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This study investigates the biological activity of pure allantoin (PA) and aqueous extract of the comfrey (Symphytum officinale L.) root (AECR) standardized to the allantoin content. Cell viability and proliferation of epithelial (MDCK) and fibroblastic (L929) cell line were studied by using MTT test. Anti-irritant potential was determined by measuring electrical capacitance, erythema index (EI) and transepidermal water loss of artificially irritated skin of young healthy volunteers, 3 and 7 days after application of creams and gels with PA or AECR. Pure allantoin showed mild inhibitory effect on proliferation of both cell lines at concentrations 40 and 100 µg/ml, but more pronounced on MDCK cells. Aqueous extract of the comfrey root effect on cell proliferation in concentrations higher than 40 µg/ml was significantly stimulatory for L929 but inhibitory for MDCK cells. Pharmaceutical preparations that contained AECR showed better anti-irritant potential compared with PA. Creams showed better effect on hydration and EI compared with the gels that contained the same components. Our results indicate that the biological activity of the comfrey root extract cannot be attributed only to allantoin but is also likely the result of the interaction of different compounds present in AECR. Topical preparations that contain comfrey extract may have a great application in the treatment of skin irritation.

Plastic deformation and fracture of two grades of fully martensitic steel are investigated with a miniature tensile stage, a custom image acquisition algorithm and digital image correlation. The image acquisition algorithm controls the camera framing rate according to user defined load, displacement and timing thresholds. This provides a greater number of images captured during periods of rapid load change over small displacements. True stress-true strain curves reveal substantial differences in material ductility and failure behavior. Fracture surfaces are examined using scanning electron microscopy and energy dispersive spectroscopy to provide insight into differences in the tensile behaviors observed for these steels.

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Clindamycin is an antibiotic effective against Gram-positive aerobes and both Gramnegative and Gram-positive anaerobic pathogens. Clindamycin (its phosphate ester) was used as a model drug for our study in order to check the efficacy of the developed vaginal gel formulations.The aim of this study was to develop an analytical method suitable for the determination of clindamycin phosphate in three different vaginal gel formulations. The main difference between the three formulations was the use of different gelation agents in the formulations (Carbopol ® 940, Carbopol ® Ultrez 10 and Pemulen ® TR 1). A new isocratic high performance liquid chromatography method based on reverse phase separation has been developed for the determination of clindamycin phosphate. The separation was achieved on a Zorbax Eclipse plus C8 column with a mobile phase of acetonitrile and pH 2.5 phosphate buffer and UV detection at 210 nm. A linear response (r>0.99) was observed in the range of 10.0-80.0 μg mL -1 . The method shows good recoveries and relative standard deviations were less than 1.0%. The method can be applied to assess the stability of clindamycin phosphate in vaginal gel formulations. It can be used for quality control and stability study samples analysis.Clindamycin phosphate concentration was different in vaginal gel formulations with different gelation agents, so the conclusion is that gelation agents (gel carriers) have a significant influence on the active drug concentration. The obtained results confirm that vaginal gel formulation with Carbopol ® 940 shows the maximal stability during the analysis and provides the optimal value of clindamycin phosphate concentration.