Reflections on the intriguing occurrence of some recently isolated natural products as racemates and scalemic mixtures

• Published in: Chirality (New York, N.Y.) Vol. 33; no. 12; pp. 915 - 930
• Main Authors: Zask, Arie, Ellestad, George A.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.12.2021
• Subjects: Alkaloids; Anthraquinone; Anthraquinones; Asarones; biomimetic syntheses; Biomimetics; configurationally unstable metabolites; enantiomerically enriched or scalemic mixtures; Lipids; Metabolites; Natural products; racemic natural products; Synthesis; biomimetic syntheses; configurationally unstable metabolites; racemic natural products; enantiomerically enriched or scalemic mixtures
• ISSN: 0899-0042; 1520-636X
• DOI: 10.1002/chir.23360

This review continues our interest in the intriguing reports of a variety of new racemic natural products (at least 11 in the past 4 years). These include the polyphenolic racemate galewone, the polycyclic prenylated acylphloroglucinol garcinielliptone; variecolortide, a combination of an anthraquinone and a isochinulin‐type alkaloid; the isoindoline alkaloid irpexine, the new hybrid phenylproanoid asarone; colletopyandione an indolydenepyradione; the enantiomerically enriched (scalemic) neolignans, gardenifolins; and meroterpenoid pabmaragramin in addition to some marine lipids. We also present a recent biomimetic synthesis of the polyketide preuisolactone A; synthesis of the polyketide spiromamakone A, which also corrected the proposed structure of another metabolite as identical to spiromamakone A; and the melicolones A and B. The continuing reports of natural racemates provoke speculation as to their role in the producing organism. The racemic melipatulinone metabolites, reported by Vu et al. from Melicope patulinervia in the Rutaceae plant family, are recently reported 2020 synergistic examples. In this case, the racemate was 2 to 5 times more active than the individual enantiomers against pancreatic lipase.