In vitro, fluorescence-quenching and computational studies on the interaction between lipoxygenase and 5-hydroxy-3′,4′,7-trimethoxyflavone from Lippia nodiflora L.

Abstract

Lippia nodiflora L. is extensively used in traditional medicine for several medicinal purposes, including their use in inflammatory disorders. In this study, the folk use of L. nodiflora was validated using the isolated natural compound, 5-hydroxy-3′,4′,7-trimethoxyflavone (HTMF) by in vitro, fluorescence spectroscopic and molecular modeling studies with lipoxygenase (LOX), because LOX plays an essential role in inflammatory responses. In this perspective, the methanol extract and HTMF are shown to demonstrate prominent inhibitory activity against soybean lipoxygenase, with an IC₅₀ value of 21.12 and 23.97 µg/ml, respectively. The data obtained from the spectroscopic method revealed that the quenching of intrinsic fluorescence of LOX is produced as a result of the complex formation of LOX–HTMF. The binding mode analysis of HTMF within the LOX enzyme suggested that hydrogen bond formation, hydrophobic interaction and π–π stacking could account for the binding of HTMF. Molecular dynamics results indicated the interaction of HTMF with LOX and the stability of ligand–enzyme complex was maintained throughout the simulation. The computational results are reliable with experimental facts and provided a good representation for understanding the binding mode of HTMF inside the active site of lipoxygenase enzyme.

• 5-hydroxy-3′,4′,7-trimethoxyflavone
• fluorescence spectroscopy
• molecular dynamics
• Lippia nodiflora
• lipoxygenase

Declaration of interest

The authors report no conflicts of interest.

We gratefully acknowledge the financial assistance given by Department of Science and Technology (DST WOS-A), New Delhi, for the grant of fellowship to A.S. (Grant No. SR/WOS-A/LS-237/2010).

Supplementary material available online

Supplementary Figure S1