Quantitative determination of aloin, antioxidant activity, and toxicity of Aloe vera leaf gel products from Greece.

Background: Aloe vera is a popular medicinal plant used widely by the cosmetic, pharmaceutical, and food industries. The A. vera leaf gel, which is used mostly for its positive effects on human health, contains over 75 different bioactive compounds, including aloin. Aloin is a toxic compound, and its content in A. vera leaf gel products depends on the different cultivation conditions and especially on leaf processing.
Results: In this study, A. vera leaf gel products, varied in terms of leaf processing, were analyzed using liquid chromatography for their aloin content, their antioxidant activity by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS ^·+ ) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH ^· ) antioxidant activity assays and their toxicity against Aliivibrio fisheri and SH-SY5Y cells. In the samples processed with industrial methods and in those filtered in the lab, the content of aloin was found below the limit (0.1 mg L ^-1 ) of the EU legislation however, the unprocessed and unfiltered samples were found to contain more than 10 mg L ^-1 . Antioxidant activity was estimated to vary from 1.64 to 9.21 μmol Trolox mL ^-1 for DPPH ^· and from 0.73 to 5.14 μmol Trolox mL ^-1 for ABTS ^·+ . Toxicity values on A. fisheri, expressed as the concentration at 50% loss of initial luminescence, ranged from 0.03 to 0.09 mg mL ^-1 . The cytotoxic study indicated that aloin A at low concentrations (1 and 10 μg mL ^-1 ) protects SH-SY5Y cells from toxicity induced by hydrogen peroxide.
Conclusions: Consequently, the filtration process of A. vera leaf gels, either laboratory or industrial, resulted in aloin A content below the EU legislation detection limits. © 2020 Society of Chemical Industry.
(© 2020 Society of Chemical Industry.)