Antiviral activity of different fractions of natural humic substances with respect to HIV-1

Abstract

Introduction: Since 1996, despite the wide application of highly active antiretroviral therapy (HAART), the number of HIV-positive patients continues to grow steadily. More than 30 million people per year get infected with HIV, and more than 3 million die of opportunistic infections on AIDS. An important fact is that all currently used antiviral resistant mutants detected HIV. This shows an urgent need for a directed search for new antiviral drugs against HIV. Purpose and Objectives: The purpose of this study was to investigate the anti-HIV-activity of humic substances fractions isolated from low-mineralized silt sulfide muds against laboratory strains of HIV -1. The humic substances were isolated from peloids deposited in the region of sanatorium «Sergievsk mineral water», Samara region, Russia. The corresponding HS samples were fulvic, hymatomelanic and humic acids from peloids. The study was carried out with respect to antiviral activity against laboratory strains of HIV-1LAI.2 - Materials and methods: Antiviral activity was measured using the screening analysis system inhibitors EASY-HIT developed at the Institute of Virology, Helmholtz-ZentrumM unchen. The study involved two steps: firstly, the screening for antiviral activity of the HS fractions studied was conducted using cell culture LC5-RIC; 2. Secondly, the assessment of cytotoxicity of HS fractions studied was performed using the MTT assay with cell culture of T-lymphoma line KE37.1-IIIB. Antiviral activity was measured by ELISA reader Tecan Infinite M200. Results: The results showed that all fractions of HS from peloids within the studied range of concentrations (from 0.00125% to 1%) did not dispaly pronounced cytotoxicity. At the same time, the humic acid and hymatomelanic acid fractions exhibited a distinct antiviral activity within the concentration range from 0.0001% to 1% with respect to HIV-1, while fulvic acids did not show this activity. The most profound antiviral activity was exhibited by hymatomelanic acids, whose lowest effective concentration accounted for 3 ng/mL. Conclusion: The follow up studies on possible mechanism of antiviral activity have shown that the HS samples displayed antiviral activity at the stage of reverse transcription of DNA to RNA. Thus, the fractions of HS of low-mineralized silt sulfide muds can be considered as promising precursors for developing powerful antiviral drugs with low cytotoxicity.