THE STEROL COMPOSITION OF 5 PLANT-SPECIES GROWN AS CELL-SUSPENSION CULTURES

The free sterols, steryl esters, steryl glycosides and acylated steryl glycosides were examined from five plant species grown as cell suspen sion cultures, i.e. Apium graveolens, Morinda citrifolia, Nicotiana ta bacum, Solanum tuberosum and Tabernaemontana divaricata. The amount an d composition of the various steryl lipid classes varied between plant species, but some features previously reported in suspension cultures of A. graveolens were common to other species. Firstly, stigmasterol, which represented between 3 and 44% of the free sterols of the cultur es, was either undetected or contributed very little to the steryl est er fraction. Secondly, the precursor sterols (cycloartenol, obtusifoli ol) were esterified in greater proportion to palmitic acid than to the C-18 fatty acids. There did not appear to be a simple relationship be tween the amount of free sterol and the extent of esterification in th e various cultures, as the free sterol:esterified sterol ratio varied from 0.39 to 79.25. The composition of the steryl lipids of S. tuberos um differed markedly from that of the other cultures. The steryl glyco sides of this species contained both pyranosides and furanosides, whic h were separable under the GC conditions employed. The steryl lipids o f N. tabacum and S. tuberosum were also at variance with reported lipi d analyses of the whole plant tissue of these species.