**3. Results and Discussion**

### *3.1. Phenolic Profile of A. vera Gel by HPLC*

The data in Table 2 and Figure 1 show the six identified phenolic compounds of *A. vera* gel by HPLC. Caffeic acid is the most abundant, followed by coumaric, syringic, sinapic, ferulic, and cinnamic acids, and their percentages are displayed in Table 2. These data were matched with the studies by López et al. [58], who found that *A. vera* gel contains catechin, sinapic acid, and quercitrin; Elbandy et al. [59], who observed that gallic protocatecuic, vanillic, ferulic acids, cinnamic, p-coumaric acids, hesperidin, rosmarinicrutin, quercitrin, narengenin, hesperitin, kampferol, and apigenin are the main components of *A. vera* gel; and Numan [60], who confirmed that the gel contains the phenolic compounds quercetin, catechin, aloe emodin, sinapic acid, and aloin [58,60].



R.T.: retention time.

**Figure 1.** Phenolic profile of *A. vera* gel by HPLC.
