Antiviral potential of a proteolytic inhibitor from Streptomyces chromofuscus 34-1

International audienceThe novel proteinaceous protease inhibitor, isolated from the culture supernatants of Streptomyces chromopfuscus 34-1 (SS 34-1) demonstrated a specific and selective anti-influenza virus effect. By the use of complementary virological assays it was demonstrated that the expression of the viral haemagglutinin (HA) on the surface of infected cells, the virus-induced cytopathic effect (CPE) and the infectious virus yields (IVY), used as measures of A/Germany/34, strain Rostock (H7N1) (A/Rostock) virus growth, were all reduced at non-toxic concentrations of SS 34-1 in a dose-dependent way. In a single cycle of viral growth, the penetration of viral particles and the late stages of viral replication were the most susceptible to inhibition. The preparation protected mice from mortality in the experimental A/Aichi/2/68 (H3N2) influenza virus infection. The SS 34-1-treatment (0.16 mg/mouse/day) of virus-infected mice led to a considerable reduction of mortality rate (index of protection = 71.0%) and marked prolongation of mean survival time (+ 5.5 days). The lesions of the lungs due to infection as well as lung infectious virus titres were significantly reduced - delta log(10)TCID(50)/ml up to 4.5. The application of SS 34-1 induced a continuous rise of the anti-protease activity but did not cause substantial changes in the lung protease activity of healthy mice. The infection triggered a slight reduction of protease activity in the lungs at 5 and 48 h p.i. and a marked increase at 24 hand 6 day p.i. Protease inhibition in the lungs was reduced at 24 and 48 h p.i. and an increase was observed at 5 h, 6 and 9 day p.i. SS 34-1-treatment brought both activities to normal levels. It was assumed that SS 34-1 exerted its inhibitory effect indirectly, through an increase of the protease-inhibitory activity. Histopathological examination of the lungs showed that under SS 34-1-treatment pulmonary lesions were less severe than those of untreated controls. The isolated novel protease inhibitor was purified by anion-exchange chromatography and reversed phase-HPLC. Analysis by differential scanning calorimetry (DSC) revealed that at pH 7.5 the denaturation temperature was 75 degrees C and the denaturation itself was irreversible. Analysis by circular dichroism (CD) in the UV region 190-250 nm showed that at pH 7.5 the spectrum presented 2 minima at 208 and 222 nm, typical for an a-helical structure. At pH 2.5 and after heating the spectrum corresponded to an unordered structure

Preventive effect of a polyphenol-rich extract from geranium sanguineum l. On hepatic drug metabolism in influenza infected mice

The decreased hepatic drug metabolism (predominately first phase) is one of the essential reasons for numerous side effects and for increased drug toxicity during influenza virus infection (IVI). The present study aims to investigate some mechanisms of the preventive effect of a standardized polyphenol complex from the medicinal plant Geranium sanguineum L. (PPhC) (10 mg/kg nasally). A verified experimental model of IVI A/Aichi/2/68 (H3N2) (4.5 lg LD50) in male ICR (Institute of Cancer Research, USA) mice was used. Changes in hepatic monooxygenase activities as well as nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome C reductase activity and cytochtome P450 content were studied on days 2, 6, 9, 21 of the infection together with thiobarbituric acid reactive substances in the liver supernatant. Our data clearly demonstrates that IVI affects all components of the electronic chain of cytochrome P-450. N-demethylases and hydroxylases as well as the activity of cytochrome C reductase and cytochtome P-450 content were decreased in the course of the virus infection. This implies that free radicals play an important role not only in the pathogenesis of IVI, but also in the modulation of the hepatic monooxygenase activity. This is also consistent with the established polyphenol complex PPhC from the medicinal plant Geranium sanguineum L. preventive effect against increased thiobarbituric acid reactive substances (TBARS)-levels. PPhC restored most of the monooxygenase activities that were inhibited in IVI animals, even over the control levels, probably via multiple mechanisms that may entail antioxidant activity and selective antiviral and protein-binding effects. In contrast to infected animals, in healthy mice, PPhC showed moderate reversible inhibitory effect on hepatic monooxygenase activities