Introduction

Recently, the incidence of lifestyle-related disorders, such as type 2 diabetes and metabolic syndrome, has globally increased, intensifying the search for functional foods that target key molecular pathways [1]. Additionally, the recovery of natural antioxidants from agricultural waste is at the forefront [2]. Our previous research identified pistachio (Pistacia vera L.) shells (PSs) as an appealing source of hypoglycemic compounds, efficiently recovered by microwave-assisted extraction [3]. Nevertheless, assessing PS extract bioactivity after digestion is of the utmost importance to confirm its application as a nutraceutical ingredient for managing hyperglycemia.

Methods

This work examined, for the first time, the impact of in vitro gastrointestinal digestion on the total phenolic and flavonoid contents and the antioxidant and hypoglycemic properties of PS extract. The metabolomic profiles of undigested PS extract and its digests were analysed by LC-ESI-LTQ-Orbitrap-MS, providing insights into the biotransformation processes occurring during digestion.

Results

Significant differences between the undigested PS extract and its digests were observed. The phytoconstituents' concentration decreased significantly after digestion compared to the undigested extract, reaching a maximum bioaccessibility of 43.7% in the gastric environment. The low recovery rate (9.95%) suggested the compounds’ poor stability in intestinal conditions. Concerning the bioactivity, the undigested PS extract inhibited 60.6% of α-glucosidase activity, decreasing significantly after gastric (18.7%) and (15.3%) intestinal digestion. Conversely, comparable α-amylase inhibitory effects were observed in the gastric and intestinal phases (48.2 and 46.6%, respectively). Lastly, multivariate data analysis proved the interdependency between the phytochemical composition and bioactivity of undigested PS extract and its digests.

Conclusions

This study represented a step forward for applying PS extract as a nutraceutical ingredient for lifestyle-related disorders. Further studies should be focused on formulating PS extract to enhance the delivery of bioactive compounds at the gastrointestinal level.

References

[1] Pinto, D., et al., Food Research International, 2020, 136, 109449

[2] Muccilli, V. et al., Heliyon, 2024, 10 (2), e24469

[3] Maccarronello, A. E., et al., Food chemistry, 2024, 443, 138504