Cycloartanol

Tanaka and his group evaluated antihyperglycemic effects of five phytosterols named as lophenol (68), 24-methyllophenol (69), 24-ethyl-lophenol (70), cycloartanol (71) and 24-methylene-cycloartanol (72), isolated from Aloe barbadensis Miller, in type 2 diabetic db/db mice. In... 

Cyanidin-3-O-P D-rutinoside Fr° ° Cyanidin-3-O-P-D-glucosyl-rutinoside Cycloartanol, 23-trans-dehydro, 31-nor, 24-methyl Fixed... 

Cycloartanol ferulate Sd oiP ° Cycloartanol, 24-methylene, ferulate Sd oiioso42, 278.7° ° °... 

Govindan, M., Abbas, S. A., and Schmitz, F. J., New cycloartanol sulfates from the alga Tydemania expeditionis inhibitors of the protein tyrosine kinase pp60v src, J. Nat. Prod., 57, 74, 1994. 

Obtusifoliol Gramisterol Cycloeucalenol Citrostadienol p-Amyrin a-Amyrin Cycloartenol 24-methylene cycloartanol Cyclobranol... 

The full paper on the synthesis of pollinastanol from cycloartanol has been published.21 The revision of stereochemistry at C-4 in the Buxus alkaloids, suggested by 13C chemical shift considerations,22 has been confirmed by X-ray analysis of the derivative (18) of cyclobuxidine F.23 Assignments of the 13C resonances of a series of cycloartanes have been reported.24... 

Pascal, S., Taton, M. and Rahier, A. (1990) Oxidative C4-demethylation of 24-methylene cycloartanol by a cyanide-sensitive enzymatic system from higher plant microsomes. Biochem. Biophys. Res. Commun., 172,98-106. 

A. Other Unaponifiable Compounds Cycloartenol, (3-amyrin, and 24-methylene cycloartanol are the major triterpenols, which constitute less than 1% of WGO. Hydrocarbons are minor components in the WGO unsaponifiable fraction (Table 7). According to Kuksis (42), 50% of the hydrocarbons was squalene and the reminder consisted of n-C29 alkanes. The presence of lutein and cryptoxanthin in WGO were first reported in 1935 and 1940, respectively (43, 44). Recently, Panfili et al. (45), reported that petroleum-ether-extracted WGO contained 25 ppm lutein, 23 ppm zeaxanthin, and 8 ppm (3-carotene. 

Rice bran Total 1055 mg/Kg campesterol (24%) stigmasterol (11%) sitosterol (52%) A -avenasterol (8%) 3 main unknown compounds in addition to obtusifoliol and gramisterol. cycloartenol and 24-methylene-cycloartanol present as y-oryzanoi (see text). 

Triterpenols and sterols are present as free or esterified with fatty acids (oleic acid and linoleic acid as the most relevant). Total content of triterpens is between 100-300 mg/100 g of oil. 24-Methylen-cycloartanol and cycloartenol are dominant. Erythrodiol, uvaol and triterpenic acids (ursolic, oleanolic acids etc) have been described in the imsaponifiable fraction of olive oil. The terpenoid fraction is complex and many constituents are still imdefined. 

All of the above results refer to rat liver systems. Presumably, the same result also applies to lanosterol (73) preparedby feeding yeast with [2- C,2R- H,3R]mevalonic acid or its (2S)-isomer. However, although steroids are widely distributed in nature (see also Section 13), the first formed triterpenoid in higher plants (with the exception of certain Euphorbia sp. ) is cycloartanol (75). As expected, 2,3-oxidosqualene (71) is incoi porated and the labelling pattern is presumably the same as lanosterol (73) with [2- C,3R,5R- H]mevalonic acid. When [2- C,3R,4R- H]mevalonic acid is fed, six tritium atoms are incorporated [see (75)]. The extra tritium atom is as expected at Cyclo-... 

Fig. 7. The formation of 24-methylene cycloartanol, cyclolaudenol and cyclosadol by methylation of cycloartenol.

Fig. 8. Formation of 24-methylene lophenol and 24-ethylidene lophenol from 24-methylene cycloartanol [9].

Apart from 24-methylene cycloartanol (2-F) and cyclolaudenol (2-G), which in maize and barley embryos could give rise to 24a- and 24 -methyl sterols respectively, a further primary product of methylation, cyclosadol (2-T) has recently been foimd in maize and barley embryos. Its significance in the major pathway of sterol synthesis is still under investigation, but minor components such as 4-T and 8-T have also been reported in maize. The overall pattern of the type of compounds formed by the first attack of 5-adenosyl methionine on cycloartenol is outlined in Fig. 7. 

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