Exploring the anti-inflammatory potential of anthocyanin-rich crops

Anthocyanins (ACNs) are a class of purple-red pigments belonging to the flavonoid family largely present in the human diet. Their consumption is correlated to a lower risk of developing chronic diseases, such as cardiovascular and neurodegenerative diseases, diabetes and cancer, thanks to their ability to modulate several pathways, first and foremost inflammation. Being unhealthy diet one of the major, but most preventable, risk factors of inflammatory-related chronic diseases, there is a growing interest in developing and studying plant-based foods enriched in health-promoting phytonutrients, with a focus on climate change resilience and sustainability. We previously demonstrated that the consumption of an ACN-rich diet from purple corn (Red Diet – RD) protected mice from Doxorubicin-induced cardiotoxicity compared to mice consuming an ACN-free yellow diet. RD improved the short-/mid-term survival, but not the long-term, probably due to the low bioavailability of ACNs limiting the dose reaching the heart. Thus, we aimed at finding a strategy to improve their bioavailability and health promoting-activity through nano-encapsulation of purple corn ACNs. In terms of circular economy, we developed nanoparticles of zein (Zn-NPs), the main storage protein of maize. Interestingly, ACNs loaded in Zn-NPs were able to protect Doxorubicin-insulted HL-1 cardiomyocytes as 12.5-fold higher dose of free ACNs. However, in an in vitro model of intestinal absorption based on CaCo-2 cells, the main ACN of purple corn, C3G, was maintained in the apical compartment at 80% when provided in Zn-NPs, suggesting a possible increase in ACN stability and/or a delay in their release. Nonetheless, encapsulated ACNs showed a slightly stronger anti-inflammatory activity in CaCo-2 cells compared to free ACNs, thus suggesting a potential use of ACN loaded Zn-NPs against intestinal inflammation. In parallel, we investigated the anti-inflammatory potential of extracts from three potato varieties from upland cultivation, which may represent a resilient source of beneficial phytonutrients. When provided at plasma-relevant doses, only the carotenoid-rich Desirée and the ACN-rich Bleuet varieties where able to counteract LPS-induced inflammation in THP-1 macrophages, whereas chlorogenic acid (CGA)-rich Kennebec showed an anti-inflammatory activity only at supraphysiological doses. We also observed that the high CGA in Bleuet extract interfered with ACN anti-inflammatory activity, since the isolated ACN fraction from Bleuet exhibited stronger anti-inflammatory effects than the whole Bleuet extract and the addition of CGA to the ACN fraction significantly reduced its anti-inflammatory effect, probably competing for the same transporters.This could indicate a new starting point to develop/select ACN-rich varieties with a lower content of CGA.