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【期刊论文】Novel biotransformation of pentacyclic triterpenoid acids by Nocardia sp. NRRL 5646
余伯阳, Jian Zhang, a Zhi-Hong Cheng, a Bo-Yang Yu, a, * Geoffrey A. Cordellb and Samuel X. Qiuc, *
Tetrahedron Letters 46(2005)2337-2340,-0001,():
-1年11月30日
Six pentacyclic triterpene acids, ursolic acid, oleanolic acid, betulinic acid, 23-hydroxybetulinic acid, glycyrrhetinic acid, and senegenin, were metabolized by the microbe Nocardia sp. NRRL 5646 to selectively furnish their corresponding 28-methyl esters. Notably, ursolic acid (1) was converted to oleanolic acid methyl ester (4) via two intermediates, oleanolic acid (2), and ursolic acid methyl ester (3), which are formed by participation of retro-biosynthetic methyl migration from C-19 to C-20. Senegenin (11) was selectively converted to a nortriterpene methyl ester, senegenic acid methyl ester (12), via an unprecedented C-C bond cleavage. The stereochemical assignments of compounds 11 and 12 were made unambiguously for the first time using 2D NMRspectroscopy.
Biotransformation, Nocardia sp., NRRL 5646, Pentacyclic triterpenoid acids, Retro-synthetic methyl migration, Senegenin, C-C bond cleavage, 2D NMRspectrosc opy, Natural products.,
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【期刊论文】STEROIDAL GLYCOSIDES FROM THE SUBTERRANEAN PARTS OF LIRIOPE SPICATA VAR. PROLIFERA
余伯阳, BO-YANG YU, SHENG-XIANG QIU, KYAW ZAW, Guo-JuN XU, * YUSUAKI HIRAI, † JUNZO SHOJI, † HARRY H. S. FONG and A. DOUGLAS KNGHORN‡
,-0001,():
-1年11月30日
In a continuation of phytochemical studies on the underground organs of Liriope spicata var. prolifera, four new steroidal glycosides, lirioproliosides A-D, along with two known compounds, 25(S)-ruscogenin 1-O-[a-L-rhamnopyranosyl(1→2)[fl-D-xylopyranosyl(1→3)]-fl-D-fucopyranoside and ophiopogonin A, were identified. The structures of lirioproliosides A-D were established by a combination of spectroscopic and chemical methods as 25(S)-ruscogenin 1-O-[a-L-rhamnopyranosyl(1→2)][fl-D-xylopyranosyl(1→3)]-fl-D-fucopyranoside-3-O-a-L-rhamnopyranoside, 25(S)-ruscogenin 1-O-[3-O-acetyl-a-L-rhamnopyranosyl(1→2)]-fl-D-fucopyranoside, 25(S)-ruscogenin (1-O-[2-O-acetyl-a-L-rhamnopyranosyl(1→3)]-fl-D-fucopyranoside and ruscogenin (1-O-[2-Oacetyl-β-L-rhamnopyranosyl(1→2)]-fl-D-fucopyranoside, respectively. Among these steroidal glycosides, ophiopogonin A and lirioprolioside B, and lirioproliosides C and D, were isolated as epimeric pairs. Copyright
Liriope spicata var., prolifera, Liliaceae, underground organs, steroidal glycosides, lirioproliosides A,, B,, C and D, 25(, S), -ruscogenin 1-O-[a-L-rhamnopyranosyl (, 1→2), ][fl-D-xylopyranosyl(, 1→3), ]-fl-D-fucopyranoside, ophiopogonin.,
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