Novel tetrahydrofuran derivatives from Trigonostemon howii with their potential anti-HIV-1 activities.

A novel tetrahydrofuran derivative, trigonohowine (1), together with five known tetrahydrofuran derivatives (2-6), were isolated from the stems and leaves of Trigonostemon howii. The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with the data reported in literature. Among them, trigonohowine (1) represents the first example of a new type of tetrahydrofuran derivative, possessing an unprecedented carbon skeleton containing 23 carbon atoms on the carbon skeleton and the known compouds (2-6) are rare tetrahydrofuran derivatives in the plant kingdom with various carbon skeletons. All isolated compounds were evaluated for their anti-HIV-1 activities. Compounds 1-6 showed significant anti-HIV-1 activities with EC50 ranged from 0.08 to 1.03 µM. These findings suggest that the discoveries of these tetrahydrofuran derivatives with significant anti-HIV-1 activities isolated from T. howii could be of great importance to the development of new anti-HIV agents.

Carbazole alkaloids from Clausena hainanensis with their potential antiproliferative activities.

Five new carbazole alkaloids, clausehainanines A-E (1-5), together with seven known analogues (6-12) were isolated from the stems and leaves of C. hainanensis. Their structures were elucidated by extensive spectroscopic methods. Among them, compounds 1-5 were an unusual type of carbazole alkaloids, possessing diverse isopentenyl derivatives as substituents at C-2. 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. Alkaloids 1-12 showed significant antiproliferative effects against various human cancer cell lines with IC50 values ranging from 0.12 to 15.56 µM. These findings suggest that the discoveries of these carbazole alkaloids with significant cytotoxic activities isolated from C. hainanensis could be of great importance to the development of new anticancer agents.

Cytotoxic indole alkaloids from Nauclea orientalis.

A new indole alkaloid, nauclorienine (1), along with seven known alkaloids (2-8), were isolated from the stems and leaves of Nauclea orientalis. Among them, nauclorienine (1) was a new indole alkaloid holding a rare corynanthe-type skeleton, and the known compounds (2-8) were isolated from N. orientalis for the first time. Their structures were elucidated on the basis of extensive spectroscopic data analyses. All isolated 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 1-4 exhibited significant inhibitory effects against various human cancer cell lines with IC50 values comparable to those of cisplatin.

Bioactive furanocoumarins from the stems and leaves of Clausena hainanensis.

A new furanocoumarin, clauhainanin A (1), together with seven known furanocoumarins (2-8), were isolated from the stems and leaves of Clausena hainanensis. The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in the literature. All known compounds (2-8) were isolated from C. hainanensis for the first time. All isolated compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1-8 exhibited significant inhibitory effects with IC50 values ranging from 1.36 to 18.96 µM.