Fine-tuning of membrane permeability by reversible photoisomerization of aryl-azo derivatives of thymol embedded in lipid nanoparticles
Samanta MoffaSimone CarradoriFrancesco MelfiAntonella FontanaMichele CiullaPietro Di ProfioMassimiliano AschiRafal Damian WolickiSerena PilatoGabriella Siani
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Responsiveness of liposomes to external stimuli, such as light, should allow a precise spatial and temporal control of release of therapeutic agents or ion transmembrane transport. Here, some aryl-azo derivatives of thymol are synthesized and embedded into liposomes from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine to obtain light-sensitive membranes whose photo-responsiveness, release behaviour, and permeability towards ClKeywords:
Membrane permeability
Thymol
Thyme is a herb with broncholytic und secretomotoric effects. Its activity on β2 receptors as a possible mechanism of action was demonstrated. Major components are thymol and carvacrol which are claimed to be responsible for its effects and, therefore, used for standardization in the German pharmacopoeia (0.03 % phenols calculated as thymol). Our aim was to investigate the impact of thymol by using thyme extracts with either normal or extremely low thymol concentrations (< 0.005 % or > 0.038 %). The antispasmodic effect on smooth muscles of the trachea and the ileum and the effect on ciliary activity (respiratory clearance) were investigated. In addition, pure thymol and carvacrol were investigated separately and in spiking experiments. Thymol and carvacrol had a concentration-dependent antispasmodic effect in the rat trachea either being stimulated by acetylcholine, K+ or Ba++. The same result was observed with respect to the increase of mucociliary transport in mice. Extracts with very low thymol contents are effective in all models used except acetylcholine-induced rat ileum contraction. When thyme extracts with normal thymol contents or with very low thymol contents were compared, the extract with normal thymol contents was more effective, both as a relaxant (rat ileum) and as an antispasmodic compound (rat trachea contraction induced by either acetylcholine, Ba++ or K+) and in ciliary transport experiments. Thyme extracts with very low thymol contents (practically free of volatile oil) were equally effective with respect to endothelin effects. When an extract with very low thymol contents is spiked with increasing concentrations of thymol, a concentration-dependent increase concerning the antispasmodic effect (Ba++-induced trachea contraction) is observed. In conclusion, the data show that in various models of antispasmodic effect (ileum and trachea) and by measuring ciliary activity, thymol (and carvacrol) is (are) active, although other not identified components of thyme extract appear to be very important as well, since extracts with very low thymol contents are active. On the basis of these results the standardization on thymol alone appears not to be justified.
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Antispasmodic
Carvacrol
Thymus vulgaris
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The aim of this work is to do a stability study of two chemo-typical active ingredients (thymol and carvacrol) of the essential oil of thyme “Thymus satureoides” collected from Azilal Region, Morocco. Specimen identification was performed for the raw obtained plant materials and the essential oil extraction carried out through initial and final chemical characterization of the essential oil - at t = 0 - and - at t = 6 months. Results show that a significant decrease (13%) in the initial thymol concentration was recorded during the assumed duration of the stability study (6 months). Carvacrol recorded an even larger drop and was approaching 25%, during the same study period. Key words: Stability, concentration, essential oil, thymus satureoides, thymol, carvacrol.
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Thymol (2-isopropyl-5-methylphenol) is the main monoterpene phenol found in thyme essential oil. This compound has revealed several biological properties, including antibacterial, anti-inflammatory and antioxidant activities. In this work, a comparison was made between the performance of different green solvents (ethanol, limonene and ethyl lactate), by pressurized liquid extraction (PLE) and supercritical fluid extraction (SFE) at different conditions, to extract thymol from three different varieties of thyme (Thymus vulgaris, Thymus zygis and Thymus citriodorus). Additionally, new solubility data of thymol in limonene and ethanol at ambient pressure and temperatures in the range 30-43 °C are reported.The highest thymol recoveries were attained with T. vulgaris (7-11 mg g(-1)). No thymol could be quantified in the PLE samples of T. citriodorus. The highest concentrations of thymol in the extracts were obtained with limonene. Thymol is very soluble in both solvents, particularly in ethanol (∼900 mg g(-1) at ∼40 °C), and is the main compound (in terms of peak area) present in the essential oil extracts obtained.The three solvents show good capacity to extract thymol from T. vulgaris and T. zygis by PLE. Although PLE proved to be a suitable technology to extract thymol from thyme plants, the highest concentrations of thymol were obtained by SFE with supercritical CO2 .
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Thymus vulgaris
Monoterpene
Supercritical fluid extraction
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The aim of this study was to evaluate the antimicrobial activity of thymol and thymol-loaded nanostructured lipid carriers (NLCs) on inoculated sausages at 4 °C over a period of 28 days. To this end, sausage samples containing 600 mg/kg thymol, 600 mg/kg thymol-loaded NLC, 600 mg/kg thymol + 60 mg/kg nitrite, and 600 mg/kg thymol-loaded NLC + 60 mg/kg nitrite were prepared, and each treatment was divided into three portions to be inoculated with S. aureus, E. coli, and C. perfringens (105.5 CFU/g). The mean diameter and zeta potential of thymol-NLCs were 140 nm and −0.52 mV, respectively. Thymol-NLCs showed (two-fold) higher values for MIC and MBC than that of thymol, but similar halo diameters were detected for both against all bacteria examined in the agar well diffusion test. The control and nitrite-containing sausages showed an increasing trend in bacterial growth and the bacterial population was the largest in these samples. The bacterial growth within samples treated with thymol or thymol-NLCs was around 3.90–4.67 log CFU/g lower in comparison with the control. In this regard, no significant differences were detected between the thymol and thymol-NLC samples against each bacterium. A first-order reaction was detected for bacterial growth in all sausages. Overall, the higher antimicrobial property of thymol and its NLC compared with nitrite makes thymol a good alternative to nitrite with regards to its antimicrobial capability.
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Thymol and carvacrol are natural monoterpene phenols found in high concentration in various essentials oils including the oil of thyme. These monoterpene phenols are known to possess strong antiseptic activities [1]. In this study, I detail the effect that pH has on the synergism of thymol and carvacrol against the model organism, Saccharomyces cerevisiae . For every 0.1 unit interval in the pH range (6.4-8.4), IC 50 values were measured based on the thymol content in the mixture of thymol and carvacrol. The maximum potency of 0.399 mg L -1 was achieved at pH 6.4 using a 1:9 ratio of thymol to carvacrol – over 5 times more potent than thymol alone at pH 7.4 (IC 50 = 2.05 mg L -1 ). Understanding the synergy of the components in essential oils is one of the first steps in establishing alternative treatments to fight drug-resistant microorganisms. By combining essential oils or their components with existing antibiotic or antifungal agents, effective treatment of superbugs can be elucidated [2].
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Gelatin
Active packaging
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Background: Thymol is a natural phenolic monoterpenoid widely used in pharmaceutical and food preservative applications. Thymol isomeric with carvacrol, extracted primarily from Thymus species (Trachyspermum ammi) and other plants sources such as Baccharisgrise bachii and Centipeda minima, has ethnopharmacological characteristics. <p></p> Methods: This review was prepared by analyzing articles published on thymol moiety in last decade and selected from Science Direct, Scopus, Pub Med, Web of Science and SciFinder. The selected articles are classified and gives brief introduction about thymol and its isolation, illustrates its natural as well as synthetic sources, and also therapeutic benefits of thymol worldwide <p></p> Results: Thymol has been covering different endeavors such as antimicrobial, antioxidant, antiinflammatory, antibacterial, antifungal, antidiarrhoeal, anthelmintic, analgesic, digestive, abortifacient, antihypertensive, spermicidal, depigmenting, antileishmanial, anticholinesterase, insecticidal and many others. This phenolic compound is among the essential scaffolds for medicinal chemists to synthesize more bio-active molecules by further derivatization of the thymol moiety. <p></p> Conclusion: Thymol is an interesting scaffold due to its different activities and derivatization of thymol is proved to enhance its biological activities. However, more robust, randomised, controlled clinical trials would be desirable with well-characterised thymol preparations to corroborate its beneficial effects in diseased patients. Moreover, in view of the potential use of thymol and thymol-rich essential oils in the treatment of human infections, comprehensive studies on chronic and acute toxicity and also teratogenicity are to be recommended.
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Thymus vulgaris
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