Abstract
BackgroundThe influenza virus can cause seasonal infections with mild to severe symptoms, circulating worldwide, and it can affect people in any age group. Therefore, this infection is a serious public health problem that causes severe illness and death in high-risk populations. Every year, 0.5% of the world’s population is infected by this pathogen. This percentage can increase up to ten times during pandemics. Influenza vaccination is the most effective way to prevent disease. In addition, anti-influenza drugs are essential for prophylactic and therapeutic interventions. The oseltamivir (OST, a neuraminidase inhibitor) is the primary antiviral used in clinics during outbreaks. However, OST resistant viruses may emerge naturally or due to antiviral pressure, with a prevalence of 1–2% worldwide. Thus, the search for new anti-influenza drugs is extremely important. Currently, several groups have been developing studies describing the biotechnological potential of microalgae and cyanobacteria, including antiviral activity of their extracts. In Brazil, this potential is poorly known and explored.MethodsWith the aim of increasing the knowledge on this topic, 38 extracts from microalgae and cyanobacteria isolated from marine and freshwater biomes in Brazil were tested against: cellular toxicity; OST-sensitive and resistant influenza replications; and neuraminidase activity.ResultsFor this purpose, Madin-Darby Canine Kidney (MDCK)-infected cells were treated with 200 μg/mL of each extract. A total of 17 extracts (45%) inhibited influenza A replication, with seven of them resulting in more than 80% inhibition. Moreover, functional assays performed with viral neuraminidase revealed two extracts (from Leptolyngbya sp. and Chlorellaceae) with IC50 mean < 210 μg/mL for influenza A and B, and also OST-sensitive and resistant strains. Furthermore, MDCK cells exposed to 1 mg/mL of all the extracts showed viability higher than 80%.DiscussionOur results suggest that extracts of microalgae and cyanobacteria have promising anti-influenza properties. Further chemical investigation should be conducted to isolate the active compounds for the development of new anti-influenza drugs. The data generated contribute to the knowledge of the biotechnological potential of Brazilian biomes that are still little explored for this purpose.
Highlights
Lower acute respiratory infections (ARIs) are a persistent and pervasive public health problem, since they constitute one of the main causes of morbidity and mortality, with greater burden of disease worldwide than human immunodeficiency virus infection, malaria, cancer, or heart attacks (Mizgerd, 2008; Pichon, Lina & Josset, 2017).World Health Organization (WHO) data indicate influenza A viruses as the main viral agents causing ARI, and of great epidemiological importance
We exposed Madin-Darby Canine Kidney (MDCK) to dimethyl sulfoxide (DMSO) in the same proportion as we used in the extracts test, 1.0% V/V in culture medium, which did not affect the cells viability
The results showed that redox mitochondrial activity of the tested cells with extracts was inhibited at most by 20% after 48 h of exposure
Summary
Lower acute respiratory infections (ARIs) are a persistent and pervasive public health problem, since they constitute one of the main causes of morbidity and mortality, with greater burden of disease worldwide than human immunodeficiency virus infection, malaria, cancer, or heart attacks (Mizgerd, 2008; Pichon, Lina & Josset, 2017).World Health Organization (WHO) data indicate influenza A viruses as the main viral agents causing ARI, and of great epidemiological importance. The influenza virus can cause seasonal infections with mild to severe symptoms, circulating worldwide, and it can affect people in any age group. This infection is a serious public health problem that causes severe illness and death in high-risk populations. Several groups have been developing studies describing the biotechnological potential of microalgae and cyanobacteria, including antiviral activity of their extracts. With the aim of increasing the knowledge on this topic, 38 extracts from microalgae and cyanobacteria isolated from marine and freshwater biomes in Brazil were tested against: cellular toxicity; OST-sensitive and resistant influenza replications; and neuraminidase activity. For this purpose, Madin-Darby Canine Kidney (MDCK)-infected cells were treated with 200 μg/mL of each extract. MDCK cells exposed to 1 mg/mL of all the extracts showed viability higher than 80%
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