Antiviral action of aqueous extracts of propolis from Scaptotrigona aff. postica against Zica, Chikungunya, and Mayaro virus

Abstract

The limited availability of antivirals for new highly pathogenic strains of virus has become a serious public health problem that kills thousands of people annually. For this reason, the search for new products against these agents has become an urgent necessity. Many studies have been carried out with this aim. Among the multiple sources of research for new antibiotics and antivirals, bioprospecting from insect exudates or their products has become an increasingly frequent option. Insects appeared on the planet about 350 million years ago and have been one of the beings with greater adaptability and resistance to the most varied biomes. Insects have been found in all known ecosystems. Their survival for so long, in such different environments, is an indication that they have a very efficient protection system against environmental infections, despite not having a developed immune system like mammals. Historically, since the ancient civilizations of Egypt and Rome, the products obtained from the bee, such as honey and propolis, have been of great pharmacological importance, being used as antimicrobial, anti-inflammatory, antitumor, healing several other functions. Investigations on the chemical composition and biological activity of propolis have been carried out, mainly in the species Apis mellifera, and this product has shown activity against some important viruses, such as poliovirus, influenza, HIV, hepatitis, and others. However, for the Meliponini species, known as stingless bees, there are few studies, either on their chemical composition or on their biological activities. The importance of studying these bees is because they come from regions with native forests, and therefore with many species of plants not yet studied, in addition to which they are regions still free of pesticides, which guarantees a greater fidelity of the obtained data. Previous studies by our group with crude hydroalcoholic extract of propolis demonstrated an intense antiviral activity against Herpes, influenza, and rubella viruses. All studies carried out with propolis are done with alcoholic extracts. In this work, we chose to use aqueous extracts, which eliminates the presence of other compounds besides those originally present in propolis, in addition to extracting substances different from those obtained in alcoholic extracts, which makes this work unprecedented. Therefore, this study aimed to identify, isolate and characterize compounds with antiviral effects from aqueous propolis extracts from Scaptotrigona aff postica, in emerging viruses such as zicavirus, chikungunya, and Mayaro. The evaluation of the antiviral activity of the crude and purified material was performed by reducing infectious foci in cultures of infected cells treated with propolis extracts in infected cultures and treated or not treated with propolis. The chemical characterization of the elements present in the extracts was performed by high pressure liquid chromatography. The results obtained indicate a high reduction of Zicavirus (64x) and Mayaro (256x) when was used 10% v/v of propolis and 256 x for chikungunya virus when was used 5% v/v of propolis. When compared to infected-only cultures. Even when was used 2% v/v of propolis, was observed a reduction of 128 fold in Mayaro virus replication. When purified fraction was used, the reduction observed was of 16 fold for Zicavirus, 32 fold for Mayaro virus and 125 fold for chikungunya virus. Likewise, it was observed that the antiviral response was dose-dependent, being more intense when propolis was added 2 hours after the viral infection. At the moment we are carrying out the chemical characterization of the purified compounds that showed antiviral action.