紫草素的安定性及配方研究
紫草是製備紫雲膏的主要生藥成份 , 其作用以治療傷口 , 皮膚疾病與燒
燙傷為主 . 紫草主成份紫草素為一對光敏感的化合物 , 在室外光下其光解 主要是經光氧化作用產生一新類的產物 (-)-5,8-dihydroxy-2-(1-
hydroxy-3-oxo-4-methyl-4-pentenyl)-1,4-naphthoquinone. 本研究發
現紫草素的光解乃擬一次動力學降解 . 紫草素的光安定性受光源種類 , 溶媒的極性 , 溶液中氧含量 , 容器種類與酸鹼質的影響 , 但與離子強度無 關 . 動
力學的研究顯示紫草素的光解可能有自由基的參與 . 此外 , 紫草素可藉
與氫氧丙烷基 -B- 環糊精錯合形成包接化合物而能有效增加紫草素的溶解度
, 光安定性及體外藥物滲透性 . 紫草素 - 氫氧丙烷基 -B- 環糊精包接化合物 的存在可借助紅外線光譜 , 熱分析與粉末 X- 光繞射技術印證 .
Studies on the stability and formulation of alkannin/shikonin enantiomers
Alkannin/shikonin (A/S) is a major component in crude drug
"Shikon", which is used as a major ingredient to prepare
Shiunko ointment for the treatment of wounds, skin disease, and burns. Photochemical decomposition of A/S under sunlight mainly leads to (-)-5,8-dihydroxy-2-(1-hydroxy-3-oxo-4-methyl-4-
pentenyl)-1,4-naphthoquinone, a newly discovered naphthoquinone analogue, through the photo-oxidation process. The
photodegradation of A/S follows an apparent first-order kinetics. A/S was subject to degradation by light source, solvent polarity, oxygen content in the solution, container
material, and pH but not affected by ionic strength. The results of kinetic studies imply that a free radical reaction was very likely involved in the photolytic process of A/S. The
solubility, photostability, and in-vitro permeability of A/S could be significantly improved through the formation of
inclusion complex of A/S with HPCD. The existence of A/S-HPCD inclusion complex was elucidated through FTIR, DSC, and powder X-ray diffractometry.
