Hylocereus costaricensis peel contains large amounts of betacyanins and can be exploited as a source of natural
colorants. This work aimed the chemical characterization and evaluation of bioactive properties of this byproduct
and the optimization of the ultrasound-assisted extraction (UAE) of betacyanins using the response
surface methodology (RSM). Oxalic and malic acids and traces of fumaric acid were detected, as well as the four
tocopherol isoforms, predominantly γ-tocopherol. Four betacyanins were identified and used as response criteria
for UAE optimization, namely phyllocactin, isobetanin, isophyllocactin, and betanin. Sample processing at 487 W for 38 min result in the maximum betacyanin content (36 ± 1 mg/g dw). The peel extract inhibit the oxidative
haemolysis, with IC50 values of 255 and 381 μg/mL for Δt of 60 and 120 min, respectively, and the growth of
pathogenic bacteria, with minimum inhibitory concentrations ranging from 5 to 20 mg/mL. Furthermore, no
toxicity was observed for normal cells.
The authors are grateful to the Foundation for Science and Technology
(FCT, Portugal) for financial support by national funds FCT/
MCTES to CIMO (UIDB/00690/2020); C. L. Roriz PhD’s grant (SFRH/
BD/117995/2016), L. Barros and C. Calhelha also thank the national
funding by FCT, P.I., through the institutional scientific employment
program-contract for their contracts, and S.A. Heleno (CEECIND/
03040/2017) and J. Pinela (CEECIND/01011/2018) through the individual
scientific employment program-contract. The authors are also
grateful to the European Regional Development Fund (ERDF) through
the Regional Operational Program North 2020, within the scope of
project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural® and
GreenHealth (Norte-01-0145-FEDER-000042. Finally, P. Morales is also
grateful to UCM ALIMNOVA Research Group (GR105/18).
