Effect of preventive measures in the containment of SARS-CoV-2 epidemic: a comparative study.

From the time when the first cases of COVID-19 were reported in Wuhan City, China, in December 2019, strict regulations are being implemented by policy makers to contain the spread of the virus. The measures taken in different countries spanned from complete isolation and lockdown to different degrees of restrictions to people's movement, contact between people, hygiene and sanitation. Accordingly, the success in containing the virus also differed. Italy was one among the worst-affected countries in the world despite the lockdown measures adopted. A combination of lockdown and Level-3 State of Emergency measures were adopted in Portugal and South Africa, which helped to delay and flatten the epidemic curve. The timely application of Level-3 State of Emergency in Mozambique resulted in recording low infection rates. Above all the tripod, orderly movement of people, social distance and hygiene and sanitation is the keystone measure to prevent spread of the virus. However, for successful outcome, the measures have to be tailored to the local context.

Cardiovascular effects in vitro of aqueous extract of wild strawberry (Fragaria vesca, L.) leaves.

In contrast to the strawberry fruits, strawberry leaves as a source of bioactive compounds with potentially beneficial biological effects have been largely overlooked. In this study we examined direct, dose-dependent effects of wild strawberry (Fragaria vesca, L.) leaves aqueous extract, in two experimental models and animal species, the isolated guinea pig hearts and rat aortic rings. Vasodilatory potential of the wild strawberry leaves extract was compared with vasodilatory activity of aqueous extract of hawthorn (Crataegus oxycantha, L) leaves with flowers, which can be regarded as a reference plant extract with a marked vasodilatory activity. The extracts were analysed by their "phenolic fingerprints", total phenolic content and antioxidative capacity. Their vasodilatory activity was determined and compared in the isolated aortic rings from 24 rats that were exposed to the extracts doses of 0.06, 0.6, 6, and 60 mg/100ml. Both extracts induced similar, dose-dependent vasodilation. Maximal relaxation was 72.2+/-4.4% and 81.3+/-4.5%, induced by the strawberry and hawthorn extract, respectively. To determine vasodilatory mechanisms of the wild strawberry leaves extract, endothelium-denuded and intact rings exposed to nitric oxide (NO) synthase inhibitor L-NAME or cyclooxygenase inhibitor indomethacin were used. Removal of the endothelium prevented and exposure to L-NAME or indomethacin strongly diminished the vasodilatatory response to the extract. In the isolated hearts (n=12), the wild strawberry extract was applied at concentrations of 0.06, 0.18, 0.6, and 1.8 mg/100ml. Each dose was perfused for 3.5 min with 15 min of washout periods. Heart contractility, electrophysiological activity, coronary flow and oxygen consumption were continuously monitored. The extract did not significantly affect heart rate and contractility, main parameters of the cardiac action that determine oxygen demands, while coronary flow increased up to 45% over control value with a simultaneous decrease of oxygen extraction by 34%. The results indicate that the aqueous extract of wild strawberry leaves is a direct, endothelium-dependent vasodilator, action of which is mediated by NO and cyclooxygenase products and which potency is similar to that of the hawthorn aqueous extract.

Effect of cisplatin and 6-bromo-6-deoxy-L-ascorbic acid on some biochemical and functional parameters in mice.

The results of the present study demonstrate that 6-bromo-6-deoxy-L-ascorbic acid (6-BrAA), an antioxidative derivative of ascorbic acid, is capable of lowering the toxicity of cisplatin, cis-diaminedichloroplatinum (cis-DDP), an anticancerogenic drug. The biological aspects and pharmacological significance of a combined treatment of these two substances were investigated in a mouse model. The results indicate that the effectiveness of 6-BrAA on biological response(s) is strongly dependent on the dose of cis-DDP. Injection of 10 mg/kg body weight (bw) of cis-DDP following pretreatment with 6-BrAA (480 mg/kg bw) enhances the tissue-protecting effect of 6-BrAA and reduces, to some extent, the ensuing nephro-, liver and spleen toxicity. On the other hand, 6-BrAA in animals treated with a higher dose of cis-DDP (15 mg/kg bw) leads to exacerbation of the toxic cis-DDP effect and concurrent loss of the protective potential of 6-BrAA with respect to tissue damage. The exact mechanism(s) of 6-BrAA protection and exacerbation of the toxic cis-DDP effect is unclear, although scavenging or generating of free radicals may play an important role. The results obtained may be of importance in planning the rational use of cis-DDP and 6-BrAA administration in the potential treatment of cancer.

Ascorbic acid and 6-deoxy-6-chloro-ascorbic acid: potential anticancer drugs.

The role of ascorbic acid (AA) in prevention and suppression of carcinogenesis has been known for a long time. It was also found that AA may inhibit the growth of some tumor cells in vitro and in vivo. We examined the influence of ascorbic acid and 6-chloro-6-deoxy ascorbic acid (6-Cl-AA) on the growth of various human cell lines: lung fibroblasts (Hef), ovarian adenocarcinoma (OVCAR), colon adenocarcinoma (HT-29), laryngeal carcinoma (HEp2) cells, HEp2 cells resistant to vincristine (HEp2VA3), cervical carcinoma (HeLa) cells, HeLa cells resistant to cisplatin (Helacis), breast adenocarcinoma (SK-BR-3) cells, and SK-BR-3 resistant to doxorubicin (SK-BR-3-Dox), as well as mouse fibroblasts L929, mouse melanoma B16 (Mel B16) cells and Chinese hamster fibroblasts (V79). Both drugs arrested the growth of: HeLa, SK-BR-3, SK-BR-3-Dox, L929, and Mel B16 cells, but did not influence the growth of others: Hef, OVCAR, HEp2, HEp2VA3 and V79. 6-Cl-AA suppressed more the proliferation of HeLacis, SK-BR-3-Dox and Mel B16 cells than AA, while AA was active only against HT-29 cells. Inhibitory effect of 6-Cl-AA was confirmed by the in vivo experiments on solid melanoma B16 tumors. Our results indicate that AA and 6-Cl-AA could serve as potential antitumor agents, especially against some tumor cells resistant to chemotherapy.

One-electron oxidation and reduction reactions of vitamin C derivatives: 6-bromo- and 6-chloro-6-deoxy-ascorbic acid.

6-Bromo- and 6-chloro-6-deoxy derivatives of ascorbate anion are able to transfer an electron to the oxidizing radicals .OH, Br2.- and RS. with the same rate constants as the ascorbate anion itself. The resulting radicals also show the same kinetic stabilities and optical absorption spectra as the well-characterized ascorbate radical anion (lambda max = 360 nm; epsilon 360 = 330 m2 mol-1). This proves that there is no influence of the structural changes in the side chain on the antioxidant capacity of the ascorbate moiety. In contrast, measured reduction of the 6-halo-6-deoxy derivatives occurs significantly faster (up to one order of magnitude) than the reduction of unsubstituted ascorbate. For example, absolute rate constants of 4.6 x 10(9) and 2.2 x 10(7) dm3 mol-1 s-1 have been measured for the reactions of bromo-derivative with eaq- and (CH3)2COH respectively. These radical-induced reductions proceed via dissociative electron capture and, under cleavage of the C-halogen bond, yield C-6 carbon-centered radicals. In the presence of oxygen the corresponding peroxyl radical is readily formed. This radical is again able to oxidize the ascorbate moiety (rate constant 2 x 10(7) dm3 mol-1 s-1). Results are discussed in terms of biological relevance of the investigated compounds regarding their ability to act as efficient antioxidants and bioreductive antitumour agents simultaneously.