Agnatasterone A and B, Unusual Pregnane Steroids Isolated from the North‐East Atlantic Sponge Axinella agnata

• Published in: Helvetica Chimica Acta
• Main Authors: Guella, Graziano, Pietra, Francesco
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1988
• Subjects: North East Atlantic
• Online Access: http://dx.doi.org/10.1002/hlca.19880710108; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fhlca.19880710108; https://onlinelibrary.wiley.com/doi/pdf/10.1002/hlca.19880710108

Abstract Two novel pregnatrienolones isolated in very small amounts from the North‐East‐Atlantic demosponge Axinella agnata (Tetractinomorpha, Axinellida) are unique in having C(2)C(3) (or C(3)C(4)), C(7)C(8), and C(16)C(17) bonds and a 12β‐OH group which, being strongly H‐bonded to a 20‐keto group, resists acylation. 1 H‐ and 13 C‐NMR spectroscopy of the steroids and of products of their selective epoxidation or reduction allow us to propose the structures (+)‐12β‐hydroxy‐5α‐pregna‐2,7,16‐trien‐20‐one ( = agnatasterone A, (+)‐ 1 ), and (+)‐12β‐hydroxy‐5α‐pregna‐3,7,16‐trien‐20‐one ( = agnatasterone B. (+)‐ 5 ), for the two steroids with minimal recourse to model compounds.