New calamenene sesquiterpenes fromTarenna madagascariensis

Abstract

Four calamenene sequiterpenes, (+)-(7R,10S)-15-hydroxycalamenene (3), (+)-(7R,10S)-2,15-dihydroxycalamenene (4), (+)-(7R,10S)-2-hydroxy-15-calamenal (5), (+)-(7R,10S)-15-calamenal (6), along with the amorphane sesquiterpene (+)-(1S,6R,7R,10S)-1-hydroxy-3-oxo-amorph-4-ene (16), have been isolated from the Madagascan shrub Tarenna madagascariensis (Rubiaceae) and their structures determined by spectroscopic methods and chemical correlations. Furthermore, five known related sesquiterpenes [(+)-(7R,10S)-2-hydroxycalamenene (1), (+)-(7R,10S)-3-hydroxycalamenene (2), (-)-alpha-cadinol (13), cadinenal (14), 6-epicadinenal (15)], and three known lignans [(-)-hinokinin, (-)-dihydrocubebin, (-)-cubebin] were also isolated from the same plant. This is the first report of compounds 3, 4, 5, 6, and 16 from a natural source.

In VitroAnticancer Potential of Tree Extracts from the Walloon Region Forest

“…However, in the current study, a washing step was used prior to the realization of the MTT colorimetric assay, decreasing the risk of interference [8]. Furthermore, the MTT assay was used here to grossly analyze the presence of in vitro growth inhibitory compounds in Walloon Region trees, as we already successfully did with other types of plants [6,9,10] and marine invertebrates [11]. A literature and patent search was carried out on more than 50 common Belgian tree species using the keywords "cancer," "tumor," "growth inhibitory activity," "growth inhibition," "cytotoxic," and "cytotoxicity" and the search engine SciFinder (Medline + Caplus).…”

Total Synthesis of Lignan Lactone (–)-Hinokinin

“…The generation of 22 presumably resulted from the introduction of oxygen under this reductive condition, and the amount of 22 was considerably increased (TLC monitoring) when oxygen was intentionally bubbled into the reaction tube. Finally, heating of 21 with excess PCC in toluene completed the total synthesis of lignan lactone (–)-hinokinin 1 in acceptable yield [ 62 , 63 ], which displayed identical spectral properties to the reported data [ 3 – 5 , 18 , 21 , 24 , 26 ].…”

“… −31 ( c 0.21, CHCl 3 ), {lit. [ 5 ] −34 ( c 2.85, CHCl 3 ); lit. [ 21 ] −30 ( c 0.99, CHCl 3 )}; 1 H NMR (400 MHz, CDCl 3 ) δ 6.44–6.73 (m, 6H), 5.92 (s, 4H), 4.11 (dd, J = 9.0, 6.7 Hz, 1H), 3.85 (dd, J = 9.2, 6.8 Hz, 1H), 2.97 (dd, J = 14.1, 5.0 Hz, 1H), 2.83 (dd, J = 14.1, 7.3 Hz, 1H), 2.48–2.65 (m, 2H), 2.45 (m, 2H).…”

“…They display diverse biological activities, especially antiviral and antitumor properties. For example, hinokinin ( 1 ) [ 3 – 5 ] has been found to exhibit antileukemic, antiviral, antifungal, and pesticidal activities [ 6 – 26 ]. Mammalian lignin enterolactone ( 2 ), which is formed by the action of intestinal bacteria from plant lignan precursors present in the diet, inhibit breast cancer and colon cancer, and may also inhibit cardiovascular disease [ 27 , 28 ].…”

Calamenenes – aromatic bicyclic sesquiterpenes – from the Indian gorgonianSubergorgia reticulata(Ellis and Solander, 1786)

“…Calamenenes are aromatic bicyclic sesquiterpenes of cadinane skeleton found in several terrestrial and marine organisms (Bunko, Ghisalberti, & Jefferies, 1981;Kashman, 1979;Kelman, Benayahu, & Kashman, 2000;Nakashima et al, 2002;Nishizawa, Inoue, Sastrapradja, & Hayashi, 1983;Salmoun et al, 2007). Thus, (þ)-2-hydroxy calamenene, a potent fish toxin, has been obtained from the seeds of Dysoxylum acutangulum and Dysoxylum alliaceum (Nishizawa et al, 1983).…”