Inhibitory potential of α-Amyrin from Calotropis procera against HIV-1 reverse transcriptase: insights from in silico and in vitro assays

The global HIV epidemic continues to present significant public health challenges, with millions affected worldwide, necessitating the exploration of novel antiretroviral agents. This study aims to evaluate the inhibitory potential of α-amyrin, a phytochemical from Calotropis procera , against HIV-1 reverse transcriptase (RT) through molecular docking and in vitro assays. The study involved in silico molecular docking to assess the binding affinity of α-amyrin with HIV-1 RT (PDB ID: 1JLB), followed by pharmacokinetic analysis to predict its drug-likeness and ADMET properties. An in vitro HIV-1 RT inhibition assay was conducted using a colorimetric ELISA kit, with nevirapine as the reference drug. Molecular docking revealed a strong binding affinity of α-amyrin to HIV-1 RT, with a binding energy of -7.33 kcal/mol. The compound formed two hydrogen bonds with key residues (Cys181 and Gln182) in the allosteric binding site. In vitro assays demonstrated dose-dependent RT inhibition, with an IC₅₀ of 26 µg/mL, comparable to nevirapine (IC₅₀ = 21 µg/mL). At the highest concentration (200 µg/mL), α-amyrin achieved 82% inhibition, while nevirapine displayed 92% inhibition. Lower concentrations (12.5–100 µg/mL) showed gradual inhibitory effects, indicating α-amyrin's potential efficacy even at moderate doses. Pharmacokinetic predictions confirmed its favorable absorption, metabolism, and low toxicity profile. The dual approach combining in silico and in vitro analyses highlights α-amyrin as a promising candidate for HIV-1 RT inhibition. Its strong binding affinity, significant enzymatic inhibition, and favorable pharmacokinetics suggest its potential for further development as a plant-based NNRTI, addressing drug resistance concerns and contributing to improved antiretroviral therapies.