Sterols from the Green Alga Ulva australis

• Published in: Marine drugs Vol. 15; no. 10; p. 299
• Main Authors: Li, Guo-Liang, Guo, Wei-Jie, Wang, Guang-Bao, Wang, Rong-Rong, Hou, Yu-Xue, Liu, Kun, Liu, Yang, Wang, Wei
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.09.2017; MDPI
• Subjects: 24-vinylcholesta-3β,5α,6β,24-tetraol; 5,28-stigmastadiene-3β,24-diol-7-one epimers; Aldehyde reductase; Aldehyde Reductase - chemistry; Algae; Analytical methods; Aquatic plants; Chlorophyta; Chlorophyta - chemistry; Data processing; Epoxy compounds; Glycerol; Humans; Magnetic resonance spectroscopy; Magnetic Resonance Spectroscopy - methods; Mass spectrometry; Mass spectroscopy; Metabolites; NMR; Nuclear magnetic resonance; p-Hydroxybenzoic acid; p-Hydroxyphenylacetic acid; Parabens - chemistry; Phenylacetates - chemistry; Recombinant Proteins - chemistry; Recombinants; Secondary metabolites; Sterols; Sterols - chemistry; Ulva - chemistry; Ulva australis; Ulva australis; Chlorophyta; 5,28-stigmastadiene-3β,24-diol-7-one epimers; 24-vinylcholesta-3β,5α,6β,24-tetraol
• ISSN: 1660-3397; 1660-3397
• DOI: 10.3390/md15100299

Three new sterols, (24 )-5,28-stigmastadiene-3β,24-diol-7-one ( ), (24 )-5,28-stigmastadiene-3β,24-diol-7-one ( ), and 24 and 24 -vinylcholesta-3β,5α,6β,24-tetraol ( ), together with three known sterols ( - ) were isolated from the green alga . The structures of the new compounds ( - ) were elucidated through 1D and 2D nuclear magnetic resonance spectroscopy as well as mass spectrometry. Compounds - were identified as isofucoterol ( ), 24 ,28 and 24 ,28 -epoxy-24-ethylcholesterol ( ), and (24 )-stigmastadiene-3β,24-diol ( ) on the basis of spectroscopic data analyses and comparison with those reported in the literature. Compounds - were isolated from . for the first time. These compounds, together with the previously isolated secondary metabolites of this alga, were investigated for their inhibitory effects on human recombinant aldose reductase in vitro. Of the compounds, 24 ,28 and 24 ,28 -epoxy-24-ethylcholesterol ( ), 1- -palmitoyl-3- -(6'-sulfo-α-d-quinovopyranosyl) glycerol, (2 )-1- -palmitoyl-3- -[α-d-galactopyranosyl(1→2)β-d-galactopyranosyl] glycerol, 4-hydroxybenzoic acid, 4-hydroxyphenylacetic acid, and 8-hydroxy-(6 )-octenoic acid weakly inhibited the enzyme, while the three new sterols, - were almost inactive.