Reactions of Low-Valent Gallium Species with Organic Azides: Formation of Imido-, Azoimido-, and Tetrazene Complexes.

The reactivity of two α-diimine-ligated digallanes, [L2-Ga-GaL2-] (La = [(2,6-iPr2C6H3)NC(CH3)]2, dpp-dad, 1; Lb = 1,2-[(2,6-iPr2C6H3)NC]2C10H6, dpp-bian, 2), and a gallylene, [(La)2-GaNa(THF)3] (3), toward organic azides was studied. Reaction of digallane 1 or 2 with trimethylsilyl azide (Me3SiN3), 2-azido-benzonitrile (2-CNC6H4N3), or tosylazide (TosN3) results in imido-bridged complexes, [(La)·-Ga(µ-NSiMe3)2Ga(La)·-] (4) [(Lb)·-Ga(µ-NSiMe3)2Ga(Lb)·-] (5), [(Lb)·-Ga(µ-2-CNC6H4N)2Ga(Lb)·-] (6), and [(Lb)·-Ga(µ-NTos)2Ga(Lb)·-] (7), with elimination of dinitrogen. Treatment of 1 or 2 with 1-adamantyl azide (1-AdN3), on the other hand, affords the unsymmetrical dinuclear complexes [(La)·-Ga(NAd)(N3Ad)Ga(La)·-] (8) and [(Lb)·-Ga(NAd)(N3Ad)Ga(Lb)·-] (9), which contain both imido and triazene bridges. Different from the Ga(II) complexes 1 and 2, the reactions of Ga(I) species 3 with benzylazide or trimethylsilyl azide result in the tetrazene complex {Na(THF)}2[(La)2-Ga(benzyl-N4-benzyl)]2 (10) and amide complex {Na(THF)4}[(La)2-Ga(NHSiMe3)(benzyl)] (11). It is likely that these latter transformations proceed via the transient formation of the corresponding Ga═N imide complex, which undergoes either cycloaddition with a second azide (to form 10) or activation of the C-H bond of methyl in one solvent toluene molecule (to yield 11).

[Synthesis and biological evaluation of nitrate-oleanolic acid hybrids as inhibitors of HepG2 cell apoptosis].

To find novel antihepatitis drugs, a series of nitrate-oleanolic acid (OA) hybrids (10a, 10b, 11a-11e and 12a-12c) were designed and synthesized on the basis of previous studies using OA as lead compound, which is widely found in natural plants and liver-specific metabolism. In the present study, ten novel NO-releasing derivatives of OA were synthesized by connecting nitrate to the OA-3-OH through varying lengths of linkers containing antioxidants which were designed to increase the ability of these target compounds to scavenge free radicals. The structures of these objective compounds were determined by IR, MS, 1H NMR and elemental analysis. Their protective effects on anti-Fas mediated HepG2 cell apoptosis were in vitro evaluated by LDH assay. Compound 12a is the most potent inhibitor. Its effect on anti-Fas mediated HepG2 cell apoptosis and amount of NO-releasing in vitro are similar to those of positive control NCX-1000.

Effects of the extract of a Chinese herb Tripterygium wilfordii hook f on rat pituitary gland.

In China, the ethylacetate extract of the herb Tripterygium wilfordii Hook f (TWEE), containing the major active ingredient triptolide, is often used with favorable effect on rheumatoid arthritis patients, in alternation with the use of prednisone. The mechanism of this therapeutic effect, however, has not been completely delineated. In this study, we studied how TWEE and prednisone affect the pituitary and adrenal glands in rats. Thirty normal male Sprague-Dawley rats (ten per group) were randomly assigned to receive: (1) TWEE (25 mg/kg, twice a day), (2) prednisone (2 mg/kg, twice a day), or (3) vehicle (control) (0.5% sodium carboxymethyl cellulose 1 ml, twice a day), orally for 30 days. Pituitary and trunk blood were collected on day 31. Adrenocorticotropic hormone (ACTH) expression in the pituitary gland was assessed morphologically by immunohistochemical techniques. Plasma ACTH concentrations and serum corticosterone concentrations were quantitatively measured by radioimmunoassay. We found that TWEE significantly increased plasma ACTH concentration and serum corticosterone concentration and dramatically increased the number of ACTH-positive cells in the pituitary. Our findings indicate that TWEE can promote the synthesis and secretion of ACTH cells--in the pars distalis of the rat pituitary gland and the production of corticosterone in the zone fasciculata of the adrenal cortex. Our results indicate that TWEE has a cortical hormone-like function and can promote adrenal cortex function by activating the hypothalamus-pituitary-adrenal axis.

[Basic study of biodegradable controlled release chemotherapy].

This study sought to assess the biocompatibility of P(DA-SA)-Adriamycin, a new controlled-release chemotherapy system, in rabbit brain, and to examine its controlled release effect both in vitro and in vivo and its curative effects in vitro. The reaction of animal brain to the implanted P(DA-SA) or P(DA-SA)-Adriamycin was observed. The controlled-release profiles in phosphate buffer solutions and in rabbit brain were measured by UV spectrometry. Then, through flow cytometer, the rate of apoptosis in cultured glioma cells was tested. The reaction of rabbit brain to P(DA-SA) polymer was moderate and not significantly different from that to Gelfoam. The controlled-release rate of P(DA-SA)-Adriamycin in vitro and in vivo was stable and the duration of controlled-release of P(DA-SA)-Adriamycin spanned three weeks. The rate for apoptosis of glioma cells of P(DA-SA)-Adriamycin group was 69.9%, which was significantly higher than that of the control group. In conclusion, P (DA-SA)-Adriamycin controlled release chemotherapy system that bears curative effect has favorable controlled-release effect and good biocompatibility in rabbit brain. This system has potential value in treatment of malignant brain tumor.