Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the ...Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form （94.3%）, were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol （58.5% of total sterols） and cholesterol （35.9% of total sterols）. Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% （in the prostatic secretory granules, PSGs） to 63.8% （in the seminal plasma）. Spermatozoa contained an intermediate proportion of desmosterol （59.8%）, which was asymmetrically distributed between the heads （52.0% of the total content of sterols） and the tails （81.8%）. Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L^-1. In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.展开更多
The LXRs?agonist, 24S,25-epoxycholesterol 1,was synthesized stereoselectively (100% d.e.) in 56% overall yield from methyl hyodeoxycholanate 4 in 9 steps with des-mosterol acetate 11 as the key intermediate and the mo...The LXRs?agonist, 24S,25-epoxycholesterol 1,was synthesized stereoselectively (100% d.e.) in 56% overall yield from methyl hyodeoxycholanate 4 in 9 steps with des-mosterol acetate 11 as the key intermediate and the modified Sharpless asymmetric dihydroxylation as the key step. TheLXRa subtype selective agonist 5a,6a:24S,25-diepoxycho-lesterol 2 and the novel LXRs?ligand 5b,6b:24S,25-diepo-xycholesterol 3 were also synthesized from 1.展开更多
文摘Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form （94.3%）, were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol （58.5% of total sterols） and cholesterol （35.9% of total sterols）. Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% （in the prostatic secretory granules, PSGs） to 63.8% （in the seminal plasma）. Spermatozoa contained an intermediate proportion of desmosterol （59.8%）, which was asymmetrically distributed between the heads （52.0% of the total content of sterols） and the tails （81.8%）. Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L^-1. In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.
基金supported by the National Natural Science Foundation of China(Grant No.20072047)the State Key Laboratory of Biological Organic Chemistry in Shanghai Institute of Organic Chemistry,Chongqing Science and Technology Committee(Grant No.6617)the Third Military Medical University.
文摘The LXRs?agonist, 24S,25-epoxycholesterol 1,was synthesized stereoselectively (100% d.e.) in 56% overall yield from methyl hyodeoxycholanate 4 in 9 steps with des-mosterol acetate 11 as the key intermediate and the modified Sharpless asymmetric dihydroxylation as the key step. TheLXRa subtype selective agonist 5a,6a:24S,25-diepoxycho-lesterol 2 and the novel LXRs?ligand 5b,6b:24S,25-diepo-xycholesterol 3 were also synthesized from 1.
