Triterpenoid profile of fruit and leaf cuticular waxes of edible honeysuckle Lonicera caerulea var. kamtschatica

Edible honeysuckle (honeyberry) Lonicera caerulea is becoming popular as a novel berry crop with several useful features such as early fruit ripening and exceptional hardiness, particularly resistance to pests and diseases as well as severe frosts in winter and droughts in summer. The triterpenoid profile of fruit and leaf cuticular waxes of edible honeysuckle (a Russian cultivar Chernichka) was analyzed by GC-MS. The major compounds identified were the tetracyclic triterpenoids campesterol, cholesterol, cycloartanol, cycloart-23-ene-3,25-diol, 24-methylenecycloartanol (only in leaves), sitosterol, stigmasta-3,5-dien-7-one, and stigmasterol; and the pentacyclic triterpenes: α-amyrin, β-amyrin, hop-22(29)-en-3-one, oleanolic acid, and ursolic acid. Several remarkable features of the analyzed triterpenoid contents were revealed, including the relatively low abundance of triterpenoids in fruit waxes (6.5% of wax extract) compared to leaf waxes (22%), and a particularly high proportion of tetracyclic triterpenoids (tetracyclic to pentacyclic compound ratios of 4:1 in fruits and almost 7:1 in leaves). These rare features distinguish the triterpenoid profile of the cuticular waxes of L. caerulea var. kamtschatica from the majority of triterpenoid profiles in plant cuticular waxes investigated to date. To our knowledge, this is the first quantitative compositional study on triterpenoid compounds in the cuticular waxes of edible honeysuckle, supplementing the knowledge of cuticular triterpenoid diversity and distribution.