Unprecedented Quassinoids with Promising Biological Activity from Harrisonia perforata

Abstract

Perforalactone A( 1 ), an ew 20S quassinoid with au nique cagelike 2,4-dioxaadamantane ring system and am igrated side chain, was isolated from the plant Harrisonia perforata together with two biosynthetically related new quassinoids.T he structures of these natural products were elucidated by NMR spectroscopy, X-rayd iffraction analysis, computational modeling,a nd the CD excitation chirality method. The compounds exhibited notable biological properties,i ncluding insecticidal activity against Aphis medicaginis Koch and antagonist activity at the nicotinic acetylcholine receptor of Drosophila melanogaster.The structural features of these compounds may be related to their promising biological characteristics.T heir biosynthesis and an alternative origin of quassinoid-type natural products are also discussed.

Exciton coupling between enones: Quassinoids revisited

“…Its ECD spectrum (discussed below) was also interpreted in terms of exciton chirality to establish the absolute configuration. 15 Here, however, we dispute that the ECD spectrum of 2 is determined by the exciton coupling between the two enones. In fact, the lack of one αmethoxy substituent (at C-12) makes the two enone chromophores not equivalent; the exciton chirality mechanism, which is degenerate and moderately strong in quassin (1), becomes nondegenerate and much less efficient in perforalactone C (2).…”

“…[10][11][12][13][14] Recently, three new biologically active quassinoids, perforalactones A-C, were isolated from Harrisonia perforata. 15 Perforalactone C (2, Chart 1) is very similar to quassin, being in fact 12-demethoxy-19-acetoxyquassin. It also contains two enone chromophores, although only one has an αmethoxy substituent (at C-2).…”

“…Subsequently, the absolute configurations of other quassinoids have been established by different methods, including biogenetic considerations, Mosher's method, and empirical correlations of ECD and optical rotation data . Recently, three new biologically active quassinoids, perforalactones A‐C, were isolated from Harrisonia perforata . Perforalactone C ( 2 , Chart 1) is very similar to quassin, being in fact 12‐demethoxy‐19‐acetoxyquassin.…”

Natural Products Research in China From 2015 to 2016

“…A new 20 S - quassinoid with an unusual cagelike 2,4-dioxaadamantane nucleus and a migrated side chain, perforalactone A ( 523 ), together with perforalactones B ( 524 ) and C ( 525 ), were produced by twigs and stems of Harrisonia perforata . Compounds 523 and 524 showed inhibitory activites against nicotinic acetylcholine receptor (nAChR) with IC 50 values of 15.8 and 1.26 nM, respectively (imidacloprid, 0.79 nM) (Fang et al, 2015 ).…”

Two novel diterpenoid heterodimers, Bisebracteolasins A and B, from Euphorbia ebracteolata Hayata, and the cancer chemotherapeutic potential of Bisebracteolasin A

“…Its root is poisonous and is used in traditional Chinese medicine for the treatment of many diseases such as cancer, swelling, and warts 16 – 25 . As part of our ongoing search for structurally unique and bioactive constituents from medicinal plants 26 – 32 , we investigated E. ebracteolata and discovered two new diterpenoid heterodimers featuring monomers with an unprecedented seco-2,3-rosane skeleton (Fig. 1 ).…”