Cytotoxic ent-kaurane diterpenoids from Isodon macrophyllus.

Two new ent-kaurane diterpenoids, dayecrystals D-E (1-2), together with nine known compounds, isojaponin A (3), rabdosin A (4), lushanrubescensin J (5), wikstroemioidin B (6), maoyecrystal C (7), rabdosin B (8), isodonal (9), shikokianin (10), and effusanin A (11), were isolated from the leaves of Isodon macrophyllus. The structures of the new compounds were elucidated using 1D and 2D NMR spectroscopy. The (13)C-NMR spectral data of compound 4 are reported for the first time. All of the compounds were tested for their cytotoxicities against DU145 and LoVo human tumor cells. Compounds 4, 10, and 11 showed inhibitory effects on DU145 cells with IC(50) values 5.90, 4.24, and 3.16 microM, and LoVo cells with IC(50) values 14.20, 17.55, and 3.02 microM, respectively.

[Chemical constituents of Isodon macrophyllus (II)].

OBJECTIVE: To study the chemical constituents of Isodon macrophyllus. METHODS: Compounds were spearated and purified by silica gel column chromatography and their structures were elucidated on the basis of spectral data and chemical evidences. RESULTS: Six compounds were obtained from EtOAc extract of leaves of Isodon macroplhllus and identified as rabdophyllin H(I), lushan-ruhescensins F(II), maovecrystal J(III), Taibaijap onicain A(IV), rabdosinate(V), dancostero(VI). CONCLUSION: Co mpounds II-IV were isolated from this plant for the first time.

[Effect of calpain on the degradation of tau protein in rat brain cortex extracts].

Calpain is a calcium-activated protease and has two ubiquitously distributed mammalian isoforms, namely calpain 1 (calpain I, mu-calpain and CAPN1) and calpain 2 (calpain II, m-calpain and CAPN2). Calpains regulate the function of many proteins by limited proteolysis. To determine the nature of different subtypes of calpain on degradation of microtubule-associated protein tau, the rat cortex extracts were incubated with 0.2 mmol/L, 1 mmol/L, 3 mmol/L and 5 mmol/L of CaCl(2 )for 15 min at 37 degrees C, respectively, and it was found that Ca(2+) treatment at concentrations 1-5 mmol/L led to significant proteolysis of the tau protein and this degradation was blocked by calpain inhibitor, calpeptin. In addition, when the extracts containing 1 mmol/L CaCl(2 )were treated with mu-calpain inhibitor (0.05 micromol/L of calpastatin) or m-calpain inhibitor (100 micromol/L calpain inhibitor IV) or both, the Ca(2+)-induced degradation of tau protein was blocked to about 8.6% 92.5% and 97.8% compared with the group with 1 mmol/L CaCl(2), respectively. These data suggest that both mu-calpain and m-calpain in brain cortex extracts are activated by Ca(2+) and both of them degraded tau protein, although, m-calpain plays a more important role in proteolysis of the tau protein.