Delta 7-avenasterol

High throughput screening of mutants of oat that are defective in triterpene synthesis.[Pubmed:20557911]

Phytochemistry. 2010 Aug;71(11-12):1245-52.

The triterpenes are a large and diverse group of plant natural products that have important functions in plant protection and food quality, and a range of pharmaceutical and other applications. Like sterols, they are synthesised from mevalonate via the isoprenoid pathway, the two pathways diverging after 2,3-oxidosqualene. During triterpene synthesis 2,3-oxidosqualene is cyclised to one of a number of potential products, the most common of these being the pentacyclic triterpene beta-amyrin. Plants often produce complex mixtures of conjugated triterpene glycosides which may be derived from a single triterpene skeleton. The delineation, functional analysis and exploitation of triterpene pathways in plants therefore represent a substantial challenge. Here we have carried out high throughput screening to identify mutants of diploid oat (Avena strigosa) that are blocked in the early steps of triterpene synthesis. We also show that mutants that are affected in the first committed step in synthesis of beta-amyrin-derived triterpenes, and so are unable to cyclise 2,3-oxidosqualene to beta-amyrin (sad1 mutants), accumulate elevated levels of primary sterols. The major differences were in Delta-7-campesterol and Delta-7-avenasterol, which both increased several fold relative to wild-type levels. This is presumably due to accumulation of squalene and 2,3-oxidosqualene and consequent feedback into the sterol pathway, and is consistent with previous reports in which specific oxidosqualene cyclase inhibitors and elicitors of triterpene biosynthesis were shown to have inverse effects on the flux through the sterol and triterpene pathways.

Topical antiinflammatory activity of phytosterols isolated from Eryngium foetidum on chronic and acute inflammation models.[Pubmed:10189959]

Phytother Res. 1999 Feb;13(1):78-80.

Eryngium foetidum L. (Apiaceae) is a Caribbean endemic plant, used in folk medicine for the treatment of several antiinflammatory disorders. A preliminary phytochemical study showed that the hexane extract is rich in terpenic compounds. Chromatographic fractionation of this extract yielded: alpha-cholesterol, brassicasterol, campesterol, stigmasterol (as the main component, 95%) clerosterol, beta-sitosterol, delta 5-avenasterol, delta (5)24-stigmastadienol and Delta 7-avenasterol. The topical antiinflammatory activity of the hexane extract and of stigmasterol was evaluated by auricular oedema, induced by 12-0-tetradecanoylphorbol acetate (TPA), in the mouse, using single and multiple applications of the phlogistic agent. Both reduced the oedema in a similar proportion in the two model assays (acute and chronic). Meloperoxidase activity was strongly reduced by both the extract and the compound, in the acute but not the chronic model. These results indicate that the leaves of Eryngium foetidum L may be effective against topical inflammation processes. Stigmasterol also exerts a significant topical antiinflammatory activity although it cannot be considered to be a major antiinflammatory agent, therefore other bioactive components are probably involved in the activity of the hexane extract.