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In this study, chitosan-coated liposomes were developed. To entrap lyophilized tamarind extract containing alpha-hydroxy acids (AHAs) together with tartaric acid, the reverse phase evaporation method was used to obtain well-formed liposomes loaded with the extract. The highest entrapment efficiency of 68.3 +/- 3.0% into the liposomes was obtained with liposomes consisting of phosphatidylcholine and cholesterol in a molar ratio of 2 : 1 after the extrusion process. The average particle size of the prepared liposomes was 158 +/- 26 nm showing a negative zeta potential of -6 mV. For the preparation of the chitosan-coated liposomes, two selected independent parameters were varied: chitosan concentrations of 0.1, 0.5 and 1.0% w/v and volumes of the chitosan solutions of 1, 2 and 3 mL, to study the effects of such parameters on the entrapment efficiency of the extract-loaded liposomes. Variation in the volumes of the chitosan solution did not affect the entrapment efficiency of the liposomes. However, the entrapment efficiency of the AHAs in the chitosan-coated liposomes significantly increased with increasing chitosan concentrations. The size of the chitosan-coated liposomes was in the range of 200-300 nm with a positive zeta potential in the range of 6-29 mV. An in vitro release study using dialysis technique was performed to evaluate the release profile of the tartaric acid from the chitosan-coated liposomes. The obtained results showed the effect of the chitosan-coated liposomes on the lower release rate and on the amount of tartaric acid in comparison with that of the uncoated liposomes. The study in an in vitro skin cell model indicated that the developed system could enhance the potential of tamarind's AHAs on the stimulation of human keratinocyte proliferation being two-fold higher than the solution of the tamarind extract.

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In this study, we developed the hydrogel patch containing curcuminoids for application in cosmetic purpose. The powder of curcuminoids extracted from rhizome of Curcuma longa Linn. was first formulated into o/w microemulsions before incorporating into the polymer solution. The polymer solutions consisted of chitosan derived from various sources or the blended chitosan starch. We found that chitosan from squid pen gave the patch with highest strength and flexibility. After incorporation of curcuminoids microemulsion into the polymer solution of squid chitosan in ratio of 1 : 1 by weight, values of tensile strength and per cent elongation at break of the obtained patch decreased (from 4.55 +/- 0.41 N mm(-2) to 2.26 +/- 0.01 N mm(-2) for tensile strength and from 40.27 +/- 1.46% to 29.65 +/- 2.77% for elongation at break). The DSC thermogram of the squid patch containing curcuminoids implied non-crystalline structure of polymeric network, corresponding to porous characteristics of the patch surface. The results showed that the curcumin content remained at a concentration of 96% and 40% of the initial content after being kept at 4 degrees C and room temperature, respectively. When the patch was kept at 50 degrees C, the remaining curcumin could not be detected. According to vertical diffusion cell method, we found a rapid rate of curcumin release from the patch. The curcumin release pattern, which fitted well to the Higuchi's model, exhibited two distinct phases: the rapid phase (0-15 min), where the release rate of the curcumin averaged 0.74 microg min(-1) mm(-2), and the slow phase (15-120 min), where the release rate averaged 0.13 microg min(-1) mm(-2). Any sign of skin irritation was not observed in volunteers after single application of the curcuminoids patch in the under-eye area for 30 min. This finding indicates mildness to skin of the developed patch.

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The aim of this study was to evaluate the efficacy of Thai basil oils and their micro-emulsions, on in vitro activity against Propionibacterium acnes. An agar disc diffusion method was employed for screening antimicrobial activity of the essential oils of Ocimum basilicum L. (sweet basil), Ocimum sanctum L. (holy basil) and Ocimum americanum L. (hoary basil) against P. acnes. Minimum inhibitory concentration (MIC) values of the basil oils were determined using an agar dilution assay. The obtained results indicated that the MIC values of sweet basil and holy basil oils were 2.0% and 3.0% v/v, respectively, whereas hoary basil oil did not show activity against P. acnes at the highest concentration tested (5.0% v/v). Gas chromatography-mass spectrometry analysis revealed that methyl chavicol (93.0%) was the major compound in sweet basil oil, and eugenol (41.5%), gamma-caryophyllene (23.7%) and methyl eugenol (11.8%) were major compounds in holy basil oil. Hoary basil oil contained high amounts of geraniol (32.0%) and neral (27.2%) and small amounts of methyl chavicol (0.8%). The Oil-in-water (o/w) micro-emulsions of individual basil oils with concentrations corresponding to their MIC values were formulated. The stable o/w micro-emulsion system for basil oil consisted of 55.0% v/v water phase, 10.0% v/v oil phase (2.0 or 3.0% v/v sweet basil or 3.0% v/v holy basil oil plus 7.0% v/v isopropyl myristate), 29.2% v/v polysorbate 80 and 5.8% v/v 1,2-propylene glycol. Hydroxyethylcellulose at a concentration of 0.5% w/v was used as thickening agent. According to the disc diffusion assay, the formulations containing sweet basil oil exhibited higher activity against P. acnes than those containing holy basil oil, and the thickened formulations tended to give a lower activity against P. acnes than the non-thickened formulations. The prepared micro-emulsions were stable after being tested by a heat-cool cycling method for five cycles. These findings indicate the possibility to use Thai sweet and holy basil oil in suitable formulations for acne skin care.

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Synopsis The aim of this study was to develop hydrogel patch using crosslinked chitosan-starch as polymeric matrix for controlling the release of the natural alpha-hydroxy acid (AHA) contained in the extract of tamarind's fruit pulp. The chitosan (MW 100 000) was blended with corn, tapioca or rice starch in various ratios and then crosslinked with glutaraldehyde. The physical characteristics, mechanical resistance, bio-adhesion property and surface morphology of the prepared hydrogel patches with and without the extract were investigated. The release patterns of the hydrogel patches containing the extract were investigated by measuring the amount of tartaric acid, a major AHA present in the tamarind's fruit pulp extract, accumulated in the receptor medium of the vertical diffusion cell at various time intervals over a period of 6 h. The results indicated that the formulations of chitosan : corn starch 4.5 : 0.5 with glutaraldehyde 0.02% w/w (C(4.5)C(0.5)G(0.02)) or 0.04% w/w (C(4.5)C(0.5)G(0.04)), chitosan : tapioca starch 4.5 : 0.5 with glutaraldehyde 0.04% w/w (C(4.5)T(0.5)G(0.04)) or 0.05% w/w (C(4.5)T(0.5)G(0.05)), and chitosan : rice starch 4.5 : 0.5 with glutaraldehyde 0.04% w/w (C(4.5)R(0.5)G(0.04)) and chitosan : rice starch 4.0 : 1.0 with glutaraldehyde 0.03% w/w (C(4.0)R(1.0)G(0.03)) provided the flexible and elastic patches with good bio-adhesive property. The tensile strength values ranged from 5 to15 N mm(-2) and the elasticity ranged from 30 to 60%. The addition of the extract in these formulations significantly increased the tensile strength values of the obtained patches. The patch of C(4.0)R(1.0)G(0.03) formulation containing the extract showed relatively highest porosity, corresponding to its highest amount (12.02 +/- 0.33 mg) and rate (0.452 +/- 0.012 mg mm(-2) min(-1/2)) of tartaric acid released. The amounts of tartaric acid released from the developed hydrogel patches were proportional to a square root of time (Higuchi's model), particularly the release from C(4.0)R(1.0)G(0.03) (R(2), 0.9978 +/- 0.0020) and C(4.5)R(0.5)G(0.04) (R(2), 0.9961 +/- 0.0024) patches.

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A cosmetic patch containing tamarind fruit extract was formulated and developed by blending two types of natural polymers: chitosan with molecular weight of 100 000 and starch such as corn, potato or tapioca starch. The physicochemical characteristics, i.e. flexibility, colour, transparency, integrity, gloss, water sorption and bioadhesion property and the stability of the patch without tamarind content were investigated. Stability test was performed by keeping the prepared patches at 4 degrees C, at room temperature or at 45 degrees C for 2 weeks. The results showed that the formulations composed of chitosan:corn starch ratio of 4.5 : 0.5 (CC(4.5 : 0.5)) and chitosan:tapioca starch ratios of 4.5 : 0.5 (CT(4.5 : 0.5)) and 4.0 : 1.0 (CT(4 : 1)) provide patches with favourable physical characteristics, high water sorption, good bioadhesion ability and good stability. After the lyophilized tamarind extract in an amount corresponding to 5% of tartaric acid was incorporated into the formulations of CC(4.5 : 0.5), CT(4.5 : 0.5) and CT(4 : 1), the ability of the patches to adhere to skin was improved. However, after keeping the test patches at room temperature or at 45 degrees C for 6 weeks, their colours were intensified while their flexibilities and skin adhesion properties decreased. A 12-h in vitro permeation was investigated by studying the cumulative amount of tartaric acid permeated through the Silastic membrane (Dow-Coming, Midland, MI, USA). The CC(4.5 : 0.5) patch tended to give the highest amount of tartaric acid released. The release pattern of all the blended polymeric matrices was exhibited in two distinct phases: the rapid phase, where the flux averaged 3.61 microg min(-1) mm(-2); and the slow phase, where the flux averaged 1.89 microg min(-1) mm(-2).

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To investigate the effect of repeated administration time on the development of tolerance, male ICR mice, housed under 12:12-h light/dark cycle (7:00 AM, lights on), were treated with haloperidol 4 mg/kg/day i.p. at 9:00 AM or 9:00 PM, the time nearly corresponding to the maximal or minimal catalepsy responses to a single dose, respectively, for 14 days and catalepsy responses were monitored at 1 h after administration each day. The findings indicated that, on day 1 to day 6, a greater development of tolerance was seen in the group of mice treated at 9:00 AM, and catalepsy behavior exhibited a significant difference between the two dosing times (P < 0.01). The study of D(2) receptor mRNA expression in mouse striatum revealed that the phase of D(2) receptor mRNA rhythm was similar to that of catalepsy response, with the maximum around mid-light and the minimum around mid-dark. After repeated administration, the increase in D(2) receptor mRNA levels in mice treated with haloperidol at 9:00 AM was higher than that of mice treated with haloperidol at 9:00 PM. In addition, from a [(3)H]spiperone binding study, the amount of binding site [(3)H]spiperone after repeated injection of haloperidol at 9:00 AM was greater than that after repeated injection at 9:00 PM. These findings demonstrate the importance of dosing time on the susceptibility to extrapyramidal effects and the relation of administration time to D(2) receptor change and tolerance.

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