New Aqueous Gel Based on Soluble Cyclodextrin/Vitamin A Inclusion Complex

Rameb (randomized dimethyl--cyclodextrin) was mixed with vitamin A propionate (PVA) (molar ratio 10/1 in water) and a water soluble complex was formed and studied by HPLC and NMR (structure, concentration and stability of PVA). Then solution was used to form an aqueous gel. The skin absorption of PVA through stratum corneum, epidermis and dermis of human skin (on modified Franz cells) was assayed by HPLC and was compared to that of a reference gel (or oil) without cyclodextrin. The solution obtained contains a maximum of 10 mg/mL PVA (if saturated with Rameb) and the PVA can remain stable up to 90 days in solution, and up to 1 year if freeze-dried (storage at 4 °C, in the dark). The results of the different experiments of skin distribution were statistically analyzed and show that when complexed with Rameb, the amount of PVA that penetrates each skin layer is significantly higher than pure PVA. The results also show that PVA cannot pass through the dermis and enter the circulation.     

Thermal Analysis Studies on Human Skin and Skin Barrier Modulation by Fatty Acids and Propylene Glycol

The thermal behaviour of human stratum corneum (SC) with various hydration levels was studied using differential thermal analysis DSC within the temperature range of –130 to 120°C. SC containing 20% water, resembling the intact condition, shows thermal transitions at around –20°C (representing water in skin), –10, 40, 70°C (representing skin lipids), 85°C (representing protein-associated lipids) and 100°C (representing skin protein). Dehydration of SC causes the transitions at –20 and 100°C to be invisible. Lipid extraction followed by dehydration eliminates all transitions. Further hydration produces a transition of water at around 0°C with a huge change in enthalpy. The perturbation effects of penetration enhancers fatty acids (FA) and propylene glycol (PG) were studied using DTA on SC after pretreatment with PG alone and FA/PG. The application of PG alone shifted the transitions at 70 and 85°C to lower temperatures. Additionally, the application to dehydrated stratum corneum removes the transitions at –10°C. Saturated fatty acids, e.g. nonanoic and decanoic acids, exert barely noticeable effects on the thermal behaviour of SC suggesting that they easily mix with the skin lipids. Thermal analysis also revealed that the cis-9- and 13-isomers of octadecenoic acid (monounsaturated fatty acids) form a separate domain containing mostly the pure fatty acids within the SC lipids and suppress the lipid transitions at 70/80°C. Polyunsaturated fatty acids linoleic and -linolenic acids — form separate domains but do not completely suppress the SC lipid transitions at 70/80°C as monounsaturated acids do. This study suggests different ways of perturbation by various fatty acids.This revised version was published online in November 2005 with corrections to the Cover Date.     

Improvement of the Antimicrobial Activity of Oregano Oil by Encapsulation in Chitosan—Alginate Nanoparticles

Oregano oil (OrO) possesses well-pronounced antimicrobial properties but its application is limited due to low water solubility and possible instability. The aim of this study was to evaluate the possibility to incorporate OrO in an aqueous dispersion of chitosan—alginate nanoparticles and how this will affect its antimicrobial activity. The encapsulation of OrO was performed by emulsification and consequent electrostatic gelation of both polysaccharides. OrO-loaded nanoparticles (OrO-NP) have small size (320 nm) and negative charge (−25 mV). The data from FTIR spectroscopy and XRD analyses reveal successful encapsulation of the oil into the nanoparticles. The results of thermogravimetry suggest improved thermal stability of the encapsulated oil. The minimal inhibitory concentrations of OrO-NP determined on a panel of Gram-positive and Gram-negative pathogens (ISO 20776-1:2006) are 4–32-fold lower than those of OrO. OrO-NP inhibit the respiratory activity of the bacteria (MTT assay) to a lower extent than OrO; however, the minimal bactericidal concentrations still remain significantly lower. OrO-NP exhibit significantly lower in vitro cytotoxicity than pure OrO on the HaCaT cell line as determined by ISO 10993-5:2009. The irritation test (ISO 10993-10) shows no signs of irritation or edema on the application site. In conclusion, the nanodelivery system of oregano oil possesses strong antimicrobial activity and is promising for development of food additives.     

Insights on the Inhibitory Power of Flavonoids on Tyrosinase Activity: A Survey from 2016 to 2021

Tyrosinase is a multifunctional copper-containing oxidase enzyme that initiates melanin synthesis in humans. Excessive accumulation of melanin pigments or the overexpression of tyrosinase may result in skin-related disorders such as aging spots, wrinkles, melasma, freckles, lentigo, ephelides, nevus, browning and melanoma. Nature expresses itself through the plants as a source of phytochemicals with diverse biological properties. Among these bioactive compounds, flavonoids represent a huge natural class with different categories such as flavones, flavonols, isoflavones, flavan-3-ols, flavanones and chalcones that display antioxidant and tyrosinase inhibitor activities with a diversity of mechanistic approaches. In this review, we explore the role of novel or known flavonoids isolated from different plant species and their participation as tyrosinase inhibitors reported in the last five years from 2016 to 2021. We also discuss the mechanistic approaches through the different studies carried out on these compounds, including in vitro, in vivo and in silico computational research. Information was obtained from Google Scholar, PubMed, and Science Direct. We hope that the updated comprehensive data presented in this review will help researchers to develop new safe, efficacious, and effective drug or skin care products for the prevention of and/or protection against skin-aging disorders.     

皮肤颜色检测仪的研究

皮肤颜色检测仪可用来对正常皮肤和病变皮肤进行对比测量,经过数据分析为医生对皮肤病的诊断及治疗提供科学的依据。皮肤颜色检测仪由衍射光栅分光式单色系统及单片计算机系统构成。为提高仪器的实用性,采用了光纤探头装置。光纤探头具有体积小、不怕弯曲等特点,可方便地对人体各部位进行检测。其检测数据可由打印机打印,也可由显示器显示。本仪器通过临床应用收效良好,并通过了省级科研成果鉴定,为国内首创。本仪器不仅适用于皮肤颜色的检测,而且可用于布匹等其它物体表面的测色。     

液相色谱串联质谱法测定化妆品中的双酚A、辛基酚及壬基酚

建立了护肤化妆品中双酚A、辛基酚和壬基酚的超高效液相色谱串联质谱分析方法。样品经二氯甲烷提取,氨基固相萃取柱净化后,用甲醇定容,采用Waters UPLC BEH C18色谱柱,以甲醇-0.05%氨水为流动相,梯度洗脱分离后,串联四极杆质谱多反应监测方式检测,以保留时间和子离子比定性,外标法定量。在优化条件下,该方法 5 min内可完成4种待测物的分析。双酚A、辛基酚和壬基酚在0.5～50.0μg/L范围内线性关系良好,相关系数均大于0.999,方法的定量下限(LOQs)均为0.5μg/kg;在加标水平为0.5、1.0、10.0μg/kg时,护肤霜和护肤水样品中4种待测物的平均加标回收率为80%～96%,相对标准偏差(n=6)小于15%。该方法准确、快速、灵敏,适用于护肤化妆品中双酚A、辛基酚和壬基酚的快速确认和定量检测。     

Potential Clinical Applications of the Postbiotic Butyrate in Human Skin Diseases

Human skin is the largest organ and the most external interface between the environment and the body. Vast communities of viruses, bacteria, archaea, fungi, and mites, collectively named the skin microbiome (SM), cover the skin surface and connected structures. Skin-resident microorganisms contribute to the establishment of cutaneous homeostasis and can modulate host inflammatory responses. Imbalances in the SM structure and function (dysbiosis) are associated with several skin conditions. Therefore, novel target for the skincare field could be represented by strategies, which restore or preserve the SM natural/individual balance. Several of the beneficial effects exerted by the SM are aroused by the microbial metabolite butyrate. Since butyrate exerts a pivotal role in preserving skin health, it could be used as a postbiotic strategy for preventing or treating skin diseases. Herein, we describe and share perspectives of the potential clinical applications of therapeutic strategies using the postbiotic butyrate against human skin diseases.     

Atmospheric DBD plasma Deposition of ECO‐Friedly Release Liners for Pressure Sensitive Adhesive Tapes

The presented paper reports on the development of eco‐friendly non‐silicone containing release liners on plastic foils for pressure sensitive adhesive tapes. A solvent free process based on aerosol assisted dielectric barrier discharge (DBD) plasma deposition was used to obtain nano‐sized coatings. Various precursors have been investigated ranging from hydrocarbons and fluorinated hydrocarbons to (meth)acrylates and fluorinated (meth)acrylates. Best results were obtained using 2‐ethylhexyl acrylate. To improved the stability of release properties upon ageing, addition of photo initiators and acrylic cross‐linkers have been evaluated. Tape adhesion tests showed stable release values below 25 cN/20 mm for 2‐ethylhexyl acrylate plasma coatings with acrylic cross‐linkers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

MATHEMATICAL ESTIMATION OF PHYSIOLOGICAL DISTURBANCES IN HUMAN DERMAL PARTS AT EXTREME CONDITIONS： ONE DIMENSIONAL STEADY STATE CASE

A mathematical model for the thermoregulation in the dermal layers of the human body is proposed. The skin is composed mainly of three layers — epidermis, dermis and subcutaneous tissues. The relative constancy of the body temperature is remarkable because there is a continuous exchange of heat with the external environment as well as within the different compartments of the body. A model describes the distribution of dermal temperature as a function of internal and external parameters, such as temperature of the incoming arterial blood, blood flow, ambient temperature, and heat exchange with the environment. It is shown that substantial changes in human dermal temperature can be accomplished only through changes in the temperature of the incoming arterial blood or substantial suppression of blood flow. Other parameters can lead only to temperature changes near the skin surface.