Comparative study of the interaction mechanism of astilbin, isoastilbin, and neoastilbin with CYP3A4.

The interactions of human CYP3A4 with three selected isomer flavonoids, such as astilbin, isoastilbin and neoastilbin, were clarified using spectral analysis, molecular docking, and molecular dynamics simulation. During binding with the three flavonoids, the intrinsic fluorescence of CYP3A4 was statically quenched in static mode with nonradiative energy conversion. The fluorescence and ultraviolet/visible (UV/vis) data revealed that the three flavonoids had a moderate and stronger binding affinity with CYP3A4 due to the order of the Ka1 and Ka2 values ranging from 104 to 105  L·mol-1 . In addition, astilbin had the highest affinity with CYP3A4, then isoastilbin and neoastilbin, at the three experimental temperatures. Multispectral analysis confirmed that binding of the three flavonoids resulted in clear changes in the secondary structure of CYP3A4. It was found from fluorescence, UV/vis and molecular docking analyses that these three flavonoids strongly bound to CYP3A4 by means of hydrogen bonds and van der Waals forces. The key amino acids around the binding site were also elucidated. Furthermore, the stabilities of the three CYP3A4 complexes were evaluated using molecular dynamics simulation.

Interaction mechanism of pelargonidin against tyrosinase by multi-spectroscopy and molecular docking.

The interaction mechanism of pelargonidin (PG) with tyrosinase was investigated by multi-spectroscopy and molecular docking. As a result, PG had strong inhibitory activity on tyrosinase with the IC50 value of 41.94 × 10-6  mol·L-1 . The inhibition type of PG against tyrosinase was determined as a mixed-mode. Meanwhile, the fluorescence of tyrosinase was quenched statically by PG, and accompanied by non-radiative energy transfer. The three-dimensional (3-D) fluorescence, ultraviolet-visible spectroscopy (UV-Vis) and circular dichroism spectroscopies (CD) indicated that PG decreased the hydrophobicity of the micro-environment around tryptophan (Trp) and tyrosine (Tyr), which resulted in the conformational change of tyrosinase. In addition, fluorescence and molecular docking analysis indicated that PG bound to tyrosinase via hydrogen bonds (H-bonds) and van der Waals force (vdW force). We herein recommended that PG might be a potential candidate drug for the treatment of melanin-related diseases.

Spectroscopic studies and molecular docking on the interaction of delphinidin-3-O-galactoside with tyrosinase.

The inhibitory effects of delphinidin-3-O-galactoside (DG) on the activities of tyrosinase (EC 1.14.18.1) (TY) from the edible Agaricus bisporus mushroom were investigated by enzyme kinetics, multispectroscopic methods, and molecular docking. As a result, DG showed strong inhibition on TY with the IC50 of 34.14 × 10-6  mol L-1 . The inhibition mode of DG against TY was mixed type with α values of 5.09. The binding constant Ka and related thermodynamic parameters at the three different temperatures showed that the fluorescence quenching of TY by DG was static quenching. Synchronous fluorescence, three-dimensional fluorescence, ultraviolet-visible spectroscopy, and circular dichroism spectroscopies confirmed that the conformation or microenvironment of the TY protein were changed after binding with DG. Molecular docking revealed that DG had strong binding affinity to TY through hydrogen bonding and van der Waals force, and the results were consistent with the fluorescence data. Our findings suggested that DG may be potential TY inhibitor.

Inhibitory effects of astilbin, neoastilbin and isoastilbin on human cytochrome CYP3A4 and 2D6 activities.

Astilbin, neoastilbin and isoastilbin are three flavonoid isomers from Smilacis glabrae Roxb. (S. glabrae). Several studies have shown that consumption of flavonoids can increase the risk of food/drug-drug interaction by affecting the activities of human cytochrome CYP3A4 and 2D6. In the present study, an ultrahigh-performance liquid chromatography and triple quadrupole mass spectrometry method was developed for the determination of the interaction between three flavonoid isomers and two CYPs. Under the optimized reaction conditions, the Km values were 18.9 and 36.4 µM and the Vmax values were 0.02 and 0.20 µM/min for CYP3A4 and 2D6 in vitro, respectively. Astilbin showed the strongest inhibition on CYP3A4, followed by isoastilbin and neoastilbin with IC50 values of 2.63, 3.03 and 6.51 µM. Neoastilbin showed the strongest inhibition on CYP2D6, followed by isoastilbin and astilbin, with IC50 values of 1.48, 11.87 and 14.16 µM, respectively. The three isomers showed reversible inhibition on both enzymes. Neoastilbin and astilbin were noncompetitive type for CYP3A4 and 2D6, isoastilbin was a mixture and noncompetitive type for CYP3A4 and 2D6, respectively. Our study suggests that the three isomers may increase the risk of food/drug-drug interactions by affecting the activities of CYP3A4 and 2D6.

Interaction study of astilbin, isoastilbin and neoastilbin toward CYP2D6 by multi-spectroscopy and molecular docking.

Astilbin, isoastilbin and neoastilbin are the three flavonoid isomers prevalent in Rhizoma Smilax glabra. The interactions between human cytochrome P450 2D6 (CYP2D6) and the three isomers were investigated by multiple spectroscopic coupled with molecular docking. As a result, the fluorescence intensity of CYP2D6 was quenched statically by the three isomers. Meanwhile, astilbin had the strongest binding ability to CYP2D6, followed by isoastilbin and neoastilbin under the identical temperature. Synchronous fluorescence, three-dimensional fluorescence, ultraviolet-visible spectroscopy, circular dichroism and Fourier-transform infrared spectra confirmed that the conformation and micro-environment of CYP2D6 protein were changed after binding with the three isomers. As suggested from molecular docking, the three isomers had strong binding affinity to CYP2D6 via the bonding of hydrogen and van der Waals forces, and the results were in agreement with the fluorescence results. The findings here suggested that astilbin, isoastilbin and neoastilbin may cause the herb-drug interactions for their inhibition of CYP2D6 activity.

Interactions of potato-derived and human recombinant 5-lipoxygenase with sec-O-glucosylhamaudol by multi-spectroscopy and molecular docking.

5-lipoxygenase (5-LOX) was a key enzyme involved in many inflammatory diseases. Sec-O-glucosylhamaudol (SOG) was a chromone found in Saposhnikovia divaricata (Turcz.) Schischk (S. divaricate). The potato-derived 5-LOX (p-5-LOX) and human recombinant 5-LOX (h-5-LOX) were selected as model protein due to their simple usability and high stability in this study. Thus, the binding interactions of p-5-LOX and h-5-LOX with SOG were investigated by multi-spectroscopy and molecular docking. As a result, the fluorescence intensities of the two 5-LOX were quenched statically by SOG. However, the binding ability of SOG to h-5-LOX was higher than that of p-5-LOX at the same temperature. The results of multi-spectroscopy revealed that the conformation and micro-environment of the two 5-LOX proteins were changed after binding with SOG. Fluorescence assay and molecular docking indicated that hydrogen bond and electrostatic gravitation were the main forces between the two 5-LOX and SOG. Our results here suggested that SOG may exert anti-inflammatory effect by inhibiting 5-LOX activity.

Interaction study of engeletin toward cytochrome P450 3A4 and 2D6 by multi-spectroscopy and molecular docking.

The inhibitory effects of engeletin on the activities of human cytochrome P450 3A4 and 2D6 (CYP3A4 and CYP2D6) were investigated by enzyme kinetics, multi-spectroscopy and molecular docking. Engeletin was found to strongly inhibit CYP3A4 and CYP2D6, with the IC50 of 1.32 µM and 2.87 µM, respectively. The inhibition modes of engeletin against CYP3A4 and CYP2D6 were a competitive type and a mixed type, respectively. The fluorescence of the two CYPs was quenched statically by engeletin, which was bound to CYP3A4 stronger than to CYP2D6 at the same temperature. Circular dichroism spectroscopy, three-dimensional fluorescence, ultraviolet-visible spectroscopy and synchronous fluorescence confirmed that the conformation and micro-environment of the two CYPs protein were changed after binding with engeletin. Molecular docking, ultraviolet-visible spectroscopy and the fluorescence data revealed that engeletin had strong binding affinity to the two CYPs through hydrogen and van der Waals forces. The findings here suggested that engeletin may cause the herb-drug interactions for its inhibition of CYP3A4 and CYP2D6 activities.