Improved Chromatographic Methods for Determination of Bioactive Compounds from Aloe vera Leaves

In this work three chromatographic methods were developed to reduce the total time of the analysis of main compounds in Aloe vera extracts. The first method was developed in a regular reverse phase chromatographic system using a particulate reverse phase C-18 column. Methods already published were used as a starting point for the development of the new method. All the compounds were separated in 32 minutes. The second method was developed in a regular reverse phase chromatographic system employing a monolithic type column. Using a 4.5？mL min？1 flow, the total time of analysis was reduced to 6 minutes with very similar resolution values. The third method was developed in an ultraperformance liquid chromatographic system, and the final time for the analysis of the phenolic compounds was reduced to 4 minutes. The analytical properties of the three chromatographic methods were compared for the main compounds in the chromatograms. Robustness of the three new methods was also checked with regard to the injection volume and the amount of methanol in the sample. A fast method (4？min) is then available for bioactive compounds from Aloe vera determination. 1. Introduction Aloe vera has long been used as a remedy in many cultures. Aloe preparations, including products based on both the gel and the leaf, are used, among other reasons, as laxatives, in creams for skin, in functional foods, and as treatment for a wide range of diseases [1]. Aloin is the main anthraquinone in aloe leaf, which occurs naturally as a mixture of two diastereoisomers aloin A and aloin B. In addition to these compounds, other compounds including aloenin, aloenin B, and isoaloesin have been related to the biological properties of Aloe vera extracts [2]. Among the most recent properties studied for these compounds, the effects of aloin derivatives against some human breast cancer cell lines [3] have been reported. Other activities found for these compounds include several antimicrobial properties [4] and some oxidant and antioxidant properties on free radical-induced DNA breaks [5]. There are several factors which can influence the levels of aloin derivatives in the leaves of aloe plants, including cultivar conditions, age of the plant, and the health conditions. Therefore, the starting material to obtain the extracts can show clear differences [6]. These variations in the composition of Aloe can result in related products with different chemical and physical properties. Therefore, analytical methods to determine the aloin amounts in different plant material and manufactured products are