Cytotoxic constituents from the fruiting branches of Callicarpa americana collected in southern Florida.
Bioassay-guided fractionation of the combined fruits, leaves, and twigs (fruiting branches) of Callicarpa americana, collected from a plot in a forested area in southern Florida, led to the isolation of six new clerodane diterpenes (1-6) and eight known compounds. The structures of 1-6 [12(S),16xi-dihydroxycleroda-3,13-dien-15,16-olide (1), 12(S)-hydroxy-16xi-methoxycleroda-3,13-dien-15,16-olide (2), 12(S)-hydroxycleroda-3,13-dien-15,16-olide (3), 16xi-hydroxycleroda-3,11(E),13-trien-15,16-olide (4), 3beta,12(S)-dihydroxycleroda-4(18),13-dien-15,16-olide (5), and 12(S)-hydroxycleroda-3,13-dien-16,15-olide (6)] were elucidated by interpretation of spectroscopic data and chemical methods. The absolute configuration at C-12 in 1 and 3 was ascertained using the Mosher ester technique. The cytotoxicity of all isolates was tested against a panel of human cancer cell lines, and compounds 1, 4, and 6, and the known compounds genkwanin, 16xi-hydroxycleroda-3,13-dien-15,16-olide, and 2-formyl-16xi-hydroxy-3-A-norcleroda-2,13-dien-15,16-olide were active (ED50 <5 microg/mL). However, 1 was found to be inactive against human cancer cells implanted in mice using a hollow-fiber tumor model.
Jones
William P
WP
Program for Collaborative Research in the Pharmaceutical Sciences, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, USA.
Lobo-Echeverri
Tatiana
T
Mi
Qiuwen
Q
Chai
Hee-Byung
HB
Soejarto
Djaja D
DD
Cordell
Geoffrey A
GA
Swanson
Steven M
SM
Kinghorn
A Douglas
AD
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D032408:Callicarpa / Q000737:chemistry*; D004195:Disease Models, Animal; D045785:Diterpenes, Clerodane / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D005431:Florida; D005638:Fruit / Q000737:chemistry; D006801:Humans; D051379:Mice; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*
D000972:Antineoplastic Agents, Phytogenic; D045785:Diterpenes, Clerodane