A Further Bakkenolide A Derivative fromHomogyne alpina

Unusual Sesquiterpene Lactones from Ligularia virgaurea spp. oligocephala

“…Compound 1 is a bicarbocycle sesquiterpene related in structure to bakkenolide A, which has cytotoxic activity,3d but possesses a novel carbon framework. New compound 2 has an eremophilane-type carbon skeleton.…”

Pyrrolizidine Alkaloids of the GenusHomogyne

“…The occurrence of petasitenine (1) and neopetasitenine (2) in H. alpina, as reported earlier (5), was confirmed. In addition, senkirkine (3) and 12-acetylsenkirkine (4) were isolated.…”

“…The bioactivities of the pure compounds in the BST and in human solid tumor cell lines are given in Table 1. Annonacin was first isolated from Annona densicoma (2) and has since been reported in Annona squamosa (3), Goniofhalamus giganteus (4), and Annona muricafa (5). The isolation of annonacin-lO-one from Annona muricata has been recently reported by Cortes and coworkers (6).…”

Total Synthesis of Bakkanes

“…Several biological activities have been attributed to sesquiterpene lactones, including some of the bakkanes shown above. [13][14][15] Cytotoxic activity is a characteristic of Petasites japonicus (Japan), 7,9,12,[28][29][30] Petasites albus (Czechoslovakia, 9 Scotland 16 ), Cacalia hastata (Japan), 31 Ligularia hodgsonii (Japan), 32 Petasites hydridus (Scotland), 16 Petasites flagrans (Scotland), 16 Homogyne alpina (Czechoslovakia, 33 Switzerland 34 ), Cetraria islandica (Norway), 35 Petasites palmatus (Japan), 36 Ligularia persica (Iran), 37 Hertia cheirifolia (France), 38 Ligularia sagitta (China), 39 Ligularia intermedia (China) 40 2 Petasites japonicus (Japan), 7,[28][29][30]41 Petasites formosanus (Taiwan) 18 3…”

“…Before presenting each of the several total syntheses of bakkanes, studies concerning the construction of b-methylene-g-butyrolactones will be discussed. Homogyne alpine (Switzerland) 34…”