- ERIOSIDE, A NEW COUMARIN GLUCOSIDE FROM LASIOSIPHON ERIOCEPHALUS
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Key Word Index: Lasiosiphon eriocephalus; Thymelaeaceae; 6,8-dihydoxy-7-O-D-glucosyloxycoumarin.
- Bhandari, Prabha,Tandon, Sheela,Rastogi, R. P.
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- Cytotoxic and antimicrobial constituents of the bark of Diospyros maritima collected in two geographical locations in Indonesia
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Bioactivity-directed fractionation of extracts of two Diospyros maritima bark samples from Indonesia, one collected at sea level in a beach forest in Java and the other collected at a slight elevation away from the sea shore on the island of Lombok, yielded a diverse set of secondary metabolites. The naphthoquinone plumbagin (1), although found in extracts of both specimens, constituted a much larger percentage of the former sample, which also yielded a series of plumbagin dimers, maritinone (2), chitranone (3), and zeylanone (4). The latter sample yielded a new naphthoquinone derivative, (4S)-shinanolone (5), and a new natural product coumarin, 7,8-dimethoxy-6-hydroxycoumarin (6), along with three other analogues of plumbagin, 2-methoxy-7-methyljuglone (7), 3-methoxy-7-methyljuglone (8), and 7-methyljuglone (9). The structures of compounds 5 and 6 were elaborated by physical, spectral, and chemical methods. All of the isolates were evaluated in both cytotoxicity and antimicrobial assays, and structure-activity relationships of these naphthoquinones are proposed. Plumbagin (1) and maritinone (2) were evaluated also for in vivo antitumor activity in the hollow fiber assay, but both were found to be inactive.
- Gu, Jian-Qiao,Graf, Tyler N.,Lee, Dongho,Chai, Hee-Byung,Mi, Qiuwen,Kardono, Leonardus B. S.,Setyowati, Fransisca M.,Ismail, Rachman,Riswan, Soedarsono,Farnsworth, Norman R.,Cordell, Geoffrey A.,Pezzuto, John M.,Swanson, Steven M.,Kroll, David J.,Falkinham III, Joseph O.,Wall, Monroe E.,Wani, Mansukh C.,Kinghorn, A. Douglas,Oberlies, Nicholas H.
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- Gastroprotective efficacy and safety evaluation of scoparone derivatives on experimentally induced gastric lesions in rodents
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This study investigated the gastroprotective efficacy of synthesized scoparone derivatives on experimentally induced gastritis and their toxicological safety. Six scoparone derivatives were synthesized and screened for gastroprotective activities against HCl/ethanol- and indomethacin-induced gastric ulcers in rats. Among these compounds, 5,6,7-trimethoxycoumarin and 6,7,8-trimethoxycoumarin were found to have gastroprotective activity greater than the standard drug rebamipide; 6-methoxy-7,8-methylenedioxycoumarin, 6-methoxy-7,8-(1-methoxy)-methylenedioxycoumarin, 6,7-methylenedioxycoumarin, and 6,7-(1-methoxy)-methylenedioxycoumarin were found to be equipotent or less potent that of rebamipide. Pharmacological studies suggest that the presence of a methoxy group at position C-5 or C-8 of the scoparone’s phenyl ring significantly improves gastroprotective activity, whereas the presence of a dioxolane ring at C-6, C-7, or C-8 was found to have decreased activity. In order to assess toxicological safety, two of the potent gastroprotective scoparone derivatives-5,6,7-trimethoxycoumarin and 6,7,8-trimethoxycoumarin-were examined for their acute toxicity in mice as well as their effect on cytochrome P450 (CYP) enzyme activity. These two compounds showed low acute oral toxicity in adult male and female mice, and caused minimal changes to CYP3A4 and CYP2C9 enzyme activity. These results indicate that compared to other scoparone derivatives, 5,6,7-trimethoxycoumarin and 6,7,8-trimethoxycoumarin can improve gastroprotective effects, and they have low toxicity and minimal effects on drug-metabolizing enzymes.
- Son, Dong Ju,Lee, Gyung Rak,Oh, Sungil,Lee, Sung Eun,Choi, Won Sik
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p. 1945 - 1964
(2016/08/11)
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- Total synthesis of six 3,4-unsubstituted coumarins
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In this article we describe a new methodology for the total synthesis of 3,4-unsubstituted coumarins from commercially available starting materials. Six examples were prepared, including five naturally occurring coumarins-7-hydroxy- 6,8-dimethoxycoumarin (isofraxidin), 7-hydroxy-6-methoxycoumarin (scopoletin), 6,7,8-trimethoxycoumarin, 6,7-dimethoxycoumarin (scoparone), and 7,8-dihydroxycoumarin (daphnetin) and one synthetic coumarin, 7-hydroxy-6-ethoxycoumarin. Moreover, five important o-hydroxybenzaldehyde intermediates were also obtained, namely 2,4-dihydroxy-3,5- dimethoxybenzaldehyde, 2,4-dihydroxy-5-methoxybenzaldehyde, 5-ethoxy-2,4- dihydroxybenzaldehyde, 2-hydroxy-3,4,5-trimethoxybenzaldehyde, and 2-hydroxy-4,5-dimethoxybenzaldehyde. The method developed herein involves just three or four steps and allows for the rapid synthesis of these important molecules in excellent yields. This is the first synthesis of 6,7,8-trimethoxycoumarin and 7-hydroxy-6-ethoxycoumarin.
- Gao, Wenqing,Li, Qingyong,Chen, Jian,Wang, Zhichao,Hua, Changlong
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p. 15613 - 15623
(2014/01/17)
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