The chemopreventive flavonoid apigenin induces G2/M arrest in keratinocytes

Apigenin is a plant flavonoid which has been shown to significantly inhibit UV-induced mouse skin tumorigenesis when applied topically, and may represent an alternative sunscreen agent in humans. We have investigated the molecular mechanism(s) by which apigenin inhibits skin tumorigenesis. Initial studies examined the effects of apigenin on the cell cycle. DNA flow cytometric analysis indicated that culturing cells for 24 h in medium containing apigenin induced a G2/M arrest in two mouse skin derived cell lines, C50 and 308, as well as in human HL-60 cells. The G2/M arrest was fully reversible after an additional 24 h in medium without apigenin. We investigated the effects of apigenin on cyclin B1 and p34cdc2, since cyclin B1/p34cdc2 complexes regulate G2/M progression. Western blot and immune complex kinase assays using whole cell lysates from 308 and C50 cells treated for 24 h with 0-70 microM doses of apigenin demonstrated that apigenin treatment did not change the steady-state level of p34cdc2 protein, but did inhibit p34cdc2 H1 kinase activity in 308 cells. Western blot analysis showed that apigenin treatment of C50 cells and 308 cells inhibited the accumulation of cyclin B1 protein in a dose-dependent manner. The apigenin levels detected in cultured keratinocytes were relevant to those detected in epidermal cells of Sencar mice treated with tumor inhibitory doses of apigenin. In conclusion, we present evidence that apigenin induces a reversible G2/M arrest in cultured keratinocytes, the mechanism of which is in part due to inhibition of the mitotic kinase activity of p34cd2, and perturbation of cyclin B1 levels.

Increase in activity of essential oil components carvacrol and thymol against Escherichia coli O157:H7 by addition of food stabilizers

The major components of oregano and thyme essential oils that had previously been shown to inhibit Escherichia coli O157:H7 were determined by high-performance liquid chromatography with UV detection and liquid chromatographic tandem mass spectrometry. The MICs and MBCs of carvacrol, thymol, p-cymene, and gamma-terpinene against a strain of E. coli O157: H7 phage type 34 isolated from bovine feces were determined by microdilution assay. The constituents were then tested in checkerboard assays to detect possible interactions. Carvacrol and thymol displayed bacteriostatic and bactericidal properties with MICs of 1.2 mmol/liter and were additive in combination. p-Cymene and gamma-terpinene displayed no measurable antibacterial activity up to 50 mmol/liter, and neither influenced the activity of carvacrol or thymol. Growth curves in the presence of nonlethal concentrations of carvacrol with the addition of agar (0.05%, wt/vol) or carrageenan (0.125%, wt/vol) as stabilizer were produced by optical density measurement. The stabilizers agar and carrageenan both significantly improved the effectiveness of carvacrol in broth, possibly because of a delay in the separation of the hydrophobic substrate from the aqueous phase of the medium. When carvacrol was dissolved in ethanol before addition to broth, stabilizers were not needed. Carvacrol and thymol, particularly when used in combination with a stabilizer or in an ethanol solution, may be effective in reducing the number or preventing growth of E. coli O157:H7 in liquid foods.

Antiparasitic activity of two Lavandula essential oils against Giardia duodenalis, Trichomonas vaginalis and Hexamita inflata

Two essential oils derived from Lavandula angustifolia and Lavandula x intermedia were investigated for any antiparasitic activity against the human protozoal pathogens Giardia duodenalis and Trichomonas vaginalis and the fish pathogen Hexamita inflata: all of which have significant infection and economic impacts. The study has demonstrated that low (< or = 1%) concentrations of L. angustifolia and L. x intermedia oil can completely eliminate T. vaginalis, G. duodenalis and H. inflata in vitro. At 0.1% concentration, L. angustifolia oil was found to be slightly more effective than L x intermedia oil against G. duodenalis and H. inflata. The potential applications are discussed.

Essential oil-mediated glycerosomes increase transdermal paeoniflorin delivery: optimization, characterization, and evaluation in vitro and in vivo

In this study, a novel glycerosome carrier containing essential oils was prepared for topical administration of paeoniflorin (PF) to enhance its transdermal drug delivery and improve drug absorption in the synovium. The formulation of glycerosomes was optimized by a uniform design, and the final vehicle was composed of 5% (w/v) phospholipid, 0.6% (w/v) cholesterol, and 10% (v/v) glycerol, with 2% (v/v) Speranskia tuberculata essential oil (STO) as the transdermal enhancer. The in vitro transdermal flux of PF loaded in the STO-glycerosomes was 1.4-fold, 1.6-fold, and 1.7-fold higher than those of glycerosomes, liposomes, and tinctures, respectively. In vivo studies showed that the use of STO-glycerosomes was associated with a 3.1-fold greater accumulation of PF in the synovium than that of common glycerosomes. This finding was confirmed by in vivo imaging studies, which found that the fluorescence intensity of Cy5.5-loaded STO-glycerosomes in mice knee joints was 1.8-fold higher than that of the common glycerosomes 5 h after administration. The glycerosomes mediated by STO exhibited considerable skin permeability as well as improved drug absorption in the synovium, indicating that STO-glycerosomes may be a potential PF transdermal delivery vehicle for the treatment of rheumatoid arthritis caused by synovium lesions.

Antimicrobial, Antioxidant, Anti-Acetylcholinesterase, Antidiabetic, and Pharmacokinetic Properties of Carum carvi L. and Coriandrum sativum L. Essential Oils Alone and in Combination

Herbs and spices have been used since antiquity for their nutritional and health properties, as well as in traditional remedies for the prevention and treatment of many diseases. Therefore, this study aims to perform a chemical analysis of both essential oils (EOs) from the seeds of Carum carvi (C. carvi) and Coriandrum sativum (C. sativum) and evaluate their antioxidant, antimicrobial, anti-acetylcholinesterase, and antidiabetic activities alone and in combination. Results showed that the EOs mainly constitute monoterpenes with γ-terpinene (31.03%), β-pinene (18.77%), p-cymene (17.16%), and carvone (12.20%) being the major components present in C. carvi EO and linalool (76.41%), γ-terpinene (5.35%), and α-pinene (4.44%) in C. sativum EO. In comparison to standards, statistical analysis revealed that C. carvi EO showed high and significantly different (p < 0.05) antioxidant activity than C. sativum EO, but lower than the mixture. Moreover, the mixture exhibited two-times greater ferric ion reducing antioxidant power (FRAP) (IC₅₀ = 11.33 ± 1.53 mg/mL) and equipotent chelating power (IC₅₀ = 31.33 ± 0.47 mg/mL) than the corresponding references, and also potent activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC₅₀ = 19.00 ± 1.00 mg/mL), β-carotene (IC₅₀ = 11.16 ± 0.84 mg/mL), and superoxide anion (IC₅₀ = 10.33 ± 0.58 mg/mL) assays. Antimicrobial data revealed that single and mixture EOs were active against a panel of pathogenic microorganisms, and the mixture had the ability to kill more bacterial strains than each EO alone. Additionally, the anti-acetylcholinesterase and α-glucosidase inhibitory effect have been studied for the first time, highlighting the high inhibition effect of AChE by C. carvi (IC₅₀ = 0.82 ± 0.05 mg/mL), and especially by C. sativum (IC₅₀ = 0.68 ± 0.03 mg/mL), as well as the mixture (IC₅₀ = 0.63 ± 0.02 mg/mL) compared to the reference drug, which are insignificantly different (p > 0.05). A high and equipotent antidiabetic activity was observed for the mixture (IC₅₀ = 0.75 ± 0.15 mg/mL) when compared to the standard drug, acarbose, which is about nine times higher than each EO alone. Furthermore, pharmacokinetic analysis provides some useful insights into designing new drugs with favorable drug likeness and safety profiles based on a C. carvi and C. sativum EO mixture. In summary, the results of this study revealed that the combination of these EOs may be recommended for further food, therapeutic, and pharmaceutical applications, and can be utilized as medicine to inhibit several diseases.

Constituents of aromatic plants: eucalyptol

The subacute toxicity studies reported up to now in rats and mice suggested that mice were less susceptible than rats to the toxicity of eucalyptol. In fact, after gavage, it was found toxic in male rats at doses higher than 600 mg/kg while no effect was seen in mice up to 1200 mg/kg. However, the limitations and the quality of the study do not allow the extrapolation of a 'no effect level'. Several reports in rat and brushtail possum show the formation of hydroxylated bicycled products of eucalyptol as main metabolites. Moreover, metabolites which require ring opening have been also detected. Following the accidental exposure of human beings, death was reported in two cases after ingestion of 3.5-5 ml of essential eucalyptus oil, but a number of recoveries have also been described for much higher amounts of oil.

Chemotherapeutic potential of the volatile oils from Zanthoxylum rhoifolium Lam leaves

In this work, the anti-tumor properties of the volatile oil from Zanthoxylum rhoifolium Lam leaves and some terpenes (alpha-humulene, beta-caryophyllene, alpha-pinene and beta-pinene) were investigated in vitro and in vivo using the Ehrlich ascites tumor model. Treatment of Ehrlich ascites tumor-bearing mice with 20 mg/kg of the volatile oil and beta-caryophyllene for 4 days has significantly increased survival, whereas administration of alpha-humulene, alpha-pinene and beta-pinene were ineffective in affording protection. Volatile oil and beta-caryophyllene exhibited little direct activity against Ehrlich tumor cells in vitro, while alpha-humulene, alpha-pinene and beta-pinene did not such activity. Investigation of the effects of the volatile oil (and terpenes) treatment on total natural killer cells (NK cell) activity from tumor-bearing mice as a possible mechanism of these compounds in vivo revealed that volatile oil and beta-caryophyllene significantly improved NK cell cytotoxicity against YAC-1, a Moloney virus-induced mouse T-cell lymphoma of A/SN origin and Ehrlich ascites cells. As expected, tumor growth in non-treated mice markedly suppressed NK cell cytolysis while the volatile oil and beta-caryophyllene reversed this effect when mice were treated with 20-mg/kg dosages of these compounds for 4 days. Summing up, volatile oil exhibits anti-tumor efficacy and significative immunomodulatory action in vivo, which may be related to beta-caryophyllene associated to the synergism of other natural compounds presented in volatile oil from Z. rhoifolium Lam leaves.

Effect of different terpene-containing essential oils on permeation of estradiol through hairless mouse skin

Purpose of the present investigation was to evaluate six terpene-containing essential oils for their capacity to promote permeation of estradiol (ES) through hairless mouse skin in vitro. Tests on cajuput, cardamom, melissa, myrtle, niaouli and orange oil, all used at the 10% w/w concentration in propylene glycol (PG), evidenced niaouli oil (NIA) as the best permeation promoter for ES. Tests on the main terpene components of NIA (1,8 cineole, alpha-pinene, alpha-terpineol and D-limonene), evaluated neat (10% w/w in PG) or in admixture, confirmed the better promoting activity of whole NIA. The present data point to the validity of complex terpene mixtures, such as that composing NIA, as transdermal penetration enhancers for moderately lipophilic drugs like ES.

Pharmacokinetics and tissue distribution of the sesquiterpene alpha-humulene in mice

A quantitative study was undertaken to assess the plasma and tissue levels, tissue distribution and skin (ear) absorption of the sesquiterpene alpha-humulene, the main active constituent isolated from the plant Cordia verbenacea (Boraginaceae ), after oral, intravenous and topical administration in mice. The alpha-humulene levels were quantified by GC-MS analysis. The peak alpha-humulene concentration was achieved 15 min following its oral administration (150 mg/kg). Then, the alpha-humulene plasma concentration gradually decreased and it was almost undetectable at 2 hours after intravenous administration and 12 hours after oral administration. When the oil of C. verbenacea was given orally (1 g/kg), the peak alpha-humulene plasma concentration was observed after 30 min, being detectable only up to 2 h. The oral bioavailability of alpha-humulene was found to be 18 %. The half-lives of alpha-humulene were very short, 16.8 min after oral administration and 1.8 min after intravenous administration. However, the elimination half-lives were longer, 118.2 min and 55 min, for oral and intravenous routes, respectively. We also assessed the amount of alpha-humulene in some selected tissues at 0.5 and at 4 h after oral administration. We found a high amount of the compound in the liver, followed by the kidneys, heart, lungs, spleen and brain, 0.5 h after oral administration. Notably, the yield of alpha-humulene decreased significantly in all analyzed tissues, especially in the liver, 4 h after oral administration. Of note, 30 minutes after topical administration of Acheflan formulations (cream and aerosol) containing 0.5 % of C. verbenacea essential oil, a schedule of treatment that produces marked and similar topical anti-inflammatory activity, the amount of alpha-humulene absorbed in the ear was very similar (about 2 microg/ear). It is concluded that alpha-humulene exhibited a rapid onset and relatively good absorption following oral and topical administration. Taken together, these findings further contribute to an explanation of the topical and systemic anti-inflammatory and antinociceptive properties previously reported for the essential oil and for alpha-humulene obtained from Cordia verbenacea, they also provide support for the clinical studies conducted with the phytomedicine Acheflan.

The Effects of Essential Oils and Terpenes in Relation to Their Routes of Intake and Application

Essential oils have been used in multiple ways, i.e., inhaling, topically applying on the skin, and drinking. Thus, there are three major routes of intake or application involved: the olfactory system, the skin, and the gastro-intestinal system. Understanding these routes is important for clarifying the mechanisms of action of essential oils. Here we summarize the three systems involved, and the effects of essential oils and their constituents at the cellular and systems level. Many factors affect the rate of uptake of each chemical constituent included in essential oils. It is important to determine how much of each constituent is included in an essential oil and to use single chemical compounds to precisely test their effects. Studies have shown synergistic influences of the constituents, which affect the mechanisms of action of the essential oil constituents. For the skin and digestive system, the chemical components of essential oils can directly activate gamma aminobutyric acid (GABA) receptors and transient receptor potential channels (TRP) channels, whereas in the olfactory system, chemical components activate olfactory receptors. Here, GABA receptors and TRP channels could play a role, mostly when the signals are transferred to the olfactory bulb and the brain.

Drug cocktail interaction study on the effect of the orally administered lavender oil preparation silexan on cytochrome P450 enzymes in healthy volunteers

This cocktail study evaluated the interaction potential of the oral lavender oil preparation silexan with major P450 (cytochrome P450) enzymes.

SUBJECTS AND METHODS

Sixteen healthy male or female Caucasians completed this double-blind, randomized, 2-fold crossover study. Silexan (160 mg) or placebo were administered once daily for 11 days. Additionally, on day 11 of both study periods, 150 mg caffeine (CYP1A2), 125 mg tolbutamide (CYP2C9), 20 mg omeprazole (CYP2C19), 30 mg dextromethorphan-HBr (CYP2D6), and 2 mg midazolam (CYP3A4) were administered orally. Formal interaction was excluded if the 90% confidence interval (CI) for the silexan over placebo ratios for phenotyping metrics (primary: AUC(0-t)) was within a 0.70-1.43 range.

RESULTS

According to the AUC(0-t) comparisons, silexan had no relevant effect on CYP1A2, 2C9, 2D6, and 3A4 activity. Secondary phenotyping metrics confirmed this result. Mean ratios for all omeprazole-derived metrics were close to unity. The 90% CI for the AUC(0-t) ratio of omeprazole but not for omeprazole/5-OH-omeprazole plasma ratio 3 hours post-dose or omeprazole/5-OH-omeprazole AUC(0-t) ratio (secondary CYP2C19 metrics) was above the predefined threshold of 1.43, probably caused by the inherent high variability of omeprazole pharmacokinetics. Silexan and the phenotyping drugs were well tolerated. Repeated silexan (160 mg/day) administration has no clinically relevant inhibitory or inducing effects on the CYP1A2, 2C9, 2C19, 2D6, and 3A4 enzymes in vivo.

A novel formulation design about water-insoluble oily drug: preparation of zedoary turmeric oil microspheres with self-emulsifying ability and evaluation in rabbits

To enhance in vivo absorption of zedoary turmeric oil (ZTO) and develop new formulations of a water-insoluble oily drug, novel ZTO microspheres with self-emulsifying ability, called self-emulsifying microspheres here, were prepared in a liquid system by the quasi-emulsion solvent diffusion method. The microspheres containing hydroxypropyl methylcellulose acetate succinate (HPMCAS-LG), Talc and Aerosil 200 formed the stable surfactant-free emulsion when exposed to the pH 6.8 phosphate buffer, and were significantly different from the conventional self-emulsifying systems (SES), defined as isotropic mixtures of oil, surfactant and drug. Micromeritic properties, the efficiency of emulsification and the drug-release rate of the resultant microspheres were investigated. The bioavailability of the microspheres to the conventional self-emulsifying formulation for oral administration was evaluated in 12 healthy rabbits. A HPLC method was employed to determine the plasma concentration of Germacrone, an indexical component found in ZTO. The release rates of ZTO and Germacrone from the microspheres were enhanced significantly with increasing amounts of dispersing agents, and the efficiency of self-emulsification greatly depended on the HPMCAS-LG/Aerosil 200 ratio. The emulsion droplets released from the microspheres were much smaller than that of the conventional SES. The microsphere bioavailability (F) to the conventional SES for oral administration was 157.7%. Our method greatly improved the bioavailability of the water-insoluble oily drug from the self-emulsifying microspheres over the conventional SES and it is useful for the oily drug to form solid preparations.

Constraint of feeding by chronic ingestion of 1,8-cineole in the brushtail possum (Trichosurus vulpecula)

Eucalyptus leaf-eating marsupials such as the brushtail possum (Trichosurus vulpecula) ingest large amounts of terpenes, especially 1,8-cineole (cineole)--the major component of many eucalyptus oils. Brushtail possums were acclimated to a non-Eucalyptus diet with increasing concentrations of cineole (0.5-4.0% wet weight) added over 18 d. We measured food and cineole consumption and urinary metabolites of cineole. Food intake decreased with cineole content, indicating that it was constrained by the maximum tolerable intake of cineole that was 3.8 +/- 0.2 g kg(-1) or 5.2 +/- 0.3 g kg(-0.75) (mean +/- SE, N = 6). The pattern of metabolites was similar at all cineole intakes (56% hydroxycineolic acids, 27% cineolic acids, 13% hydroxycineoles, and 4% dihydroxycineoles). In another experiment, possums maintained on artificial diet were abruptly presented with 4% cineole for 5 d. Food intake fell by 45 +/- 6% (mean +/- SE, N = 6) and mean cineole intake was 2.9 +/- 0.3 g kg(-1). There was evidence of induction of secondary oxidative pathways, as hydroxycineoles were the major metabolites (48% total) on the first day, but rapidly dropped to 15% on subsequent days as the acid metabolites increased. These findings indicate that ingestion of cineole is not constrained by selective saturation of individual enzymes involved in its multiple pathways of oxidation, but rather the total detoxification capacity appears to limit feeding on a cineole diet.

Phytochemical compositions and biological activities of essential oil from Xanthium strumarium L

The chemical composition of the essential oil (EO) from fresh cocklebur (Xanthium strumarium L.) leaves was investigated by GC-MS. The antimicrobial activity of the EO was tested against Gram-positive and Gram-negative bacteria and fungi. Scolicidal activity was assayed against Echinococcus granulosus protoscolices. In total, 34 compounds were identified, accounting for 98.96% of the EO. The main compounds in the EO were cis-β-guaiene (34.2%), limonene (20.3%), borneol (11.6%), bornyl acetate (4.5%), β-cubebene (3.8%), sabinene (3.6%), phytol (3.1%), β-selinene (2.8%), camphene (2.2%), α-cubebene (2.4%), β-caryophyllene (1.9%), α-pinene (1.8%) and xanthinin (1.04%). The antibacterial and antifungal screening of the EO showed that all assayed concentrations significantly inhibited the growth of Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger (MIC = 0.5 ± 0.1, 1.3 ± 0.0, 4.8 ± 0.0, 20.5 ± 0.3, 55.2 ± 0.0 and 34.3 ± 0.0 µg/mL, respectively). The scolicidal assay indicated that the EO exhibited a significant activity against E. granulosus protoscolices. To the best of our knowledge, this is the first report on the scolicidal activity of X. strumarium. Because of the emergence of antimicrobial drug resistance, the study of new effective natural chemotherapeutic agents, such as the X. strumarium EO, possibly with low side effects, represents a very promising approach in biomedical research.

Ethnopharmacology, phytochemistry, and biological activities of Cymbopogon citratus (DC.) Stapf extracts

Cymbopogon citratus is a widely distributed perennial herb belonging to the Poaceae family and has been extensively consumed for its medicinal, cosmetic, and nutritional effects for centuries. A large number of reports have been published describing the pharmacological, biological, and therapeutic actions of this herb. In this review, we summarized the literatures on related studies (up to January, 2014) that highlighted the pharmacologic and biological effects of the major phytochemicals isolated from C. citratus extracts and its essential oil. The components of the essential oils found in C. citratus have a similar pharmacokinetic properties, including absorption, distribution, metabolism, and excretion. They are quickly absorbed following oral, pulmonary, and dermal administration. Based on the published reports, it can also be inferred that, after absorption from the small intestine, some phytochemicals in C. citratus can undergo oxidation, glucuronidation, sulfation, and/or O-methylation. Excretion is through urine, feces and/or expired volatiles. The biotransformation reactions of C. citratus bioactive constituents are essential for its relatively safe consumption and therapeutic applications. The data available so far warrant further studies evaluating C. citratus pharmacokinetics. Reliable pharmacokinetic data in humans would be critical for a better understanding of the the systemic handling of C. citratus.

Prebiotic Carbohydrates: Effect on Reconstitution, Storage, Release, and Antioxidant Properties of Lime Essential Oil Microparticles

The aim of this study was to include prebiotic biopolymers as wall material in microparticles of lime essential oil. Whey protein isolate (WPI), inulin (IN), and oligofructose (OL) biopolymers were used in the following combinations: WPI, WPI/IN (4:1), and WPI/OL (4:1). The emulsion droplets in the presence of inulin and oligofructose showed larger sizes on reconstitution. There was no significant difference in solubility of the particles, but the wettability was improved on addition of the polysaccharides. The size of the oligofructose chains favored the adsorption of water. Prebiotic biopolymers reduced thermal and chemical stability of the encapsulated oil. Microparticles produced with WPI showed a higher bioactive compound release rate, mainly due to its structural properties, that enabled rapid diffusion of oil through the pores. The use of prebiotic biopolymers can be a good option to add value to encapsulated products, thus promoting health benefits.

Anti-Candida albicans activity and pharmacokinetics of pogostone isolated from Pogostemonis Herba

The present work was designed to evaluate the in vitro and in vivo anti-Candida activity of pogostone (PO), a natural product isolated from Pogostemon cablin (Blanco) Benth. PO showed potent in vitro activity against clinical Candida spp. isolates tested in this study. PO and the reference drug voriconazole (VRC) were equally effective against all the fluconazole-resistant Candida albicans strains, with MIC ranging from 3.1 μg/ml to 50 μg/ml. Besides, PO was fungicidal against all Candida isolates with MFC ranging from 50 μg/ml to 400 μg/ml. By contrast, VRC was fungistatic as it failed to elicit a fungicidal effect against the Candida spp. isolates at the highest tested concentration (400 μg/ml). Furthermore, oral and topical PO administration effectively reduced the fungal load in vagina of vulvovaginal candidiasis mouse models. Topical PO administration (1.0-4.0 mg/kg) demonstrated higher activity against the vulvovaginal candidiasis than VRC (4.0 mg/kg). The pharmacokinetics and safety profile of PO were also investigated. The pharmacokinetics assay revealed that PO was easily absorbed after oral administration in mice, which might account for its in vivo anti-Candida effect. The acute toxicity test showed that the median lethal dose of PO in mice was 355 mg/kg, which was much higher than the daily dose used for the therapeutic experiments. This study demonstrated the potential of PO as a promising candidate for the treatment of Candida infections, particularly for vulvovaginal candidiasis.

Development of sesquiterpenes from Alpinia oxyphylla as novel skin permeation enhancers

To improve the drug permeation into and/or across the skin, essential oils extracted from Alpinia oxyphylla (AO) were evaluated using in vitro and in vivo permeation techniques with Wistar rats as the animal model. Hydrocarbons and oxygenated sesquiterpenes were the major components in the lower-polarity fraction (AO-1) and higher-polarity fraction (AO-2), respectively. Permeation of indomethacin was significantly enhanced after treatment with AO-1 and AO-2 in the in vitro and in vivo studies. AO-2 generally showed a higher ability to promote drug permeation compared to AO-1. The increment of skin/vehicle partitioning may be the predominant mechanism for this enhancing activity. Both transepidermal water loss (TEWL) and colorimetric evaluation showed limited irritation to skin by AO essential oils at the macroscopic level. Human skin fibroblasts were used to investigate the in vitro screening of skin toxicity. AO-1 slightly increased prostaglandin E(2) (PGE(2)) formation from skin fibroblasts. A striking result was observed with AO-2, which greatly inhibited the release of PGE(2). Moreover, both AO essential oils had no statistically significant effect on PGE(2) release by human lung epithelial cells. The results of this study indicate that skin disruption and inflammation do not necessary correspond to the enhancing efficiency of the enhancers tested.

Toxicity of Australian essential oil Backhousia citriodora (lemon myrtle). Part 2. Absorption and histopathology following application to human skin

The in vitro percutaneous absorption of the essential oil of lemon myrtle (Backhousia citriodora) has been studied in freshly excised human full-thickness abdominal skin obtained from patients undergoing elective surgery. Absorption of lemon myrtle oil in human skin discs (4.9 cm(2)) was evaluated using a Franz cell diffusion system following topical application of neat lemon myrtle oil (100 microl or 18.29 mg/cm(2)) to the epidermal surface at exposure durations of 1 to 12 h. Gas chromatography mass spectrometry (GCMS) was used as an analytical technique to determine the absorption of lemon myrtle oil components in full-thickness skin. Citral; (consisting of isomers, geranial and neral) was the only component of lemon myrtle oil found to be absorbing into skin at all exposure periods. At the maximum exposure duration of 12 h, the total absorption of citral in the full-thickness skin disc was 0.29+/-0.07 mg/cm(2) (mean+/-S.D., n=4) of the applied dose. Although the absorption of lemon myrtle oil components was limited, haematoxylin and eosin (H&E) staining showed significant losses in the cellular functioning of skin including; losses of integrity and solubilisation of the stratum corneum, cellular necrosis (to 15%) and cellular vacuolation (to 25%) on comparison to control skin. When a formulated product containing 1% lemon myrtle oil (0.18 mg/cm(2)) was applied to human skin discs (4.9 cm(2)) at 8 h exposure the total absorption of citral in the full-thickness skin disc was 5.12+/-0.60 x 10(-4) mg/cm(2) (mean+/-S.D., n=4) of the applied dose. No other components were detected. The histopathological assessment indicated limited damage to epidermal cells. The combination of the above methodologies enabled the generation of data that could be used for a comprehensive evaluation of the toxicity effects of lemon myrtle oil for topical application.

A preliminary 13-week oral toxicity study of ginger oil in male and female Wistar rats

Zingiber officinale Roscoe, ginger, is a major spice extensively used in traditional medicine. The toxicity profile of ginger oil was studied by subchronic oral administration for 13 weeks at doses of 100, 250, and 500 mg/kg per day to 6 groups of Wistar rats (5/sex per dose). Separate groups of rats (5/sex per group) received either paraffin oil (vehicle) or were untreated and served as comparative control groups. There was no mortality and no decrease in body weight or food consumption as well as selective organ weights during the study period. Administration of ginger oil to rats did not produce any treatment-related changes in hematological parameters, hepatic, renal functions, serum electrolytes, or in histopathology of selected organs. The major component of ginger oil was found to be zingiberene (31.08%), and initial studies indicated the presence of zingiberene in the serum after oral dosing. These results confirmed that ginger oil is not toxic to male and female rats following subchronic oral administrations of up to 500 mg/kg per day (no observed adverse effect level [NOAEL]).

In vivo and in vitro percutaneous absorption of cancer preventive flavonoid apigenin in different vehicles in mouse skin

PURPOSE

In vivo and in vitro percutaneous absorption of apigenin was investigated in three vehicles previously used in cancer prevention studies to determine the drug delivery properties for optimal chemo-preventive activity.

METHODS

In vivo percutaneous absorption of apigenin on SENCAR mice was studied with DMSO and acetone/DMSO (A/D, 4:1) vehicle. In vitro percutaneous absorption studies used whole mouse skin, without subcutaneous fat, mounted on Franz diffusion cells with 37 degrees C Dulbecco's phosphate-buffered saline as the receptor fluid. The skin was treated with [G-3H]-apigenin in DMSO, A/D (4:1), or propylene glycol/DMSO (PG/D, 4:1).

RESULTS

Apigenin uptake by epidermal cells and distribution in epidermis following in vivo topical treatment in two vehicles was in the order of A/D > DMSO, while apigenin distribution in dermis and subcutaneous fat was not different between DMSO and A/D. Total apigenin absorption in mouse skin in vitro was in the order of A/D > DMSO > PG/D. However, apigenin sub-tissue distribution within epidermis determined by tape-stripping and by determination of apigenin in dermal and epidermal tissue indicated that DMSO delivered more apigenin into viable epidermis than A/D while A/D deposited more apigenin in the stratum corneum. Apigenin absorption in mouse skin with DMSO or A/D showed saturation kinetics while apigenin in PG/D showed very low absorption initially and non-saturated absorption in a period of 6 hr. HPLC-scintillation profiles of in vitro samples showed no evidence of apigenin metabolism in mouse skin.

CONCLUSIONS

Delivering apigenin into viable epidermis appears to be a necessary property for an apigenin formulation to be effective in skin cancer prevention.

In vitro permeation through porcine buccal mucosa of Salvia desoleana Atzei & Picci essential oil from topical formulations

In the light of recent studies, which have shown that the essential oil derived from some Lamiaceae species has appreciable anti-inflammatory activity, moderate anti-microbial action and the ability to inhibit induced hyperalgesia, an assessment of the diffusion and permeation of Salvia desoleana Atzei & Picci (S. desoleana) essential oil through porcine buccal mucosa was considered useful for a possible application in the stomatological field. Topical formulations (microemulsions, hydrogels and microemulsion-hydrogels) were prepared for application to the buccal mucosa. The mucosa permeation of the oil from the formulations was evaluated using Franz cells, with porcine buccal mucosa as septum between the formulations (donor compartment) and the receptor phase chambers. The study also aimed at optimising the permeability of the S. desoleana essential oil by means of an enhancer, the diethylene glycol monoethyl ether Transcutol. The diffusion of the oil through the membrane was determined by evaluating the amount of essential oil components present in the receiving solution, the flux and the permeation coefficient (at the steady state) in the different formulations at set intervals. Qualitative and quantitative determinations were done by gas chromatographic analysis. All the formulations allow a high permeability coefficient in comparison with the pure essential oil. In particular, the components with a terpenic structure (beta-pinene, cineole, alpha-terpineol and linalool) have the highest capacity to pass through the porcine buccal mucosa when compared to the other components (linalyl acetate and alpha-terpinil acetate). Moreover, the enhancer, diethylene glycol monoethyl ether largely increases the permeation of the essential oil components in relation to the concentration.

GC analysis of essential oils in the rumen fluid after incubation of Thuja orientalis twigs in the Rusitec system

Methods for the chemical analysis of toxic plant substances in the rumen of ruminants are of importance for the diagnosis of intoxications with poisonous plants. The present work establishes a method to estimate monoterpene components of the essential oil of thuja (Thuja orientalis, Cupressaceae) in these types of samples. Alpha-thujone, which is regarded as the toxic principle, is present at a concentration of 50-60% in the essential oil. The rumen simulation technique (Rusitec) was used to simulate natural digestion. Chopped twigs of thuja were subjected to rumen content in a closed container with an overflow device. The flow of saliva was simulated by the continuous addition of a buffer solution. Samples for analysis were taken from the overflow at 24 and 48 h. A further sample was taken from the remaining liquid fraction of the rumen content in the container at 48 h. The essential oils were extracted with hexane and concentrated. A quantitative determination was done by capillary gas chromatography. Together in the three fractions analysed this resulted in total mean recoveries of 6.8% for alpha-thujone, 5.3% for beta-thujone, 18.9% for fenchone and 27.8% for camphor. The observation that the thujones were recovered to a lesser extent than other oil components is evidence of their fast decomposition in the rumen medium. Under these circumstances the calculated detection limit is 100-200 g thuja twigs in cows with rumen volumes of 60-100 litres. The main essential oil degradation products found in the rumen fluid of all three fractions in the Rusitec system were discovered to be iso-3-thujanol, neo-3-thujanol, carvomenthol and carvomenthone.

Transdermal absorption enhancing effect of the essential oil of Rosmarinus officinalis on percutaneous absorption of Na diclofenac from topical gel

CONTEXT

Rosemary essential oil has been used topically for several purposes (analgesic, anti acne, and anti-inflammatory) in Iranian traditional medicine.

OBJECTIVES

This investigation aimed to study the effect of essential oil of Rosmarinus officinalis L. (Lamiaceae) on the transdermal absorption of Na diclofenac from topical gel.

MATERIAL AND METHODS

Diclofenac sodium topical gel was prepared with HPMC K4M and Carbopol 934P as a gelling agent, and several vehicles. The most stable gel was chosen and enhancing effects of the essential oil with different concentrations (0.1, 0.5, and 1.0% w/w) on the permeation of diclofenac were evaluated. The anti-nociceptive effect of preparations was evaluated based on the formalin and tail flick tests in mice.

RESULTS

The major constituents of the essential oil were 1,8-cineol (15.96%), α-pinene (13.38%), camphor (7.87%), bornyl acetate (6.54%), verbenone (5.82%), borneol (5.23%), camphene (4.96%), and (E)-caryophyllene (3.8%). Topical diclofenac containing 0.5% essential oil showed more analgesic effect after 25, 30, and 35 min (p < 0.001) than the reference drug in the tail flick test. The analgesic effect of preparation containing 1% essential oil was more than reference gel after 15 min (p < 0.05). This difference was observed after 20, 25, 30, 35, and 40 min (p < 0.001) too. Rosemary essential oil 1% promoted analgesic effect of drug in comparison with diclofenac gel in the formalin early phase (p < 0.05). The enhancing effect of rosemary was observed in 0.5 and 1% concentration (p < 0.05 and p < 0.001, respectively) in the late phase.

CONCLUSION

This study proved the enhancing effect of 0.5 and 1% of rosemary essential oil on diclofenac percutaneous absorption.

Influence of vehicle, distant topical delivery, and biotransformation on the chemopreventive activity of apigenin, a plant flavonoid, in mouse skin

PURPOSE

This study was designed to (a) establish a short-term in vivo system to evaluate topical formulations of apigenin, (b) determine whether apigenin should be topically delivered to the local skin tissue or systemic circulation, (c) investigate if biotransformation was involved in apigenin's chemopreventive activity.

METHODS

The effect of topical applied apigenin in acetone/DMSO (A/D, 9:1) on the promotion of skin tumorigenesis was studied. The influence of apigenin in DMSO, A/D (4:1), and propylene glycol/DMSO (PG/D, 4:1) on 12-O-tetradecanoylphorbol-13 acetate (TPA) induced ornithine decarboxylase (ODC) activity was compared. Distant topical delivery of apigenin was conducted on abdominal skin and ODC activity was monitored in dorsal skin. Potential glucuronidation/sulfation of apigenin in intact skin was assessed by measuring isolated apigenin before and after enzyme hydrolysis with glucuronidase/sulfatase. The epidermal extracts from apigenin-treated SENCAR mice were analyzed for metabolites by HPLC.

RESULTS

Apigenin (5 mumol) in A/D did not significantly reduce skin tumor incidence in contrast to previous data with DMSO. Inhibition of TPA-induced ODC by apigenin in three vehicles was in the order of DMSO > A/D > PG/D. TPA-induced ODC in dorsal skin was not inhibited by apigenin delivered from abdominal skin. The quantity of apigenin recovered from epidermal extract was not different before and after beta-glucuronidase/sulfatase treatment. Metabolites were not observed in the HPLC profiles of epidermal extracts from apigenin treated mice.

CONCLUSIONS

(a) The short-term TPA-induced ODC was validated for evaluating topical formulations of apigenin. (b) Topical delivery of apigenin should target the local skin tissue. (c) Glucuronidation/sulfation appeared not to be involved in apigenin's chemopreventive activity.