Pouteria macrophylla fruit extract microemulsion for cutaneous depigmentation : evaluation using a 3D pigmented skin model

Here, we verify the depigmenting action of Pouteria macrophylla fruit extract (EXT), incorporate it into a safe topical microemulsion and assess its effectiveness in a 3D pigmented skin model. Melanocytes-B16F10- were used to assess the EXT effects on cell viability, melanin synthesis, and melanin synthesis-related gene transcription factor expression, which demonstrated a 32% and 50% reduction of intra and extracellular melanin content, respectively. The developed microemulsion was composed of Cremophor EL®/Span 80 4:1 (w/w), ethyl oleate, and pH 4.5 HEPES buffer and had an average droplet size of 40 nm (PdI 0.40 ± 0.07). Skin irritation test with reconstituted epidermis (Skin Ethic RHETM) showed that the formulation is non-irritating. Tyrosinase inhibition was maintained after skin permeation in vitro, in which microemulsion showed twice the inhibition of the conventional emulsion (20.7 ± 2.2% and 10.7 ± 2.4%, respectively). The depigmenting effect of the microemulsion was finally confirmed in a 3D culture model of pigmented skin, in which histological analysis showed a more pronounced effect than a commercial depigmenting formulation. In conclusion, the developed microemulsion is a promising safe formulation for the administration of cutite fruit extract, which showed remarkable depigmenting potential compared to a commercial formulation

Structural Insights into Human Peroxisome Proliferator Activated Receptor Delta (PPAR-Delta) Selective Ligand Binding

Peroxisome proliferator activated receptors (PPARs δ, α and γ) are closely related transcription factors that exert distinct effects on fatty acid and glucose metabolism, cardiac disease, inflammatory response and other processes. Several groups developed PPAR subtype specific modulators to trigger desirable effects of particular PPARs without harmful side effects associated with activation of other subtypes. Presently, however, many compounds that bind to one of the PPARs cross-react with others and rational strategies to obtain highly selective PPAR modulators are far from clear. GW0742 is a synthetic ligand that binds PPARδ more than 300-fold more tightly than PPARα or PPARγ but the structural basis of PPARδ:GW0742 interactions and reasons for strong selectivity are not clear. Here we report the crystal structure of the PPARδ:GW0742 complex. Comparisons of the PPARδ:GW0742 complex with published structures of PPARs in complex with α and γ selective agonists and pan agonists suggests that two residues (Val312 and Ile328) in the buried hormone binding pocket play special roles in PPARδ selective binding and experimental and computational analysis of effects of mutations in these residues confirms this and suggests that bulky substituents that line the PPARα and γ ligand binding pockets as structural barriers for GW0742 binding. This analysis suggests general strategies for selective PPARδ ligand design

Tyrosinase inhibitory activity, molecular docking studies and antioxidant potential of chemotypes of Lippia origanoides (Verbenaceae) essential oils.

The essential oils (EOs) of the aerial parts of Lippia origanoides (LiOr), collected in different localities of the Amazon region, were obtained by hydrodistillation and analyzed by GC and CG-MS. Principle component analysis (PCA) based on chemical composition grouped the oils in four chemotypes rich in mono- and sesquiterpenoids. Group I was characterized by 1,8-cineole and α-terpineol (LiOr-1 and LiOr-4) and group II by thymol (LiOr-2). The oil LiOr-3 showed β-caryophyllene, α-phellandrene and β-phellandrene as predominant and LiOr-5 was rich in (E)-nerolidol and β-caryophyllene. All samples were evaluated for antioxidant activity and inhibition of tyrosinase in vitro and in silico. The highest antioxidant activity by the DPPH free radical method was observed in LiOr-2 and LiOr-5 oils (132.1 and 82.7 mg TE∙mL-1, respectively). The tyrosinase inhibition potential was performed using L-tyrosine and L-DOPA as substrates and all samples were more effective in the first step of oxidation. The inhibition by samples LiOr-2 and LiOr-4 were 84.7% and 62.6%, respectively. The samples LiOr-1, LiOr-4 and LiOr-5 displayed an interaction with copper (II) ion with bathochromic shift around 15 nm. In order to elucidate the mechanism of inhibition of the main compounds, a molecular docking study was carried out. All compounds displayed an interaction between an oxygen and Cu or histidine residues with distances less than 4 Å. The best docking energies were observed with thymol and (E)-nerolidol (-79.8 kcal.mol-1), which suggested H-bonding interactions with Met281 and His263 (thymol) and His259, His263 ((E)-nerolidol)

Stability and Antioxidant Activity of <i>Pouteria macrophylla</i> Fruit Extract, a Natural Source of Gallic Acid

Pouteria macrophylla (cutite) fruits are rich in phenolic acids, resulting in antioxidant and skin depigmenting activity. The aim of this study, then, is to evaluate the cutite extract stability under three variations of light, time, and temperature using a Box–Behnken experimental design to analyze through the surface response the variations of the total phenolic content (TPC), antioxidant activity (AA), and gallic acid content (GA). A colorimetric assay was also performed, and a decrease in the darkening index was noticed due to the high phenolic coloration in the presence of light, indicating less degradation to extract stability. The experimental planning showed variations in all responses, and second-order polynomial models were calculated and considered predictable, as well as the effects were significant. The TPC exhibited a variation in less concentrated samples (0.5% p/v) at higher temperatures (90 °C). In contrast, the temperature was the only influential variable for AA, where only higher temperatures (60–90 °C) were able to destabilize the fruit extract. Differently, GA showed only the concentration as the influential variable, exhibiting that neither temperature nor time of exposure could affect the gallic acid content stability of P. macrophylla extract. For this, P. macrophylla extract was shown to be highly stable, providing a great perspective on cosmetic application

Alignment of amino acid residues forming the binding site of the different human PPAR isotypes.

<p>Residues placed in arm I (A), arm II (B) and arm III (C) are shown. Residues involved in the hPPARδ-LBD:GW0742 interactions are underscored. Residues in black, bold and gray represent identical residues, residues with same chemical character and residues with different chemical character, respectively.</p

Crystallographic structure of the complex hPPARδ-LBD:GW0742.

<p><i>(A)</i> The ligand (magenta sticks) occupies the PPARδ-LBD (grey cartoon) and performs interactions with residues belonging to the arm I (yellow), arm II (green) and arm III (orange). <i>(B)</i> Stereo view of the binding site, showing the electron density calculated for the ligand (omit map, contoured at σ = 1.0) and the PPARδ residues that stabilize the ligand. Polar interactions between hPPARδ-LBD and the GW0742 ligand are shown as dashed lines. Nitrogen, oxygen, sulfur and fluoride atoms are colored blue, red, yellow and light blue, respectively. The residues from arms I, II and III are colored in yellow, green and orange, respectively. Figures were generated with the Pymol software (Schrödinger).</p

PPAR transactivation assays.

<p>PPAR activation induced by <i>(A)</i> the δ-selective agonist GW0742; <i>(B)</i> the pan-agonist benzafibrate; <i>(C)</i> the α-selective agonist GW7647 and <i>(D)</i> the γ-selective agonist rosiglitazone. All data were normalized by the level of <i>Renilla</i> luciferase activity. ▪/<b>#</b> wtPPARδ, ▴/xx PPARδVal312Met, •/<b>//</b>PPARδIle328M, <>\vskip -1\scale 80%\raster="rg1"<>/ = PPARα and ◂/<>\vskip -1\scale 70%\raster="rg2"<>PPARγ.</p

UV- vis spectrum of <i>L</i>. <i>origanoides</i> oils (1 mg.mL^-1).

<p>(A) Without CuSO₄ (250 μM). (B) with CuSO₄ (250 μM).</p

Three-dimensional structure of PPARδ-selective agonist GW0742, as found in our hPPARδ:GW0742 crystal structure (PDB id 3TKM).

<p>Typical structural features of PPAR agonists are displayed. Carbon, fluoride, sulfur, oxygen and nitrogen atoms are colored white, light grey, grey, dark grey and black, respectively.</p

Lowest-energy docked poses of essential oil components in the binding site of tyrosinase.

<p>(A) Tropolone (yellow). (B) Thymol (green). (C) α-Terpineol (green). (D) 1,8-Cineole (green). (E) β-Caryophyllene (green). (F) (<i>E</i>)-Nerolidol (green). Key amino acid residues are shown in CPK colors. Hydrogen bonds are illustrated with dashed lines.</p