Serinocyclins A and B, Cyclic Heptapeptides from Metarhizium anisopliae

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• 作者：Stuart B. Krasnoff ; Ivan Keresztes ; Richard E. Gillilan ; Doletha M. E. Szebenyi ; Bruno G. G. Donzelli ; Alice C. L. Churchill ; Donna M. Gibson
• 刊名：Journal of Natural Products
• 出版年：2007
• 出版时间：December 2007
• 年：2007
• 卷：70
• 期：12
• 页码：1919 - 1924
• 全文大小：287K
• 年卷期：v.70,no.12(December 2007)
• ISSN：1520-6025

文摘

Two new cyclic heptapeptides, serinocyclins A (1) and B (2), were isolated from conidia of the entomopathogenic fungus Metarhizium anisopliae. Structures were elucidated by a combination of mass spectrometric, NMR, and X-ray diffraction techniques. Serinocyclin A (1) contains three serine units, a hydroxyproline (Hyp), a β-alanine (β-Ala), and two uncommon nonproteinogenic amino acids, 1-aminocyclopropane-1-carboxylic acid (Acc) and γ-hydroxylysine (HyLys). The peptide sequence established for 1 by NMR is cyclo-(Acc-Hyp-Ser1-HyLys-β-Ala-Ser2-Ser3). Serinocyclin B (2) has Lys in place of the HyLys unit found in 1. Chiral amino acid analysis indicated the presence in both compounds of one (2S,4R)-Hyp, two L-Ser, and one D-Ser residue. A Lys found in the hydrolyzate of 2 was established as D-configured. A crystal structure of 1 established the position of the D-Ser (Ser2) and the absolute configuration of the HyLys unit (2R,4S). The absence of methyl groups is unusual among fungal peptides and, along with the charged lysyl side chain and multiple hydroxyl groups, contributes to the polar nature of the compounds. Serinocyclin A produced a sublethal locomotory defect in mosquito larvae at an EC₅₀ of 59 ppm.