Stereoselective syntheses of four dolabellane-type diterpenes, 3,7,12-dolabellatriene, ent -dolabeserpenoic acid A, 3,7,18-dolabellatriene, and 3,4-epoxy-7,18-dolabelladiene were achieved. The syntheses feature chemoenzymatic cyclization of unnatural substrates using a diterpene cyclase, CotB2. Three unnatural substrates bearing synthetically useful functional groups, such as vinyl halide or ketone moieties, were designed based on the biosynthetic reaction mechanism of CotB2. CotB2-mediated cyclization of these unnatural substrates uniformly afforded 5/11-fused carbocycles bearing a vinyl halide or ketone moiety. C1-homologation of the resulting cyclic products delivered the target natural products in an optically active form. The cyclization reaction mechanism is proposed based on DFT calculations of the cation reaction pathways.

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This review focuses on recent developments in the use of natural products as therapeutics for Alzheimer's disease. The compounds span a diverse array of structural classes and are organized according to their mechanism of action, with the focus primarily on the major hypotheses. Overall, the review discusses more than 180 compounds and summarizes 400 references.

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Five isopimarane diterpenes (7beta-hydroxyisopimara-8,15-dien-14-one, 14alpha-hydroxyisopimara-7,15-dien-1-one, 1beta,14alpha-dihydroxyisopimara-7,15-diene, 7beta-hydroxyisopimara-8(14),15-dien-1-one and 7beta-acetoxyisopimara-8(14),15-dien-1-one) have been isolated from the leaves of Hypoestes serpens (Acanthaceae). All compounds exhibited antifungal activity against both the plant pathogenic fungus Cladosporium cucumerinum and the yeast Candida albicans; two of them also displayed an acetylcholinesterase inhibition. The structures of the compounds were determined by means of spectrometric methods, including 1D and 2D NMR experiments and MS analysis.

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Two new diterpenes, fusicoserpenol A and dolabeserpenoic acid A, with antifungal activity, were isolated from leaves of Hypoestes serpens (Acanthaceae). Their structures were elucidated by means of spectrometric methods including 1D and 2D NMR experiments and MS analysis. X-ray crystallographic analysis confirmed the structure of fusicoserpenol A and established the relative configuration.

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From a defatted chloroform extract of the aerial parts of Hypoestes serpens a new diterpene exhibiting relaxant activity on isolated rat aorta was obtained. The structure of this compound, named serpendione (1), was fully established by the interpretation of its spectral data.

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