RÉSUMÉ
ABSTRACT Achyrocline satureioides (Lam.) DC. Asteraceae, ‘marcela del campo', possess several pharmacological properties. Previously we reported antiviral activity of an aqueous extract of A. satureioides against an alphavirus, Western Equine Encephalitis virus. Alphaviruses are highly virulent pathogens which cause encephalitis in humans and equines. There are no effective antiviral to treat its infections. The aim of this study was to evaluate in vitro cytotoxic and antiviral activities against Western Equine Encephalitis virus of five water extract chromatographic fractions from A. satureioides and identify the main compounds of the bioactive fraction. Also, it was to assess in vivo cytogenotoxic ability of the active fraction. Cytotoxicity studies revealed low toxicity of the most of fractions in Vero and in equine peripheral blood mononuclear cells. Antiviral studies showed that the water crude extract – Sephadex LH 20 – fraction 3 MeOH–H2O (Fraction 3) was active against Western Equine Encephalitis virus with Effective Concentration 50% = 5 µg/ml. Selectivity Indices were 126.0 on Vero and 133.6 on peripheral blood mononuclear cells, four times higher than aqueous extract selectivity index. Regarding the mechanism of action we demonstrated that F3 exerted its action in intracellular replication stages. Further, fraction 3 showed important virucidal action. Fraction 3 contains, in order of highest to lowest: chlorogenic acid, luteolin, 5,7,8-trimethoxyflavone, 3-O-methylquercetin and caffeic acid. Fraction 3 did not induce in vivo toxic nor mutagenic effect. Therefore, it is safe its application as antiviral potential. Further studies of antiviral activity in vivo will be developed using a murine model.
RÉSUMÉ
The State of Pará comprises 26% of Brazilian Amazon region, where a large diversity of arboviruses has been described. This study sought to assess the prevalence and distribution of hemagglutination inhibition (HI) antibodies against antigens of four alphaviruses (Togaviridae: Alphavirus ) from the species: Eastern equine encephalitis (EEEV), Western equine encephalitis (WEEV), Mayaro virus (MAYV), and Mucambo virus (MUCV) in 753 serum samples of horses in Pará State, Brazil. All investigated arboviruses were detected and indicate that horses are susceptible to these alphaviruses, and show evidences of their active circulation in farm animals in the Brazilian Amazon.(AU)
O estado do Pará corresponde a 26% da Amazônia brasileira, onde uma grande diversidade de arbovírus foi descrita. Este estudo procurou avaliar a prevalência e a distribuição de anticorpos inibidores da hemaglutinação (IH) contra antígenos de quatro alfavirus (Togaviridae: Alphavirus ), das espécies: Vírus da encefalite equina do leste (EEEV), Vírus da encefalite equina do oeste (WEEV), Vírus mayaro (MAYV) e Vírus mucambo (MUCV), de 753 amostras de soro de equinos no estado do Pará, Brasil. Todos os arbovirus pesquisados foram detectados, indicando que os equinos são suscetíveis a esses Alphavirus e mostrando evidências de sua circulação ativa em animais de fazenda na Amazônia brasileira.(AU)