Comparative Anti-Inflammatory Effects of Green and Red Lentil Polyphenols on Murine Dendritic Cells

Lentils are highly nutritious, polyphenol-rich pulses with potential functional properties. Here, we investigated the anti-inflammatory effects of polyphenolic extracts obtained from green and red lentil extracts (GLE and RLE) on murine bone marrow-derived dendritic cells (DCs) serving as sentinels of the immune system. GLE and RLE were analyzed for their total polyphenol content, polyphenolic profile and antioxidant activity. Our analysis revealed that GLE and RLE had comparable total content of polyphenols and similar high antioxidant capacity, but different polyphenol profiles. GLE was characterized by high levels of catechin and gallocatechin than RLE, while RLE showed higher kaempferol, myrtillin, rutin and rhoifolin content. The polyphenolic extracts were subsequently evaluated for their biological effects on immature DCs exposed to lipopolysaccharide (LPS) inflammatory stimulus. RLE induced a dose-dependent reduction in IL-1α, IL-1β and IL-6 levels similarly to quercetin, used as positive control. GLE also resulted in a dose-dependent reduction in IL-1β and IL-6 levels, however these effects were associated with marked cytotoxicity. Gene expression analysis revealed a significant reduction of IL-1α and IL-1β transcription occurring in LPS-stimulated DCs treated with 25 μM GAE of RLE, without inducing inflammatory activation in unstimulated cells. Our results demonstrate that red lentils are good source of bioactive compounds with immunomodulatory activities with enhanced anti-inflammatory activity alongside reduced cytotoxicity.