Thunalbene, a stilbene derivative from the orchid Thunia alba

Abstract: Covering: up to the end of March 2012 Stilbenoids, a family of polyphenols known for the complexity of their structure and for their diverse biological activities, occur with a limited but heterogeneous distribution in the plant kingdom. The most prominent stilbene containing plant family, the Vitaceae, represented by the famous wine producing grape vines Vitis vinifera L., is one of the richest sources of novel stilbenes currently known, together with other families, such as Dipterocarpaceae, Gnetaceae and Fabaceae. This review focuses on the distribution of stilbenes and 2-arylbenzofuran derivatives in the plant kingdom, the chemical structure of stilbenes in the Vitaceae family and their taxonomic implication.

Abstract: The aim of this review is to survey the various naturally occurring phenanthrene compounds that have been isolated from different plants. Only one review has previously been published on this topic. Gorham (1989) reviewed the structures, biosynthesis, separations and spectroscopy of stilbenes and phenanthrenes. The present study furnishes an overview of the hydroxy or/and methoxy-substituted 9,10-dihydro/phenanthrenes, methylated, prenylated and other monomeric derivatives, dimeric and trimeric phenanthrenes and their biological activities. A fairly large number of phenanthrenes have been reported from higher plants, mainly in the Orchidaceae family, in the species Dendrobium, Bulbophyllum, Eria, Maxillaria, Bletilla, Coelogyna, Cymbidium, Ephemerantha and Epidendrum. A few phenanthrenes have been found in the Hepaticae class and Dioscoreaceae, Combretaceae and Betulaceae families. Their distribution correlates strongly with the taxonomic divisions. These plants have often been used in traditional medicine, and phenanthrenes have therefore been studied for their cytotoxicity, antimicrobial, spasmolytic, anti-inflammatory, antiplatelet aggregation, antiallergic activities and phytotoxicity. On the basis of 120 references, this review covers the phytochemistry and pharmacology of phenanthrenes, describing 252 compounds. This contribution stems from our work on the medicinal plant Tamus communis.

Abstract: Stilbenoids are formed by a particular branch of the flavonoid biosynthetic pathway. They are of special interest to natural product researchers for their roles in plant resistance to fungal pathogens and their biological effects. This review in the volume of Bioactive Natural Products provides a comprehensive account of the occurrence, chemistry, biological roles and activities of the stilbenoids. Nearly 800 stilbenoids, isolated from natural sources in the recent 12 years, are grouped into structural types and discussed in terms of their reported pharmacological activity. The major groups of stilbenoids which are discussed in detail include stilbenes, bibenzyls, bisbibenzyls, phenanthrenoids, stilbene oligomers etc. Detailed tables and figures list the occurrence of stilbenoids in major plant species, and methods used for extracting and analyzing stilbenoids are discussed. Biosynthetic pathways and chemical synthesis are reviewed and the biological activities of stilbenoids are also addressed. The coverage of the new structures is from 1994 to 2006.

Abstract: A naturally occurring 1,1‘-biphenanthrene, blestriarene C (1), was prepared in 13 steps and 30% overall yield. The key steps are the ester-mediated nucleophilic aromatic substitution on 2,6-di-tert-butyl-4-methoxyphenyl 5-isopropoxy-2-methoxybenzoate (4) by 2-methoxy-4-methoxymethoxy-6-methylphenylmagnesium bromide (5) and a novel intramolecular cyclization of the resulting 4-isopropoxy-2‘-methoxy-4‘-methoxymethoxy-6‘-methylbiphenyl-2-carboxylic ester 14 to 7-isopropoxy-4-methoxy-2-(methoxymethoxy)phenanthren-9-ol (15). The racemic blestriarene C was optically resolved by chiral HPLC on a preparative scale to give several 10-mg yields of both the enantiomers in up to 95% ee. The absolute stereochemistry was determined to be Sa-(−) by the axial chirality recognition method, which was based on the stereospecific formation of a 12-membered cyclic diester containing two biaryl-o,o‘-diyl unites joined by ester −CO2− linkages. The validity of the method was confirmed by an X-ray crystallographic analysis and ab...

Abstract: Ethyl acetate extract of Pholidota chinensis L. showed strong NO production inhibitory activity in murine macrophage-like cell line, RAW 264.7, which was activated by a lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Fractionation of the active extract led to the isolation of two new stilbene derivatives, 2,3'-dihydroxy-5-methoxy-3,4-methylenedioxydihydrostilbene (Pholidotol A) and 2-hydroxy-5-methoxy-3,4,3',4'-dimethylenedioxydihydrostilbene (Pholidotol B) together with six known stilbene derivatives. Pholidotols A both B and inhibited Nitric oxide (NO) production with an IC(50) value at 24.3 and 17.1 microM, respectively.

Abstract: The principal antineoplastic constituent of the South African tree Combretum caffrum has been isolated and designated combretastatin A-1. The structure of this new cis-stilbene was unequivocally established by X-ray crystal structure determination and total synthesis. A Wittig reaction sequence in THF comprised the synthetic key step (92.5% yield) and provided a very favorable 9:1 ratio of the cis:trans [1c:2c, geometrical isomers]. Selective hydrogenation of combretastatin A-1 afforded combretastatin B-1, a companion cell growth inhibitory constituent of C. caffrum. Combretastatin A-1 provided 26-29% life extension at 2.75-11 mg/kg dose levels with ED50 0.99 microgram/ml against the murine P-388 lymphocytic leukemia in vivo and in vitro systems. Both combretastatin A-1 and combretastatin B-1 are potent inhibitors of microtubule assembly in vitro and among the most potent inhibitors of the binding of colchicine to tubulin yet described. The structural simplicity and ready synthesis of combretastatin A-1 and combretastatin B-1 suggest that these new biosynthetic products will become useful in a variety of biological endeavors.

Abstract: Two new substituted bibenzyls (1,2-diarylethanes) aloifol I and aloifol II and a new substituted 9,10-dihydrophenanthrene, 6-O-methylcoelonin in addition to batatasin III, coelonin and gigantol have been isolated and characterized. The three new compounds are 1-(4′-hydroxy-3′,5′-dimethoxyphenyl)-2-(3″-hydroxyphenyl)ethane, 1-(4′-hydroxy-3′,5′-dimethoxyphenyl)-2-(4″-hydroxy-3″-methoxyphenyl)ethane and 2,7-dihydroxy-4,6-dimethoxy-9,10-dihydrophenanthrene.

Abstract: Eleven of the major non-polar constituents of the dried bark of Virola elongata were isolated. A new neolignan, virolongin, two new lignans, dihydrosesartemin and β-dihydroyangambin, as well as the neolignan, eusiderin, the lignans, epi-sesartemin, epi-yangambin and yangambin, the cis and trans isomers of 3,5,4′-trimethoxystilbene and sitosterol were identified. The structures of virolongin, dihydrosesartemin and β-dihydroyangambin were determined.

Abstract: Lusianthrin and lusianthridin, two new stilbenoids, were isolated from the orchid Lusia indivisa . The structures of lusianthrin and lusianthridin were established from detailed spectral and chemical evidence.