Cheng-Hui Xu

Daphnane-type diterpenoids from Trigonostemon howii.

Nine new daphnane-type diterpenoids (1-9), named trigohownins A-I, and four known analogues were isolated from Trigonostemon howii. Their structures were elucidated on the basis of extensive NMR and MS analyses. Trigohownins A (1) and D (4) exhibited moderate cytotoxic activity against the HL-60 tumor cell line, with IC50 values of 17.0 and 9.3 μM, respectively.

Diterpenoids from Croton laui and their cytotoxic and antimicrobial activities.

Fourteen new diterpenoids including clerodane (1-12), labdane (13), and norlabdane (14) types, as well as nine known analogues were isolated from the aerial parts of Croton laui. Their structures were established on the basis of spectroscopic analysis, and that of crotonolide H (11) was confirmed by single-crystal X-ray crystallography. Crotonolide A (1) exhibited moderate cytotoxicity against two tumor cell lines, HL-60 (human premyelocytic leukemia, IC50 9.42 μM) and P-388 (murine leukemia, IC50 7.45 μM), and crotonolide G (10) displayed significant antibacterial activity against a panel of Gram-positive bacteria.

Constituents of Trigonostemon heterophyllus

Six new diterpenoids, 1-6, a new prenylated sesquiterpenoid, 7, and six known compounds were isolated from Trigonostemon heterophyllus. The structures of 1-7 were elucidated on the basis of NMR and MS analysis. The daphnane diterpenoids trigoheterins A (1) and B (2) possess a rare 4,6-oxetane moiety within this compound class, and trigoheteric acid methyl ester (6) is the first example of a 15,16-dinor-3,4-seco-cleistanthane. Trigoheterin E (5) exhibited cytotoxic activity against the HL-60 (IC₅₀) 1.8 μM) and A-549 (IC₅₀ 10.0 μM) human cancer cell lines.

Cytotoxic diterpenoids from Sapium insigne.

Chemical investigation into the twigs and leaves of Sapium insigne afforded seven new diterpenoids, sapinsignoids A-G (1-7), together with 10 known diterpenoids. The structures of 1-7 were assigned on the basis of detailed spectroscopic analysis and chemical degradation. Compounds 1-4 exhibited significant cytotoxicity against the A-549 tumor cell line (IC(50) 0.2-1.8 μM), while compounds 1-3 showed moderate cytotoxicity against the HL-60 cell line (IC(50) 2.7-6.5 μM).

Chemical constituents from Brucea javanica

Fourteen apotirucallane-type triterpenoids, named brujavanones A-N, were isolated from the twigs of Brucea javanica, along with four known quassinoids and seven known lignans from the seeds of B. javanica. Their structures were elucidated on the basis of extensive spectroscopic data analysis. The structure of a previously reported triterpenoid, bruceajavanin C, was revised as its C-21 epimer. The cytotoxic activities of triterpenoids and quassinoids against two human tumor cell lines, HL-60 and A-549, were evaluated, but all the compounds were inactive (IC₅₀>10 μM).

Ciliatonoids A and B, Two Limonoids from Toona ciliata

Three new ring B-seco limonoids, ciliatonoids A-C (1-3), were isolated from Toona ciliate and structurally characterized by spectroscopic data, X-ray crystallography, and electronic circular dichroism analysis. Ciliatonoids A and B feature an unprecedented limonoid architecture, while ciliatonoid C belongs to a rare class of limonoids. Biological evaluation showed that compound 3 exhibited modest activities against the tested tumor cell lines.

Phainanolide A, Highly Modified and Oxygenated Triterpenoid from Phyllanthus hainanensis

Phainanolide A (1), a highly modified triterpenoid incorporating an unprecedented 6/9/6 heterotricyclic system and a highly oxygenated 5,5-spirocyclic ketal lactone, along with three new triterpenoids 2-4 were isolated from Phyllanthus hainanensis. Their structures were completely elucidated by a combination of diverse methods including 2D NMR, quantum chemical NMR and ECD calculations, and NMR data analogy with model compounds. Compounds 1-4 exhibited both remarkable cytotoxic and immunosuppressive activities.

Diterpenoids and Lignans from Cephalotaxus fortunei

Five new diterpenoids including two Cephalotaxus troponoids (1 and 2), two 17-nor-cephalotane-type diterpenoids (3 and 4), and an abietane-type diterpenoid (5), two new lignans (6 and 7), and a new trisnorneoligan (8) along with eight known compounds were identified from the twigs and leaves of Cephalotaxus fortunei. The structure of 11-hydroxyhainanolidol was revised as 10-hydroxyhainanolidol (9) by X-ray crystallographic data. Compounds 3 and 4 are the first examples of 17-nor-cephalotane-type diterpenoids that are likely the biosynthesis precursors of the co-occurring troponoids (e.g., 1, 2, and 9). Compound 1 exhibited cytotoxic activities against HL-60 and A-549 cells with IC50 values of 0.77 ± 0.05 and 1.129 ± 0.057 μM, respectively.

Cytotoxic 8,9-seco-ent-kaurane diterpenoids from Croton kongensis

Abstract Chemical study on the ethanolic extract generated from the aerial parts of Croton kongensis led to the isolation of three new 8,9-seco-ent-kaurane diterpenoids, kongeniods A‒C (1‒3), together with seven known analogs (4–10). The structures of these compounds were assigned by spectroscopic data analysis. The vitro cytotoxic tests showed that compounds 1–3 exhibited strong activities against HL-60 cell lines with IC50 values of 0.47, 0.58, and 1.27 μM, respectively.