An analytical method for the determination of the concentrations of total lycopene and its cis and all-trans isomers in human plasma has been developed using high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS). This method was based on the observation that, during negative ion atmospheric pressure chemical ionization with collision-induced dissociation, a unique fragment of m/z 467 was formed from the molecular ion of m/z 536 by elimination of a terminal isoprene group. The use of multiple reaction monitoring facilitated the selective detection of lycopene isomers and an internal standard without interference from the isobaric carotenoids a-carotene and beta-carotene, which are also abundant in human plasma. Measurement of total lycopene was carried out using a C18 high-performance liquid chromatography (HPLC) column and an isocratic mobile phase consisting of acetonitrile/methyl tert-butyl ether (95:5) so that all lycopene isomers eluted as a single chromatographic peak. all-trans-Lycopene was separated from its various cis isomers by using a C30 carotenoid column and a gradient solvent system from methanol to methyl tert-butyl ether. The effects of sample preparation and handling parameters on the stability of lycopene were evaluated such as the stability of lycopene in the HPLC autosampler and the effect of saponification upon lycopene isomerization. For example, the half-life of all-trans-lycopene in the HPLC mobile phase in the autosampler at 4 degrees C was determined to be approximately 16 h. Also, saponification of plasma samples was determined to cause lycopene degradation and isomerization so that lycopene recovery was reduced. The accuracy and interassay precision of this LC-MS-MS assay for lycopene showed a standard deviation of less than 10% over the range of 5-500 pmol injected on-column. The limit of detection was 11.2 fmol injected on-column, and the limit of quantitation was 22.8 fmol.

Fractionation of an ethyl acetate-soluble extract of the stem bark of Dichapetalum gelonioides, collected in the Philippines, using the LNCaP (hormone-dependent human prostate) cell line as a monitor, led to the purification of three dichapetalin-type triterpenoids [dichapetalins A (1), I (2), and J (3)], along with two dolabrane norditerpenoids (6, 7), and the additional triterpenoids zeylanol (8), 28-hydroxyzeylanol (9), and betulinic acid. Since compounds 1-3 exhibited promising selectivity against the SW626 (human ovarian cancer) cell line, a recollection of the plant material was carried out, in order to obtain more of these compounds for additional biological testing. Two further phenylpyranotriterpenoids [dichapetalins K (4) and L (5)] were isolated from the recollected plant material. The structures of the new compounds 2-5 and 9 were determined based on spectroscopic data interpretation, and the relative configuration of 6 was confirmed using X-ray crystallography. Compounds 4-6 and the methyl ester, 6a, exhibited broad cytotoxic activity when tested against a panel of human tumor cell lines. Dichapetalin A (1) was not active when evaluated in an in vivo hollow fiber assay in the dose range 1-6 mg/kg. Dichapetalum Thouars represents the major genus in the family Dichapetalaceae (syn. Chailletiaceae), and comprises 124 species, of which the majority (86 species) are found in Africa, with the others occurring in tropical Asia (19 species) and South America (19 species). 2 Many Dichapetalum species are poisonous to livestock due to the presence of fluorinated compounds such as fluoracetic acids and ω-fluorinated fatty acids. 3-6 The leaves of D. gelonioides have been used to treat amenorrhea in the Philippines. 7 Several phenylpyranotriterpenoids (dichapetalins A-H) have been isolated and structurally characterized from the roots of D. madagascariense Poir. 8-10 The absolute configuration of dichapetalin A was determined by single-crystal X-ray diffraction analysis. 9 While this # Dedicated to Dr. Norman R. Farnsworth of the University of Illinois at Chicago for his pioneering work on bioactive natural products.*Author to whom correspondence should be addressed. Tel.: (614) compound was reported to show potent activity in the brine shrimp lethality bioassay, exceeding that of podophyllotoxin by seven-fold, and also exhibited cytotoxicity for L1210 murine leukemia cells (EC 90 <0.0001 μg/mL), the KB cell line and an unspecified murine bone marrow cell line were not sensitive to this triterpenoid. 8As a part of our program on the discovery of new anticancer agents from plants, an ethyl acetatesoluble extract has been investigated of the stem bark of D. gelonioides (Roxb.) Engl., collected in 1994 on Palawan Island in the Philippines. Only one phytochemical investigation has been reported previously on this species, resulting in the isolation of the triterpenoid, friedelin. 11 Activity-guided fractionation using the LNCaP (hormone-dependent human prostate cancer) cell line led to the isolation of tw...

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