Phenolics and terpenoids from a wild edible plant Lactuca orientalis (Boiss.) Boiss. A preliminary study

Lactuca orientalis, hitherto phytochemically unexamined plant, has been used as a food or forage plant in some countries of the Near East. Six neolignans – derivatives of dihydrodehydrodiconiferyl alcohol, one sesquiterpene lactone – leucodin, one apocarotenoide – loliolide, and two simple phenolic compounds – vanilin and methyl 4-hydroxybenzoate were isolated from roots and aerial parts of the plant. Three of the isolated neolignans, i.e. 4-O-methyldihydrodehydrodiconiferyl alcohol and its two glucosides, were found for the first time in the genus Lactuca. Moreover, presence of dihydroconiferin, nucleosides (adenosine and uridine) and caffeic acid derivatives was revealed in the plant material using combined chromatographic and spectroscopic (¹H NMR) techniques. Major phenolic constituents of young shoots and leaves, i.e.: caffeic acid derivatives (caftaric acid, chlorogenic acid, caffeic acid and cichoric acid), dihydroconiferin and neolignans (dihydrodehydrodiconiferyl alcohol, 4-O-methyldihydrodehydrodiconiferyl alcohol), were quantified. Cichoric acid (c. 0.66% dry weight) and dihydrodehydrodiconiferyl alcohol (c. 0.76% dry weight) were the most abundant phenolic compounds detected in the examined tissue.