectral analyses. The structure of 1 was also confirmed by X‐ray crystallographic analysis. The three known phthalides, identified as 5,7‐dihydroxyisobenzofuran‐1(3H)‐one ( 4 ), anaphatol ( 5 ), and 7‐O‐(β‐glucopyranosyl)‐5‐hydroxyisobenzofuran‐1(3H)‐one ( 6 ), were isolated from the genus Gnaphalium for the first time. 相似文献
6.
Five new clerodane diterpene glycosyl derivatives, caseariasides A–E ( 1 – 5 , resp.) and three new ent‐kaurane diterpene glucosides, sylvestrisides C–E ( 6 – 8 , resp.) were isolated from the leaves of Casearia sylvestris. Their structures were determined on the basis of chemical and spectroscopic analyses. 相似文献
7.
Three new phenolic compounds, irisdichototins D, E, and F ( 1 – 3 , resp.) were isolated from the stems of Iris dichotoma. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D‐NMR techniques. 相似文献
8.
Wei‐Lie Xiao Ying‐Li Wu Shan‐Zhai Shang Fei He Xiao Luo Guang‐Yu Yang Jian‐Xin Pu Guo‐Qiang Chen Han‐Dong Sun 《Helvetica chimica acta》2010,93(10):1975-1982
Four new highly oxygenated nortriterpenoids, lancifodilactones O–R ( 1 – 4 ), together with six known ones, i.e., 5 – 10 , were isolated from the leaves and stems of Schisandra lancifolia. Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments and mass spectrometry. Compounds 1 – 3 were evaluated for their cytotoxicity against NB4, A549, SHSY5Y, PC‐3, and MCF‐7 cell lines. No compounds exhibited significant cytotoxicity, the IC50 values being above 50 μM . 相似文献
9.
Xue Zhang Hong‐Wei Liu Hao Gao Hui‐Ying Han Nai‐Li Wang Hou‐Ming Wu Xin‐Sheng Yao Zhao Wang 《Helvetica chimica acta》2007,90(12):2386-2394
Nine new sesquiterpenes, i.e., dendronobilins A–I ( 1 – 9 ), with copacamphane‐type ( 1 ), picrotoxane‐type ( 2 – 6 ), muurolene‐type ( 7 ), alloaromadendrane‐type ( 8 ), and cyclocopacamphane‐type ( 9 ) skeletons, were isolated from the 60% EtOH extract of the stems of Dendrobium nobile. Their structures were established as (1R,2R,4S,5S,6S,8S,9R)‐2,8‐dihydroxycopacamphan‐15‐one ( 1 ), (2β,3β,4β,5β)‐2,4,11‐trihydroxypicrotoxano‐3(15)‐lactone ( 2 ), (2β,3β,5β,9α,11β)‐2,11‐epoxy‐9,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 3 ), (2β,3β,5β,12R*)‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 4 ), (2β,3β,5β,12S*)‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 5 ), (2β,3β,5β,9α)‐9,10‐cyclo‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 6 ), (9β,10α)‐muurol‐4‐ene‐9,10,11‐triol ( 7 ), (10α)‐alloaromadendrane‐10,12,14‐triol ( 8 ), and (5β)‐cyclocopacamphane‐5,12,15‐triol ( 9 ) on the basis of spectroscopic analysis. The absolute configuration of compound 1 was tentatively assigned as (1R,2R,4S,5S,6S,8S,9R) according to its CD spectrum and the octant rule. Compounds 1 and 4 – 9 were inactive in our preliminary in vitro immunomodulatory bioassay. 相似文献
10.
Juan Li Hang Chang Wenyu Zhao Huifang Pi Hanli Ruan Peng Zhang 《Helvetica chimica acta》2014,97(5):689-693
Two new amide alkaloids, vaginatunine A and B ( 1 and 2 , resp.), and a new C18‐diterpenoid alkaloid vaginatunine C ( 3 ), together with four known alkaloids, were isolated from the tubers of Aconitum vaginatum. Their structures were determined by means of spectroscopic analyses and comparison of the data with those reported previously. 相似文献
11.
Ting‐Quan Yang Ying‐Tong Di Hong‐Ping He Qiang Zhang Yu Zhang Xiao‐Jiang Hao 《Helvetica chimica acta》2011,94(3):397-403
Three new Daphniphyllum alkaloids, daphlongeranines C–E ( 1 – 3 ), along with 13 known ones, were isolated from the fruits of Daphniphyllum longeracemosum. Their structures were elucidated on the basis of extensive spectroscopic analyses, especially 2D‐NMR experiments. 相似文献
12.
Muhammad Aijaz Anwar Shazia Yasmeen Sadia Ferheen Nighat Afza Abdul Malik Mahboob Ali Kalhoro 《Helvetica chimica acta》2013,96(9):1801-1806
Three new isomeric biisoflavonoids, dapholidins A–C ( 1 – 3 , resp.), have been isolated from the AcOEt‐soluble fraction of the MeOH‐soluble extract of the roots of Daphne oleoides, along with the known compounds daphwazirin ( 4 ), daphnetin 8‐O‐β‐D ‐glucopyranoside ( 5 ), daphnin ( 6 ), daphneticin 4″‐O‐β‐D ‐glucopyranoside ( 7 ), and 6,7‐dihydroxy‐3‐methoxy‐8‐[2‐oxo‐2H‐1‐benzopyran‐7‐(O‐β‐D ‐glucopyranosyl)‐8‐yl]‐2H‐1‐benzopyran‐2‐one ( 8 ). The structures of the new compounds were determined by spectroscopic analyses, including 1D‐ and 2D‐NMR. 相似文献
13.
Yu‐Zhi Zhou Huan Chen Li Qiao Xuan Lu Hui‐Ming Hua Yue‐Hu Pei 《Helvetica chimica acta》2008,91(7):1277-1285
Five new aromatic glycosides, 1 – 5 , named as carthamosides B4–B8, together with three known compounds, 4′‐(hydroxyphenacyl)‐β‐D ‐glucopyranoside ( 6 ), benzyl‐O‐α‐L ‐rhamnopyranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 7 ), and 4‐(methoxybenzyl)‐O‐β‐D ‐glucopyranoside ( 8 ), have been isolated from the air‐dried flower of Carthamus tinctorius. Their structures were identified on the basis of chemical and spectroscopic methods. 相似文献
14.
Zu‐Shang Su Sheng‐Ping Yang Sheng Zhang Lei Dong Jian‐Min Yue 《Helvetica chimica acta》2011,94(8):1515-1526
Eleven new limonoids, meliarachins A–K ( 1 – 11 , resp.), together with five known ones, were isolated from the twigs and leaves of Melia azedarach. The structures of the new compounds were elucidated on the basis of spectroscopic analysis. Compounds 4 and 8 exhibited moderate antibacterial activities against Gram‐positive bacteria. 相似文献
15.
Six new neolignans, casearialignans A–F ( 1 – 6 , resp.) and one known lignan syringaresinol‐β‐D ‐glucoside were isolated from the leaves of Casearia sylvestris. Their structures were determined on the basis of 1D‐ and 2D‐NMR, and HR‐ESI‐MS analyses. The relative and absolute configurations were determined by the value of the coupling constants and CD spectral analysis, respectively. 相似文献
16.
Xiang‐Dong Qin Yan Zhao Yuan Gao Fu‐Cai Ren Shu Yang Fei Wang 《Helvetica chimica acta》2015,98(9):1325-1331
Three novel curcuminoids, curcumaromins A–C ( 1 – 3 , resp.), along with a known compound, longiferone B ( 4 ) were isolated from Curcuma aromatica Salisb . The structures of the new compounds were elucidated as (1E,4Z,6E)‐5‐hydroxy‐7‐{4‐hydroxy‐3‐[(1R*,6R*)‐3‐methyl‐6‐(propan‐2‐yl)cyclohex‐2‐en‐1‐yl)phenyl}‐1‐(4‐hydroxyphenyl)hepta‐1,4,6‐trien‐3‐one ( 1 ), 2,3‐dihydro‐2‐(4‐hydroxyphenyl)‐6‐[(E)‐2‐(4‐hydroxyphenyl)ethenyl]‐5‐[(1R*,6R*)‐3‐methyl‐6‐(propan‐2‐yl)cyclohex‐2‐en‐1‐yl]‐4H‐pyran‐4‐one ( 2 ), and (1E,6E)‐1,7‐bis(4‐hydroxyphenyl)‐4‐[(1R*,6R*)‐3‐methyl‐6‐(propan‐2‐yl)cyclohex‐2‐en‐1‐yl]hepta‐1,6‐diene‐3,5‐dione ( 3 ) on the basis of spectroscopic analysis. Curcumaromins A–C ( 1 – 3 ) represented the first examples of menthane monoterpene‐coupled curcuminoids. The known compound, longiferone B ( 4 ), was the first daucane sesquiterpene isolated from the genus Curcuma. 相似文献
17.
A phytochemical investigation of the BuOH‐soluble fraction of the EtOH extract from the stems of Glycosmis pentaphylla resulted in the isolation of three new phenolic glycosides, glycopentosides D–F ( 1 – 3 , resp.). Their structures were determined by using spectroscopic analysis including UV, 1H‐ and 13C‐NMR, DEPT, COSY, ROESY, HMBC, HSQC, HR‐ESI‐MS, and acid hydrolysis. 相似文献
18.
Three new glycosides with the same saccharides, namely miliusoside A ( 1 ), miliusoside B ( 2 ), and miliusoside C ( 3 ), together with five known compounds were isolated from the stems of Miliusa balansae. Their structures were elucidated on the basis of detailed spectroscopic analysis and by comparison with the spectra of related model compounds. There was a rarely encountered α‐D ‐apiose moiety occurring in all new compounds. 相似文献
19.
Chuan‐Rui Zhang Hong‐Bing Liu Shi‐Hui Dong Yan Wu Jian‐Min Yue 《Helvetica chimica acta》2013,96(3):499-504
Three new alkaloids, macrodumines A–C ( 1 – 3 , resp.), along with ten known analogs, were isolated from the twigs and leaves of Daphniphyllum macropodum. Their structures were elucidated on the basis of spectroscopic methods. The 11‐OH configuration of the known alkaloid hydroxydaphgraciline ( 4 ) was assigned as α for the first time by comparing the NMR data with those of macrodumine C ( 3 ). 相似文献
20.
The first total synthesis of naturally occurring mappain has been achieved by a convergent sequence. The key strategy involved in the synthesis of mappain was a (E)‐stilbene formation by Horner–Wadsworth–Emmons reaction of the corresponding prenylated benzaldehyde with a geranylated benzyl phosphonate. 相似文献