- Xanthone glucoside from an insect pathogenic fungus Conoideocrella luteorostrata NBRC106950
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A new compound, 3-O-(4-O-methyl-β-D-glucopyranosyl) xanthone (1) was isolated from the culture of Conoideocrella luteorostrata NBRC106950. The structure of 1 was mainly determined by 1H, 13C, 2D-NMR and HREIMS spectral analyses. The absolute configuration of 4-O-methylglucopyranosyl moiety was determined by the optical rotation of aqueous layer of hydrolyzed 1 as D-configuration.
- Yoneyama, Tatsuro,Iguchi, Miki,Yoshii, Kento,Elshamy, Abdelsamed I.,Ban, Sayaka,Noji, Masaaki,Umeyama, Akemi
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- Increment of antimycobaterial activity on lichexanthone derivatives
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A new dihydropyranexanthone derived from the natural xanthone lichexanthone (1) was synthesised and, together with other 18 derivatives including ω-bromo and ω-aminoalkoxylxanthones (containing methyl, ethyl, propyl, tertbutylamino and piperidinyl moieties), were tested against Mycobacterium tuberculosis. Nine ω-aminoalkoxylxanthones showed good antimycobacterial activity, and their in vitro cytotoxicity was determined using VERO cells in order to calculate the selectivity index (SI). One of these nitrogenated xanthone derivatives showed very promising results, with MIC of 2.6 μM and SI of 48. This MIC is comparable to values found in "first and second line" drugs commonly used to treat TB. In order to understand better about this compound, it was evaluated together with two other ones that showed good SI, against resistant clinical strains of M. tuberculosis to verify the existence of cross-resistance. A chemometrical approach was useful to establish a pattern of antitubercular activity among the group of ω- aminoalkoxylxanthones, according to some structural and chemical features.
- Micheletti, Ana Camila,Honda, Neli Kika,Pavan, Fernando R.,Leite, Clarice Q.F.,De Fatima Cepa Matos, Maria,Perdomo, Renata Trentin,Bogo, Danielle,Alcantara, Glaucia Braz,Beatriz, Adilson
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p. 904 - 910
(2014/01/06)
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- Antimycobacterial activity of lichen substances
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We describe here the extraction and identification of several classes of phenolic compounds from the lichens Parmotrema dilatatum (Vain.) Hale, Parmotrema tinctorum (Nyl.) Hale, Pseudoparmelia sphaerospora (Nyl.) Hale and Usnea subcavata (Motyka) and determined their anti-tubercular activity. The depsides (atranorin, diffractaic and lecanoric acids), depsidones (protocetraric, salazinic, hypostictic and norstictic acids), xanthones (lichexanthone and secalonic acid), and usnic acid, as well seven orsellinic acid esters, five salazinic acid 8',9'-O-alkyl derivatives and four lichexanthone derivatives, were evaluated for their activity against Mycobacterium tuberculosis. Diffractaic acid was the most active compound (MIC value 15.6 μg/ml, 41.6 μM), followed by norstictic acid (MIC value 62.5 μg/ml, 168 μM) and usnic acid (MIC value 62.5 μg/ml, 182 μM). Hypostictic acid (MIC value 94.0 μg/ml, 251 μM) and protocetraric acid (MIC value 125 μg/ml, 334 μM) showed moderate inhibitory activity. The other compounds showed lower inhibitory activity on the growth of M. tuberculosis, varying from MIC values of 250 to 1370 μM.
- Honda,Pavan,Coelho,de Andrade Leite,Micheletti,Lopes,Misutsu,Beatriz,Brum,Leite
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experimental part
p. 328 - 332
(2011/06/10)
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- Acylation of Multiple Anions of Poly-β-ketones by Hydroxy- and Alkoxybenzoates. Cyclization of the Resultant Tetraketones to Benzophenones and Xanthones
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The dianion (2) of 2,4-pentanedione and the trianion (10) of 2,4,6-heptanetrione were acylated by lithium salts of the unprotected hydroxybenzoates methyl 2-hydroxy-4-methoxy-6-methylbenzoate (1b), methyl 2,6-dihydroxy-4-methoxybenzoate (7b), and methyl 2,4-dimethoxy-6-hydroxybenzoate (7c), as well as by the alkoxybenzoates methyl 2,4,6-trimethoxybenzoate (7d) and methyl 2,4,6-tribenzoxybenzoate (7e).The aryl 1,3,5,7-octanetetraones (11b-d and 12) resulting from acylation of 10 were cyclized in biomimetic processes to naturally occurring benzophenones and xanthones.Hydrogenolysis of 1-(2,4,6-tribenzoxyphenyl)-1,3,5,7-octanetetraone (11e) and cyclization gave norlichexanthone (20).
- Sandifer, Ronda M.,Bhattacharya, Ajit K.,Harris, Thomas M.
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p. 2260 - 2267
(2007/10/02)
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