Phochinenins A – F, Dimeric 9,10‐Dihydrophenanthrene Derivatives, from Pholidota chinensis

Abstract

Six new compounds, phochinenins A -F (1 -6), dimerized from 9,10-dihydrophenanthrene and dihydrostilbene through direct coupling or an oxygen bridge, along with eight known compounds, were isolated from the whole plants of Pholidota chinensis. Their structures were elucidated on the basis of extensive spectroscopic investigations (1D-, 2D-NMR, and HR-EI-MS).

Chemical Constituents from the Aerial Parts of Cyrtopodium paniculatum

“…The relative configuration of the methine protons H-2 and H-3 on the furan ring was defined as trans-based on NOESY correlations between H-2 and H-5 /9 , suggesting these protons are on the same side of the furan ring. This was also supported by the coupling constant of 6.6 Hz, typical of trans-dihydrophenanthrenofuran derivatives [55,56], which allows the possibility of two enantiomeric stereoconfigurations, either (2 R, 3 R) or (2 S, 3 S). The absolute configurations of compound 6 could not be ascertained as its optical rotation was zero, suggesting a racemization of the trans form.…”

“…These biphenanthrene derivatives occur mostly in species of the genus Bletilla [33,41,71,[78][79][80], Bulbophyllum [55,[81][82][83] and Cremastra [54,[84][85][86][87][88]. The existence of dimers together their respective monomers in the same species provides support for a proposed biogenetic pathway for biaryl-derived compounds occurring from their corresponding monomers as a result of free radical [56] or an enzymatic oxidative phenolic coupling reaction [82,[89][90][91]. This study reveals for the first time the chemical diversity of phenolic constituents produced by an endemic South-American orchid, Cyrtopodium paniculatum.…”

Five New Biphenanthrenes from Cremastra appendiculata

“…The PE and EtOAc partitions were chromatographed over silica gel, Sephadex LH-20 and ODS columns, and semi-preparative HPLC to obtain eleven biphenanthrenes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) (Figure 1). Their structures were elucidated based on extensive spectroscopic analyses (Supplementary Materials).…”

“…The UV spectrum showed absorption maximum at 203, 264, and 308 nm. The 1 H-NMR spectrum displayed eleven aromatic protons signals including one set of ABX coupling systems at δ H 9.36 (1H, d, J = 9.0 Hz, H-5), 7.09 (1H, dd, J = 9.0, 3.0 Hz, H-6) and 7.04 (1H, d, J = 3.0 Hz, H-8); four singlets signals at δ H 6.97 (1H, s, H-3), 6.92 (1H, s, H-3 ), 8.96 (1H, s, H-5 ) and 7.02 (1H, s, H-8 ); two pairs of doublets signals at δ H 7.28 (1H, d, J = 9.0 Hz, H-9), 6.90 (1H, d, J = 9.0 Hz, H-10), 7.20 (1H, d, J = 9.0 Hz, H-9 ), and 6.71 (1H, d, J = 9.0 Hz, H-10 ). In addition, two methoxy singlets signals at δ H 4.10 (6H, s, H-11, H-11 ) were observed as well.…”

“…The phenanthrenes isolated thus far may be classified into three major groups: monophenanthrenes, biphenanthrenes, and triphenanthrenes, and most natural phenanthrenes occur in monomeric form [1]. To date, less than one hundred biphenanthrenes and two triphenanthrenes have been isolated from the Orchidaceae family [2][3][4][5][6][7][8][9][10][11][12][13]. Biphenanthrenes have been reported to possess various biological activities including cytotoxicity, antimicrobial, spasmolytic, anti-inflammatory, antiplatelet aggregation, and antiallergic activities [1].…”