Potent anti-platelet constituents from Centaurea iberica

New naturally occurring nitrogenous compounds 1 and 2, along with a new dimeric lignan glucoside 3, have been isolated from the ethyl acetate soluble fraction of Centaurea iberica. Their structures have been elucidated through spectroscopic techniques. All the isolated compounds showed significant platelet aggregation inhibition.     

Xanthones from the bark of Garcinia Xanthochymus

Two novel xanthones, 1,6-dihydroxy-4,5-dimethoxyxanthone (1) and 1,5,6-trihydroxy-7,8-di(3-methyl-2-butenyl)-60,60- dimethylpyrano(20,30:3,4)xanthone (2) were isolated from the bark of Garcinia xanthochymus by normal phase and reverse phase silica gel column chromatography. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques.     

Xanthones from the stems of Cratoxylum cochinchinense

Four new xanthones, 1‐methoxy‐3,7,8‐trihydroxyxanthone (1), 1‐methoxy‐4,7,8‐trihydroxyxanthone (2), 1‐methoxy‐4,7‐dihydroxyxanthone (3), and 1,4‐dimethoxy‐2,7‐dihydroxyxanthone (4) were isolated from the stems of Cratoxylum cochinchinense along with four known xanthones (5–8). The structures of new compounds were determined by extensive spectroscopic analyses, mainly 1D and 2D NMR and HRESIMS data. Copyright © 2012 John Wiley & Sons, Ltd.     

Xanthones from the green branch of Garcinia dulcis

Two new prenylated xanthones, namely dulcisxanthone H and dulcisxanthone I along with garciniaxanthone C, were isolated from the dichloromethane extract of the green branch of Garcinia dulcis. Their structures were elucidated by the analysis of 1-D and 2-D NMR spectral data. Their antibacterial activities were also examined.     

Three New Xanthones from Polygala crotalarioides

Polygala crotalarioides Buch. Ham. (Polygalaceae) is known to be a folk tonic medicine used in Yunnan Wa nationality1. Its bioactivities attracted us to investigate its chemical constituents. Three new xanthones were isolated from the roots of Polygala cr…     

New Isoprenylated Xanthones from Cudrania tricuspidata

A phytochemical investigation of the roots of Cudrania tricuspidata afforded three new isoprenylated xanthones, cudratricusxanthones N–P ( 1 – 3 , resp.), together with five known compounds, 4 – 8 . The structures of the new compounds were elucidated by extensive spectroscopic analyses.     

Two New Xanthones from Polygala crotalarioides

Two new xanthones, 1,6,8-trihydroxy-2,3-methylenedioxyxanthone 1 and 1,4-dihydroxy-6, 7-methylenedioxyxanthone 2, were isolated from the roots of Polygala crotalarioides. Their structures were elucidated by spectroscopic and chemical methods.     

Xanthones from stems of Hypericum chinense

Six new xanthones, 4,6-dihydroxy-2,3-dimethoxyxanthone (1), 2,6-dihydroxy-3,4-dimethoxyxanthone (2), 6-hydroxy-2,3,4-trimethoxyxanthone (3), 3,6-dihydroxy-1,2-dimethoxyxanthone (4), 4,7-dihydroxy-2,3-dimethoxyxanthone (5), and 3,7-dihydroxy-2,4-dimethoxyxanthone (6) were isolated from the stems of Hypericum chinense, together with four known xanthones. Their structures were established based on spectroscopic studies.     

红厚壳中两个新呫酮类化合物的结构研究

呫酮类化合物存在于很多藤黄科植物中，并具有多样的生物活性．为了进一步发现其活性成分，本文对藤黄科植物红厚壳根的化学成分进行了研究，从中分离得到11个呫酮类化合物，其中两个为新化合物．经多种光谱方法确定了各化合物的结构，两个新化合物分别命名为红厚壳呫酮C（Calophyllumin C)(1)和红厚壳呫酮M(Caloxanthone)(2)．     

New Xanthones from Polygala crotalarioides

Introduction Xanthonesaresecondarymetabolitescommonly occurringinafewhigherplantfamilies,fungiandli chen.Theirhightaxonomicvalueinsuchfamiliesand theirpharmacologicalproperties,includinginvitrocy totoxicity,invivoantitumouractivity,antifungal,anti bacteri…     

Two Unusual Xanthones from the Bark of Garcinia xanthochymus

A new xanthone derivative, garcinexanthone F ( 1 ), which was found to possess an α,β‐unsaturated γ‐lactone moiety, and a new bisxanthone, bigarcinenone B ( 2 ), with a terpene bridge providing the xanthone? xanthone linkage, were isolated from the bark of Garcinia xanthochymus. Their structures were elucidated by spectroscopic methods, especially 2D‐NMR techniques. The antioxidant assay in vitro showed that compounds 1 and 2 exhibited significant scavenging activities against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical with IC₅₀ values of 22.32 and 20.14 μM , and against HO^. radical with IC₅₀ values of 1.16 and 2.85 μM , respectively.     

Xanthones from Garcinia mangostana (Guttiferae)

Studies on the stem of Garcinia mangostana have led to the isolation of one new xanthone mangosharin (1) (2,6-dihydroxy-8-methoxy-5-(3-methylbut-2-enyl)-xanthone) and six other prenylated xanthones, alpha-mangostin (2), beta-mangostin (3), garcinone D (4), 1,6-dihydroxy-3,7-dimethoxy-2-(3-methylbut-2-enyl)-xanthone (5), mangostanol (6) and 5,9-dihydroxy-8- methoxy-2,2-dimethyl-7-(3-methylbut-2-enyl)-2H,6H-pyrano-[3,2-b]-xanthene-6-one (7). The structures of these compounds were determined by spectroscopic methods such as 1H NMR, 13C NMR, mass spectrometry (MS) and by comparison with previous studies. All the crude extracts when screened for their larvicidal activities indicated very good toxicity against the larvae of Aedes aegypti. This article reports the isolation and identification of the above compounds as well as bioassay data for the crude extracts. These bioassay data have not been reported before.     

Novel Prenylated Xanthones from Garcinia gerrardii HARVEY

Three novel prenylated xanthones, 1–3 , have been isolated from the root bark of Garcinia gerrardii HARVEY ex T. R. SIM (G. natalensis SCHLECHTER ; G. transvaalensis BURTT DAVY ; Guttiferae). Structure elucidation was achieved by a combination of one- and two-dimensional NMR spectroscopic techniques, including long-range HETCOR, mass spectroscopy, and chemical methods. Garcigerrin A ( 1 ) and B ( 2 ) are pyrano derivatives of 3 . They all show a rare 1,4,5 oxygenation pattern of the xanthone nucleus. Xanthone 3 is fungicidal against Cladosporium cucumerinum.     

Polyprenylated Xanthones and Benzophenones from the Bark of Garcinia oblongifolia

A new polyprenylated xanthone (=9H‐xanthen‐9‐one) and a new polyprenylated benzophenone, namely oblongifolixanthone A ( 1 ) and garciniagifolone A ( 2 ), were isolated from the bark of Garcinia oblongifolia, together with five known compounds including the four xanthones 3 – 5 and 7 and a benzophenone 6 . The structures of 1 and 2 were established by detailed analysis of their spectroscopic data, especially 1D‐ and 2D‐NMR spectra and HR‐ESI‐MS data. All these compounds were assayed for their cytotoxic activities against three human tumor cell lines (HeLa, SGC7901, and HepG2). The 1,3,6,7‐tetrahydroxy‐9H‐xanthen‐9‐one ( 3 ) was inactive, and the other compounds showed weak to moderate activity.