Andrographolide, a lacton diterpenoid, due to its many biological activities, was subjected to a semi-synthetic work by reacting andrographolide (a) with hydroxybenzaldehyde under microwave irradiation. This reaction led to three new andrographolide analogues, which are 3,19-2-hydroxybenzylidene andrographolide (b), 3,19-3-hydroxybenzylidene andrographolide (c), and 3,19-4-hydroxybenzylidene andrographolide (d), respectively. The yields were 85%, 86%, 86% for compounds b, c, d respectively. These new compounds had already been studied previously by pharmacophore screening and molecular docking simulation, which revealed their affinity to HIV-1 protease. Furthermore, their inhibitory activity against HIV-1 protease was measured by in vitro fluorometric method at (Ex/Em) = 330/450 nm which resulted 18.14, 10.72, 9.93, 8.32 µM respectively for IC50 value. The increased activity of these compounds may reflect the binding of the hydroxybenzaldehyde moiety with the hydrophobic area of the HIV-1 protease.
Key words: Andrographolide; ARVs, HIV, HIV-1 protease inhibitors, hydroxybenzylidene andrographolide.
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