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The most prominent feature of UV-induced photoaged skin is decreased type 1 procollagen. Increase of the TGF-β/Smad signaling through inhibition of the TβRI dephosphorylation by the GADD34-PP1c phosphatase complex represents a promising strategy for the increase in type 1 collagen production and prevention of UV-induced skin photoaging. In this study, the molecular docking and dynamics simulations, and pharmacophore modeling method were run to investigate a possible binding site as well as binding modes between apigenin, daidzein, asiaticoside, obovatol, and astragaloside IV and PP1c. Through docking study, the possible binding site for these phytochemicals was predicted as the hydrophobic (PP1-substrate binding) groove. The result indicates that PP1 is the significant target of these compounds. Moreover, the 20,000-ps MD simulations present that the binding locations and modes predicted by the docking have been slightly changed considering that the MD simulations proffer more reliable details upon the protein-ligand recognition. The MM-GBSA binding free energy calculations and pharmacophore modeling rationally identify that the highly hydrophobic surfaces/pockets at close proximity of the catalytic core are the most favorable binding locations of the herbal compounds, and that some experimental facts upon a possible mechanism of increase in collagen biosynthesis can be explained. The present study theoretically offers the reliable binding target of the herbal compounds, and therefore helps to understanding the action mechanism for natural small molecules that enhance collagen production.

Secoiridoids are bioactive compounds, which are present in plants and exhibit anti-inflammatory activity. In this work, to understand the structural basis of five secoiridoids; amarogentin, amaroswerin, gentiopicrin, sweroside, and swertiamarin for potent inhibitors of the target proteins associated with the collagen degradation pathway, namely MMP-1, MMP-3, MMP-9 and transcription factor AP-1, molecular docking, binding mode modeling, and MD simulations were carried out. The binding inhibitory effects of the secoiridoids were screened on these proteins. The obtained results in terms of binding conformation, binding free energy, protein–ligand interaction profile, structural flexibility, and binding energy decomposition of the secoiridoid inhibitors were elucidated. The molecular modeling clarified inhibitory effect on account of the five secoiridoids towards all three Matrix metalloproteinases (MMPs). Moreover, amarogentin and gentiopicrin may interfere with gene expression via binding to AP-1. Among all screened secoiridoids, amarogentin and gentiopicrin exhibited an interesting binding affinity to the MMPs and AP-1. The results suggest that amarogentin has the highest potential for application as an anti-aging agent with the MMP inhibitory and anti-transcriptional activities, even though further studies are needed to determine the anti-aging effect in vitro, in vivo and by clinical evaluation.

P-glycoprotein (P-gp) is a 170-kDa membrane protein. It provides a barrier function and help to excrete toxins from the body as a transporter. Some bioflavonoids have been shown to block P-gp activity. To evaluate the important amino acid residues within nucleotide binding domain 1 (NBD1) of P-gp that play a key role in molecular interactions with flavonoids using structure-based pharmacophore model. In the molecular docking with NBD1 models, a putative binding site of flavonoids was proposed and compared with the site for ATP. The binding modes for ligands were achieved using LigandScout to generate the P-gp–flavonoid pharmacophore models. The binding pocket for flavonoids was investigated and found these inhibitors compete with the ATP for binding site in NBD1 including the NBD1 amino acid residues identified by the in silico techniques to be involved in the hydrogen bonding and van der Waals (hydrophobic) interactions with flavonoids. These flavonoids occupy with the same binding site of ATP in NBD1 proffering that they may act as an ATP competitive inhibitor.

Nevirapine (NVP) and its structurally related analogs including nicotinamide (NAM), benzamide (BZM) and benzophenone (BZP) were used as templates in the synthesis of molecularly imprinted polymers for NVP. Molecular modeling was used to estimate binding energy of the complex formation between methacrylic acid (MAA) monomer and the selected templates, while equilibrium binding studies were applied to evaluate the polymer binding efficiency. The data indicated that NAM is the best candidate to prepare MIPs for retaining NVP due to a relatively similar binding energy between the NVP–MAA and NAM–MAA complex. The NAM-imprinted polymer showed a high binding affinity and selectivity toward NVP. When the polymer was applied as a sorbent in solid-phase extraction of NVP from human plasma, high recovery and reproducibility were obtained.