Opposite effects of isoniazid and fasting on the expression of CYP2E1 protein and mRNA in house musk shrew (Suncus murinus).

The effects of isoniazid and fasting on hepatic CYP2E1 in the suncus were investigated. Aniline hydroxylation and N-nitrosodimethylamine demethylation, which are known to be catalyzed by CYP2E1, in liver microsomes were induced and suppressed by the treatment with isoniazid and the fasting, respectively. Immunoblot analysis indicated that CYP2E1 protein in liver microsomes from isoniazid-treated suncus was increased in contrast to the result with the fasting of the suncus. Northern blot analysis showed that the treatment of suncus with isoniazid increased the expression of CYP2E1 mRNA in livers although the fasting of the suncus significantly decreased CYP2E1 mRNA. These results suggest that the regulation of hepatic CYP2E1 in the suncus by treatment with isoniazid and fasting was different from that in rats.

Evidence for the lack of hepatic N-acetyltransferase in suncus (Suncus murinus).

The abilities of liver cytosol fractions from the suncus and Sprague-Dawley (SD) rats to N-acetylate aniline, p-aminobenzoic acid, p-aminosalicylic acid and 2-aminofluorene (AF) were compared. The cytosol from rats N-acetylated these substrates at efficient rates, whereas the cytosol from the suncus did not N-acetylate these substrates at detectable rates. When AF was given to the suncus, 2-acetylaminofluorene (AAF), a metabolite of AF formed by N-acetyltransferase (NAT), was not detectable in serum, whereas the metabolite was seen clearly in rats. Northern blot and Southern blot analyses, using cDNAs coding for human NATs as probes, indicated that not only the transcripts but also the genes of the enzymes were undetectable in suncus. These results suggest that the suncus is among the few species known to lack NATs.

Activities of drug-metabolizing enzymes in the liver of Suncus murinus: possible lack of N-acetyltransferase activity in liver cytosol.

The amounts of several drug-metabolizing enzymes in livers of Suncus murinus (suncus) were studied in comparison with rats. The content of cytochrome P450 in suncus was less than one third that seen in rats. Activities of glutathione S-transferase, UDP-glucuronyltransferase and arylhydroxycarbon hydroxylase in suncus were less than half those in rats. Activity of flavin-containing monooxygenase in suncus was 71% that of rats. Interestingly, N-acetyltransferase (NAT) activity in suncus liver cytosols was not detectable: no detectable activities were seen with aniline, p-aminobenzoic acid and p-amino-salicylic acid as substrates. We propose that suncus is a unique animal possibly lacking NAT in liver cytosol.

Decrease in the content of cytochrome P450IIE by fasting in liver microsomes of house musk shrew (Suncus murinus).

The effects of fasting on hepatic cytochrome P450 in the mature male house musk shrew, Suncus murinus (suncus), were studied by Western blot analyses and enzyme assays. The content of P450IIE protein was decreased, by fasting, to 24% of the control level in contrast to the results with rats, in which P450IIE protein was increased to 172% by fasting. These changes reflected on catalytic activities, such as aniline hydroxylase and N-nitrosodimethylamine demethylase activities, which were decreased to about 45% and 28%, respectively, of the control levels by fasting, while in fasting rats, the catalytic activities of these enzymes were 2-3-fold higher than in controls.

Effects of Catuaba extracts on microbial and HIV infection.

Pretreatment of mice with hot water and alkaline extracts of Catuaba casca (Erythroxylum catuaba Arr. Cam.) effectively protected them from lethal infection of Escherichia coli and Staphylococcus aureus. The extracts significantly inhibited both the human immunodeficiency virus (HIV)-induced cytopathic effect and the expression of HIV antigen in HIV-1HTLV-IIIB or HIV-2ROD infected human lymphotropic virus type I (HTLV-1) positive MT-4 cells. The 50% effective concentrations of the active fractions (21-263 micrograms/ml) were 1/4 - 1/43 of their 50% cytotoxic concentrations. Their anti-HIV activity was shown to be induced, at least in part, via the inhibition of HIV adsorption to the cells. The data suggest a medicinal potential of Catuaba extracts against opportunistic infection in HIV patients.

Formation of an antibacterial metabolite from a new macrolide compound 23-O-benzyl-5-mycaminosyl-tylonolide (TMC-101), by a hepatic microsomal drug-metabolizing enzyme system.

Upon incubation of 23-O-benzyl-5-mycaminosyl-tylonolide (TMC-101) with liver microsomes in the presence of an nicotinamide adenine dinucleotide phosphate-generating system, at least four metabolites were formed: two of them were also formed by an enzyme(s) in rat serum. One of the metabolites formed by liver microsomes possessed antibacterial activity comparable to TMC-101 as examined by bioautography using Micrococcus luteus ATCC 9341 as a tester strain. Incubation of TMC-101 with rat serum degraded most of the parent compound and did not form the active metabolite. The capacity of liver microsomes to produce the active metabolite was increased by pretreatment of rats with 3-methylcholanthrene, phenobarbital and polychlorinated biphenyl. The metabolite with the antibacterial activity was estimated not to be formed by the N-demethylation of TMC-101, and was chemically unstable.

[Antitussive and expectorant effects of Asada-ame extract].

Asada-ame containing Platycodi Radix, Ginseng Radix, Ephedrae Herba and Ipecacuanhae Radix extracts has been hitherto widely used as an antitussive and expectorant. In the present study, the antitussive effect and tracheo-bronchial secretory activity of Asada-ame extract (AE) were investigated with laboratory animals. Antitussive effect was evaluated with the puncture electrode-induced cough method in conscious guinea pigs. AE showed a significant antitussive effect which lasted more than one hr. 50% Antitussive doses were 76 mg/kg, i.p., and 500 mg/kg, p.o. Airway secretory effect was evaluated with the stopper method in anesthetized dogs. With oral administration of AE, the volume of respiratory tract fluid (RTF) increased, and viscosity of RTF, which was determined using the glass plate method, was decreased in a dose-dependent manner. The effects of AE on secretory activity of canine tracheal secretory cells were investigated in vitro with the histological/histochemical technique. With AE treatment, the thickness of the acini of submucosal glands was decreased, and the ratio of acinar inner diameter of the gland to tracheal wall was increased. Furthermore, the number of acid glycoprotein-containing submucosal glandular cells was decreased by AE, suggesting a mucolytic effect of AE. The above findings indicate that AE has significant antitussive and expectorant effects.