RESUMEN
Long exposure of UV radiation increases risk of skin diseases such as cancer and photoallergic reactions. UV-B [280-320 nm] radiation is mainly responsible for inducing skin problems. Skin protection is a suitable method in the fight against ultraviolet radiation induced damage. Various synthetic agents have been used as photo protective but because of their potential toxicity in humans, they have limited use. Natural substances have been recently considered as potential sunscreen resources because of their absorption in the UV region and their antioxidant activity. In the present study, the UV protective effects of 20 extracts from four common medicinal plants were evaluated. Their phenol and flavonoid contents and antioxidant activities were determined and correlation between SPF and these contents were evaluated. SPFs were between 0.102 and 24.470. The highest value was reached with ultrasonic extract of Crataegus pentagyna [SPF = 24.47] followed by methanolic extract of Feijoa sellowiana [SPF = 1.30]. Good correlation was found between SPF and phenolic contents [Correlation Coefficient = 0.55 and p = 0.01] but no correlations were found between SPF and flavonoid contents or antioxidant activity. These extracts can be used alone or as additives in other sun screen formulations to enhance their SPF
RESUMEN
The increasing effect of liquisolid systems on dissolution behavior of poor soluble drugs has been proved. In this research, the effect of glycerin, as a nonvolatile solvent, on release profile of indomethacin was evaluated. The Avicel as carrier and silica as coating powder material in 20: 1 ratio were used. Indomethacin was dispersed in glycerin with different ratios. The binary mixtures of Avicel and silica were added to the mixture containing the drug and glycerin under continuous mixing. Starch as disintegrate was mixed with all formulations for a period of 10 minutes. After preparing several formulations, the release profiles were evaluated. To evaluate any interaction between indomethacin and the other components in liquisolid formulations, the differential scanning calorimeter [DSC] was used. The results showed that liquisolid formulations exhibited significantly higher drug dissolution rates in comparison with directly compressed tablet. The enhanced rate of indomethacin dissolution from liquisolid tablets was probably due to an increase in wetting properties and surface area of drug particles available for dissolution. Also, it has been shown that the fraction of molecularly dispersed drug [F[M]] in the liquid medication of liquisolid systems was directly proportional to their indomethacin dissolution rate [D[R]]. An attempt was made to correlate the percentage drug dissolved in 10-minutes with the solubility of indomethacin in glycerin. The liquisolid compacts technique can be a promising alternative for the formulation of water insoluble drugs, such as indomethacin into rapid release tablets