Bibenzyl derivatives from the orchid Bulbophyllum protractum

Mono-, Bi-, and triphenanthrenes from the tubers of Cremastra appendiculata.

Abstract: Six newphenanthrene derivatives, including three monophenanthrenes (1-3), two biphenanthrenes (4 and 5), and a triphenanthrene (6), have been isolated from an ethanolic extract of the tubers of Cremastra appendiculata. Using spectroscopic methods, the structures of compounds 1-6 were determined as 1-hydroxy-4,7-dimethoxy-1-(2-oxopropyl)-1H-phenanthren-2-one (1), 1,7-dihydroxy-4-methoxy-1-(2-oxopropyl)-1H-phenanthren-2-one (2), 2-hydroxy-4,7-dimethoxyphenanthrene (3), 2,7,2'-trihydroxy-4,4',7'-trimethoxy-1,1'-biphenanthrene (4), 2,2'-dihydroxy-4,7,4',7'-tetramethoxy-1,1'-biphenanthrene (5), and 2,7,2',7',2' '-pentahydroxy-4,4',4' ',7' '-tetramethoxy-1,8,1',1' '-triphenanthrene (6), respectively. Compounds 1-6 and two known compounds, cirrhopetalanthin (7) and flavanthrinin (8), obtained previously from this plant, were evaluated against six human cancer cells and a normal cell line.

Stilbenoids: Chemistry and bioactivities

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.

Phenanthrene and other aromatic constituents of Bulbophyllum vaginatum

Abstract: Two new phenanthrenes (4-methoxyphenanthrene-2,3,7-triol and 4-methoxyphenanthrene-2,3,6,7-tetrol) and two new 9,10-dihydrophenanthrenes (5-methoxy-9,10-dihydrophenanthrene-2,3,7-triol and 4-methoxy-9,10-dihydrophenan-threne-2,3,6,7-tetrol), along with the known 4,6-dimethoxyphenanthrene-2,3,7-triol and its 9,10-dihydro derivative, 3,4′,5-trihydroxy-3′-methoxybibenzyl (tristin), dihydroferulic acid, p -coumaric acid, 3,4-dihydroxybenzoic acid and (±)-syringaresinol were isolated from the dichloromethane extract of the orchid Bulbophyllum vaginatum . The structures of these compounds were determined through spectroscopic analysis.

Cytotoxic phenolics from Bulbophyllum odoratissimum

Abstract: A phytochemical study of the whole plant of Bulbophyllum odoratissimum (J.E. Smith) Lindl (Orchidaceae) and cytotoxicity measurement of its isolated compounds have been carried out. The ethyl acetate extract yielded nine phenolics, identified as moscatin ( 1 ), 7-hydroxy-2,3,4-trimethoxy-9,10-dihydrophenanthrene ( 2 ), coelonin ( 3 ), densiflorol B ( 4 ), gigantol ( 5 ), batatasin III ( 6 ), tristin ( 7 ), vanillic acid ( 8 ) and syringaldehyde ( 9 ). Compounds 4 and 8 were discovered in the Bulbophyllum genus for the first time and all compounds, except for 9, have not been reported in this plant before. The isolated compounds were evaluated in vitro for their inhibitory ability against the growth of human leukaemia cell lines K562 and HL-60, human lung adenocarcinoma A549, human hepatoma BEL-7402 and human stomach cancer SGC-7901. Densiflorol B ( 4) the most active compound, exhibited IC 50 values of 0.08–3.52 μg/ml against the five tested cell lines.

Isolation, structure, synthesis, and antimitotic properties of combretastatins B-3 and B-4 from Combretum caffrum.

Abstract: Further investigation of a CH2Cl2 fraction prepared from the South African tree Combretum caffrum for substances inhibitory to the murine P-388 lymphocytic leukemia (PS system) cell line has led to the isolation of two new bibenzyls, designated combretastatins B-3 and B-4, accompanied by the previously known bibenzyls 7, 8, and 9. The structure of each substance was ascertained by results of mass and nmr spectral analyses and confirmed by crystal structure determination (for 7) or synthesis. Combretastatins B-3 and B-4 gave PS ED50 values of 0.4 and 1.7 micrograms/ml, respectively, and bibenzyls 7, 8, and 9 were comparably cell growth inhibitory against the PS cell line with ED50 results of 1.7, 2.5, and 0.25 ug/ml, respectively. All the bibenzyls caused leukemia cells to accumulate in mitosis at cytotoxic drug concentrations; however, a wide range of in vitro activity against the protein tubulin (the major component of the mitotic spindle) was observed.

Coelonin, A 9,10-dihydrophenanthrene from the orchids Coelogyne ochracea and Coelogyne elata

Abstract: 2,7-Dihydroxy-4-methoxy-9,10-dihydrophenanthrene was isolated and identified from the whole plant of Coelogyne ochracea and C. elata.

Two substituted bibenzyls and a dihydrophenanthrene from Cymbidium Aloifolium

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.

Lusianthrin and lusianthridin, two stilbenoids from the orchid Lusia indivisa

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.

Structure of flavanthrin, the first dimeric 9,10-dihydrophenanthrene derivative from the orchid eria flava

Abstract: Flavanthrin, the first dimeric 9,10-dihydrophenanthrene derivative, was isolated from the orchid Eria flava which also yielded the previously reported 9,10-dihydrophenanthrene coelonin ( 2a ). The structure of flavanthrin was established as the 1.1'-dimer ( 1a ) of its congener coelonin from spectral and chemical evidence.