Unusually cyclized triterpenoids: occurrence, biosynthesis and chemical synthesis

Abstract

The review introduced chemical diversity in structures, biological activities, biosynthesis and chemical synthesis of unusual cyclized triterpenoids.

Purification, Molecular Docking and Cytotoxicity Evaluation of Bioactive Pentacyclic Polyhydroxylated Triterpenoids from Salvia urmiensis

“…The 13 C NMR spectrum revealed 30 carbon resonances which were resolved into seven singlet methyl, nine methylene, which one of them was an oxygenated CH 2 , six methine, and eight quaternary carbon atoms as categorized by HSQC and DEPT-Q experiments (Table 1). 13 C NMR data showed one tri-substituted C=C group (δ C 126.7, 145.0) and three oxygen-bearing sp 3 carbons at δ C 66.1, 67.0 and 74.9 as well as one oxygen-bearing sp 2 carbon at δ C 217.9, indicating of a carbonyl functional group. According to these functionalities and 7 degrees of hydrogen deficiency, a polyhydroxylated oleanane type triterpenoid was suggested for the structure.…”

“…Analysis of the HMBC and COSY spectra confirmed the location of substituents. The position of the carbonyl group was assigned at C-3 (δ C 217.9) based on its HMBC correlations with the signals of CH 3 -23 (δ H 0.99), CH 3…”

“…So, this study was aimed at discovering novel and potentially bioactive triterpenoids from the Salvia urmiensis species. For this, an ethyl acetate fraction of the acetone extract of the aerial parts of the plant was chromatographed to yield five novel polyhydroxylated triterpenoids (1)(2)(3)(4)(5). Their structure was elucidated by extensive spectroscopic methods including 1D ( 1 H, 13 C, DEPT-Q) and 2D NMR (COSY, HSQC, HMBC, NOESY) experiments, as well as HRESIMS analysis.…”

Structural diversity, hypothetical biosynthesis, chemical synthesis, and biological activity ofGanodermameroterpenoids

“…Rearrangement reactions play a critical role in constructing novel skeletons of natural products, [58][59][60] with a carbocation oen a vital intermediate in this process. 61,62 The possible biosynthetic pathway of ganodermaone A (104) 63 from G. cochlear is taken as an example of a possible carbocation-related rearrangement reaction.…”

Convenient synthesis of perhydrobenz[e]indene triketone, a key intermediate for the total synthesis of stelletins

“…Isomalabaricanes, first isolated 1 from the sponges of the genus Stelletta , are a rare group of tricyclic triterpenes bearing a common and highly strained trans – syn – trans fused perhydrobenz[ e ]indene scaffold 2 with the central B ring in the boat conformation. 3 Their structures are also characterized by a highly conjugated polyene system as a side chain positioned at C13, 4 while a ketone group is always located at the C12 position of the tricyclic parent core.…”