Cytotoxic Screening and Enhanced Anticancer Activity of Lippia alba and Clinopodium nepeta Essential Oils-Loaded Biocompatible Lipid Nanoparticles against Lung and Colon Cancer Cells.

Plant and herbal essential oils (EOs) offer a wide range of pharmacological actions that include anticancer effects. Here, we evaluated the cytotoxic activity of EO from Lippia alba (chemotype linalool), L. alba (chemotype dihydrocarvone, LaDEO), Clinopodium nepeta (L.) Kuntze (CnEO), Eucalyptus globulus, Origanum × paniculatum, Mentha × piperita, Mentha arvensis L., and Rosmarinus officinalis L. against human lung (A549) and colon (HCT-116) cancer cells. The cells were treated with increasing EO concentrations (0-500 µL/L) for 24 h, and cytotoxic activity was assessed. LaDEO and CnEO were the most potent EOs evaluated (IC50 range, 145-275 µL/L). The gas chromatography-mass spectrometry method was used to determine their composition. Considering EO limitations as therapeutic agents (poor water solubility, volatilization, and oxidation), we evaluated whether LaDEO and CnEO encapsulation into solid lipid nanoparticles (SLN/EO) enhanced their anticancer activity. Highly stable spherical SLN/LaDEO and SLN/CnEO SLN/EO were obtained, with a mean diameter of 140-150 nm, narrow size dispersion, and Z potential around -5mV. EO encapsulation strongly increased their anticancer activity, particularly in A549 cells exposed to SLN/CnEO (IC50 = 66 µL/L CnEO). The physicochemical characterization, biosafety, and anticancer mechanisms of SLN/CnEO were also evaluated in A549 cells. SLN/CnEO containing 97 ± 1% CnEO was highly stable for up to 6 months. An increased in vitro CnEO release from SLN at an acidic pH (endolysosomal compartment) was observed. SLN/CnEO proved to be safe against blood components and non-toxic for normal WI-38 cells at therapeutic concentrations. SLN/CnEO substantially enhanced A549 cell death and cell migration inhibition compared with free CnEO.

Anti-cancer mechanisms of linalool and 1,8-cineole in non-small cell lung cancer A549 cells.

Linalool and 1,8-cineole are plant-derived isoprenoids with anticancer activities in lung cancer cells, nevertheless, the cellular and molecular mechanisms of action remain poorly understood. The purpose of this study was to determine the anticancer mechanisms of action of linalool and 1,8-cineole in lung adenocarcinoma A549 cells. Linalool (0-2.0 mM) and 1,8-cineole (0-8.0 mM) inhibited cell proliferation by inducing G0/G1 and/or G2/M cell cycle arrest without affecting cell viability of normal lung WI-38 cells. None of the two monoterpenes were able to induce apoptosis, as observed by the lack of caspase-3 and caspase-9 activation, PARP cleavage, and DNA fragmentation. Linalool, but not 1,8-cineole, increased reactive oxygen species production and mitochondrial membrane potential depolarization. Reactive oxygen species were involved in cell growth inhibition and mitochondrial depolarization induced by linalool since the antioxidant N-acetyl-L-cysteine prevented both effects. Besides, linalool (2.0 mM) and 1,8-cineole (8.0 mM) inhibited A549 cell migration. The combination of each monoterpene with simvastatin increased the G0/G1 cell cycle arrest and sensitized cells to apoptosis compared with simvastatin alone. Our results showed that both monoterpenes might be promising anticancer agents with antiproliferative, anti-metastatic, and sensitizer properties for lung cancer therapy.

Citrus reticulata peel oil inhibits non-small cell lung cancer cell proliferation in culture and implanted in nude mice.

Non-small cell lung cancer (NSCLC) accounts for most cases of lung cancer. The peel oil of mandarin Citrus reticulata Blanco cv. Dancy (MPO) is a natural source of essential oils and carotenoids. Volatile and non-volatile lipid compounds were characterized by chromatographic methods. We demonstrate that MPO causes a dose-dependent growth inhibition of NSCLC model cells (A549) in culture and tumour growth in vivo of the same cells implanted in nude mice fed with MPO-supplemented diets. MPO induced cell cycle arrest mainly at the G0/G1 phase and reduced the amount of membrane-bound Ras protein along with apoptosis induction. No toxicological effect was found in liver parameters analysed in treated mice and histopathological analyses of their organs did not show any morphological changes. In conclusion, the data suggest that MPO possesses significant antitumor activity without causing systemic toxicity, proposing it as a dietary supplement that may be helpful in cancer prevention.

Modulation by geraniol of gene expression involved in lipid metabolism leading to a reduction of serum-cholesterol and triglyceride levels.

BACKGROUND: Geraniol (G) is a natural isoprenoid present in the essential oils of several aromatic plants, with various biochemical and pharmacologic properties. Nevertheless, the mechanisms of action of G on cellular metabolism are largely unknown. HYPOTHESIS/PURPOSE: We propose that G could be a potential agent for the treatment of hyperlipidemia that could contribute to the prevention of cardiovascular disease. The aim of the present study was to advance our understanding of its mechanism of action on cholesterol and TG metabolism. STUDY DESIGN/METHODS: NIH mice received supplemented diets containing 25, 50, and 75 mmol G/kg chow. After a 3-week treatment, serum total-cholesterol and triglyceride levels were measured by commercial kits and lipid biosynthesis determined by the [(14)C] acetate incorporated into fatty acids plus nonsaponifiable and total hepatic lipids of the mice. The activity of the mRNA encoding HMGCR-the rate-limiting step in cholesterol biosynthesis-along with the enzyme levels and catalysis were assessed by real-time RT-PCR, Western blotting, and HMG-CoA-conversion assays, respectively. In-silico analysis of several genes involved in lipid metabolism and regulated by G in cultured cells was also performed. Finally, the mRNA levels encoded by the genes for the low-density-lipoprotein receptor (LDLR), the sterol-regulatory-element-binding transcription factor (SREBF2), the very-low-density-lipoprotein receptor (VLDLR), and the acetyl-CoA carboxylase (ACACA) were determined by real-time RT-PCR. RESULTS: Plasma total-cholesterol and triglyceride levels plus hepatic fatty-acid, total-lipid, and nonsaponifiable-lipid biosynthesis were significantly reduced by feeding with G. Even though an up-regulation of the mRNA encoding HMGCR occurred in the G treated mouse livers, the protein levels and specific activity of the enzyme were both inhibited. G also enhanced the mRNAs encoding the LDL and VLDL receptors and reduced ACACA mRNA, without altering the transcription of the mRNA encoding the SREBF2. CONCLUSIONS: The following mechanisms may have mediated the decrease in plasma lipids levels in mice: a down-regulation of hepatocyte-cholesterol synthesis occurred as a result of decreased HMGCR protein levels and catalytic activity; the levels of LDLR mRNA became elevated, thus suggesting an increase in the uptake of serum LDL, especially by the liver; and TG synthesis became reduced very likely because of a decrease in fatty-acid synthesis.