Lippia origanoides essential oil: an efficient and safe alternative to preserve food, cosmetic and pharmaceutical products.

AIMS: The aim of this work was to evaluate the efficacy and safety of Lippia origanoides essential oil as a preservative in industrial products. METHODS AND RESULTS: The composition, antimicrobial activity, mutagenic and toxic potential of L. origanoides were determined. Then, the effect of essential oil as a preservative in food, cosmetics and pharmaceutical products was evaluated. The essential oil of L. origanoides consisted mainly of oxygenated monoterpenes (38·13%); 26·28% corresponded to the compound carvacrol. At concentrations ranging from 0·312 to 1·25 µl ml-1 and in association with polysorbate 80, the essential oil of L. origanoides inhibited the growth of all the tested micro-organisms. The medium lethal dose in mice was 3·5 g kg-1 , which categorizes it as nontoxic according to the European Union criteria, and negative results in the Ames test indicated that this oil was not mutagenic. In combination with polysorbate 80, the essential oil exerted preservative action on orange juice, cosmetic and pharmaceutical compositions, especially in the case of aqueous-based products. CONCLUSIONS: Lippia origanoides essential oil is an effective and safe preservative for orange juice, pharmaceutical and cosmetic products. SIGNIFICANCE AND IMPACT OF THE STUDY: This study allowed for the complete understanding of the antimicrobial action and toxicological potential of L. origanoides essential oil. These results facilitate the development of a preservative system based on L. origanoides essential oil.

Toxicological evaluation of isopropylparaben and isobutylparaben mixture in Sprague-Dawley rats following 28 days of dermal exposure.

The alkyl esters of p-hydroxybenzoic acid (Parabens) have been of concern due to their probable endocrine disrupting property especially in baby consumer products. The safety of parabens for use as a preservative in cosmetics has come into controversy, and thus consumer demand for paraben-free products is ever increasing. Thus, more comprehensive studies are needed to conclusively determine the safety of the multiple prolonged exposure to parabens with cosmetic ingredients. This study was conducted to investigate the potential repeated 28 days dermal toxicity (50, 100, 300, or 600 mg/kg bw/day) of isopropylparaben (IPP), isobutylparaben (IBP), or the mixture of IPP and IBP in rats. There were no significant changes in body and organ weights in any group. However, histopathological examinations showed that weak or moderate skin damages were observed in female rats by macroscopic and microscopic evaluations. In female rats, no observed adverse effect levels (NOAELs) of IPP with no skin lesion and IBP for skin hyperkeratosis, were estimated to be 600 mg/kg bw/day, and 50 mg/kg bw/day, respectively. With regard skin hyperkeratosis, the lowest observed adverse effect level (LOAEL) of the mixture of IPP and IBP was estimated to be 50 mg/kg bw/day. Analysis of six serum hormones (estrogen, testosterone, insulin, T3, TSH, or FSH) in animals showed that only FSH was dose-dependently decreased in the mixture groups of 100 mg/kg bw/day or higher. These data suggest that the mixture of IPP and IBP showed a synergistic dermal toxicity in rats and should be considered for future use in consumer products.

Influence of different additives and their concentrations on corneal toxicity and antimicrobial effect of benzalkonium chloride.

PURPOSE: The aim of this study was to examine the ophthalmic additives responsible for modulating acute corneal epithelial toxicity induced by benzalkonium chloride (BAC) and investigate the ability of polyoxyethylene hydrogenated castor oil 40 (HCO-40) and polysorbate 80 (PS-80) to reduce the corneal toxicity and antimicrobial effects of BAC. METHODS: Cytotoxicity of the additives, which included glycerin, polyvinyl alcohol, propylene glycol, polyethylene glycol, and PS-80, on rabbit corneal epithelial cells was examined using the cell proliferation assay in the presence and absence of 0.02% BAC. The corneal transepithelial electrical resistance change after a 60-second exposure to HCO-40 or PS-80 mixed with 0.02% BAC was measured in living rabbits. Corneal damage was examined using scanning electron microscopy. The antimicrobial activities of HCO-40 and PS-80 with 0.02% BAC against Staphylococcus aureus, Propionibacterium acnes, Pseudomonas aeruginosa, Escherichia coli, and Streptococcus pneumoniae were assessed. RESULTS: Of all the tested additives, only PS-80 could prevent the BAC-induced cytotoxicity. Corneal epithelial barrier function disorder caused by 0.02% BAC was significantly alleviated by either PS-80 or HCO-40 in a concentration-dependent manner. Scanning electron microscopy images showed an improvement of BAC-induced corneal epithelial toxicity after the addition of HCO-40 or PS-80. The antimicrobial effect of the BAC against P. aeruginosa, E. coli, and S. pneumoniae was reduced after adding HCO-40 or PS-80. CONCLUSIONS: HCO-40 and PS-80 reduce acute corneal toxicity and the antimicrobial effect of BAC. Possible interactions between BAC and other additives should be taken into consideration when evaluating the toxicity and antibacterial properties of BAC.

Parabens. From environmental studies to human health.

Parabens are a group of substances commonly employed as preservatives, mainly in personal care products, pharmaceuticals and food. Scientific reports concerning their endocrine disrupting potential and the possible link with breast cancer raised wide discussion about parabens' impact and safety. This paper provides holistic overview of paraben usage, occurrence in the environment, methods of their degradation and removal from aqueous solution, as well as hazards related to their endocrine disrupting potential and possible involvement in carcinogenesis.

Sulfur fumigation, a better or worse choice in preservation of Traditional Chinese Medicine?

Sulfur fumigation (SF) in Traditional Chinese Medicine (TCM) is a highly efficient and important traditional preservation method in China. This method has generated a great deal of concern and has been disputed in the last few years because of its uncertain safety. SF can alter the quality of TCMs by damaging the bioactive compounds, changing chemical profiles, and generating detrimental exogenous materials. However, SF is still widely used in the herbal medicinal industry because of its various benefits, such as its pesticidal and anti-bacterial effects, easy operation, and low-cost. This review contains the current situation, chemical mechanism and reactions during SF, the pharmacological and pharmacokinetic research, and the influence of quality caused by SF. In addition, a quantification-operation sulfur fumigation device (QOSFD), which can maintain the quality of TCMs by controlling the SF processing parameters, has been designed and introduced. The key technologies of this device involve controlling the O(2) content and the temperature of SO(2) as well as the quantification of sulfur in SF. This device can reduce the possibility of reaction between bioactive compounds and sulfur/sulfurous acid, as well as control the limitation of SO(2) residues. The QOSFD is regarded as a promising preservation technique in the field of TCM, medicinal materials, agriculture, and fruit industry.

In vitro and in vivo evaluation of a preservative-free cationic emulsion of latanoprost in corneal wound healing models.

PURPOSE: Cationic emulsions (CEs), developed as vehicles for lipophilic drugs, have been shown to be safe and effective for the treatment of dry eye. The aim of this study was to investigate the effects of a preservative-free latanoprost 0.005% CE (latanoprost-CE) in in vitro and in vivo models of corneal wound healing. METHODS: An in vitro wound was made by scraping through a confluent layer of human corneal epithelial cells. Cytotoxicity, cell migration, and proliferation were analyzed after an exposure to phosphate-buffered saline, CE, latanoprost-CE, 0.02% benzalkonium chloride (0.02%BAK), and Xalatan (latanoprost). In vivo, the recovery and integrity of corneal wound healing were assessed in rat eyes instilled twice a day for 5 days with the above treatments after deepithelialization of the superior cornea. RESULTS: In vitro wound distances decreased at 2 and 24 hours for human corneal epithelial cells exposed to CE, latanoprost-CE, and phosphate-buffered saline, whereas they progressively increased for 0.02%BAK-treated and latanoprost-treated cells. The greater wound closure was associated with a higher number of Ki67-positive cells. In CE- and latanoprost-CE-treated rats, reepithelialization of the cornea was enhanced, restoring normal appearance and function. In contrast, 0.02%BAK or latanoprost delayed corneal healing, induced inflammation, and decreased MUC5-AC expression. CONCLUSIONS: Both models effectively evaluated the cytotoxicity and dynamic recovery of corneal wound healing, and their correlation supports the potential of the in vitro model as a reliable alternative to in vivo ocular toxicity tests. Both models demonstrated that in the face of corneal injury, CEs favored corneal healing, whereas BAK was deleterious.

Polyoxyethylene hydrogenated castor oil modulates benzalkonium chloride toxicity: comparison of acute corneal barrier dysfunction induced by travoprost Z and travoprost.

PURPOSE: To determine the element that modulates benzalkonium chloride (BAC) toxicity by using a new electrophysiological method to evaluate acute corneal barrier dysfunction induced by travoprost Z with sofZia (Travatan Z(®)), travoprost with 0.015% BAC (Travatan(®)), and its additives. METHODS: Corneal transepithelial electrical resistance (TER) was measured in live white Japanese rabbits by 2 Ag/AgCl electrodes placed in the anterior aqueous chamber and on the cornea. We evaluated corneal TER changes after a 60-s exposure to travoprost Z, travoprost, and 0.015% BAC. Similarly, TER changes were evaluated after corneas were exposed for 60 s to the travoprost additives ethylenediaminetetraacetic acid disodium salt, boric acid, mannitol, trometamol, and polyoxyethylene hydrogenated castor oil 40 (HCO-40) with or without BAC. Corneal damage was examined after exposure to BAC with or without travoprost additives using scanning electron microscopy (SEM) and a cytotoxicity assay. RESULTS: Although no decreases of TER were noted after exposure to travoprost Z with sofZia and travoprost with 0.015% BAC, a significant decrease of corneal TER was observed after 0.015% BAC exposure. With the exception of BAC, no corneal TER decreases were observed for any travoprost additives. After corneal exposure to travoprost additives with BAC, HCO-40 was able to prevent the BAC-induced TER decrease. SEM observations and the cytotoxicity assay confirmed that there was a remarkable improvement of BAC-induced corneal epithelial toxicity after addition of HCO-40 to the BAC. CONCLUSIONS: Travoprost Z with sofZia and travoprost with BAC do not induce acute corneal barrier dysfunction. HCO-40 provides protection against BAC-induced corneal toxicity.

Effects of glucan on immunosuppressive actions of mercury.

Global cycling of mercury results in the presence of mercury salts in the environment. The well-established negative effects of mercury on the immune system led us to the study whether natural immunomodulator glucan can overcome the immunosuppressive effects of mercury. Two types of mercury, thimerosal and mercury acetate, were administered in a dose of 2-8 mg/L of drinking water to mice. After 2 weeks, all mice exhibited profound suppression of both cellular (phagocytosis, natural killer cell activity, mitogen-induced proliferation, and expression of CD markers) and humoral (antibody formation and secretion of interleukin-6, interleukin-12, and interferon-gamma) responses. The mice were then fed with a diet containing a standard dose of glucan. Our results showed that simultaneous treatment with mercury and glucan resulted in significantly lower immunotoxic effects of mercury, which suggests that glucans can be successfully used as a natural remedy of low-level exposure to mercury.

Comparative toxicity of preservatives on immortalized corneal and conjunctival epithelial cells.

PURPOSE: Nearly all eye drops contain preservatives to decrease contamination. Nonpreservatives such as disodium-ethylene diamine tetra-acetate (EDTA) and phosphate-buffered saline are also regularly added as buffering agents. These components can add to the toxicity of eye drops and cause ocular surface disease. To evaluate the potential toxicity of these common components and their comparative effects on the ocular surface, a tissue culture model utilizing immortalized corneal and conjunctival epithelial cells was utilized. METHODS: Immortalized human conjunctival and corneal epithelial cells were grown. At confluency, medium was replaced with 100 microL of varying concentrations of preservatives: benzalkonium chloride (BAK), methyl paraben (MP), sodium perborate (SP), chlorobutanol (Cbl), and stabilized thimerosal (Thi); varying concentrations of buffer: EDTA; media (viable control); and formalin (dead control). After 1 h, solutions were replaced with 150 microL of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide). After 4 h, solutions decanted, 100 microL of acid isopropanol added, and the optical density determined at 572 nm to evaluate cell viability. RESULTS: Conjunctival and corneal cell toxicity was seen with all preservatives. Depending upon concentration, BAK exhibited from 56% to 89% toxicity. In comparison, Cbl exhibited from 50% to 86%, MP from 30% to 76%, SP from 23% to 59%, and Thi from 70% to 95%. EDTA with minimal toxicity (from 6% to 59%) was indistinguishable from SP. CONCLUSIONS: Generally, the order of decreasing toxicity at the most commonly used concentrations: Thi (0.0025%) > BAK (0.025%) > Cbl (0.25%) > MP (0.01%) > SP (0.0025%) approximately EDTA (0.01%). Even at low concentration, these agents will cause some degree of ocular tissue damage.

The mucosal toxicity of different benzalkonium chloride analogues evaluated with an alternative test using slugs.

PURPOSE: The objective of this study was to evaluate the mucosal toxicity of different benzalkonium chloride (BAC) analogues using slugs as the alternative test organism. METHODS: The effect of different BAC analogues on the mucosal tissue of slugs was determined from the protein, lactate dehydrogenase, and alkaline phosphatase released from the foot mucosa after treatment. Additionally, mucus production and reduction in body weight of the slugs were measured. The eye irritation potency of the molecules was evaluated with the Bovine Corneal Opacity and Permeability (BCOP) assay. The antimicrobial activity of the different BAC analogues was also assessed. RESULTS: All BAC analogues induced severe damage to the mucosal epithelium of the slugs, and the irritation increased with decreasing alkyl chain length: BAC-C16 < BAC-C14 < BAC-C12 approximately BAC-mix. A similar ranking was obtained with the BCOP assay for eye irritation. The relative order of activities among the three BAC analogues was the same, i.e., BAC-C14 > or = BAC-C16 > BAC-C12. The BAC-C14 exhibited higher activity than the BAC-mix. CONCLUSIONS: The toxicity and activity of BAC analogues depend on the alkyl chain length. The use of BAC-C14 as a conservative agent in pharmaceutical preparations instead of the BAC-mix should be considered.

Lidocaine-induced bronchoconstriction in asthmatic patients. Relation to histamine airway responsiveness and effect of preservative.

Inhaled topical lidocaine, used to produce anesthesia of the respiratory tract prior to bronchoscopy, may cause bronchoconstriction in asthmatic patients. We investigated whether the degree of histamine airway responsiveness would predict the development and extent of lidocaine-induced bronchoconstriction in 20 asthmatic patients. The provocation concentration of histamine producing a 20 percent fall in FEV1 (PC20) was measured. On a separate day, challenge with 6 ml 4 percent lidocaine (Xylocaine 4 percent topical) was performed. There was no correlation between the response to lidocaine and the histamine PC20. Five patients (25 percent) showed a fall in FEV1 of greater than 15 percent (max 42.1 percent). Three responders were rechallenged double-blind with the commercial 4 percent lidocaine preparation and with a 4 percent preservative-free lidocaine solution. There was no difference in the response to these two solutions. These results demonstrate that inhaled topical lidocaine induces bronchoconstriction in a significant proportion of patients with asthma. This response is not related to airway histamine responsiveness or to the preservative in the lidocaine preparation.