Chang-Heng Tan

Terrestrinins A and B, two new steroid saponins from Tribulus terrestris.

Two new steroid saponins, named terrestrinins A (1) and B (2), along with six known compounds were isolated from the Chinese medicine herb Tribulus terrestris, and their chemical structures were elucidated as 26-O-β-D-glucopyranosyl-(25S)-furostan-4(5),20(22)-diene-3,12-dione (1) and 26-O-β-D-glucopyranosyl-(25S)-5α-furostane-3β,22α,26-triol-3-O-β-D-xylopyranosyl(1→3)-[(β-D-xylopyranosyl(1→2)]-β-D-glucopyranosyl(1→4)-[α-L-rhamnopyranosyl(1→2)]-β-D-galactopyranoside (2) on the basis of spectroscopic techniques.

Two Novel Lycopodium Alkaloids from Huperzia serrata

Huperzine Q (1) and N-oxyhuperzine Q (2), two novel irregular fawcettimine-type Lycopodium alkaloids were isolated from the CHCl3 fraction of the basic material of the whole plant of the Chinese medicinal herb Huperzia serrata. Their structures were determined as 13-epi-13β,16-epoxydihydrofawcettimine (1) and N-oxy-13-epi-13β,16-epoxydihydrofawcettimine (2) by means of spectroscopic studies and X-ray crystallographic analysis.

Tryptamine derivatives as novel non-nucleosidic inhibitors against hepatitis B virus.

A series of tryptamine derivatives were synthesized and evaluated for their anti-hepatitis B virus (HBV) activity and cytotoxicity in the HepG2.2.15 cell line. The preliminary SAR was discussed. Compounds 2e and 4a showed potent antiviral activity (IC(50)=0.4 and <1 μM, respectively) and low cytotoxicity (CC(50)=40.6 and >25 μM, respectively).

Glycosidic constituents from the roots and rhizomes of Melicope pteleifolia.

Seven new diglycosidic constituents, named pteleifosides A-G (1-7), along with ten known glycosides, were isolated from the roots and rhizomes of Melicope pteleifolia (Champ. ex Benth.) T. Hartley. The structures of the isolated compounds were established on the basis of chemical and spectroscopic methods, mainly 1D and 2D NMR data and mass spectrometry.

Three new Phlegmariurine B type lycopodium alkaloids from Huperzia serrata

Phlegmariurine B ( 1 ), a known alkaloid, along with three new analogous compounds, 2 f -hydroxyphlegmariurine B ( 2 ), 2-oxoyphlegmariurine B ( 3 ) and 11-oxophlegmariurine B ( 4 ), were isolated from the CHCl 3 fraction of total alkaloids of whole plant of the Chinese medicinal herb Huperzia serrata . Their structures were elucidated by spectral analysis.

Chemical constituents from the leaves of Aglaia perviridis

A new cinnamic acid-derived bisamide 1 and a new oplopanone-type sesquiterpenoid diglycoside 2, together with 11 known compounds, were isolated from the 95% ethanolic extract of the leaves of Aglaia perviridis. Their structures were elucidated by chemical and spectroscopic methods.

Two new pregnanes from Aglaia perviridis Hiern

Two new pregnanes, 2α,3α,20-trihydroxy-16β-acetoxy-20(R)-pregnane (1) and 2α,3α,15β-trihydroxy-16β-acetoxy-pregnane-20(R)-methacrylate (2), along with five known compounds, were isolated from the ethanolic extract of the twigs of Aglaia perviridis Hiern using chromatographic methods. The structures of 1 and 2 were elucidated on the basis of spectral data.

Three new hydroxylated serratidine alkaloids from Huperzia serrata.

A known compound, serratidine ( 1 ), along with three hydroxylated serratidine alkaloids, 6 f -hydroxyserratidine ( 2 ), 4 f -hydroxyserratidine ( 3 ) and 4 f ,6 f -dihydroxyserratidine ( 4 ) were isolated from the CHCl 3 fraction of basic materials of whole plant of the Chinese medicinal herb Huperzia serrata . The relative configurations of the above compounds were determined based on 2D NMR studies.

Chemical constituents of Trachelospermum jasminoides

Ten compounds, comprising a new C8 normonoterpenoid glycoside, trachelinoside (1), structurally as 4-(2-O-β-D-glucopyranosyl)-hydroxyethyl-5,5-dimethyldihydrofuran-2(3H)-one, together with nine known compounds, were isolated from the 85% ethanol extract of the vines and leaves of Trachelospermum jasminoides (Lindl.) Lem.

Glycosidic constituents from Carpesium cernuum L.

Carpesides A (1) and B (2), two new 8-O-4′-neolignan glucosides, and eupatriol 9-O-β-d-apiofuranosyl-(1 → 6)-β-d-glucopyranoside (3), one new monoterpenoid diglycoside, together with 10 known glycosidic compounds, were isolated from the aerial part of Carpesium cernuum L. The structures of the new glycosides are elucidated by means of chemical methods and spectroscopic studies.