Aim To investigate the chemical constituents of Piper wallichii. Methods Five compounds were isolated by silica gel column chromatography and Sephadex LH-20 gel column chromatography, and the structures of compounds w...Aim To investigate the chemical constituents of Piper wallichii. Methods Five compounds were isolated by silica gel column chromatography and Sephadex LH-20 gel column chromatography, and the structures of compounds were identified by spectral analysis. Result Five compounds were identified as piperlonguminine （trans, trans） （1）, 4-hydroxy-3,5-dimethoxy-benzoic acid （2）, galgravin （3）, β-sitosterol （4）, and daucosterol （5）. Conclusion Five compounds were isolated from Piper wallichii for the first time, and compounds 1 -3 were isolated from this genus far the first time.展开更多
Aim To synthesize trans and cis-3, 4′, 5-trihydroxystilbene by a new convenient route. Methods The reaction of 3, 5-dimethoxybenzaldehyde （3） and 4-methoxy phenylacetonitrile （4） formed the stilbene skeleton. Aft...Aim To synthesize trans and cis-3, 4′, 5-trihydroxystilbene by a new convenient route. Methods The reaction of 3, 5-dimethoxybenzaldehyde （3） and 4-methoxy phenylacetonitrile （4） formed the stilbene skeleton. After hydrolyzation, decarboxylation, and demethylation, we obtained trans-3, 4′, 5-trihydroxystilbene （resveratrol）, which can be converted to its cis-isomer by photochemical isomerization. Results Starting from 3 and 4, trans and cis-3, 4′, 5-trihydroxystilbene were synthesized, respectively. Conclusion A facile method for the synthesis of trans and cis-hydroxystilbenes from readily available materials was established.展开更多
Aim To synthesize naturally occurring (-) methyl2,2-dimethyl-3-hydroxychromanyl-6-formate. Methods Sharpless' asymmetric dihydroxylation wasemployed to construct the 3-hydroxychroman. Results First asymmetric synt...Aim To synthesize naturally occurring (-) methyl2,2-dimethyl-3-hydroxychromanyl-6-formate. Methods Sharpless' asymmetric dihydroxylation wasemployed to construct the 3-hydroxychroman. Results First asymmetric synthesis of (-) methyl 2,2-dimethyl-3-hydroxychromanyl-6-formate (1) was accomplished starting from methyl 4-hydroxy-benzoate(2), and the absolute configuration was established. Conclusion A useful method for constructingchiral 3-hydroxychroman by employing Sharpless' asymmetric dihydroxylation is achieved.展开更多
As a good antimicrobial active ingredient, 2,4,4′ trichloro 2′ hydroxydiphenyl ether has been already commercially available since 1970s. For this paper halogenated hydroxydiphenyl ethers were prepared and purifi...As a good antimicrobial active ingredient, 2,4,4′ trichloro 2′ hydroxydiphenyl ether has been already commercially available since 1970s. For this paper halogenated hydroxydiphenyl ethers were prepared and purified, and their analytical conditions by HPLC were studied. Further purification of 2,4,4′ trichloro 2′ hydroxydiphenyl ether was also studied. The adsorption ability of different decolourants, e.g. alumina and bentonite, for each component in crude product of 2,4,4′ trichloro 2′ hydroxydiphenyl ether was varied. 2,4,4′ trichloro 2′ hydroxydiphenyl ether might be adsorbed by active carbon. The colored impurities might be adsorbed by alumina. The colorless impurities might be adsorbed by bentonite.展开更多
The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The inhibitor concentration lea...The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The inhibitor concentration leading to 50% relative activity lost （IC50） was estimated to be 0.15 mmol·L^-1. The inhibition mechanism obtained from Lineweaver-Burk plots shows that ferulic acid is a competitive inhibitor and the inhibition of tyrosinase by ferulic acid is a reversible reaction. The equilibrium constant for ferulic acid binding with the tyrosinase was determined to be 0.25 mmol·L^-1 for diphenolase. Keywords tyrosinase, ferulic acid, kinetics, inhibition, L-DOPA, diphenolase展开更多
文摘Aim To investigate the chemical constituents of Piper wallichii. Methods Five compounds were isolated by silica gel column chromatography and Sephadex LH-20 gel column chromatography, and the structures of compounds were identified by spectral analysis. Result Five compounds were identified as piperlonguminine （trans, trans） （1）, 4-hydroxy-3,5-dimethoxy-benzoic acid （2）, galgravin （3）, β-sitosterol （4）, and daucosterol （5）. Conclusion Five compounds were isolated from Piper wallichii for the first time, and compounds 1 -3 were isolated from this genus far the first time.
文摘Aim To synthesize trans and cis-3, 4′, 5-trihydroxystilbene by a new convenient route. Methods The reaction of 3, 5-dimethoxybenzaldehyde （3） and 4-methoxy phenylacetonitrile （4） formed the stilbene skeleton. After hydrolyzation, decarboxylation, and demethylation, we obtained trans-3, 4′, 5-trihydroxystilbene （resveratrol）, which can be converted to its cis-isomer by photochemical isomerization. Results Starting from 3 and 4, trans and cis-3, 4′, 5-trihydroxystilbene were synthesized, respectively. Conclusion A facile method for the synthesis of trans and cis-hydroxystilbenes from readily available materials was established.
基金This research work was financially supported by the National Natural Science Foundation of China(Grant NO.20272020).
文摘Aim To synthesize naturally occurring (-) methyl2,2-dimethyl-3-hydroxychromanyl-6-formate. Methods Sharpless' asymmetric dihydroxylation wasemployed to construct the 3-hydroxychroman. Results First asymmetric synthesis of (-) methyl 2,2-dimethyl-3-hydroxychromanyl-6-formate (1) was accomplished starting from methyl 4-hydroxy-benzoate(2), and the absolute configuration was established. Conclusion A useful method for constructingchiral 3-hydroxychroman by employing Sharpless' asymmetric dihydroxylation is achieved.
文摘As a good antimicrobial active ingredient, 2,4,4′ trichloro 2′ hydroxydiphenyl ether has been already commercially available since 1970s. For this paper halogenated hydroxydiphenyl ethers were prepared and purified, and their analytical conditions by HPLC were studied. Further purification of 2,4,4′ trichloro 2′ hydroxydiphenyl ether was also studied. The adsorption ability of different decolourants, e.g. alumina and bentonite, for each component in crude product of 2,4,4′ trichloro 2′ hydroxydiphenyl ether was varied. 2,4,4′ trichloro 2′ hydroxydiphenyl ether might be adsorbed by active carbon. The colored impurities might be adsorbed by alumina. The colorless impurities might be adsorbed by bentonite.
基金Supported by the Natural Science Foundation of Guangdong Province (No. 011563, No. 04020114).
文摘The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The inhibitor concentration leading to 50% relative activity lost （IC50） was estimated to be 0.15 mmol·L^-1. The inhibition mechanism obtained from Lineweaver-Burk plots shows that ferulic acid is a competitive inhibitor and the inhibition of tyrosinase by ferulic acid is a reversible reaction. The equilibrium constant for ferulic acid binding with the tyrosinase was determined to be 0.25 mmol·L^-1 for diphenolase. Keywords tyrosinase, ferulic acid, kinetics, inhibition, L-DOPA, diphenolase
