Chemical profile, in vitro bioactivities, and antinociceptive effect of Red Pitaya extracts on zebrafish

Abstract

Aqueous and ethanolic extracts of red pitaya (Hylocereus polyrhizus) peel, pulp, and seeds were evaluated for their chemical composition by UPLC-Q-TOF-MSE, antioxidant capacity (DPPH and ABTS assays), cytotoxicity and in vitro antiproliferative effect (MTT assay), antinociceptive activity and in vivo toxicity (Zebrafish model). A total of 25 compounds were identified in the extracts, mostly betacyanins, phenolic acids, flavonoids, and organic acids. The seeds extracts displayed both the highest radical scavenging activity and total phenol content. The pulp aqueous extract and ethanolic extracts exhibited some cytotoxicity against Vero cells, depending on the concentration and exposure time. These extracts were also able to inhibit S-180 cells proliferation, however only the peel ethanolic extract showed moderate to high selective indexes (SI: 4.06, 18.63), suggesting that its antiproliferative effect is not associated with the cytotoxic effect towards non-cancer cells, such as Vero cells. Regarding the antinociceptive activity, after adjusting the dose to exclude the sedation effect, the seeds ethanolic extract displayed antinociceptive activity at the inflammatory phase, similar to morphine. The extracts (1.0, 2.5 or 5.0 mg/mL) showed to be safe for zebrafish. In summary, these findings highlight the red pitaya as a promising natural source of bioactive, both in its edible and inedible parts, which can be better probed, for instance as anticancer and antinociceptive agents. In addition, the regular consumption of red pitaya can contribute to the health promotion, and the prevention of chronic diseases.