New anthraquinone derivatives from the roots of Berchemia floribunda

A new naphthoquinone-anthraquinone dimer named floribundiquinone E(1)and a new anthraquinone 2-acetylphyscion(2)were isolated from the roots of Berchemia floribunda Brongn.Their structures were elucidated on the basis of spectroscopicmethods.     

Spicachlorantins G-J, new lindenane sesquiterpenoid dimers from the roots of Chloranthus spicatus

Four new lindenane sesquiterpenoid dimers, spicachlorantins G-J (1-4), were isolated from the roots of Chloranthus spicatus together with seven known compounds, including chloramultilide A, shizukaol B, shizukaol D, shizukaol F, shizukaol P, chlorahololide D, and cycloshizukaol A. The planar structures of the new compounds were established by 1D-, 2D-NMR, and MS analyses. The absolute configurations of these compounds were determined by analyzing rotating Overhauser enhancement and exchange spectroscopy (ROESY) and circular dichroism (CD) spectra.     

Chemical Constituents from Berchemia formosana

Centrifugal partition chromatography, Sephadex LH-20 and flash chromatography were applied to separate flavonoids and coumarins from Berchemia formosana. This first chemical investigation led to the isolation of ten compounds. Based on spectral analysis, they were determined to be quercetin ( 1 ), rutin ( 2 ), (+)-dihydroquercetin ( 3 ), (+)-dihydrokaempferol ( 4 ), naringenin ( 5 ), 2-hydroxy-naringenin ( 6 ), 2-hydroxy-naringenin-7-O-β-glucoside ( 7 ), (-)-catechin ( 8 ), (-)-gallocatechin ( 9 ) and scopoletin ( 10 ). Among these 7 is a novel natural product and was found to be composed of two inseparable diastereoisomers. The presence of the rare 2-hydroxyflavanones 6 and 7 in B. formosana is of interest for chemotaxonomy.     

Berchemolide, a novel dimeric vanillic acid glucoside from Berchemia racemosa.

A new phenol glycoside named berchemolide was isolated together with (+)-catechin and (-)-epicatechin (as acetates), from the stems of Berchemia racemosa Sieb. et Zucc. (Rhamnaceae). The structure of berchemolide, having a dimeric dilactone structure with a 22-membered ring, was determined on the basis of spectral and chemical investigations. The conformation of berchemolide was calculated by MNDO (modified neglect of diatomic overlap).     

Modeling of supercritical fluid extraction of flavonoids from Calycopteris floribunda leaves

The aim of this study was to obtain flavonoids extracts from Calycopteris floribunda leaves using supercritical fluid extraction (SFE) with CO₂ and a co-solvent. Pachypodol, a potential anticancer drug lead compound separated from the extracts, was examined. Classical organic solvent extraction (CE) with ethanol was performed to evaluate the high pressure method. HPLC analysis was introduced to interpret the differences between SFE and CE extracts in terms of antioxidant activity and the concentration of pachypodol. SFE kinetics and mathematical modeling of the overall extraction curves (OEC) were investigated. Evaluation of the models against experimental data showed that the Sovová model performs the best. The supercritical fluid extraction process was optimized using a central composite design (CCD), where temperature and pressure were adjusted. The optimal conditions of SFE were: pressure of 30 MPa and temperature of 35°C.     

A new dimeric alkylresorcinol from the stem barks of Swintonia floribunda (Anacardiaceae)

From an EtOAc-soluble fraction of the stem barks of Swintonia floribunda (Anacardiaceae), one new dimeric alkylresorcinol named integracin E (1), together with 4 known compounds (2–5) were isolated. Their chemical structures were elucidated based on the spectroscopic data interpretation. The absolute configuration of 1 was determined by the specific rotation analysis of its acid-catalyzed hydrolysis product. Compound 1 showed potent tyrosinase inhibitory activity with an IC₅₀ value of 48.2?μM.     

Two phthalide dimers from the radix of Angelica sinensis

The phytochemical investigation of extracts from the radix of Angelica sinensis yielded a new phthalide dimer, 3,3'Z-6.7',7.6'-diligustilide, along with a known dimer, levistolide A. Their structures were established on the basis of spectral data, particularly using 1D-NMR and several 2D shift-correlated NMR pulse sequences (1H-1H COSY, HSQC, HMBC and NOESY).     

Radical pairs from photolysis of phenoxy dimers

Ultraviolet photolysis of solid samples of the dimers of phenoxy radicals has been found to produce closely associated radical pairs in some cases. An electron spin resonance investigation of these trapped radical pairs is reported in this note.     

Bioactive stilbene dimers from Gnetum cleistostachyum

Two new stilbene dimers, named bisisorhapontigenin A (1) and cis shegansu B (2), together with gnetuhainin P (3) and gnetulin (4), were isolated from the lianas of Gnetum cleistostachyum C. Y. Cheng. Their structures were elucidated by means of spectroscopic evidences, including UV, IR, MS, 1H NMR, 13C NMR, NOE and 2D NMR, respectively. The pharmacological activities of compounds 1, 2 and 3 also have been tested.     

Xanthones from the roots ofSwertia iberica

From the roots ofSwertia iberica, together with the previously known swertiaperennin decussatin, gentiakochianin, and norswertianin, we have isolated two new xanthones — isogentiakochianin and swertiaiberin. On the basis of UV, IR, PMR, and mass spectroscopy, the structure of 1,3,8-trihydroxy-7-methoxyxanthone is proposed for isogentiakochianin, and that of 1,2,3-trihydroxy-7,8-dimethoxyanthone for swertiaiberin.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 190–195, March–April, 1980.     

Coumarins from the roots ofFerula nevskii

Chemistry of Natural Compounds -