Tirso Rios

Prenylflavans from Tephrosia watsoniana

Abstract The aerial parts of tephrosia watsoniana afforded five new flavonoids named tephrowatsin A, B, C, D and E. Their structures and stereochemistries were established by spectroscopic methods and chemical transformations.

Ligustrin, a guaianolide isolated from europatorium ligustrinum DC

Abstract The structure of ligustrin a constituent of Eupatorium ligustrinum DC. has been established as a sesquiterpene lactone of the guaiane series presented by formula Ia.

Highly oxygenated flavonoids from Ageratum corymbosum

Abstract The investigation of Ageratum corymbosum resulted in the isolation of four new highly oxygenated flavonoids, and their structures established by spectroscopic and degradative evidence as 5,6,7,5′-tetramethoxy-3′,4′-methylenedioxyflavanone; 5,6,7,8,5′-pentamethoxy-3′,4′-methylenedioxyflavanone; 5,6,7,8,2′,4′,5′-heptamethoxy-flavone and 5,2′,4′-trihydroxy-6,7,8,5′-tetramethoxyflavone. The recently reported gardenin A monomethyl ether and 5′-methoxylucidin dimethyl ether (eupalestin) were also isolated.

The structures of eupalin and eupatolin. Two new flavonol rhamnosides isolated from Eupatorium ligustrinum D.C.

Abstract Two new flavonols, eupalitin and eupatolitin were isolated from Eupatorium ligustrinum D.C. as their rhamnosides. The structure of eupalitin (II) was established as the 3,5,4′-trihydroxy-6,7dimethoxyflavone and that for eupatolitin (IX) as 3,5,3′,4′-tetrahydroxy-6,7 dimethoxyflavone. In eupalin and eupatolin a rhamnose molecule is attached at the 3 position.

Zoapatanolide A and B, two new heliangolides from Montanoa tomentosa☆

Abstract The re-investigation of Montanoa tomentosa afforded, in addition to known diterpenoids of the kaurene class, two new sesquiterpene lactones, zoapatanolide A and B, of the heliangolide type.

An unusual prenyl biflavanol from Tephrosia tepicana

Abstract The roots and aerial parts of Tephrosia tepicana afforded a prenyl biflavanol. The structure and stereochemistry were established by spectroscopic methods, some chemical transformations and confirmed by X-ray diffraction. Tepicanol A is the first biflavanol with a 4,4″biflavanyl ether group to be isolated from the genus Tephrosia.

The crystal structure of 6-epi-desacetyllaurenobiolide, a germacra-1(10),4-diene-12,8α-olide from Montanoa grandiflora ☆

Abstract A chloroform extract of Montanoa grandiflora afforded a novel 6β-hydroxy-germacradien-8,12-olide. Its structure was shown to be 6- epi -desacetyllaurenobiolide by spectral studies, chemical transformations and single crystal X-ray diffraction. The X-ray data demonstrate that the ten-membered ring exists in the crystal in the highly unusual [ 15 D 5 , 1 D 14 ] conformation, in which the methyl group at C-4 is α-oriented and the methyl group at C-10 is β-oriented. The two double bonds are approximately parallel rather than crossed.

Viridiflorin, an isoflavone from Tephrosia viridiflora

Abstract A new isoflavone, viridiflorin, has been isolated from Tephrosia viridiflora . Its structure was established as 4′,5,7-trihydroxy-2′,5′-dimethoxy-6-prenylisoflavone based on spectral evidence and chemical transformation.

TWO POLYMETHOXYFLAVONES FROM AGERATUM HOUSTONIANUM

Abstract Besides agecorynin C, eupalestin and lucidin dimethyl ether, two new highly oxygenated flavones were isolated from Ageratum houstonianum . Their structures were established by spectroscopic and degradative evidence as 5, 6, 7, 8, 2′, 3′, 4′, 5′-octamethoxyflavone and 5, 6, 7, 2′, 3′, 4′, 5′-heptamethoxyflavone.

Alkyl glycerol monoethers in the marine spongeDesmapsamma anchorata

Abstract1-O-Hexadecylglycerol (chimyl alcohol), 1-O-heptadecylglycerol and 1-O-octadecylglycerol (batyl alcohol) have been identified as the major native constituents of a mixture of free alkyl glycerol ethers isolated from the contained water and the methanolic extract of the spongeDesmapsamma anchorata. Minor components were the free C14, C15, C19, C20 and C21 alkyl glycerol monoethers. The alkyl glycerol monoethers were analyzed and identified by gas chromatography/mass spectrometry of their isopropylidene derivatives. This is the first report on the occurrence of free C15, C19, C20 and C21 alkyl glycerol monoethers in a sponge.