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.     

Comparative analysis of the underground parts ofGentiana species by HPLC with diode-array and mass spectrometric detection

Summary The aim of this work was to compare the chemical composition of the underground parts (roots and rhizomes) ofGentiana cruciata L.,Gentiana pneumonanthe L., andGentiana asclepiadea L.— the three gentians native to Hungary—with that of the widely used stomachicGentiana lutea L., to determine which of the three Hungarian species could be used as a substitute forGentiana lutea in pharmaceutical preparations. The four gentians were compared by means of RPHPLC with diode-array detection (DAD) and electrospray ionization-mass spectrometric detection (ESI-MSD). The quantities of the lead compounds, the secoiridoid-glycosides, in 220 samples of the underground parts of gentians originating from several locations in Hungary, were determined by a more economical RPHPLC-DAD method. The occurrence of the characteristic compounds investigated—bitter principles and xanthones—in the underground parts of the speciesGentiana asclepiadea L. suggest it might be a potential replacement forGentiana lutea L. in pharmaceutical products. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Polyketide anthraquinone,diphenyl ether,and xanthone derivatives from the soil fungus Penicillium sp. PSU-RSPG99

Three new polyketides including one new diphenyl ether, penicillither (1), one new anthraquinone, penicilliquinone (2), and one new xanthone, penicillixanthone (3), together with twelve known compounds were isolated from the soil fungus Penicillium sp. PSU-RSPG99. Their structures were identified by spectroscopic evidence. In addition, the position of a chlorine atom in 1 was confirmed by the plausible biosynthetic pathway from the isolated chlorobenzophenone. Known GKK1032B displayed mild antimycobacterial and moderate cytotoxic (against human oral carcinoma, KB, human breast cancer, MCF-7, and noncancerous Vero cell lines) activities.     

Synthesis of toxyloxanthone B

A synthesis of the naturally occurring xanthone toxyloxanthone B is described, in which the key step is the regioselective addition of a methyl salicylate to a substituted benzyne, followed by cyclization of the intermediate aryl anion to form the xanthone, the regiochemistry of the aryne addition being confirmed by X-ray crystallography. Subsequent introduction of the pyran ring by [3,3]-rearrangement and deprotection completed the synthesis.     

Three New Caged Prenylxanthones from Garcinia bracteata

Three new caged prenylxanthones (xanthone=9H‐xanthen‐9‐one), named neobractatin ( 1 ), 3‐O‐methylneobractatin ( 2 ), and 3‐O‐methylbractatin ( 3 ), along with eight known compounds, were isolated from the twig of Garcinia bracteata. The structures of the new compounds were elucidated on the basis of 1D‐ and 2D‐NMR experiments, including HMBC, HSQC, ¹H,¹H‐COSY, and ROESY, as well as HR‐MS analysis.     

Preparative separation of major xanthones from mangosteen pericarp using high‐performance centrifugal partition chromatography

Mangosteen fruit pericarp (MFP) is a rich source of xanthones, which has shown remarkable pharmacological activities. To isolate xanthones, previous methods included labor intensive and time‐consuming solid‐phase extractions (Sephadex LH20, silica gel) and sequential solvent extraction. In this study, major xanthones (α‐ and γ‐mangostins) in MFP were isolated at high purity in one step utilizing high‐performance centrifugal partition chromatography with solvent system composed of petroleum ether, ethyl acetate, methanol and water (10:5:5:1). In one run, 200 mg crude extract of MFP was injected and 55.4 mg α‐mangostin and 12.4 mg γ‐mangostin were obtained with the purity of 93.6 and 98.4%, respectively. The yields of them were 86.3 and 76.3%, respectively. As α‐ and γ‐mangostins are reported to show potent antioxidant, anti‐inflammatory and anticancer activities, this method can be used for the large‐scale production of them for future in vitro and in vivo biological studies.     

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.     

New Xanthones from Polygala crotalarioides

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

Novel methods to extract flavanones and xanthones from the root bark of Maclura pomifera

A comparison between the extraction yields of xanthones and flavanones from the root bark of the Maclura pomifera by solid-liquid extraction (SLE), matrix solid phase dispersion (MSPD), and an alternative method using sea sand as a sample disruptor, is presented here. Two extraction solvents were used for all extraction techniques, dichloromethane and methanol:water, (9:1, v/v). The extraction procedures were reproducible as the R.S.D. values were less than 5% for almost all compounds. A recovery above 80% was obtained for macluraxanthone using the sea sand extraction procedure. Statistical treatment, ANOVA-single factor, was used to evaluate the different extraction procedures, and homogenization of plant material with sand followed by elution with dichloromethane provided the most efficient and rapid extraction method.