Unveiling the Phytochemical Diversity of Pereskia aculeata Mill. and Pereskia grandifolia Haw.: An Antioxidant Investigation with a Comprehensive Phytochemical Analysis by Liquid Chromatography with High-Resolution Mass Spectrometry

<b>Background/Objectives:</b><i>Pereskia aculeata</i> and <i>Pereskia grandifolia</i> belong to the Cactaceae family, despite their foliar and woody stem characteristics. Both species are commonly known as Ora-pro-nóbis (derived from Latin, meaning "pray for us"), a name rooted in their historical use in colonial Brazil due to their nutritional value, particularly <i>P. aculeata</i>, which is frequently described as a high-protein food source. The goal of the present study was to compare these species based on phytochemical composition and antioxidant capacity. <b>Methods</b>: Both species were investigated for their chemical antioxidant properties (DPPH and phosphomolybdenum complex) and cellular anti-ROS activity using the CACO-2 cell line. A comprehensive phytochemical analysis was performed using LC-MS and GC-MS. <b>Results</b>: <i>P. aculeata</i> exhibited a more abundant content of phenolics and flavonoids, with greater structural variability in phenolic compounds and glycosylated flavonoids than <i>P. grandifolia.</i> Still, <i>P. aculeata</i> showed a more potent chemical antioxidant effect. By contrast, in <i>P. grandifolia</i>, a series of novel saponins was now discovered and characterized. In addition, the compounds from this species exhibited a greater cellular antioxidant activity than those of <i>P. aculeata</i>. Tryptophan-derived alkaloids, such as abrine (N-methyltryptophan), were present in both species, but hypaphorine only in <i>P. aculeata</i>. <b>Conclusions</b>: Both species of <i>Pereskia</i> exhibit potential health benefits, including distinct antioxidant activity, among other unexplored effects, given their significant variability in phytochemicals. These differences could be investigated in greater depth using combined LC-MS and GC-MS, thereby enabling more confident structural investigations of these natural compounds.