A scheme for rapid evaluation of the intermolecular three-body polarization effect in water clusters.

The ability to accurately and rapidly evaluate the intermolecular many-body polarization effect of the water system is very important for computer simulations of biomolecule in aqueous. In this paper, a scheme is proposed based on the polarizable dipole-dipole interaction model and used to rapidly estimate the intermolecular many-body polarization effect in water clusters. We use a bond-dipole-based polarization function to evaluate the polarization energy. We regard two OH bonds of a water molecule as two bond-dipoles and set the permanent OH bond-dipole moment of a water molecule to be 1.51 Debye. We estimate the induced OH bond-dipole moment via a simple formula in which only one correction factor is needed. This scheme is then applied to tens of water clusters to calculate the three- and four-body interaction energies. The three-body interaction energies of 93 water clusters produced by our scheme are compared with those produced by the counterpoise-corrected CCSD(T)/aug-cc-pVDZ, MP2/aug-cc-pVDZ, M06-2X/jul-cc-pVTZ methods, by the AMOEBApro13, iAMOEBA, AMOEBA+, AMOEBA+(CF) methods, and by the MB-pol method. The four-body interaction energies of 47 water clusters yielded by our scheme are compared with those yielded by the counterpoise-corrected MP2/aug-cc-pVDZ and M06-2X/ jul-cc-pVTZ methods, by the AMOEBApro13, AMOEBA+, AMOEBA+(CF) methods, and by the MB-pol method. The comparison results show that the scheme proposed in this paper can reproduce the counterpoise-corrected CCSD(T)/aug-cc-pVDZ three-body interaction energies and reproduce the counterpoise-corrected MP2/aug-cc-pVDZ four-body interaction energies both accurately and efficiently. We anticipate the scheme proposed here can be useful for computer simulations of liquid water and aqueous solutions.

[Effect of HumicAcid-Heavy Metals on the Nitrogen Removal Performance of ANAMMOX Bacteria and Its Kinetic Analysis].

The effects of two typical heavy metal ions[Cu(Ⅱ) and Ni(Ⅱ)] and humic acid on ANAMMOX nitrogen removal (SAA) were studied through batch experiments, and the kinetic model was analyzed. At the same time, the effects of humic acid-heavy metal on ANAMMOX nitrogen removal were discussed. The results showed that ANAMMOX was promoted when ρ[Cu(Ⅱ)] and ρ[Ni(Ⅱ)] were 3 mg·L-1, and SAA was increased by 8.64% and 7.78%, respectively; ANAMMOX was inhibited when the ρ[Cu(Ⅱ)] and ρ[Ni(Ⅱ)] were 20 mg·L-1 and 5 mg·L-1, respectively, and the inhibition effect was more significant with the increase in heavy metal ion concentration. The index fitting showed that the IC50 of Cu(Ⅱ) and Ni(Ⅱ) on ANAMMOX were 29.67 mg·L-1 and 28.75 mg·L-1, respectively. SAA was increased by 7.37% when the ρ(humic acid) was 1 mg·L-1, and the inhibition rate reached 36.80% when the humic acid concentration was 40 mg·L-1. The linear fitting showed that the IC50 of humic acid on ANAMMOX was 58.36 mg·L-1. The modified Michaelis-Menten model could better describe the inhibitory kinetic behavior of heavy metals and humic acid on ANAMMOX. The model fitting showed that the complete inhibition concentrations (I*) of Cu(Ⅱ), Ni(Ⅱ), and humic acid on ANAMMOX were 49.59, 74.46, and 84.27 mg·L-1, respectively. An appropriate amount of humic acid was beneficial to improve the inhibition of heavy metals on ANAMMOX bacteria activity, and excessive humic acid would cause inhibition on ANAMMOX bacteria again.

[Warm-needle moxibustion therapy may reduce aspirin-induced gastric mucosal injury in rats].

OBJECTIVE: To observe the effect of warm-needle moxibustion on the gastric mucosal injury caused by anti-rheumatic dose of Aspirin. METHODS: Forty SD rats were equally randomized into blank group, model group, warm needling group and Omeprazole (for relieving peptic ulcer) group, with 10 rats in each. The rats were forced to undergo 12 hours' fasting and 4 hours' water-deprivation before the experiments. Normal saline (10 mL/kg) was given to the rats in the blank group. Gastric mucosa lesion model was established by intragastric infusion of aspirin (420 mg/kg). Warm needling was applied to "Zhong-wan" (CV 12), "Xiawan" (CV 10), "Zusanli" (ST 36) and "Neiguan" (PC 6) for 30 min, once a day for 7 days. The rats of the Omeprazole group were fed with Omeprazole( 10 mg/100 g body weight) once a day for 7 days. According to Guth's method, the ulcer index (UI) of the gastric mucosa was calculated following killing the rats. The activity of superoxide dismutase (SOD) and the levels of malondialdehyde (MDA) in the serum and gastric mucosa were detected with hydroxylamine method and thiobarbituric acid method, respectively. RESULTS: Compared with the blank group, the gastric UI, MDA levels of both serum and gastric mucosa in the model group were increased obviously (P<0. 01), while serum and gastric mucosal SOD activity in the model group were decreased considerably (P<0. 01). In comparison with the model group, the gastric UI, and both serum and gastric mucosal MDA contents in the warm needling group and Omeprazole group were down-regulated significantly (P<0. 01), whereas both serum and mucosal SOD activity in the warm needling group and serum SOD activity in the Omeprazole group were up-regulated significantly (P<0. 01). Comparison between the warm needling group and Omeprazole group showed that the UI, both serum and gastric mucosal SOD activity, and serum MDA level of the former group were evidently higher than those of the Omeprazole group (P<0. 05), but gastric mucosal MDA level of the warm needling group was apparently lower than that of the Omeprazole group (P<0.05). CONCLUSION: Warm-needle moxibustion can reduce the gastric lesion (ulcer) caused by aspirin in the rat, which may be closed associated with its effects in up-regulating both serum and gastric mucosal SOD activity and down-regulating both serum and gastric mucosal MDA levels.

Induction of leukemia cell apoptosis by cheliensisin A involves down-regulation of Bcl-2 expression.

AIM: To investigate the apoptosis-inducing effect of cheliensisin A (GC-51), a novel styryl-lactone isolated from Goniothalamus cheliensis, on human promyelocytic leukemia HL-60 cells and the mechanism of action involved. METHODS: Apoptotic cell death was determined by morphological examination and DNA agarose gel electrophoresis. The activity of caspase-3 was assessed using Western blotting and the expression of Bcl-2 and Bax genes was analyzed using the reverse transcription-polymerase chain reaction (RT-PCR) method. RESULTS: GC-51 significantly inhibited the proliferation of HL-60 cells with an IC50 of 2.4+/-0.2 micromol/L and effectively induced apoptosis in HL-60 cells. Exposure of HL-60 cells to 10 micromol/L GC-51 for 8 h resulted in approximately 53% of the cells undergoing apoptosis. Caspase-3 was activated in GC-51-treated cells, which was manifested by the appearance of the 17 kDa active form of caspase-3 and the cleavage of poly(ADP-ribose) polymerase (PARP). Meanwhile, GC-51 markedly reduced the expression of the anti-apoptotic gene Bcl-2 and increased the expression of the pro-apoptotic gene Bax. The apoptosis-inducing effect of GC-51 was cAMP-dependent protein kinase (PKA) dependent because PKA, but not the protein kinase C, specific inhibitor H-89, blocked the induction of apoptosis by GC-51 in HL-60 cells. CONCLUSION: The results demonstrate that GC-51 effectively induces apoptosis in HL-60 cells and that this effect is PKA-dependent and involves the downregulation of Bcl-2 expression and the activation of caspase-3.

Constituents from the stems of Goniothalamus griffithii.

A new cyclopeptide, grifficyclocin A (1), and a new aporphine alkaloid, griffinin (2) were isolated together with two known styryllactones from the stems of Goniothalamus griffithii. Their structures were identified spectroscopically and chemically. Among them, the griffinin (2) was isolated as the enol form in two tautomers, and the two known styryllactones, goniothalamin (3) and 8- O-acetylgoniotriol (4), showed selective in vitro antitumor activities.

Abietane diterpenoids from Coleus xanthanthus.

Eight new abietane diterpenoids, coleon U 11-acetate (1), 16-acetoxycoleon U 11-acetate (2), and xanthanthusins F-K (3-8), together with five known analogues, coleon U (9), 16-O-acetylcoleon C (10), coleon U-quinone (11), 8alpha,9alpha-epoxycoleon U-quinone (12), and xanthanthusin E (13), were isolated from the aerial parts of Coleus xanthanthus. The structures of 1-8 were elucidated on the basis of spectral methods. Compounds 1, 5, and 11-13 were evaluated for their cytotoxicity against K562 human leukemia cells.

Diterpenoids from Isodon enanderianus.

Four ent-kauranoids, 6-epiangustifolin and enanderinanins F-H, as well as 11 known ent-kaurane diterpenoids, macrocalin B, xerophilusin A, trichorabdal A, trichorabdal B, effusin, angustifolin, longikaurin D, longikaurin F, enanderinanin B, xerophilusin G and shikokianin were isolated from the aerial parts of Isodon enanderianus. The new diterpenoids were identified as 6-epiangustifolin (11alpha-hydroxy-6alpha-methoxy-6,19-epoxy-6,7-seco-ent-kaur-16-en-15-one-7,20-olide), enanderinanin F (19-acetoxy-6,20:6,11beta-diepoxy-6,7-seco-ent-kaur-16-en-15-one-1beta,7-olide), enanderinanin G (1beta,6beta,7beta-trihydroxy-19-acetoxy-16beta-methoxymethyl-7alpha,20-epoxy-ent-kaur-15-one) and enanderinanin H (6beta,7beta,14beta-trihydroxy-1alpha,11beta-acetonide-7alpha,20-epoxy-ent-kaur-16-en-15-one), respectively, on the basis of spectral data, especially by 2D NMR techniques. 6-Epiangustifolin showed significant cytotoxic activity against K562 cell.