Fast and easily applicable LC-UV method for analysis of bioactive anthrones from Aloe leaf latex

Aloe leaf latex is a commonly used plant preparation in traditional medicine. However, quality control on the content of medicinally important constituents is often limited. Hence, establishing a reliable quality control method to identify and quantify bioactive markers is important to ensure safety and efficacy. In the present study, a novel liquid chromatographic (LC) method was developed and validated for efficient analysis of bioactive markers to evaluate the quality of aloe leaf latex. Quantification of marker compounds was possible in only 7 min on a monolithic column using gradient elution with 0.1 % formic acid in acetonitrile and water as mobile phases. The major compounds (aloins A and B) could be baseline separated together with related compounds within 10 min. The method showed excellent linearity with determination coefficients (r²) of 0.9999. Detection limits were 0.017 and 0.013 μg/mL, while quantification limits were 0.057 and 0.043 μg/mL for aloin A and aloin B, respectively. Relative standard deviation (RSD) values for intra- and inter-day precision were less than 2% and recoveries for both aloins were close to 100 %. The robustness was evaluated using an experimental design. The method was applied to some aloe leaf latex samples from Ethiopia. Aloin contents varied from 14 to 35 % and two unknown peaks were tentatively identified as aloinoside and microdontin.