Sterols stigmasterol

The fourth isolated and identified compound from Palmer amaranth is chondri 11 asterol (5a-stigmasta-7,22-dien-30-ol), a sterol closely related structurally to the major plant sterols, stigmasterol and sitosterol. This compound, isolated as the free sterol, is not soluble in water or 0.1% DMS0, and germination bioassays required pretreatment of the test seed with a 0.1 mM solution of the sterol in DCM. 

Plant sterols such as stigmasterol typically contain an extra ethyl group when compared with cholesterol. Now this is not introduced by an electrophilic ethylation process instead, two successive electrophilic methylation processes occur, both involving SAM as methyl donor. Indeed, it is a methylene derivative like that just seen in ergosterol formation that can act as the alkene for further electrophilic alkylation. After proton loss, the product has a side-chain with an ethylidene substituent the side-chains of the common plant sterols stigmasterol and sitosterol are then related by repeats of the reduction and dehydrogenation processes already seen in ergosterol formation. 

Owing to periodic fluctuations in the price of diosgenin. alternative law materials such as solasodinc have been used for the synthesis of steroid drugs. In the U.S., the plant sterols stigmasterol and /3-sitosterol arc a significant raw material for the synthesis of antiinflammatory glucocorLicuids and other steroid hormones. 

Degradation of the sterol stigmasterol to progesterone is achieved by the sequence shown in Figure 5.120. The double bond in the side-chain allows cleavage by ozonolysis, and the resultant aldehyde is chain shortened via formation of an enamine with piperidine. This can be selectively oxidized to progesterone. In this sequence, the ring A transformations are carried out as the... 

Before discussing our synthetic studies, mention should be made of different approaches employed in the synthesis of brassinolide by other investigators. The most practical method would be to start with a readily available steroid having the same carbon skeleton as brassinolide, and then introduce the required functional groups in rings A and B and the sidechain. In the case of 28-homobrassinolide (5), tiie ideal starting compound would be the abundant sterol stigmasterol (4). 

An important raw material for the partial synthesis of steroid hormones (and Vitamin D) is cholesterol, which (prior to the BSE crisis) was isolated from the spinal cord of cattle. Another important source is the fat in sheep s wool (lanolin), which contains around 15 % of cholesterol. Among the plant sterols, stigmasterol is of great economic significance as the starting material for the partial synthesis of steroids. It is contained from 12 to 25 % in the non-hydrolysable... 

From the commercial point of view, the cheap and readily available plant sterol, stigmasterol ( ), presently appears to be the most desirable starting material for the preparation of vitamin D metabolites. Since the two double bonds of stigmasterol exhibit nearly equal reactivity toward oxidizing agents it has been necessary to first protect the 5,6-double... 

The effects of a mixture of plant sterols (stigmasterol/sitosterol/caropes-terol, 55 15 30, wAich is representative of the mean sterol composition of membranes from maize roots), were found to be similar to those obtained with stigmasterol, the main compound of the mixture (data not shown). Cholesterol, a minor sterol in plants, is shown to be less efficient than sitosterol. In Fig.2 is represented the comparative behavior of sitosterol-and 24-methylpollinastanol-containing LUV. The cyclopropylsterol appears to be much less efficient than sitosterol as a modulator of the fluidity of soybean PC bilayers. It behaves more like (24R)-methylcholesterol. 

As a by-product of soybean oil refining, so-called deodorizer distillate (0.2-0.5% of the oil) is obtained, which contains 25-55% ffa, 20-40% trigycerides, 7-11% - tocopherol, 10-15% sterols (- stigmasterol) and 25-30% unsaponifiable matter. - Lecithin can also be gained from the oil. 

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