Quassinoid substances found in herbs such as tongkat ali

Quassinoids from Eurycoma longifolia.
J Nat Prod. 2009 Dec; Miyake K, Tezuka Y, Awale S, Li F, Kadota S. Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Ten new structurally diverse quassinoids (1-10) and 14 known compounds were isolated from the stems of Eurycoma longifolia. The new compounds were two eurycomanone-type C(20) quassinoids (1, 2), one klaineanone-type C(20) quassinoid (3), one C(19) quassinoid (4) with a 1,2-seco-1-nor-6(5-->10)-abeo-picrasan-2,5-olide skeleton, and six eurycomalactone-type C(19) quassinoids (5-10). Compounds 5 and 6 both possessed a 3,4-epoxy group observed for the first time in eurycomalactones. Compound 1 had an alpha-oriented OH group at C-14 that had not been reported previously in eurycomanone-type quassinoids. All of the isolates were evaluated for cytotoxicity toward the highly metastatic HT-1080 human fibrosarcoma cell line, and compounds 11, 23, and 24 showed potent cytotoxicity

Antimalarial activity of simalikalactone E, a new quassinoid from Quassia amara L. (Simaroubaceae).
Antimicrob Agents Chemother. 2009 Oct; Cachet N, Hoakwie F, Bertani S, Bourdy G, Deharo E, Stien D, Houel E, Gornitzka H, Fillaux J, Chevalley S, Valentin A, Jullian V. Laboratoire de Pharmacochimie des Substances Naturelles et Pharmacophores Redox, UMR 152, UPS, Université de Toulouse, 118 Route de Narbonne, F-31062 Toulouse Cedex 9, France.

Evaluation of efficacy of bruceine A, a natural quassinoid compound extracted from a medicinal plant, Brucea javanica, for canine babesiosis.
J Vet Med Sci. 2009 Jan; Nakao R, Mizukami C, Kawamura Y, Subeki, Bawm S, Yamasaki M, Maede Y, Matsuura H, Nabeta K, Nonaka N, Oku Y, Katakura K. Laboratory of Parasitology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 8, Sapporo, Japan.