LC-MS characterization of bioactive metabolites from two Yemeni Aloe spp. with antioxidant and antidiabetic properties

Two Yemeni Aloe(s) have been investigated; the resin from A. perry Baker (APR, Socotran Aloe), and the gel from A. vera (AVG, Saber Yamaniis). LC-MS for APR identified aloin B, aloinoside B/A, homonataloin B and microdontin B/A as the major components, constituting 67.7% w/w of the extract. AVG showed the same pattern of anthrones (19.5% w/w), in addition to the chromones aloesin, aloeresin A, aloeresin D and aloeresin E. Dihydro-isocoumarin glucoside was identified in both Aloe species. Aloe extracts showed high antioxidant activity: DPPH (0.09 & 0.05 mM/g TE), ABTS (0.06 & 0.03 mM/g TE), and FRAP (20.5 & 15.5 mM Fe+2 E), for APR & AVG, respectively. The antidiabetic properties was evaluated through inhibition of alpha-glucosidase enzyme. APR showed inhibitory activity with IC50 0.76 mu g/mL higher than AVG (IC50 0.76 mg/mL). Aloin A showed the highest inhibitory activity with IC50 0.34 mg/mL that was higher than acarbose (0.54 mg/mL) the positive control, indicating that the activity of Aloe extract is linked to the aloin and other anthrone compounds. These findings highlight the phytochemical profile, antioxidant and potential antidiabetic activity of the Yemeni Aloe species and draw attention to their potential application in food, medicine and cosmetic products. (C) 2020 Princess Nourah bint Abdulrahman University. Published by Elsevier B.V. on behalf of King Saud University.