Polycyclic Polyprenylated Acylphloroglucinol Congeners Possessing Diverse Structures from Hypericum henryi
摘要:
Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structural and bioactive diversity. In a systematic phytochemical investigation of Hypericum henryi, 40 PPAP-type derivatives, including the new compounds hyphenrones G-Q, were obtained. These compounds represent 12 different structural types, including four unusual skeletons exemplified by 5, 8, 10, and 17. The 12 different core structures found are explicable in terms of their biosynthetic origin. The structure of a known PPAP, perforatumone, was revised to hyphenrone A (5) by NMR spectroscopic and biomimetic synthesis methods. Several compounds exhibited inhibitory activities against acetylcholinesterase and human tumor cell lines. This study deals with the structural diversity, function, and biogenesis of natural PPAPs.
The beta-triketone core of the antidepressant phloroglucinol hyperforin (1) undergoes a series of peroxide-induced oxidative rearrangements leading to compound 5, which is formed by opening of ring A, and compound 6, which is formed by removal of the C-1 carbonyl bridge. A mechanistic rationale for this process is proposed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).
Protein additives have a dramatic effect on the H2O2 oxidation of hyperforin, either protecting the enolized phloroglucinol core from oxidation (human albumin) or promoting (HRP and ovalbumin) reaction pathways derived from the intermediacy of the enollactone 4, a minor component of the oxidation mixture in the absence of protein additives. To rationalize the exquisite specificity of several steps
蛋白质添加剂对Hyperforin的H 2 O 2氧化具有显著作用,可以保护烯醇化的间苯三酚核心免受氧化(人白蛋白)或促进(HRP和卵清蛋白)中间烯醇内酯4的中间成分衍生的反应途径(HRP和卵清蛋白)。在没有蛋白质添加剂的情况下氧化混合物。为了合理化几个步骤的精巧特异性及其机理,提出了有机催化作用。蛋白质添加剂的使用可实现烯醇内酯6的简单直接制备,这是一种有趣的用于生物活性诱导和/或调节的多功能支架。
Synthesis and Biological Evaluation of Hyperforin Analogues. Part I. Modification of the Enolized Cyclohexanedione Moiety
Modification of the St. John's wort acylphloroglucinol constituent, hyperforin (1), by acylation, alkylation, and oxidation resulted in detrimental effects on the inhibition of the synaptosomal accumulation of serotonin, showing the existence of definite structure-activity relationships in this in vitro test system and highlighting the role of the enolized cyclohexanedione moiety for activity on neurotransmitter
Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structural and bioactive diversity. In a systematic phytochemical investigation of Hypericum henryi, 40 PPAP-type derivatives, including the new compounds hyphenrones G-Q, were obtained. These compounds represent 12 different structural types, including four unusual skeletons exemplified by 5, 8, 10, and 17. The 12 different core structures found are explicable in terms of their biosynthetic origin. The structure of a known PPAP, perforatumone, was revised to hyphenrone A (5) by NMR spectroscopic and biomimetic synthesis methods. Several compounds exhibited inhibitory activities against acetylcholinesterase and human tumor cell lines. This study deals with the structural diversity, function, and biogenesis of natural PPAPs.