Minor secondary metabolites from the bark of Entandrophragma congoënse (Meliaceae)

Phytochemistry and pharmacology of the genusEntandrophragmaover the 50 years from 1967 to 2018: a ‘golden’ overview

“…The tirucallane‐type triterpenoids isolated from Entandrophragma displayed some changes in their structure ranging from intact or seco ‐ring A, as well as having a side chain which can be linear or cyclic (containing a 5‐, 6‐, or 7‐membered ring) with different levels of oxidation. 3,4‐Secotirucalla‐21‐formyl‐23‐oxo‐4(28),7,24‐trien‐3‐oic acid ( 94 ) was firstly isolated from the leave extract of E. angolense and was recently reported in 2018 from the root extract of E. congoënse can be formed through Bayer–Villiger oxidation followed by hydrolysis of congoensin B ( 97 ) obtained as a minor compound from the bark extract of E. congoënse . In the same manner, formation of seco ‐tiaminic acid A ( 95 ) obtained from the previously mentioned bark extract can be comprehensively correlated to piscidinol A ( 98 ) also isolated from the root extract of the same plant E. congoënse .…”

“…The interesting chemical components present in the plants of the genus Entandrophragma led to the isolation and characterization of 33 protolimonoids sorted in 18 tirucallane‐ ( 83 − 100 ), 11 apotirucallane‐ ( 101 − 111 ), and four glabretal‐type ( 112 − 115 ) triterpenoids in the Entandrophragma species. Among these protolimonoids, 18 were recently reported from the sole species E. congoënse …”

“…Congoensin A ( 96 ) was characterized as a novel tirucallane triterpenoid containing an opened‐ring A and a 1,5‐dihydro‐2 H ‐pyrrol‐2‐one moiety in the side chain. The formation of its side chain was proposed based on the linear side chain of tirucallol . Two novel 3,4‐ seco ‐tirucallane triterpenoids from root of E. congoënse , viz., seco‐tiaminic acids B ( 99 ) and C ( 100 ) containing an unprecedented side chain, were characterized using extensive NMR spectroscopic methods and HRMS.…”

Pyxipyrrolones: Structure Elucidation and Biosynthesis of Cytotoxic Myxobacterial Metabolites

“…This led to the identification of an ew class of natural products showing structural novelty and interesting biological activity.I solation and structure elucidation of two analogues led to the identification of pyxipyrrolone Aa nd B, harboring the novel 3-methylene-2, 3,4,5,6,7,8,isoindol-1-one scaffold. This led to the identification of an ew class of natural products showing structural novelty and interesting biological activity.I solation and structure elucidation of two analogues led to the identification of pyxipyrrolone Aa nd B, harboring the novel 3-methylene-2, 3,4,5,6,7,8,isoindol-1-one scaffold.…”

Die Pyxipyrrolone: Strukturaufklärung und Biosynthese zytotoxischer myxobakterieller Sekundärmetabolite

“…Isolation und Strukturaufklärung führte zu zwei neuen Naturstoffen, Pyxipyrrolon Aund B, die eine neuartige 3- 3,4,5,6,7,8,isoindol-1on Einheit enthalten. Es gelang die Identifizierung und Strukturaufklärung einer strukturell neuartigen Naturstoffklasse mit interessanter Bioaktivität.…”