natural-products-in-plant-pest-management

Natural Products from Plants 51Triterpenes consist of six isoprene units (C 30) and are divided into fourgroups, namely common triterpenes, steroids, saponins and cardiac glycosides.Common triterpenes are commonly found in plants as a wax layer onleaves and on some fruits e.g. limonene (Fig. 3.7).Most steroids are hydrolysed on carbon 3 and are in fact all sterols. Theyplay important roles either as hormones in plants (e.g. brassinosteroids) orvitamin precursors (e.g. 1-α-25-dihydroxy-vitamin D 3glycoside; Fig. 3.8).Brassinosteroids (e.g. brassinolide; Fig. 3.9) have growth-stimulating andyield-increasing properties and are regarded as the secondary metaboliteswith great application potential in both the agricultural and horticulturalindustries (see below).OOOHHOCOOHFig. 3.6. Gibberellic acid.OOOOOFig. 3.7. Limonene.OH CH 3HOHOHHHOOHOHOA brassinosteroid (brassinolide)HOOH1-α-25-dihydroxy-vitamin D 3 glycosideFig. 3.8. Examples of triterpenes.