The genus Phyllanthus is a large plant group containing over 600 species, of which many have been used in traditional medicine to treat human diseases and have been studied phytochemically. However, there are no previous reports on the chemical constituents of Phyllanthus songboiensis N. N. Thin (Phyllanthaceae). As part of a search for new natural product anticancer agents from diverse organisms, the aerial parts of P. songboiensis, collected in Vietnam, were found to be cytotoxic toward the HT-29 human colon cancer cell line. Using column chromatography guided by cytotoxicity to HT-29 cells, a new dichapetalin-type triterpenoid, a new dibenzylbutyrolactone-type lignan, and several known compounds were isolated from this plant. The structures of all compounds isolated were established from their IR, UV, NMR, and mass spectra, and the absolute configurations of these compounds were determined by analysis of their CD spectra. The cytotoxicity toward HT-29 cells of all isolates and the natural killer (NK) cell stimulation of some compounds were tested. Several compounds showed cytotoxicity toward HT-29 cells, and a sterol glycoside was found to stimulate NK cells in the presence of interleukin-12. This study describes for the first time the cancer cell cytotoxic and NK cell stimulatory constituents of Phyllanthus songboiensis.
In a search for anticancer agents from higher plants, a sample of the dried bark and roots of Syzygium cf. lineatum (Bl.) Merr. & Perry (Myrtaceae) collected in Vietnam showed cytotoxic activity and was selected as a lead. Separation of the methanol extract of this plant sample, using column chromatography guided by the HT-29 human colon cancer cell line, resulted in the isolation and characterization of three new and several known lignan esters and a new triterpene acetate. The structures of the new compounds were elucidated by interpretation of their ECD, IR, UV, NMR, and mass spectra, with those of the known compounds being characterized by comparison of their spectroscopic data with literature values. The conformation and relative configuration of a known lignan, (2S,3S)-2,3-bis[(4-hydroxy-3-methoxyphenyl)methyl]-1,4-butanediol 1,4-diferulate, were confirmed or revised by analysis of the single-crystal X-ray diffraction, with the absolute configuration of all analogues isolated being established by investigation of their specific rotation values and ECD spectra. All compounds isolated in the present study were evaluated for their cytotoxicity against the HT-29 cell line, and several lignan esters were found to be active. A preliminary structure-activity relationship study showed that both the ester groups and the dimeric units are required for these compounds to mediate cytotoxicity against HT-29 cells.
Brucea javanica (L.) Merr. (Simaroubaceae) is a shrub distributed from southeast Asia to northern Australia. In Asia, all parts of B. javanica have been employed as an antimalarial treatment, and the seeds of this plant have also been used for the treatment of dysentery and various skin diseases. Previous investigation on the chemical constituents of B. javanica has revealed the occurrence of apotirucallane triterpenoids, β-carboline alkaloids, and quassinoids. Quassinoids are considered the major active principles of B. javanica and have a wide spectrum of biological effects, such as potential antibabesial, anti-HIV, antimalarial, anti-tuberculosis, antitumor, cancer chemopreventive, and cytotoxic activities.
Bioactivity-guided isolation, fractionation and quantification from Aglaia perviridis Hiern (Meliaceae) (voucher specimen: Soejarto et al 14595) demonstrated it to be only the third plant of the genus Aglaia found to produce silvestrol and its epimer, 5″-episilvestrol (episilvestrol). Several fractions from the chloroform extract produced from the whole plant were found to be active against HT-29 human colorectal cancer cells in vitro. Further purification and chemical analysis of the active fractions interestingly showed them to contain episilvestrol in a higher amount compared to silvestrol, contrary to the observation of silvestrol being the more abundant compound as in Aglaia foveolata.
Two new and six known arylnaphthalene lignan lactones were discovered from Phyllanthus poilanei Beille (Phyllanthaceae) collected in South Vietnam. The structures of the new compounds were determined by interpretation of their spectroscopic data, with the structure of one of these new compounds, phyllanthusmin D, being confirmed by single-crystal X-ray diffraction analysis. Several of these compounds were cytotoxic toward the HT-29 human colon cancer cells, with phyllanthusmin D found to be potently cytotoxic in vitro showing an IC50 value of 170 nM and active when tested in an in vivo hollow fiber assay. This compound showed a different mechanism of action when compared with etoposide. It mediated its cytotoxicity toward the HT-29 cells by induction of tumor cell apoptosis through activation of caspase-3 with no inhibitory activity against DNA topoisomerase IIα.
Eight new 16,23-epoxycucurbitacin derivatives, designated as elaeocarpucins A-H (1-8), and five known cucurbitacins (9-13) were isolated from the separate methanol extracts of the fruits and stem bark of Elaeocarpus chinensis (Gardn. & Champ.) Hook. ex Benth. (Elaeocarpaceae) collected in Vietnam. Isolation work was facilitated using an LC/MS dereplication procedure, and bioassay-guided fractionation was monitored using HT-29 human cancer cells. Compounds 1-13 were evaluated in vitro against the HT-29 cell line and using a mitochondrial transmembrane potential assay. Elaeocarpucin C (3), produced by partial synthesis from compound 13, was found to be inactive when evaluated in an in vivo hollow fiber assay using three different cancer cell types (dose range 0.5–10mg/kg/day, ip).
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