Citrus reticulata peel oil as an antiatherogenic agent: Hypolipogenic effect in hepatic cells, lipid storage decrease in foam cells, and prevention of LDL oxidation.

BACKGROUND AND AIMS: Hypercholesterolemia and oxidative stress are two of the most important risk factors for atherosclerosis. The aim of the present work was to evaluate mandarin (Citrus reticulata) peel oil (MPO) in cholesterol metabolism and lipid synthesis, and its antioxidant capacity. METHODS AND RESULTS: Incubation of hepatic HepG2 cells with MPO (15-60 µL/L) reduced cholesterogenesis and saponifiable lipid synthesis, demonstrated by [14C]acetate radioactivity assays. These effects were associated with a decrease in a post-squalene reaction of the mevalonate pathway. Molecular docking analyses were carried out using three different scoring functions to examine the cholesterol-lowering property of all the components of MPO against lanosterol synthase. Docking simulations proposed that minor components of MPO monoterpenes, like alpha-farnesene and neryl acetate, as well the major component, limonene and its metabolites, could be partly responsible for the inhibitory effects observed in culture assays. MPO also decreased RAW 264.7 foam cell lipid storage and its CD36 expression, and prevented low-density lipoprotein (LDL) lipid peroxidation. CONCLUSION: These results may imply a potential role of MPO in preventing atherosclerosis by a mechanism involving inhibition of lipid synthesis and storage and the decrease of LDL lipid peroxidation.

Enzymatic Active Release of Violacein Present in Nanostructured Lipid Carrier by Lipase Encapsulated in 3D-Bioprinted Chitosan-Hydroxypropyl Methylcellulose Matrix With Anticancer Activity.

Violacein (Viol) is a bacterial purple water-insoluble pigment synthesized by Chromobacterium violaceum and other microorganisms that display many beneficial therapeutic properties including anticancer activity. Viol was produced, purified in our laboratory, and encapsulated in a nanostructured lipid carrier (NLC). The NLC is composed of the solid lipid myristyl myristate, an oily lipid mixture composed of capric and caprylic acids, and the surfactant poloxamer P188. Dormant lipase from Rhizomucor miehei was incorporated into the NLC-Viol to develop an active release system. The NLC particle size determined by dynamic light scattering brings around 150 nm particle size and ζ≈ -9.0 mV with or without lipase, but the incorporation of lipase increase the PdI from 0.241 to 0.319 (≈32%). For scaffold development, a 2.5 hydroxypropyl methylcellulose/chitosan ratio was obtained after optimization of a composite for extrusion in a 3D-bioprinter developed and constructed in our laboratory. Final Viol encapsulation efficiency in the printings was over 90%. Kinetic release of the biodye at pH = 7.4 from the mesh containing NLC-lipase showed roughly 20% Viol fast release than without the enzyme. However, both Viol kinetic releases displayed similar profiles at pH = 5.0, where the lipase is inactive. The kinetic release of Viol from the NLC-matrices was modeled and the best correlation was found with the Korsmeyer-Peppas model (R2 = 0.95) with n < 0.5 suggesting a Fickian release of Viol from the matrices. Scanning Electron Microscope (SEM) images of the NLC-meshes showed significant differences before and after Viol's release. Also, the presence of lipase dramatically increased the gaps in the interchain mesh. XRD and Fourier Transform Infrared (FTIR) analyses of the NLC-meshes showed a decrease in the crystalline structure of the composites with the incorporation of the NLC, and the decrease of myristyl myristate in the mesh can be attributed to the lipase activity. TGA profiles of the NLC-meshes showed high thermal stability than the individual components. Cytotoxic studies in A549 and HCT-116 cancer cell lines revealed high anticancer activity of the matrix mediated by mucoadhesive chitosan, plus the biological synergistic activities of violacein and lipase.

Induction of oxidative stress as a possible mechanism by which geraniol affects the proliferation of human A549 and HepG2 tumor cells.

Geraniol (GOH), like other plant-derived natural bioactive compounds, has been found to possess antiproliferative properties that are essential to cope with malignant tumors. However, the mechanisms of molecular action of GOH are not fully elucidated. The aim of this study was to evaluate the effect of GOH on some oxidative parameters in human tumor cell lines (HepG2 and A549). Cytotoxicity evaluated in cell lines by the MTT assay, genotoxicity by the comet assay, and lipid peroxidation by the TBARS. The activities of antioxidant the enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST), were also analyzed. Additionally, intracellular reactive oxygen species (ROS), nitric oxide, and lactate production were determined in HepG2 cells. Both tumor cell lines showed a clear concentration-dependent response to GOH in several of the parameters evaluated. Lipids turned out to be more sensitive than DNA to oxidative damage induced by GOH. TBARS levels increased with respect to control (p < 0.05) by 33% and 122% in HepG2 and A549 cells, respectively treated with 200 µM GOH. However, GOH caused a statistically significant decrease in SOD and CAT activities in HepG2 cells only. GST was not affected in any cell lines. GOH induced the production of ROS but not nitric oxide in HepG2, which shows that ROS were mainly responsible for oxidative damage. Lactate release increased statistically significantly compared to control (p < 0.001), by 41% and 86% at 200 and 800 µM GOH respectively, showing that this monoterpene also affected the glycolytic pathway in HepG2 cells. These results suggest that oxidative stress could mediate the anti-proliferative effects of GOH in HepG2 and A549 cells.