Kelsoenethiol and dikelsoenyl ether,two unique kelsoane-type sesquiterpenes,from the Formosan soft coral Nephthea erecta

Two new kelsoane-type sesquiterpenes, namely kelsoenethiol (1) and dikelsoenyl ether (2), were obtained from the Formosan soft coral Nephthea erecta. Their structures were elucidated through extensive spectroscopic analyses, ESI orbitrap mass and quantum chemical calculations (QCC). The cytotoxicity against A-459 (human lung carcinoma), P-388 (mouse lymphocytic leukemia), and HT-29 (human colon adenocarcinoma) cancer cell lines of 1 and 2 was evaluated in vitro. Compound 1 showed cytotoxicity against P-388 and HT-29 cells with ED_50s of 1.3 and 1.8 μg/mL, respectively.     

Bioactivity-guided isolation of cytotoxic constituents from stem–bark of Premna tomentosa

A bioassay-guided fractionation and chemical investigation of the stem bark of Premna tomentosa resulted in the isolation and characterization of four new icetexane diterpenes (1–4), along with the known compounds coniferaldehyde (5), syringaldehyde (6), lupeol (7), betulin (8), and 2-(4-methoxyphenyl)-2-butanone (9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with the spectroscopic data reported in the literature. The new compounds exhibited diverse functionalities on a common icetexane diterpene skeleton. In addition, cytotoxic activities of the icetexanes (1–3) were evaluated by determining their inhibitory effects on the human cancer cell lines (MCF-7, HT-29, Hep-G2, A-431, and A-549). Compounds 1 and 3 showed selective inhibitory activity against MCF-7 (15.96 μg/mL and 15.84 μg/mL) and HT-29 cell lines (16.21 μg/mL and 14.57 μg/mL), respectively.     

Two new cytotoxic diterpenes from the rhizomes of Hedychium spicatum

Phytochemical investigation of CHCl₃ extract of the rhizomes of Hedychium spicatum led to the isolation of two new labdane-type diterpenes, compounds 1 and 2 along with five known compounds (3–7). Their structures were established on the basis of NMR (1D and 2D) and mass spectroscopic analysis. In addition, all the isolates were tested for their cytotoxicity against the Colo-205 (Colo-cancer), A-431 (skin cancer), MCF-7 (breast cancer), A-549 (lung cancer) and Chinese hamster ovary cells (CHO). Two new compounds 1 and 2 were shown good cytotoxic activity.     

Three new abietane diterpenoids from Podocarpus fleuryi

Three new abietane diterpenoids, fleuryinols A–C (1–3), together with fourteen known compounds, were isolated from the twigs and leaves of Podocarpus fleuryi. Their structures were established by spectroscopic analysis, including 1D- and 2D-NMR spectroscopic techniques. Compounds 1–8 were tested cytotoxic activity against five human cancer cell lines, HL-60, SMMC-772, A-549, MCF-7, and SW480, of which fleuryinol B (2) and 19-hydroxyferruginol (4) exhibited moderate cytotoxic activity against some cell lines.     

New phenylpropanoids with cytotoxic activities from Drypetes hainanensis

Phytochemical investigation on Drypetes hainanensis has resulted in the isolation of three new phenylpropanoids, named drypetesins A–C (1–3). Their structures were elucidated by applying various spectroscopic techniques (NMR, UV, IR, MS, and CD). The antiproliferative activities of these compounds were evaluated in vitro against three cultured cancer cell lines. Those new isolates exhibited potent cytotoxic activities against human hepatoma (HepG2), human breast adenocarcinoma (MCF-7), and human lung carcinoma (A-549) cancer cell lines with IC₅₀ value range 5.6–14.8 μM.     

Bioactive benzylisoquinoline alkaloids from Artabotrys hexapetalus

Two new benzylisoquinoline alkaloids, namely, hexapetalines A (1) and B (2), along with 11 known alkaloids were isolated from the stems of Artabotrys hexapetalus. The structures of 1 and 2 with their absolute configurations were elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data in the literature. All new compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Alkaloids 1 and 2 exhibited inhibitory effects with IC₅₀ values comparable to those of cisplatin.     

Two novel neo-clerodane diterpenoids from Scutellaria barbata

Two novel neo-clerodane diterpenoids, barbatellarines A (1) and B (2), were isolated from the whole plants of Scutellaria barbata, along with the known compound scutebarbatine F (3). The chemical structures and relative stereochemistry of the isolated compounds were established by NMR (1D and 2D) and mass spectroscopic analyses. Compounds 2 and 3 were evaluated for in vitro cytotoxic activity against the HL-60 (human leukemia), MCF7 (human breast cancer), and LLC (Lewis lung carcinoma) cancer cell lines. Compound 2 exhibited weak cytotoxic activity against HL-60 cells, with an IC₅₀ value of 41.4 μΜ.     

Indole alkaloids from Ervatamia chinensis

Four vobasinyl–ibogan type bisindole alkaloids, ervachinines A–D (1–4), along with 12 known terpenoid indole alkaloids, were isolated from the whole plant of Ervatamia chinensis. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR, and the absolute configurations of 1–4 were determined by CD exciton chirality method. All of the compounds were evaluated for in vitro cytotoxicity against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480. Bisindole alkaloids 1–6 exhibited inhibitory effects, with IC₅₀ values comparable to those of cisplatin.     

Xanthones and a benzophenone from the roots of Pentadesma butyracea and their antiproliferative activity

A new xanthone, 3,4-dihydro-8,10,12-trihydroxy-2,2-dimethylpyrano[2,3-b]xanthen-11(2H)-one or butyraxanthone E (1), along with the known compounds 30-epi-cambogin (2), 1,7-dihydroxyxanthone (3) and 1,5-dihydroxyxanthone (4) were isolated from the roots of Pentadesma butyracea. Their structures were elucidated by spectroscopic means and comparison with published data. Their antiproliferative activities were evaluated against Drosophila S2 cells and two human cancer cell lines, THP-1 (leukemia) and HCT116 (colon cancer). Compounds 1 and 2 showed moderate antiproliferative activity against Drosophila S2 cells and the HCT116 cell line, respectively. Compound 2 was active against Drosophila S2 cells.     

Limonoids from the leaves of Toona ciliata var. yunnanensis

Twelve limonoids, toonayunnanins A–L (1–12) and eleven known compounds (13–23) were isolated from the leaves of Toona ciliata var. yunnanensis, and their structures were elucidated by means of extensive spectroscopic analyses, particularly 1D and 2D NMR techniques. The inhibitory effects of all the isolated compounds were evaluated on human tumor cell lines, such as HL-60, SMMC-7721, A-549, MCF-7 and SW480. Cedrelone (13) and dysobinin (18) showed significant cytotoxicity, and toonayunnanin B (2) and epoxyazadiradione (14), were found to be slightly cytotoxic against the above cell lines. Furthermore, this study provides valuable information for the chemotaxonomy of T. ciliata varieties.     

Regioisomeric acylated polyhydroxy triterpenoids from the stems of Barringtonia racemosa

From the stem of Barringtonia racemosa two new regioisomeric oleanane-type triterpenes were isolated and characterized as racemosol B (1) and isoracemosol B (2). The structures were elucidated by the use of spectroscopic methods. In addition, the known compounds lupeol, betulinic acid and bartogenic acid were identified. Racemosol B was evaluated for cytotoxicity against a panel of human tumor cell lines, A-549, MDA-MB-231, HeLa, and K-562 and showed moderate but cell-type selective activity.     

Sesquiterpene lactones from Inula cappa

Three new germacranolides, ineupatolides A–C (1–3), together with six known sesquiterpenoids, were isolated from the aerial parts of Inula cappa (Buch.-Ham.) DC. The structures of new compounds were elucidated by 1D-, and 2D-NMR techniques including HMQC, HMBC, ¹H–¹H COSY and ROESY spectra. The known compounds were identified by spectroscopic data analyses and data comparison. Compound 2 was finally proved to be converted from 1 with the trace existence of acid. Compounds 2 and 5 showed moderate inhibitory activity against human leukemia cell line HL-60, while compounds 2, 5, 6, 7 and 9 exhibited no antiproliferative activities on human lung cancer cell line A549.     

Dolabellane diterpenoids from Aglaia odorata

Dolabellane diterpenoids, (1R,3E,7E,10S,11S,12R)-dolabella-3,7-dien-10,18-diol (1), (1R,3S,7E,11S,12R)-dolabella-4(16),7-dien-3,18-diol (2), (1R,7E,11S,12R)-18-hydroxydolabella-4(16),7-dien-3-one (3), (1R,3S,4S,7E,11S,12R)-3,4-epoxydolabella-7-en-18-ol (4), and (1R,3R,7E,11S,12R)-dolabella-4(16),7,18-trien-3-ol (5), were obtained from the ornamental plant Aglaia odorata. Their structures were characterized on the basis of spectroscopic analyses and further confirmed by X-ray diffraction. Compounds 1 and 5 showed weak cytotoxicity against the human myeloid leukemia HL-60, hepatocellular carcinoma SMMC-7721, and lung cancer A-549 cells.     

New bisamide compounds from the bark of Aglaia eximia (Meliaceae)

Two new bisamide compounds, eximiamide A (1) and eximiamide B (2) were isolated from the bark of Aglaia eximia (Meliaceae). The chemical structures of the new compound were elucidated on the basis of spectroscopic data. All of the compounds were evaluated for their cytotoxic effects against P-388 murine leukemia cells. Compounds 1 and 2 exhibited cytotoxic activity against P-388 murine leukemia cells with IC₅₀ values of 7.6 and 8.5 μg/mL, respectively.     

Isopimarane diterpene glycosides, isolated from endophytic fungus Paraconiothyrium sp. MY-42

Six isopimarane diterpenes, compounds 1–6, were isolated from the endophytic fungus Paraconiothyrium sp. MY-42. Compound 1 possesses a 19-glucopyranosyloxy group. Its structure was first elucidated by spectroscopic data analysis and finally confirmed by X-ray crystallography, whereas structures 2–6 were mainly elucidated based on the analysis of spectroscopic evidence. Compounds 2 and 3 showed moderate cytotoxicities against the human promyelocytic leukemia cell line HL60 (IC₅₀ 6.7 μM value for 2 and 9.8 μM for 3).     

Novel γ-lactone derivatives from Trigonostemon heterophyllus with their potential antiproliferative activities

Two novel γ-lactone derivatives, trigoheterophines A (1) and B (2), together with four known furan derivatives (3–6), were isolated from the stems and leaves of Trigonostemon heterophyllus. The structures of 1 and 2 were elucidated by extensive spectroscopic methods and the known compounds were identified by comparing with the data reported in literature. Among them, trigoheterophines A (1) and B (2) represent an unusual type of γ-lactone derivatives, possessing 21 carbon atoms on the carbon skeleton, and known compouds (3–6) are rare furan derivatives in the plant kingdom with diverse long-chain hydrocarbyl groups as substituents at C-4. All isolated compounds were evaluated for their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1–6 showed significant antiproliferative effects against various human cancer cell lines with IC₅₀ values ranging from 0.28 to 12.06 μM. These findings suggest that the discoveries of these novel γ-lactone derivatives and furan derivatives with significant antiproliferative activities isolated from T. heterophyllus could be of great importance to the development of new anticancer agents.     

Cytotoxic triterpenoids from the bark of Aglaia smithii (Meliaceae)

Two new dammarane triterpenoids, aglinone (1) and aglinin E (20S,24S-epoxy-25-hydroxy-1-en-dammarene) (2) along with three known compounds, 3-epiocotillol (3), aglinin A (4), and eichlerianic acid (5), were isolated from the bark of Aglaia smithii. The chemical structures of the new compound were elucidated on the basis of spectroscopic data interpretation. All the compounds isolated were evaluated for their cytotoxic effects against P-388 murine leukemia cells. Compounds 1, 2, 4 and 5 showed cytotoxicity against P-388 murine leukemia cells with IC₅₀ values of 21, 42, 34, and 11 μg/mL, respectively.     

Synthesis and biological evaluation of amino analogs of Ludartin: Potent and selective cytotoxic agents

Diverse amino analogs of Ludartin, a cytotoxic guaianolide and a position isomer of an anticancer drug, Arglabin were prepared through Michael type addition at its highly active α-methylene-γ-lactone motif. The semisynthetic derivatives were subjected to sulphorhodamine B cytotoxicity assay against a panel of four different human cancer cell lines viz. lung (A-549), leukemia (THP-1), prostate (PC-3) and colon (HCT-116) to look into structure–activity relationship. Few of the analogs displayed potent selective cytotoxicity compared to the parent molecule-Ludartin (1). (11R)-13-(Diethyl amine)-11,13-dihydroludartin (6) and (11R)-13-(piperidine)-11,13-dihydroludartin (10) showed almost same cytotoxicity against leukemia cell lines (THP-1) as that of parent molecule-Ludartin, but were more active against colon (HCT-116) cancer cells. (11R)-13-(Morpholine)-11,13-dihydroludartin (11) displayed selectively better cytotoxicity against Leukemia cancer cells (THP-1) exhibiting IC₅₀ of 2.8 μM. (11R)-13-(6-Nitroindazole)-11,13-dihydroludartin (17) was four times more potent than Ludartin with selective cytotoxic effects against prostate cancer cells (2.2 μM) while as (11R)-13-(6-nitroindazole)-11,13-dihydroludartin (18) exhibited three-fold selective cytotoxicity for Lung (A-549) cancer cell lines exhibiting IC₅₀ of 2.6 μM.     

α-Santalol derivatives from Santalum album and their cytotoxic activities

A bioassay-guided fractionation of the heartwood of Santalum album led to the isolation of seven α-santalol derivatives including (9S,10E)-9-hydroxy-α-santalal, (10R,11S)-10,11-dihydroxy-α-santalol, (9E)-11,13-dihydroxy-α-santalol, and (10E)-12-hydroxy-α-santalic acid. Their structures were determined on the basis of results of spectroscopic analysis, including two-dimensional (2D) NMR spectroscopic data. The isolated compounds and derivatives were evaluated for cytotoxicity against HL-60 human promyelocytic leukemia cells and TIG-3 normal human diploid fibroblasts. Of these (9S,10E)-9-hydroxy-α-santalal, exhibited tumor-selective cytotoxicity. The apoptosis induction properties of sesquiterpenes with cytotoxic potency in HL-60 cells are also described.     

Cytotoxic dihydrobenzofuran neolignans from Mappianthus iodoies

Three new dihydrobenzofuran neolignans, mappiodoinins A-C (1-3), together with nine known analogues (4 -12) were isolated from the stems and leaves of Mappianthus iodoies. Their structures with the absolute configurations were elucidated by extensive spectroscopic methods. This is the first time to find dihydrobenzofuran neolignans from the genus Mappianthus. All isolated compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW-480 in vitro. Neolignans 1-12 showed significant cytotoxic effects against various human cancer cell lines with IC₅₀ values ranging from 0.16 to 18.62 μM.