Optimization of the extraction parameters of Aloe Vera polyphenols and study of antioxidant and antifungal activities: application to molds isolated from durum wheat

The main objectives of this work are to optimize the extraction parameters, to test the antioxidant activity of Aloe Vera extract and to study the impact of this extract on deteriorating molds of Algerian variety of wheat (CIRTA). The extraction was optimized by central composite design. Determination of the polyphenols, flavonoids, and proanthocyanidins was performed by using colorimetric assays. Identification and quantification of phenolic compounds were performed by RPHPLC-UV method. The antioxidant activity was tested by three methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and CUPRAC (Cupric reducing antioxidant capacity), the antifungal activity of Aloe Vera extract on isolated strains from durum wheat were tested by dilution in a solid medium method. The optimum of total phenolic got was1,044 x 104 µg GAE/g of dry extract. The extract is rich in polyphenols, flavonoids, and proanthocyanidins. The analysis of phenolic compounds of Aloe Vera by RP-HPLC-UV revealed seven phenolic compounds. Strong antioxidant activity was obtained for Aloe Vera extract. Purification and microscopic study of isolated strains gave the possibility of identifying four strains: Alternaria spp1, Alternaria spp2, Penicillium spp, and Aspergillus spp. the antifungal potential of Aloe Veravaries according to the fungal genera and the concentrations of extract used.