Merging the Non-Natural Catalytic Activity of Lipase and Electrosynthesis: Asymmetric Oxidative Cross-Coupling of Secondary Amines with Ketones.

We describe the enantioselective oxidative cross-coupling of secondary amines with ketones by combining the non-natural catalytic activity of lipase with electrosynthesis. Various 2,2-disubstituted 3-carbonyl indoles with a stereogenic quaternary carbon center were synthesized from 2-substituted indoles in yields up to 78 % with good enantio- and diastereoselectivities (up to 96 : 4 e.r. and >20 : 1 d.r.). This unprecedented protocol demonstrated that hydrolase catalysis is compatible with electrosynthesis, and the reaction can be carried out in organic solvents with a broad substrate scope and good stereoselectivity. This work provides insights into enzymatic electrosynthesis.

Cytotoxic Triterpenoids from Roots of Actinidia chinensis.

Phytochmical investigation of roots of Actinidia chinensisPlanch. led to the isolation triterpenoids 1 - 16, including a new compound 2α,3α,23,24-tetrahydroxyursa-12,20(30)-dien-28-oic acid (1). Their structures were identified on the basis of spectroscopic analysis, including 1D- and 2D-NMR, HR-ESI mass spectrometry, and by comparison with the literatures. The cytotoxicities of triterpenoids 1 - 16 against a panel of cultured human cancer cell lines (HepG2, A549, MCF-7, SK-OV-3, and HeLa) were evaluated. The new compound 1 exhibited moderate antitumor activities with IC50 values of 19.62 ± 0.81, 18.86 ± 1.56, 45.94 ± 3.62, 62.41 ± 2.29, and 28.74 ± 1.07 µm, respectively. The experiment data might be available to explain the use of roots of A. chinensis to treat various cancers in traditional Chinese medicine.

[Chemical constituents from roots of Actinidia rufa and their cytotoxicity].

To investigate the chemical compounds from the roots of Actinidia rufa, nine compounds were isolated by various column chromatography on silica gel and Sephadex LH-20, and high performance liquid chromatography (HPLC). Their structures were elucidated as 2α, 3ß, 19α, 23, 24-pentahydroxyurs-12-en-28-oic acid-28-O-ß-D-glucopyranoside (1), 2α, 3α, 19α, 24-tetrahydroxyurs-12-en-28-oic acid-28-O-ß-D-glucopyranoside (2), 2α, 3α, 24-trihydroxyurs-12-en-28-oic acid (3), 2α, 3α, 24-trihydroxyolean-12-en-28-oic acid (4), 2α, 3α, 23, 24-tetrahydroxyurs -12-en-28-oic acid (5), 2α, 3ß, 23, 24-tetrah-ydroxyurs-12-en-28-oic acid (6), 2α, 3ß, 23-trihydroxy-12-en-28-oic acid (7), 2α, 3ß, 23-trihydroxyurs-12, 20(30)-dien-28-oic acid (8), and 2α, 3α, 23-trihydroxyurs-12, 20(30)-dien-28-oic acid (9). Compounds 1 and 2 were isolated from the Actinidia genus for the first time. Compounds 2, 3, and 4 showed cytotoxic activity against human SKVO3 and TPC-1 cancer cell lines with IC50 values ranging from 10.99 to 16.41 µmol•L⁻¹, compounds 3 and 4 have cytotoxic activity against human HeLa cancer cell line with IC50 values of 15.53 and 13.07 µmol•L⁻¹, respectively.

External Noise and External Signal Induced Transition of Gene Switch and Coherence Resonance in the Genetic Regulatory System.

The transition of gene switch induced by external noises (multiplicative external noise and additive external noise) and external signals is investigated in the genetic regulatory system. Results show that the state-to-state transition of gene switch as well as resonant behaviors, such as the explicit coherence resonance (ECR), implicit coherence resonance (ICR) and control parameter coherence biresonance (CPCBR), can appear when noises are injected into the genetic regulatory system. The ECR is increased with the increase of the control parameter value when starting from the supercritical Hopf bifurcation parameter point, and there exists a critical control parameter value for the occurrence of ECR. However, the ICR is decreased as the control parameter value is increased when starting from the subcritical Hopf bifurcation point. In particular, the coherence of ECR is higher and more sensitive to noise than that of ICR. When an external signal is introduced into the system, the enhancement or suppression of the CPCBR and the number of peaks strongly depend on the frequency and amplitude of the external signal. Furthermore, the gene regulation system can selectively enhance or decrease the noise-induced oscillation signals at preferred frequency and amplitude of an external signal.

[Studies on the chemical constituents of ethyl acetate extract from the roots of Actinidia chrysantha].

OBJECTIVE: To study the chemical constituents of ethyl acetate extract from the roots of Actinidia chrysantha. METHODS: Chromatographic methods were used to isolate the compounds from ethyl acetate extract from the roots of Actinidia chrysantha and chemical and spectral methods were used to elucidate the structures of the isolated compounds. RESULTS: Five compounds were identified as stigmast-3, 6-dione (I), beta-sitosterol (II), ursolicacid (III), beta-daucosterol (IV), 2alpha, 3beta, 23-triol-12-en-28-ursolic acid (V). CONCLUSION: Those compounds are obtained from the plant for the first time.

[Anti-tumor mechanism of active components from extract of Actinidia rufa root].

OBJECTIVE: To observe effect and mechanism of n-Butanol lysate of alcohol extracts from Actinidia rufa root (monomer of R6,R8). METHOD: Tunel, Wright's stain with Giemsa's stain dyeing, and Hoechst 33258-PI double dyeing assay were used to detect the apoptosis of SGC7901 tumor cells treated with R6, R8. The SGC7901 tumor cells were randomly divided into control group and two treatment groups administered 0.05 g x L(-1) R6, R8, respectively, for 72 h). FCM assay was used to detect the apoptosis. Agarose electrophoresis assay was used to detect DNA strand break of tumor cells and reveal anti-tumor action mechanism. RESULT: The apoptosis percentage of the tumor cell in 24 h, 48 h, 72 h was (17.08 +/- 2.78)% , (29.68 +/- 2.96)%, (52.46 +/- 3.81)%; (14.75 +/- 2.14)%, (27.35 +/- 3.79)%, (45.64 +/- 5.24)%, respectively, for the treatment group, significantly higher than that in the control group (1.94 +/- 1.55)%, (2.78 +/- 1.84)%, (11.8 +/- 2.79)% (P < 0.01) by tunnel assay. Wright's stain with Giemsa's stain dyeing assay, Hoechst 33258-PI and FCM double dyeing assay showed same action. R6 and R8 had the effect of inducing the DNA histogram of tumor cells (P < 0.01). CONCLUSION: The anti-tumor mechanisms may be associated with inducing the injury of DNA and stimulating apoptosis.

Total synthesis of epothilone a through stereospecific epoxidation of the p-methoxybenzyl ether of epothilone C.

The total synthesis of epothilone A is described by the coupling four segments 4-7 a. Three of the segments, 4, 5 and 7 a, have only one chiral center; all other chiral centers were introduced by simple asymmetric catalytic reactions. The key steps are the ring opening of epoxide 5 with acetylide 8 for the construction of the C12-C13 cis double bond and a practical hydrolytic kinetic resolution (HKR) developed by Jacobsen group for the introduction the chiral center at C3. Especially, the stereospecific epoxidation of 3-O-PMB epothilone C 3 b through long-range effect of 3-O-PMB protecting group gave high yields of the C12-C13 alpha-epoxide for the synthesis of target molecule.