Topical/transdermal delivery of natural antioxidants

• Main Authors: Li Wen Chang, 張力文
• Other Authors: J. Y. Fang
• Format: Others
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/44670754856146925883

碩士 === 長庚大學 === 中醫學系天然藥物 === 98 === Free radicals have been implicated in a number of diseases and disorders, and the skin, it is exposed to a large number of environmental insults. Antioxidants have thus been proposed as protective or therapeutic agents against Reactive oxygen species (ROS)-mediated injuries. Therefore, natural antioxidants by extensive research. Silymarin, a flavonolignan from milk thistle plant, and the major component of silibinin (SB), silydianin (SD), and silychristin (SC). Transport of SB, SD, and SC under the same thermodynamic activity through and into the skin and the effects of pH were studied in vitro using a Franz diffusion assembly. The lipophilicity increased in the order of SC < SD < SB. It is apparent that compounds in the less-ionized form showed higher skin uptake compared to the more-ionized form. Hyperproliferative skin produced by UVB exposure showed increased permeation of silymarin constituents in the less-ionized form, but it did not affect deposition within the skin. The skin disruption and erythema test demonstrated that the topical application of these compounds for up to 24 h caused no apparent skin irritation. Hydroxycinnamic acid derivatives are widely distributed in plants and are known antioxidants of various food products. Ferulic acid (FA) can be used as an antioxidant to prevent ultraviolet (UV) radiation and skin carcinogenesis. To this end, the feasibility of skin absorption of FA and its derivatives (coniferyl alcohol (CA), 3-hydroxy-4-methoxycinnamic acid (HMA), coniferyl aldehyde (CD) and ferulic acid ethyl ether (FAEE)) was evaluated in the present study. The skin delivery from pH 6 and pH 9.9 buffers was the highest for ferulic acid ethyl ether (FAEE), followed by CD, CA, FA, and HMA. The skin deposition and flux of FAEE from pH 6 buffer was 136 nmol/g and 26 nmol/cm2/h, respectively. No significant difference of permeation profiles was observed between the various pH values. According to the permeation via skin with different treatments (delipidization, ethanol, and oleic acid treatments), lipid bilayers in stratum corneum were the predominant barriers for FA permeation. On the other hand, FAEE could easily partition into and penetrate across the skin by intercellular pathways. The in vivo skin deposition was the highest for ferulic acid ethyl ether (FAEE). The safety study demonstrated that the topical application of FA and the related compounds for up to 24 h did not cause skin irritation. It can be concluded that topical delivery may serve as an efficient and safe route for silymarin, FA and the derivatives against photodamage.