Xanthine oxidase inhibiting flavonol glycoside from Amberboa ramosa.

A new flavonol glycoside (1) has been isolated from the ethyl acetate soluble fraction of Amberboa ramosa and assigned the structure 5,7,4'-trihydroxy-3,8-dimethoxylflavone 5-O-beta-D-gluco-pyranoside (1). In addition, 6,4'-dihydroxy-3,5,7-trimethoxyflavone (2), 5,7-dihydroxy-4'-methoxyflavone (3) and (23R)-5alpha-cycloart-24-ene-3beta,21,23-triol (4) have also been reported for the first time from this species. The structures were deduced on the basis of 1D and 2D NMR techniques.

New natural urease inhibitors from Ranunculus repens.

Phytochemical investigations on the chloroform and ethyl acetate soluble fractions of the roots of Ranunculus repens led to the isolation of methyl 3,4,5-trihydroxybenzoate 1, R(+)- 4-methoxydalbergione 2 and R(+)-dalbergiophenol 3. The structures of these compounds were established through spectral studies including 1D and 2D NMR experiments and by comparison with literature data. These compounds showed potent inhibitory activity against urease.

Tyrosinase inhibitory lignans from the methanol extract of the roots of Vitex negundo Linn. and their structure-activity relationship.

Phytochemical investigation of the methanol extract of Vitex negundo afforded eight lignans; negundin A 1, negundin B 2, 6-hydroxy-4-(4-hydroxy-3-methoxy)-3-hydroxymethyl-7-methoxy-3,4-dihydro-2-naphthaledehyde 3, vitrofolal E 4, (+)-lyoniresinol 5, (+)-lyoniresinol-3alpha-O-beta-d-glucoside 6, (+)-(-)-pinoresinol 7, and (+)-diasyringaresinol 8. The structures of these compounds were elucidated unambiguously by spectroscopic methods including 1D and 2D NMR analysis and also by comparing experimental data with literature data. The tyrosinase inhibitory potency of these compounds has been evaluated and attempts to justify their structure-activity relationships have been made in the present work.

Chymotrypsin inhibitory triterpenoids from Silybum marianum.

Marianine, the new lanostane triterpene (1) and marianosides A (2) and B (3) have been isolated from the whole plant of Silybum marianum. Their structures were elucidated on the basis of extensive analysis of their one dimensional and two dimensional nuclear magnetic resonance (1D, 2D-NMR) spectral data. All inhibited chymotrypsin in a concentration-dependent manner.

Butyrylcholinesterase inhibitory guaianolides from Amberboa ramosa.

Phytochemical investigation of the whole plant of Amberboa ramosa led to the isolation of six sesquiterpene lactones which could be identified as 8alpha-hydroxy-11beta-methyl-1alphaH, 5alphaH, 6betaH, 7alphaH, 11alphaH-guai-10(14), 4(15)-dien-6, 12-olide(1), 3beta, 8alpha-dihydroxy-11alpha-methyl-1alphaH, 5alphaH, 6betaH, 7alphaH, 11betaH-guai-10(14), 4 (15)-dien-6, 12-olide (2), 3beta, 4alpha, 8alpha-trihydroxy-4beta-(hydroxymethyl)-1alphaH, 5alphaH, 6betaH, 7alphaH-guai-10(14), 11(13)-dien-6, 12-olide (3), 3beta, 4alpha, 8alpha-trihydroxy-4beta-(chloromethyl)-1alphaH, 5alphaH, 6betaH, 7alphaH-guai-10(14),11(13)-dien-6, 12-olide(4), 3beta, 4alpha, dihydroxy-4beta-(hydroxymethyl)-1alphaH, 5alphaH, 6betaH, 7alphaH-guai-10(14),11(13)-dien-6, 12-olide(5), 3beta, 4alpha-dihydroxy-4beta-(chloromethyl)-8alpha-(4-hydroxymethacrylate)-1alphaH, 5alphaH, 6betaH, 7alphaH-guai-10(14),11 (13)-dien-6,12-olide (6) by spectroscopic methods. All of them showed inhibitory potential against butyrylcholinesterase.

Spinoside, new coumaroyl flavone glycoside from Amaranthus spinosus.

Spinoside, new coumaroyl flavone glycoside was isolated from the n-butanol fraction of the mathanolic extract of the whole plant of Amaranthus spinosus and assigned the structure 7-p-coumaroyl apigenin 4-O-beta-D-glucopyranoside (1) on the basis of spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition alpha- xylofuranosyl uracil (2), beta-D-ribofuranosyl adenine (3) and beta-sitosterol glucoside (4) have also been isolated for the first time from this species.

Tyrosinase-inhibitory long-chain esters from Amberboa ramosa.

Long-chain esters 1 and 2 have been isolated from the chloroform-soluble fraction of Amberboa ramosa and their structures assigned to be methyl 2beta(2S)-hydroxyl-7(E)-tritriacontenoate (1) and methyl 2beta(2S)-O-beta-D-galactopyranosyl-7(E)-tetratriacontenoate (2). In addition, tricontane (3) and apigenin (4) are also reported for the first time from this species. The structures were assigned on the basis of 1D and 2D NMR techniques.

Enzyme inhibiting lignans from Vitex negundo.

Two new lignans trivially named negundins A (1) and B (2), were isolated along with (+)-diasyringaresinol (3), (+)-lyoniresinol (4), vitrofolal E (5) and vitrofolal F (6), reported for the first time from this species. The structures of the new compounds were established through spectral studies. Compound 2 showed potent inhibitory activity against lipoxygenase enzyme, while 5 showed moderate activity against butyryl-cholinesterase.