## 4 Conclusions  
In the present report, we investigated the formation of the \(\gamma\)-CD-PG both in solution and in the solid state. Solution studies were conducted by NOESY on an equimolar aqueous mixture of the two components. The results demonstrated that (i) phloroglucinol is readily included into \(\gamma\)-CD to form an inclusion complex and (ii) inclusion involves interaction of the benzenic ring of phloroglucinol with the H5 protons of \(\gamma\)-CD. The results from NOESY demonstrated that \(\gamma\)-CD-PG can be obtained by a process of co-dissolution in water, with no need for any additional co-solvent. Subsequent snap-freezing and freeze-drying to remove the water solvent allowed isolating the inclusion compound as a solid product. Powder  
Figure 7: O\({}_{2}\)\({}^{\bullet}-\) and NO\({}^{\bullet}\) scavenging activities of phloroglucinol (PG) and the inclusion compound \(\gamma\)-CD-PG along the different stages of gastrointestinal digestion. Data represent the mean \(\pm\) SD of at least three independent assays. \({}^{\bullet}p<0.05\) and \({}^{\bullet}p<0.0001\) indicate statistically significant differences.  
X-ray diffraction further showed that the compound \(\gamma\)-CD-PG belongs to the isostructural series of \(\gamma\)-CD inclusion compounds with tetragonal symmetry, in which \(\gamma\)-CD molecules form channels that hold the guest molecules inside. This contributed to the redshift of two vibrational bands of phloroglucinol as observed by FT-IR.  
When submitted to simulated digestive fluids, it became clear that encapsulation with \(\gamma\)-CD protects PG from the extreme conditions of the gastrointestinal tract allowing a sustained-release of the compound along the gastrointestinal tract, resulting in a better antioxidant activity towards O2*- and NO* at the end stage--the intestinal fluid. The controlled release of PG from the \(\gamma\)-CD appears to be mainly affected by contact time. Overall, this study indicated that encapsulation of PG with \(\gamma\)-CD could be a viable approach to improve the digestive stability and intestinal transport of phloroglucinol, preserving its bioactive properties and particularly its antioxidant activity.  
Conceptualisation, A.R.C., S.S.B., S.M.C.; methodology, B.S.B.C., A.R.C., M.D.C.; data curation, B.S.B.C., M.D.C., S.S.B.; formal analysis, B.S.B.C., M.D.C., S.S.B., S.M.C.; investigation, B.S.B.C., A.R.C., M.D.C.; writing--original draft preparation, S.S.B., M.D.C.; writing--review and editing, M.D.C., S.S.B., S.M.C., A.M.S.S.; supervision, M.D.C., S.S.B., S.M.C.; funding acquisition, S.M.C., A.M.S.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the European Union (FEDER funds through COMPETE POCI-01-0145-FEDER-031015) and national funds (FCT, Fundacao para a Ciencia e Tecnologia) through project PTDC/BAA-AGR/31015/2017, \"Algaphlor--brown algae phlorotannins: from bioavailability to the development of new functional foods\".  
Solid-state characterisation data are available upon request from the YXRD and thermal analyses services of the University of Aveiro.  
We acknowledge University of Aveiro and FCT/MCTES (Fundacao para a Ciencia e a Tecnologia, Ministerio da Ciencia, da Tecnologia e do Ensino Superior) for financial support to LAQV-REQUIMTE (Ref. UIDB/50006/2020) through national founds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement.  
The authors declare no conflict of interest.