Identification of Bichalcones as Sirtuin Inhibitors by Virtual Screening and in Vitro Testing

Sirtuins are nicotinamide adenine dinucleotide (NAD⁺)-dependent class III histone deacetylases and have been linked to the pathogenesis of numerous diseases such as HIV, metabolic disorders, neurodegeneration and cancer. Docking of the virtual pan-African natural products library (p-ANAPL), followed by in vitro testing, resulted in the identification of two inhibitors of sirtuin 1, 2 and 3 (sirt1-3). Two bichalcones; rhuschalcone IV (8) and rhuschalcone I (9), previously isolated from the medicinal plant Rhus pyroides, were shown to be active in the in vitro assay, with rhuschalcone I showing the best activity against sirt1, having an IC₅₀ = 40.8 µM. Based on the docking experiments, suggestions for improving the biological activities of the newly identified hit compounds have been provided.