Phytochemical Notes 241
Cytotoxic Constituents of Exostema mexicanum1
Canthin-6-one Alkaloids from
Rachel Mata2' , Carlos Albor2, Rogelio Pereda-Miranda2, and Jerry L. McLaughlin3 Part X in the series "Chemical Studies of Mexican Plants Used in Traditional Medicine". Taken in part from the M. S. thesis of C. Albor. For Part IX, see: Navarrete, A. et al. (1989) Planta Med. 579 2 Division de Bioqulmica y Farmacia, Facultad de Quf mica, Universidad Nacional Autónoma de Mexico, Coyoacán 04510, Mexico D.F. Department of Medicinal Chemistry and Pharmacognosy, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, Indiana 47907, USA Address for correspondence
Pierreodendron africanum Stem Barks R. Vanhaelen-Fastré1'3, M Vanhaelen1, B. Diallo', and H. Breyne2 1
Laboratory of Pharmacognosy, Université Libre de Bruxelles, Institut de Pharmacie, Campus Plaine, 205-4, Bd du Triomphe, B-1050, Brussels, Belgium 2 Projet Agrostologie et aide aux petits éleveurs du Bas-ZaIre et du Bandundu, B.P. 615, Kinshasa 1, Republic of ZaIre
Address for correspondence Received: April 19, 1989
Exostema inexicanum Gray (Rubiaceae), known in Mexico as "quina" and "melena de leon", is locally used for the treatment of malaria and dengue (1). Continuing our investigation on the chemistry of Mexican medicinal plants (2, 3), in the present work, bioactivity-directed frac-
tionation of a MeOH extract of the stem bark of B.
inexicanum, using the brine shrimp bioassay (4), led to the isolation of two cytotoxic constituents, cucurbitacins F and F-25-acetate (3), and two inactive compounds, 5-O-13-Dglucopyranosyl-3 ',4 '-dihydroxy-7-methoxy-4-phenylcoumann (2) and 2-O--D-glucopyranosylcucurbitacin F-25acetate (3). Cucurbitacin F (1) and the F-25-acetate (2) were toxic to brine shrimp (LC50 16.0 and 17.3 ppm, respec-
tively) and displayed significant cytotoxicity in several in vitro tumor cell culture test systems (Table 1). Table 1 ED50 (.tg/ml) of the cytotoxEc compounds of E. mexicanum.
2
1
Tumor system
l0
A 549 (human lung)
3.44 x
MCF7(humanbreast) HT29 (human colon)
3.27 x 10
5.23x l0
Cytotoxic Constituents of Exostema mexicanum1
Canthin-6-one Alkaloids from
Rachel Mata2' , Carlos Albor2, Rogelio Pereda-Miranda2, and Jerry L. McLaughlin3 Part X in the series "Chemical Studies of Mexican Plants Used in Traditional Medicine". Taken in part from the M. S. thesis of C. Albor. For Part IX, see: Navarrete, A. et al. (1989) Planta Med. 579 2 Division de Bioqulmica y Farmacia, Facultad de Quf mica, Universidad Nacional Autónoma de Mexico, Coyoacán 04510, Mexico D.F. Department of Medicinal Chemistry and Pharmacognosy, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, Indiana 47907, USA Address for correspondence
Pierreodendron africanum Stem Barks R. Vanhaelen-Fastré1'3, M Vanhaelen1, B. Diallo', and H. Breyne2 1
Laboratory of Pharmacognosy, Université Libre de Bruxelles, Institut de Pharmacie, Campus Plaine, 205-4, Bd du Triomphe, B-1050, Brussels, Belgium 2 Projet Agrostologie et aide aux petits éleveurs du Bas-ZaIre et du Bandundu, B.P. 615, Kinshasa 1, Republic of ZaIre
Address for correspondence Received: April 19, 1989
Exostema inexicanum Gray (Rubiaceae), known in Mexico as "quina" and "melena de leon", is locally used for the treatment of malaria and dengue (1). Continuing our investigation on the chemistry of Mexican medicinal plants (2, 3), in the present work, bioactivity-directed frac-
tionation of a MeOH extract of the stem bark of B.
inexicanum, using the brine shrimp bioassay (4), led to the isolation of two cytotoxic constituents, cucurbitacins F and F-25-acetate (3), and two inactive compounds, 5-O-13-Dglucopyranosyl-3 ',4 '-dihydroxy-7-methoxy-4-phenylcoumann (2) and 2-O--D-glucopyranosylcucurbitacin F-25acetate (3). Cucurbitacin F (1) and the F-25-acetate (2) were toxic to brine shrimp (LC50 16.0 and 17.3 ppm, respec-
tively) and displayed significant cytotoxicity in several in vitro tumor cell culture test systems (Table 1). Table 1 ED50 (.tg/ml) of the cytotoxEc compounds of E. mexicanum.
2
1
Tumor system
l0
A 549 (human lung)
3.44 x
MCF7(humanbreast) HT29 (human colon)
3.27 x 10
5.23x l0
