Design, characterization and in vitro evaluation of linalool-loaded solid lipid nanoparticles as potent tool in cancer therapy.

Linalool (LN) is a monoterpene found in essential oils of plants and herbs that produces multiple effects on the mevalonate pathway and interesting antiproliferative activity in cancer cells. However, due to its poor aqueous solubility, an efficient vehicle is needed to improve its administration and bioavailability in physiological media. LN encapsulation in solid lipid nanoparticles (SLN) with different compositions was explored and in vitro tested in two cancer cell lines. SLN of myristyl myristate (MM), cetyl esters (SS) and cetyl palmitate (CP) were prepared by sonication in the presence of Pluronic®F68 as surfactant. Nanoparticle size, morphology and distribution were determined by dynamic light scattering in combination with optical and transmission electron microscopy (TEM). SLN showed spherical shape and mean diameters in the range of 90-130nm with narrow size dispersion (PDI values lower than 0.2) and Z potentials around -4.0mV. The encapsulation percentages of LN in SLN were higher than 80% for all tested formulations and exhibited in vitro LN controlled release profiles for at least 72h. The nanoparticles were physicochemically characterized by FTIR, XRD, DSC and TGA, and the incorporation of LN into SLN was higher than 80% in tested matrices. The developed formulations, and in particular SLN (MM)-LN, showed in vitro antiproliferative effects on hepatocarcinoma (HepG2) and lung adenocarcinoma (A549) cell lines in a dose-dependent response, and higher inhibitory effects were found in comparison with free LN. The cellular uptake of SLN was demonstrated by fluorescence microscopy, enhancing the ability of nanoparticles to intracellularly deliver the cargo molecules.

Suppression by geraniol of the growth of A549 human lung adenocarcinoma cells and inhibition of the mevalonate pathway in culture and in vivo: potential use in cancer chemotherapy.

Geraniol (G)-a natural compound present in the essential oils of many aromatic plants-has attracted interest for its potential antitumor effects. The molecular mechanisms of the growth inhibition and apoptosis induced by G in cancer cells, however, remain unclear. In this study, we investigated the effects of G on cell proliferation in culture in A549 cells and in vivo in those same tumor cells implanted in nude mice fed diets supplemented with 25, 50, and 75 mmol G/kg. We demonstrated that G caused a dose- and time-dependent growth inhibition of A549 cells and tumor growth in vivo along with an induction of apoptosis. Moreover, further in vivo assays indicated that G decreased the levels of 3-hydroxymethylglutarylcoenzyme-A reductase-the rate-limiting enzyme in cholesterogenesis-in a dose-dependent manner along with cholesterogenesis and cholesterolemia in addition to reducing the amount of membrane-bound Ras protein. These results showed that the doses of G used in this work, though nontoxic to animals, clearly inhibited the mevalonate pathway, which is closely linked to cell proliferation and increased apoptosis in A549 tumors, but not in normal mouse-liver cells. Accordingly, we suggest that G displays significant antitumor activity and should be a promising candidate for cancer chemotherapy.

Transcriptional and posttranscriptional inhibition of HMGCR and PC biosynthesis by geraniol in 2 Hep-G2 cell proliferation linked pathways.

Geraniol, present in the essential oils of many aromatic plants, has in vitro and in vivo antitumor activity against several cell lines. We investigated the effects of geraniol on lipid metabolic pathways involved in Hep-G2 cell proliferation and found that geraniol inhibits the mevalonate pathway, phosphatidylcholine biosynthesis, cell growth, and cell cycle progression (with an arrest occurring at the G0/G1 interphase) and increases apoptosis. The expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting step in cholesterol synthesis, was inhibited at the transcriptional and posttranscriptional levels, as assessed by real-time RT-PCR, Western blots, and [(14)C]HMG-CoA-conversion radioactivity assays. That geraniol decreased cholesterogenesis but increased the incorporation of [(14)C]acetate into other nonsaponifiable metabolites indicated the existence of a second control point between squalene and cholesterol involved in redirecting the flow of cholesterol-derived carbon toward other metabolites of the mevalonate pathway. That exogenous mevalonate failed to restore growth in geraniol-inhibited cells suggests that, in addition to the inhibition of HMGCR, other dose-dependent actions exist through which geraniol can impact the mevalonate pathway and consequently inhibit cell proliferation. These results suggest that geraniol, a nontoxic compound found in many fruits and herbs, exhibits notable potential as a natural agent for combatting cancer and (or) cardiovascular diseases.

Cytotoxic and genotoxic effects of defence secretion of Ulomoides dermestoides on A549 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Ulomoides dermestoides (Fairmaire, 1893) is a cosmopolitan tenebrionid beetle reared by Argentine people who consume them alive as an alternative medicine in the treatment of different illnesses such as asthma, Parkinson's, diabetes, arthritis, HIV and specially cancer. AIM OF THE STUDY: To evaluate the cytotoxicity and DNA damage of the major volatile components released by Ulomoides dermestoides on human lung carcinoma epithelial cell line A549. MATERIALS AND METHODS: The defence compounds of Ulomoides dermestoides were extracted with dichloromethane and analyzed and quantified by capillary gas chromatography. The toxicity effects of the beetle's extract against A549 cell line were evaluated. Cytotoxicity was evaluated by MTT test and Trypan blue assay and genotoxicity was evaluated by the comet assay. The synthetic compounds, individually or combined, were also tested in A549 cells and normal mononuclear human cells. RESULTS: The defence compounds of Ulomoides dermestoides extracted with dichloromethane (methyl-1,4-benzoquinones, ethyl-1,4-benzoquinones and 1-pentadecene as major components) showed cytotoxic activity on A549 cells demonstrated by MTT test and Trypan blue assay, with IC(50) values of 0.26equivalent/ml and 0.34equivalent/ml, respectively (1equivalent=amount of components extracted per beetle). The inhibition of A549 cell proliferation with the synthetic blend (1,4-benzoquinone and 1-pentadecene) or 1,4-benzoquinone alone was similar to that obtained with the insect extract. 1-Pentadecene showed no inhibitory effect. Low doses of insect extract or synthetic blend (0.15equivalent/ml) inhibited mononuclear cell proliferation by 72.2±2.7% and induced significant DNA damage both in tumor and mononuclear cells. CONCLUSION: Results of this study demonstrated that defence compounds of Ulomoides dermestoides reduced cell viability and induced DNA damage. We also concluded that the insect benzoquinones are primarily responsible for inducing cytotoxicity and genotoxicity in culture cells.

In vitro antitumor activity of N-glycosyl sulfonamides.

A series of α-D-hex-2-enopyranosyl sulfonamides was evaluated for their antiproliferative activity against human hepatocellular liver carcinoma (HepG2) and human lung adenocarcinoma (A549) cell lines. The most potent compound (2,4,6-tri-O-acetyl-3-deoxy-α-D-erythro-hex-2-enopyranosyl ethanesulfonamide) showed antiproliferative properties in the micromolar range. The SARs of these sulfonamidoglycoside which includes the influence of carbohydrate rings and sulfonamide class are described.

Effect of geraniol on fatty-acid and mevalonate metabolism in the human hepatoma cell line Hep G2.

Monoterpenes have multiple pharmacological effects on the metabolism of mevalonate. Geraniol, a dietary monoterpene, has in vitro and in vivo anti-tumor activity against several cell lines. We have studied the effects of geraniol on growth, fatty-acid metabolism, and mevalonate metabolism in the human hepatocarcinoma cell line Hep G2. Up to 100 micromol geraniol/L inhibited the growth rate and 3-hydroxymethylglutaryl coenzyme A reductase (HMG-CoA) reductase activity of these cells. At the same concentrations, it increased the incorporation of cholesterol from the medium in a dose-dependent manner. Geraniol-treated cells incorporated less 14C-acetate into nonsaponifiable lipids, inhibiting its incorporation into cholesterol but not into squalene and lanosterol. This is indicative of an inhibition in cholesterol synthesis at a step between lanosterol and cholesterol, a fact confirmed when cells were incubated with 3H-mevalonate. The incorporation of 3H-mevalonate into protein was also inhibited, whereas its incorporation into fatty acid increased. An inhibition of delta5 desaturase activity was demonstrated by the inhibition of the conversion of 14C-dihomo-gamma-linolenic acid into arachidonic acid. Geraniol has multiple effects on mevalonate and lipid metabolism in Hep G2 cells, affecting cell proliferation. Although mevalonate depletion is not responsible for cellular growth, it affects cholesterogenesis, protein prenylation, and fatty-acid metabolism.

Effect of ethanol on cell growth and cholesterol metabolism in cultured Hep G2 cells.

The Hep G2 human hepatoma cell line has been recognized as an excellent in vitro human model system. For this reason, this line was used to study the effect of ethanol on HMG-CoA reductase activity concerning cell growth and cholesterol metabolism. Cells were incubated in ethanol-containing medium (0-400 mmol/L) for up to 102 h. Ethanol caused an inhibition in the growth rate and in HMG-CoA reductase activity that could be reverted by the removal of ethanol from the culture medium, indicating no cellular damage. These changes cannot be ascribed to the regulatory effect of cholesterol levels, since its content was not modified either in the cells or in the medium. The addition of mevalonate to the culture medium could not revert the growth rate inhibition evoked by ethanol. Moreover, ethanol produced an increment in the cholesterol efflux in [3H]cholesterol-prelabeled cells. We conclude that the decrease in HMG-CoA reductase activity evoked by ethanol treatment on Hep G2 cells would not be the cause but the consequence of the impairment in cellular growth, since this impairment could not be reverted by the addition of mevalonate to the culture medium.