Lupeol, a
triterpene, possesses beneficial effects like anti-inflammatory and anti-
cancer properties. Binding of
lupeol and its derivative (
phytochemicals) to
plasma proteins such as
human serum albumin (HSA) and α-1-acid
glycoprotein (AGP) is a major determinant in the disposition of drugs. Cytotoxic studies with mouse macrophages (RAW 246.7) and HeLa cell lines revealed anti-inflammatory and anti-
cancer properties for both
lupeol and
lupeol derivative. Both molecules reduced the expression of pro-inflammatory
cytokines in LPS induced macrophages. Further, apoptosis was observed in HeLa cell lines when they were incubated with these molecules for 24 h. The fluorescence quenching of HSA was observed upon titration with different concentrations of
lupeol and
lupeol derivative; their binding constants were found to be 3 ± 0.01 × 10(4) M(-1) and 6.2 ± 0.02 × 10(4) M(-1), with binding free energies of -6.59 kcal M(-1) and -7.2 kcal M(-1). With AGP, however, the
lupeol and
lupeol derivative showed binding constants of 0.9 ± 0.02 × 10(3) M(-1) and 2.7 ± 0.01 × 10(3) M(-1), with free energies of -4.6 kcal M(-1) and -5.1 kcal M(-1) respectively. Molecular displacement studies based on competition with site I-binding
phenylbutazone (which binds site I of HSA) and
ibuprofen (which binds site II) suggest that
lupeol binds site II and the
lupeol derivative site I. Molecular docking studies also confirmed that
lupeol binds to the IIIA and the
lupeol derivative to the IIA domain of HSA. Secondary structure changes were observed upon formation of HSA-
lupeol/
lupeol derivative complexes by circular dichroism spectroscopy. Molecular dynamics simulations support greater stability of HSA-
lupeol and HSA-
lupeol derivative complexes compared to that of HSA alone.