Bioactive Phenanthrene and Bibenzyl Derivatives from the Stems ofDendrobium nobile

Abstract

A new enantiomeric pair of spirodiketones, (+)- and (-)-denobilone A (1 and 2), three new phenanthrene derivatives (3-5), and three new biphenanthrenes (22-24), along with 11 known phenanthrene derivatives (6-16), five known bibenzyl derivatives (17-21), and four known biphenanthrenes (25-28), were isolated from Dendrobium nobile. The structures of 1-5 and 22-24 were elucidated using comprehensive spectroscopic methods. (+)-Denobilone and (-)-denobilone A (1 and 2) were isolated as a pair of enantiomers by chiral HPLC. The absolute configurations of (+)- and (-)-denobilone A (1 and 2) were determined by comparing their experimental and calculated electronic circular dichroism spectra. The absolute configuration of denobilone B (3) was determined by X-ray crystallographic analysis. The inhibitory activities of all compounds against nine phytopathogenic fungi and three cancer cell lines were evaluated.

Bioactive Secondary Metabolites from Orchids (Orchidaceae)

“…Recently, a new flavonoid compound was isolated from D. nobile, namely the 3-hydroxy-1-{6-hydroxy-2-methoxy-3-[(2S)-6-methoxy-2H-chromen-2-yl]phenyl} propan-1-one (17), being the first naturally occurring flav-3-ene derivative bearing a 3-hydroxypropan-1-one group. [54] From the same species, an enantiomeric pair of spirodiketones named (+)-and (À)-denobilone A (18 and 19) were reported. In previously published literature, phenanthrene derivatives with a spirolactone ring as blespirol from B. striata [64] and dendrochrysanene (20) from D. chrysanthum WALL.…”

“…Several derivatives as (+)-and (À)-denobilone A, denobilones B and C, 9,10-dihydro-7-hydroxy1,4-phenanthrenedione, hircinol, ephemeranthol-A, erianthridin, 9,10-dihydro-4,5-dihydroxy-2-methoxyphenanthrene, flavanthridin, lusianthridin, 6,7-dihydroxy-2-methoxyphenanthrene-1,4-dione, moscatin, confusarin, nudol, lusianthrin, 3 0 ,4dihydroxy-3,5 0 -dimethoxybibenzyl, 3-hydroxy-5-methoxybibenzyl, batatasin III, tristin, 3,3 0 ,5-trihydroxybibenzyl, denthyrsinol A, denthyrsinol B, denthyrsinol C, denthyrsinol, phochinenin G, phochinenin D, and 9,9 0 ,10,10 0 -tetrahydro-4,4 0 ,7,7 0 -tetrahydroxy-2,2 0 -dimethoxy-1,1 0 -phenanthrene have been recently isolated and identified from D. nobile LINDL., and preliminary evaluations of antifungal and cytotoxic effects have been reported showing poor bioactivity for almost all the tested compounds. [54] The basic of phenanthrene derivatives are quite common but other related classes of compounds have been isolated from orchids such as fluorenone and other constituents sharing the basic skeleton of 9Hfluoren-9-one. [55 -61] Dengibsin (12), nobilone (13), dendriflorin (14), and gramniphenols D and E (15 and 16) are examples of those derivatives (Fig.…”

“…Several derivatives as (+)‐ and (−)‐denobilone A, denobilones B and C, 9,10‐dihydro‐7‐hydroxy1,4‐phenanthrenedione, hircinol, ephemeranthol‐A, erianthridin, 9,10‐dihydro‐4,5‐dihydroxy‐2‐methoxyphenanthrene, flavanthridin, lusianthridin, 6,7‐dihydroxy‐2‐methoxyphenanthrene‐1,4‐dione, moscatin, confusarin, nudol, lusianthrin, 3′,4‐dihydroxy‐3,5′‐dimethoxybibenzyl, 3‐hydroxy‐5‐methoxybibenzyl, batatasin III, tristin, 3,3′,5‐trihydroxybibenzyl, denthyrsinol A, denthyrsinol B, denthyrsinol C, denthyrsinol, phochinenin G, phochinenin D, and 9,9′,10,10′‐tetrahydro‐4,4′,7,7′‐tetrahydroxy‐2,2′‐dimethoxy‐1,1′‐phenanthrene have been recently isolated and identified from D . nobile Lindl ., and preliminary evaluations of antifungal and cytotoxic effects have been reported showing poor bioactivity for almost all the tested compounds …”

“…Recently, a new flavonoid compound was isolated from D . nobile , namely the 3‐hydroxy‐1‐{6‐hydroxy‐2‐methoxy‐3‐[(2 S )‐6‐methoxy‐2 H ‐chromen‐2‐yl]phenyl}propan‐1‐one ( 17 ), being the first naturally occurring flav‐3‐ene derivative bearing a 3‐hydroxypropan‐1‐one group . From the same species, an enantiomeric pair of spirodiketones named (+)‐ and (−)‐denobilone A ( 18 and 19 ) were reported.…”

Identification of Two Phenanthrene Derivatives from Australasian Allied Species in Genus <i>Dendrobium</i>

“…[4][5][6] In contrast, the number of compounds isolated from the Australasian species is limited and compounds unique to the Australasian species have not been reported to date. For example, two phenanthrenes, 3,4-dimethoxyphenanthrene-2,7-diol (nudol) and 4-methoxyphenanthrene-2,5-diol (moscation), have been isolated from D. antennatum 7) but they are not characteristic to the Australasian clade since they have been detected in some Asian species. 8) However, we had previously detected several HPLC peaks that were characteristic of phylogenetically related species in the Australasian clade.…”