**5. Conclusions**

Hesperidin (HSD) was obtained from citrus peels through a pH-triggered precipitation method conducted just in water. The extracted hesperidin purity and yield were excellent when compared to standard methods of its extraction and a commercially available compound. HSD showed chelating activity toward bivalent ions and interacted with collagenase. HSD was used for the formulation of a promising anti-ageing face cream. Upon nanonizing, HSD nanoparticles (150 to 400 nm) were employed into up to 12 months stable nanoemulsions, whose applicability was tested in vitro on artificial skin. No nocive e ffects were observed, and the best face cream formulation (cream A2) showed good results in reducing the black circles in the under eye region. Moreover, daily topical applications of hesperidin nanoemulsion have shown a significant skin whitening e ffect, reduction in trans-epidermal water loss, and inhibition of an irritation e ffect after exposure to UV rays. This way, a clean cream active ingredient is proposed, and a promising cosmeceutical was formulated starting from agro-industrial waste.

**Supplementary Materials:** The following are available online, Figure S1. Steps of hesperidin water extraction: (a) squeezing orange peel, alkaline medium solution; (b) acidic solution and first precipitate of hesperidin; (c) precipitated hesperidin after 7 days at 4 ◦C; (d) filtration of precipitated hesperidin; (e) dried yellow powder of hesperidin. Figure S2. HSQC contour plot of hesperidin (20 mg mL−1) in DMSO-d*6* (2.50 ppm; 39.50 ppm) as a solvent, on Bruker *AVANCE* III 600 MHz equipment at 25 ◦C. Figure S3. HMBC contour plot of hesperidin (20 mg mL−1) in DMSO-d*6* (2.50 ppm; 39.50 ppm) as a solvent, on Bruker *AVANCE* III 600 MHz equipment at 25 ◦C. Figure S4. Chromatogram obtained from injection of the extracted hesperidin sample by separation through ultra-high-performance liquid chromatography (UHPLC) with reverse phase C18; the peak with the retention time at 6.877 min corresponds to hesperidin. Figure S5. Fluorescence suppression - quenching e ffect of hesperidin solution in DMSO (concentration from 0.00 to 5.09 mmol <sup>L</sup>−1) on collagenase (*Clostridium histolyticum*, Sigma-Aldrich) at 37 ◦C. Figure S6. Fluorescence suppression—quenching e ffect of hesperidin solution in DMSO (concentration from 0.00 to 5.22 mmol <sup>L</sup>−1) on collagenase (Clostridium histolyticum, Sigma-Aldrich) at 30 ◦C.

**Author Contributions:** Conceptualization, D.S. and L.T.; methodology, D.S., R.V.d.S., A.F.C., L.H.B.L.; formal analysis, D.S., R.V.d.S., A.F.C. and L.H.B.L.; investigation, D.S.; resources, L.T.; data curation, D.S., N.D. and L.T.; writing—original draft preparation, D.S.; writing—review and editing, D.S., N.D. and L.T.; supervision, L.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received funding from CAPES (code 01), CNPq (Grant number: 140837/2015-3), FUNCAMP-CITROSUCO (Grant Number 5417).

**Acknowledgments:** Authors acknowledge the Laboratory of Biology of the Skin, coordinated by Silvya Stuchi Maria-Engler, Faculty of Pharmaceutical Sciences, University of Sao Paulo for the artificial skin tests performed.

**Conflicts of Interest:** The authors declare no conflict of interest.
