LAUSR

The present work was conducted to evaluate the quantitative analysis of the leaves of Aloe vera and to evaluate their potential antioxidant, antiAlzheimer and antidiabetic properties in vitro. The acetone extract, methanolic extract and its four fractions were subjected to quantitative determination of polyphenol, flavonoid, flavonol, condensed tannin and hydrolysable tannin contents. Then, the antioxidant properties of all extracts and fractions were evaluated by using DPPH free radical scavenging, ABTS cation radical decolorization, Cupric Reducing Antioxidant Capacity and Metal Chelating Activity assays. Anti-Alzheimer activity was tested against acetylcholinesterase and butyrylcholinesterase enzymes using the Ellman method. The antidiabetic activity was evaluated by using Alpha-Glucosidase Inhibition Assay. The acetone extract showed the highest amount of total phenolic content (TPC), total flavonoid content (TFC), flavonol content (FLC) and total condensed tannins content (TCTC) compared to others extracts and fractions. The water fraction exhibited the low content of TFC, TPC and FLC. The content of total hydrolysable tannins (THTC) varied from 0.94 ± 0.01 to 1.22 ± 0.02 μg TAE/mg extract. The methanolic extract exhibited highest antioxidant activity in all tests (IC50 value: 24.21±0.30 μg/mL in DPPH assay, IC50 value : 30.75±1.67 μg/mL in ABTS assay, IC50 value: 140.99±2.95 μg/mL in metal chelating activity, and CMU J. Nat. Sci. (2020) Vol. 19 (3) 470 IC50 value: 17.50±0.47 μg/mL in CUPRAC assay). Furthermore, the n-butanol fraction indicated the highest BChE inhibitory activity (IC50 value: 79.61±2.41 μg/ml) and the good α-glucosidase inhibitory activity (IC50 value: 40.75±0.06 μg/ml). These results showed that Aloe vera leaves, can be used in food and pharmaceutical industries as natural antioxidants, as well as moderate antiAlzheimer and antidiabetic agents.