RESUMO
Measles virus (MeV) is a paramyxovirus that infects humans, principally children. Despite the existence of an effective and safe vaccine, the number of cases of measles has increased due to lack of vaccination coverage. The World Health Organization (WHO) reports that the number of cases worldwide multiplied fourfold between January and March 2019, to 112,000. Today, there is no treatment available for MeV. In recent years, it has been demonstrated that natural extracts (herbal or algal) with antiviral activity can also work as reducing agents that, in combination with nanotechnology, offer an innovative option to counteract viral infections. Here, we synthetized and evaluated the antiviral activity of gold nanoparticles using garlic extract (Allium sativa) as a reducing agent (AuNPs-As). These nanoparticles actively inhibited MeV replication in Vero cells at a 50% effective concentration (EC50) of 8.829 µg/mL, and the selectivity index (SI) obtained was 16.05. AuNPs-As likely inhibit viral infection by blocking viral particles directly, showing a potent virucidal effect. Gold nanoparticles may be useful as a promising strategy for treating and controlling the infection of MeV and other related enveloped viruses.
Assuntos
Antivirais/farmacologia , Alho/química , Ouro/farmacologia , Vírus do Sarampo/efeitos dos fármacos , Sarampo/tratamento farmacológico , Extratos Vegetais/farmacologia , Animais , Antivirais/química , Chlorocebus aethiops , Ouro/química , Humanos , Sarampo/virologia , Vírus do Sarampo/ultraestrutura , Extratos Vegetais/química , Células VeroRESUMO
Although preventable by vaccination, Measles still causes thousands of deaths among young children worldwide. The discovery of new antivirals is a good approach to control new outbreaks that cause such death. In this study, we tested the antiviral activity against Measles virus (MeV) of Polyphenol-rich extracts (PPs) coming from five seaweeds collected and cultivated in Mexico. An MTT assay was performed to determine cytotoxicity effect, and antiviral activity was measured by syncytia reduction assay and confirmed by qPCR. PPs from Ecklonia arborea (formerly Eisenia arborea, Phaeophyceae) and Solieria filiformis (Rhodophyta) showed the highest Selectivity Index (SI), >3750 and >576.9 respectively. Both PPs extracts were selected to the subsequent experiments owing to their high efficacy and low cytotoxicity compared with ribavirin (SI of 11.57). The combinational effect of PPs with sulphated polysaccharides (SPs) and ribavirin were calculated by using Compusyn software. Synergistic activity was observed by combining both PPs with low concentrations of Solieria filiformis SPs (0.01 µg/mL). The antiviral activity of the best combinations was confirmed by qPCR. Virucidal assay, time of addition, and viral penetration evaluations suggested that PPs act mainly by inactivating the viral particle. To our knowledge, this is the first report of the virucidal effect of Polyphenol-rich extracts of seaweeds.
Assuntos
Antivirais/farmacologia , Sinergismo Farmacológico , Vírus do Sarampo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Polifenóis/farmacologia , Alga Marinha/química , Animais , Antivirais/isolamento & purificação , Antivirais/toxicidade , Chlorocebus aethiops , México , Testes de Sensibilidade Microbiana , Viabilidade Microbiana , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/toxicidade , Polifenóis/isolamento & purificação , Polifenóis/toxicidade , Polissacarídeos/farmacologia , Ribavirina/farmacologia , Células VeroRESUMO
Sulfated polysaccharides (SPs) extracted from five seaweed samples collected or cultivated in Mexico (Macrocystis pyrifera, Eisenia arborea, Pelvetia compressa, Ulva intestinalis, and Solieria filiformis) were tested in this study in order to evaluate their effect on measles virus in vitro. All polysaccharides showed antiviral activity (as measured by the reduction of syncytia formation) and low cytotoxicity (MTT assay) at inhibitory concentrations. SPs from Eisenia arborea and Solieria filiformis showed the highest antiviral activities (confirmed by qPCR) and were selected to determine their combined effect. Their synergistic effect was observed at low concentrations (0.0274 µg/mL and 0.011 µg/mL of E. arborea and S. filiformis SPs, resp.), which exhibited by far a higher inhibitory effect (96% syncytia reduction) in comparison to the individual SP effects (50% inhibition with 0.275 µg/mL and 0.985 µg/mL of E. arborea and S. filiformis, resp.). Time of addition experiments and viral penetration assays suggest that best activities of these SPs occur at different stages of infection. The synergistic effect would allow reducing the treatment dose and toxicity and minimizing or delaying the induction of antiviral resistance; sulfated polysaccharides of the tested seaweed species thus appear as promising candidates for the development of natural antiviral agents.
Assuntos
Antivirais/farmacologia , Vírus do Sarampo/efeitos dos fármacos , Polissacarídeos/farmacologia , Alga Marinha/química , Animais , Antivirais/química , Chlorocebus aethiops , Sarampo/tratamento farmacológico , México , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Polissacarídeos/química , Células VeroRESUMO
This paper presents the antiviral activity found in a snake with Crotalus durissus terrificus venom (Cdt), studied by use of microplate inhibition assay, using measles virus (MV). Cdt at concentrations below 100 microg/ml showed no cytotoxicity for Vero cells. This study shows the optimal conditions for cell treatment and infection. Two factors that affect virus binding and infection efficiency were studied: the use of an adsorption step, where infection volume was varied; and the concentration of fetal bovine serum (FBS). The adsorption step, with or without FBS, increased the bound virus percentage, whereas it increased bound virus at equilibrium only in FBS-free until 2.5% FBS. In contrast, the addition of 10% FBS decreased the bound virus percentage. The inhibition of MV replication in Vero cells was observed when Cdt was added either before or during cell infection with virus. Its inhibitory concentration against MV replication was 0.1 until 100 microg/ml, respectively. The anti-MV effect of the Cdt was gradually decreased when it was added before or during infection, and little inhibition was observed when Cdt was added 1 h after infection, suggesting that the MV infection was inhibited at the time of the initial events such as at the moment of adsorption and penetration of the viral cycle. In conclusion, Cdt contains anti-MV effects that may be of potential clinical interest.
Assuntos
Venenos de Crotalídeos/farmacologia , Crotalus , Vírus do Sarampo/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , Animais , Ligação Competitiva , Chlorocebus aethiops , Venenos de Crotalídeos/toxicidade , Vírus do Sarampo/crescimento & desenvolvimento , Camundongos , Células Vero , Inativação de Vírus/efeitos dos fármacosRESUMO
Twenty-seven brassinosteroid derivatives were tested for antiviral activity against measles virus (MV) via a virus-yield reduction assay. Compounds 6b [(22S,235)-3beta-bromo-5alpha,22,23-trihydroxystigmastan-6-one], 1d [(22R,23R)-2alpha,3alpha,22,23-tetrahydroxy-beta-Homo-7-oxa-stigmastan-6-one], 8a [(22R,23R)-3beta-fluoro-22,23-dihydroxystigmastan-6-one], 9b [(22S,23S)-3beta-fluoro-5alpha,22,23-trihydroxystigmastan-6-one] and 10b [(22S,23S)-5alpha-fluor-3beta,22,23-trihydroxystigmastan-6-one], with selectivity indexes (SI) of 40, 57, 31, 37 and 53, are the derivatives with good antiviral activity against MV. These SI values are higher than those obtained with ribavirin (used as reference drug). A comparative analysis of 50% cytotoxic concentration (CC50) values, using confluent non-growing cells, gives and indication of structure-activity relationship. According to their degree of cytotoxicity the compounds were divided in three groups: low, intermediate and high cytotoxicity. By observing the chemical structures of compounds belonging to the first group we can see that less cytotoxic activities are related to the presence of a 3beta-hydroxy group on C-3 (ring A) and a double bond between C-22 and C-23 (side chain). The replacement of a 5alpha-hydroxy group by a 5alpha-fluoro group enhances cytotoxicity. Halogenated brassinosteroid derivatives in C-3 position are more cytotoxic than those with an acetoxy group in the same position. For compounds 1d, 6b, 10b and ribavirin, cytotoxicity measurements were also done with replicating cells; CC50 values were low, but they still competed favourably with ribavirin against MV.
Assuntos
Antivirais/farmacologia , Vírus do Sarampo/efeitos dos fármacos , Ribavirina/análogos & derivados , Esteroides Heterocíclicos/farmacologia , Animais , Antivirais/síntese química , Chlorocebus aethiops , Efeito Citopatogênico Viral , Formazans , Humanos , Concentração Inibidora 50 , Vírus do Sarampo/crescimento & desenvolvimento , Ribavirina/síntese química , Ribavirina/farmacologia , Esteroides Heterocíclicos/síntese química , Relação Estrutura-Atividade , Sais de Tetrazólio , Células Vero , Replicação Viral/efeitos dos fármacosRESUMO
The Expanded Programme on Immunization (EPI) has its objective the elimination of indigenous measles from the English-speaking Caribbean and Suriname by 1995. CAREC id the reference laboratory for this programme which is funded by the EPI Department, PAHO washington. One of the key components of Surveillance activities will be laboratory confirmation of suspected measles cases (i.e. those that fit the case definition laid out in the Measles Field Guide (AU)