Due to health concerns about phthalate esters, the use of alternative plasticizers is being considered. Phthalate esters enhance skin sensitization to fluorescein isothiocyanate (FITC) in mouse models. We have demonstrated that phthalate esters stimulate transient receptor potential ankyrin 1 (TRPA1) cation channels expressed on sensory neurons. We also found a correlation between TRPA1 activation and the enhancing effect on FITC-induced contact hypersensitivity (CHS) when testing various types of phthalate esters. Here we investigated the effects of an alternative plasticizer, diisopropyl adipate (DIA). Activation of TRPA1 by DIA was demonstrated by calcium mobilization using Chinese hamster ovary cells expressing TRPA1 in vitro. The effect of DIA was inhibited by a TRPA1-specific antagonist, HC-030031. The presence of DIA or dibutyl phthalate (DBP; positive control) during skin sensitization of BALB/c mice to FITC augmented the CHS response, as revealed by the level of ear-swelling. The enhancing effect of DIA was inhibited by in vivo pretreatment with HC-030031. FITC-presenting CD11c dendritic cell (DC)-trafficking to draining lymph nodes was facilitated both by DIA and by DBP. DBP and DIA were similarly active in the enhancement of interferon-γ production by draining lymph nodes, but the effect on interleukin-4 production was weaker with DIA. Overall, DIA activated TRPA1 and enhanced FITC-induced CHS, as DBP did. The adjuvant effects of adipate esters may need to be considered because they are used as ingredients in cosmetics and drug formulations topically applied to the skin. Key words adipate ester; adjuvant; contact hypersensitivity; transient receptor potential Plasticizers are widely used for plastics such as polyvinyl chloride. As plasticizers, phthalate esters are widely used for consumer products such as synthetic leather, vinyl flooring, wall coverings, paints, adhesive agents and cosmetics. Many studies have been conducted for assessment of the risk of exposure to phthalate esters in the air and food, and their accumulation in the body. 1,2) Epidemiological studies revealed an association between phthalate esters and allergies in children.3,4) A case of contact hypersensitivity in association with topical contact with dibutyl phthalate (DBP), a short-chain phthalate ester, has also been reported. 5) Due to health concerns about phthalate esters, the use of other types of acid esters is being considered. Adipate esters are candidate plasticizers.Diisopropyl adipate (DIA) is used as an emollient ingredient for cosmetics to protect the human skin from dryness. 6)DIA is also used in tacrolimus ointments as a skin penetration enhancer.7) As to drug formulations, adipate esters are used as plasticizers for biodegradable flexible films and for enhancement of skin penetration of hydrophilic drugs.8,9) Regarding safety assessment, DIA has been concluded to be safe as a cosmetic ingredient. 10,11)We have been studying fluorescein isothiocyanate (FITC)-induced contact hypersensitivity (CHS) mouse models. In ...
A novel ionic liquid crystal oligomer, sodium 1,2-bis{6-[4-(4-cyanophenyl)phenyloxy]hexyloxycarbonyl}ethanesulfonate (SBCPHS), was prepared. Its physical properties were investigated by optical microscopy, differential scanning calorimetry and X-ray diffraction measurements. The compound exhibited two columnar phases, and the columnar-to-columnar phase transition did not accompany an enthalpy change. An optically isotropic phase was induced in a binary mixture with a nematic liquid crystal, 4-cyanophenyl 6-octyloxynapthalene 2-carboxylate. The mesophase formation of the ionic oligomer and its mixture are discussed in terms of microsegregation, excluded volume effect, and antiparallel interactions between cyanobiphenyl moieties.
The liquid crystal compounds have a common structure with the cell membrane, having both a hydrophilic and hydrophobic residue, thus suggesting an affinity to the cell membrane. However, little information regarding a biological effect by liquid crystal compounds has been reported. In order to view the biological potential of liquid crystal compounds, the present study evaluated the in vitro human hematopoietic promoting effects by 18 liquid crystal-related compounds. In particular, these compounds are evaluated regarding their potential for platelet production from mature megakaryocytes by the culturing of CD34 ؉ cells derived from normal human peripheral blood. Often, in the case of severe thrombocytopenia there is no choice but to perform a transfusion of platelet concentrates. Three of the tested compounds promoted megakacyocyte generation in the culture stimulated with thrombopoietin alone. In addition, two compounds led to a significant increase in CD42a؉ particles which seemed to be platelets. At the same time, interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF), that were used as a positive control for in vitro megakaryocytopoiesis and thrombopoiesis, resulted in a dramatic increase in the total number of cells; however, their promoting activity on in vitro hematopoiesis was almost at a similar level with the compounds. These results suggest that some liquid crystal-related compounds have a promoting effect on human thrombopoiesis, and that these compounds act with a different mechanism from either IL-3 or GM-CSF since the compounds specifically stimulated thrombopoiesis. The liquid crystal compounds may therefore be useful to develop a new functional medicine or a medical application.
We have designed an amphiphilic compound in which phenylpyrimidine and d-glucamine are connected via a flexible spacer. The compound shows two thermotropic lamellar bilayer mesophases with different layer spacings. The liquid-crystalline compound showed cytostatic activity against A549 human lung carcinoma cell lines, however an amphiphilic phenylpyrimidine derivative, d-glucamine, and an equimolar mixture of them were not active on cell lines under identical conditions.
Alternative plasticizers have become more popular due to health concerns about phthalate esters. We demonstrated that phthalate esters enhanced skin sensitization to fluorescein isothiocyanate (FITC) in mouse contact hypersensitivity models. Alternative plasticizers have not been well studied as to their effect on the immune system. We previously found that diisopropyl adipate (DIPA), an aliphatic dicarboxylic acid ester, enhanced skin sensitization to FITC. Sebacate esters are also widely used as alternative plasticizers. Here we tested diisopropyl sebacate (DIPS), which has the same alcohol with an aliphatic dicarboxylic acid of longer chain, using BALB/c mice. The results showed that DIPS facilitated skin sensitization to FITC and increased FITC-presenting dendritic cell trafficking from the skin to draining lymph nodes. Furthermore, DIPS activated transient receptor potential ankyrin 1 (TRPA1). The latter feature has been commonly observed for phthalate esters and DIPA, which have adjuvant effects. In summary, the adjuvant effect of a sebacate ester was demonstrated in a mouse model. Key words sebacate ester; adjuvant; alternative plasticizer; contact hypersensitivity; mouse Due to health concerns about phthalate esters, expectation of the use of alternative plasticizers in consumer products has been increasing. 1) Phthalate esters are made up of an aromatic dicarboxylic acid and two alcohols. One group of alternative plasticizers is the adipate esters, which consist of an aliphatic dicarboxylic acid. Another type of aliphatic plasticizers is sebacate esters, which are applied for medical devices as well as drug formulation. 2-4)We have been investigating phthalate esters from an immuno-toxicological point of view. We showed that contact sensitization to fluorescein isothiocyanate (FITC) is enhanced in the presence of certain types of phthalate esters in mouse models. 5,6) Thus, phthalate esters with short chain alcohols, such as dibutyl phthalate (DBP) and di-n-propyl phthalate (DPP), exhibited strong activities among phthalate esters. 6)Those phthalate esters were shown to exhibit agonist activity toward transient receptor potential ankyrin 1 (TRPA1) cation channels, TRPA1 being used as a nociceptor by sensory neurons.7) The results may suggest a close relationship between the adjuvant activity on skin sensitization and TRPA1 agonistic activity.As to alternative plasticizers, we previously showed that diisopropyl adipate (DIPA) facilitated skin sensitization to FITC in vivo. TRPA1 agonist activity of DIPA was also shown in vitro. 8) In the present study, we investigated the activity of diisopropyl sebacate (DIPS), in which isopropyl alcohol is a shared component with DIPA. As a positive control, we employed DBP to check each experimental system. The results clearly demonstrated that DIPS also activated TRPA1 and enhanced FITC-induced contact hypersensitivity (CHS). (Osaka, Japan), FITC and Fluo 4-AM from Dojindo Laboratories (Kumamoto, Japan), dimethyl sulfoxide (DMSO) from Nacalai Tesque (Kyoto, Japan), a...
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