No abstract

Protein additives have a dramatic effect on the H(2)O(2) 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 and their mechanistic oddity, an organocatalytic effect is postulated. The use of protein additives allows a straightforward and multigram preparation of the enollactone 6, an interesting multifunctionalized scaffold for bioactivity induction and/or modulation.

The β‐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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The cover picture shows Hypericum perforatum in full bloom, its bioactive compound hyperforin and the unusual structure of two oxidized products, whose mechanism of formation is discussed in the article by L. Verotta, O. Sterner et al. on p. 1193 ff. MICROREVIEWS Contents S. Ma