New Terpenoids from Amentotaxus formosana

Amentotaxins C-V, Structurally Diverse Diterpenoids from the Leaves and Twigs of the Vulnerable Conifer Amentotaxus argotaenia and Their Cytotoxic Effects

A phytochemical investigation of the MeOH extract of the leaves and twigs of Amentotaxus argotaenia, a relict vulnerable coniferous species endemic to China, led to the isolation and characterization of 35 diterpenoids/norditerpenoids. Twenty of these are new, including 11 ent-kaurane-type (amentotaxins C-M, 1-11, respectively), three icetexane-type [= 9(10→20)abeo-abietane-type (amentotaxins N-P, 12-14, respectively)], four ent-labdane-type (amentotaxins Q-T, 15-18, respectively), and two isopimarane-type [amentotaxins U (19) and V (20)] compounds. Their structures were elucidated on the basis of spectroscopic data, single-crystal X-ray diffraction, the modified Mosher's method, and electronic circular dichroism data analyses. Compounds 1-9 are rare 18-nor-ent-kaurane-type diterpenoids featuring a 4β,19-epoxy ring. All the isolates were evaluated for their cytotoxic effects against a small panel of cultured human cancer cell lines (HeLa, A-549, MDA-MB-231, SKOV3, Huh-7, and HCT-116), and some of them exhibited cytotoxicities with IC₅₀ values ranging from 1.5 to 10.0 μM.

Fusariumins C and D, two novel antimicrobial agents from Fusarium oxysporum ZZP-R1 symbiotic on Rumex madaio Makino

Bioassay-guided fractionation of the crude extract of fermentation broth of one symbiotic strain Fusarium oxysporum ZZP-R1 derived from coastal plant Rumex madaio Makino, one traditional Chinese medicine used as a treatment of inflammation and toxication, yielded two novel compounds, fusariumins C (1) and D (2). Chemical structures of 1 and 2 were respectively determined as one meroterpene with cyclohexanone moiety and a sesquiterpene ester with a conjugated triene and an unusual oxetene ring by a combination of spectroscopic methods, including 1D and 2D NMR, mass spectrometry, and optical rotation analysis, as well as by comparison with literature data. Bioassay results indicated that compound 1 displayed potent activity against Staphyloccocus aureus with an MIC value of 6.25 μM, and compound 2 had a moderate inhibitory effect on S. aureus with an MIC value of 25.0 μM. It was the first report that phytochemical investigation of Fusarium strain from R. madaio Makino led to isolation of new antimicrobial agents.

Benzoxetes and benzothietes--heterocyclic analogues of benzocyclobutene

Benzo-condensed four-ring heterocycles, such as benzoxetes 1 and benzothietes 3 represent multi-purpose starting compounds for the preparation of various higher heterocyclic ring systems. The thermal or photochemical valence isomerizations between the benzenoid forms 1,3 and the higher reactive o-quinoid structures 2,4 provide the basis for the synthetic applications. On the other hand, this valence isomerization impedes in particular the generation and storage of 1 because the thermal equilibrium 1 ⇆ 2 is completely on the side of 2. Thus, the number of erroneous or questionable benzoxete structures published to date is surprisingly high. On the contrary, the thermal equilibrium 3 ⇆ 4 is on the side of the benzothietes 3, which makes them easily accessible, especially by different flash vacuum pyrolysis techniques. The present article gives a survey of the preparations of 1 and 2, and tries to stimulate their use in synthetic projects. Naphtho-condensed and higher condensed compounds and compounds with an exocyclic C=O or S=O double bond (lactones, thiolactones, sulfoxides and sulfones) are not covered in this article.

Xanthine oxidase inhibitory terpenoids of Amentotaxus formosana protect cisplatin-induced cell death by reducing reactive oxygen species (ROS) in normal human urothelial and bladder cancer cells

The diterpenoids (+)-ferruginol (1), ent-kaur-16-en-15-one (2), ent-8(14),15-sandaracopimaradiene-2α,18-diol (3), 8(14),15-sandaracopimaradiene-2α,18,19-triol (4), and (+)-sugiol (5) and the triterpenoids 3β-methoxycycloartan-24(24(1))-ene (6), 3β,23β-dimethoxycycloartan-24(24(1))-ene (7), 3β,23β-dimethoxy-5α-lanosta-24(24(1))-ene (8), and 23(S)-23-methoxy-24-methylenelanosta-8-en-3-one (9), isolated from Amentotaxus formosana, showed inhibitory effects on xanthine oxidase (XO). Of the compounds tested, compound 5 was a potent inhibitor of XO activity, with an IC(50) value of 6.8±0.4 μM, while displaying weak ABTS radical cation scavenging activity. Treatment of the bladder cancer cell line, NTUB1, with 3-10 μM of compound 5 and 10 μM cisplatin, and immortalized normal human urothelial cell line, SV-HUC1, with 0.3-1 μM and 10-50 μM of compound 5 and 10 μM cisplatin, respectively, resulted in increased viability of cells compared with cytotoxicity induced by cisplatin. Treatment of NTUB1 with 20 μM cisplatin and 10 or 30 μM of compound 5 resulted in decreased ROS production compared with ROS production induced by cisplatin. These results indicate that 10 or 30 μM of compound 5 in NTUB1 cells may mediate through the suppression of XO activity and reduction of reactive oxygen species (ROS) induced by compound 5 cotreated with 20 μM cisplatin and protection of subsequent cell death.