559-70-6Relevant articles and documents
Purification and properties of squalene-2,3-epoxide cyclases from pea seedlings
Abe,Sankawa,Ebizuka
, p. 1755 - 1760 (1992)
Dramatic changes in the activities of squalene-2,3-epoxide: cycloartenol cyclase and β-amyrin cyclase were observed in germinating pea seeds. By taking advantage of this phenomenon, the two cyclases were purified from pea seedlings. The cyclases were purified to homogeneity by solubilization with Triton X-100, chromatography on hydroxylapatite and diethylaminoethyl (DEAE)-cellulose, isoelectric focusing and gel filtration. Cycloartenol cyclase was purified 471-fold to a specific activity of 167 pkat/mg protein, while β-amyrin cyclase was purified 4290-fold to a specific activity of 28 pkat/mg protein. They each showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis with a molecular mass of 55 and 35 kilodaltons (kDa), respectively. The apparent K(m) values for (3S)-squalene-2,3-epoxide were estimated to be 25 and 50 μm, respectively. The cyclases required Triton X-100 or deoxycholate for their highest activity and each showed a broad pH optimum within the range of pH 6.5-7.5. Inhibition by p-chloromercuribenzene sulfonic acid and N-ethylmaleimide suggested involvement of an SH group at the active site of each enzyme.
An improved scalable synthesis of α- and β-amyrin
Serbian, Immo,Csuk, René
, (2018/07/13)
The synthesis of α- and β-amyrin was accomplished starting from easily accessible starting materials, oleanolic, and ursolic acid. The procedures allow the preparation of β-amyrin in an exceptionally short scalable manner via selective iodation and reduction. For α-amyrin, a different synthetic approach had to be chosen providing access to α-amyrin in medium-to-large scale.
Practical Synthesis of α-Amyrin, β-Amyrin, and Lupeol: The Potential Natural Inhibitors of Human Oxidosqualene Cyclase
Chen, Dongyin,Xu, Fengguo,Zhang, Pu,Deng, Jie,Sun, Hongbin,Wen, Xiaoan,Liu, Jun
, (2017/10/20)
A practical synthesis of α-amyrin (1), β-amyrin (2), and lupeol (3) was accomplished in total yields of 32, 42, and 40% starting from easily available ursolic acid (4), oleanolic acid (5), and betulin (6), respectively. Remarkably, these three natural pentacyclic triterpenes exhibited potential inhibitory activity against human oxidosqualene cyclase.
β-Amyrin Biosynthesis: Promiscuity for Steric Bulk at Position 23 in the Oxidosqualene Substrate and the Significance of Hydrophobic Interaction between the Methyl Group at Position 30 and the Binding Site
Kaneko, Ikki,Hoshino, Tsutomu
, p. 6657 - 6671 (2016/08/16)
To examine how the sterics at the 23 position of (3S)-2,3-oxidosqualene 1 influence the polycyclization cascade in β-amyrin biosynthesis, substrate analogues substituted with an ethyl group (10, 11), a hydrogen atom (12, 13), or a propyl residue (14) at the 23 position were incubated with β-amyrin synthase. The bulkier ethyl group was accepted as a substrate, leading to formation of the β-amyrin skeleton (42, 43) without truncation of the multiple cyclization reactions. Analogue 13, possessing a hydrogen atom and an ethyl group at the 23E and 23Z positions, respectively, was also converted into the β-amyrin skeleton 45. However, the analogue lacking an ethyl group at the 23Z position (12) underwent almost no conversion, strongly indicating that an alkyl group must exist at the Z position. The cyclization of the analogue with a propyl substituent at the Z position (14) was poor. Analogue 15 possessing CH2OH at the 23E position afforded a new compound 47 in a high yield as a result of trapping of the final oleanyl cation. Conversely, 16 with 23Z-CH2OH afforded novel compounds 48-50 in low yields, which resulted from the intermediary dammarenyl and baccharenyl cations. Therefore, the hydrophobic interaction between the 23Z-alkyl group and its binding site (possibly via CH/π interaction) is critical for adopting the correct chair-chair-chair-boat-boat conformation and for the full cyclization cascade.
