Isolation of Sesquiterpene-Amino Acid Conjugates, Onopornoids A-D, and a Flavonoid Glucoside from Onopordum alexandrinum.

Previous phytochemical investigations have revealed the presence of a variety of compounds such as pyrrolidine derivatives, flavonoids, and megastigmanes in Egyptian plants. Onopordum alexandrinum has been traditionally used by the natives for treatment of skin cancers and leprosy. In this paper the isolation of four new sesquiterpene-amino acid conjugates, onopornoids A-D (1-4), i.e., three elemanes and one germacrane, and a new acylated flavonoid glucoside (5) along with nine known compounds (6-14) from the whole aerial parts of the title plant is discussed. The structures were elucidated based on chemical and spectroscopic/spectrometric data.