Anti-inflammatory, antioxidant and in silico studies of Buddleja salviifolia (L). Lam leaf constituents

Buddleja salviifolia leaves are used for the treatment of eye infections and neurodegenerative conditions in South Africa. Three phenolic compounds identified as 4′-hydroxyphenyl ethyl vanillate (1), acteoside (2) and quercetin (3) from leaf extracts of the B. salviifolia were investigated for cyclooxygenase-2 (COX-2) inhibition and antioxidant activities using β-carotene-linoleic acid and DPPH assays. In silico parameters were also determined for COX-2. All the compounds exhibited good inhibition activity against COX-2 and moderate antioxidant activities at a screening concentration of 25.0 μg/ml. Acteoside was the most potent in all assays. It exhibited the lowest IC50 value (4.28 μg/ml) in the COX-2 and EC50 values of 24.15 and 63.30 μg/ml in the β-carotene-linoleic acid and DPPH assays respectively. Computational molecular docking showed its molecular interaction with important amino acid residues in the catalytic site of COX-2, revealing its potential binding mode at the molecular level. In silico study revealed that quercetin and acteoside showed the highest binding affinity (dock score of 92.18 and 68.93 k.cal/mol) and good hydrogen bond interactions with active site residues. The activities demonstrated by these compounds (1-3) suggest that they could be useful in management of inflammatory conditions.