RESUMEN
Because many therapeutic agents are contaminated by epimeric impurities or form epimers as a result of metabolism, analytical tools capable of determining epimers are increasingly in demand. This article is a proof-of-principle report of a novel DMS-MS/MS method to separate and simultaneously quantify epimers, taking PGF2 and its 8-epimer, 8--PGF2, as an example. Good accuracy and precision were achieved in the range of 10-500 ng/mL with a run time of only 1.5 min. Isopropanol as organic modifier facilitated a good combination of sensitivity and separation. The method is the first example of the quantitation of epimers without chromatographic separation.
RESUMEN
Three essential oils from three samples: fresh, air-dried and processed flowers of Chrysanthemum indicum, obtained by hydrodistillation, were analyzed by GC-MS. The results show that major constituents of the three oils were 1,8-cineole, camphor, borneol and bornyl acetate, but the percentage of these compounds varied greatly because of the processing of flowers. The antimicrobial activity of essential oils from air-dried and processed flowers was evaluated against 15 microorganisms including three yeasts and seven clinical isolated strains using disc paper and broth microdilution methods. Our results show that both essential oils possessed significant antimicrobial effect, however, some difference in antimicrobial activity between two oils was observed for several microorganisms, which was attributed to the variation in percentage of the components. With higher percentage of camphor, the oil of the processed flowers exhibited, in many cases, greater bacteriostatic activity than that of the air-dried ones.