Comparative Compositional Analysis of Regular and Decaf Coffees by LC/MS and HPLC and Potential Effects on Inflammatory Cytokines Produced during Bacterial Infections.

Authors: Park, Jae; Peters, Renee; Pham, Quynhchi; Wang, Thomas - Tom

Submitted to: Food & Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2024
Publication Date: 1/19/2024
Citation: Park, J.B., Peters, R.C., Pham, Q., Wang, T.T. 2024. Comparative compositional analysis of regular and decaf coffees by LC/MS and HPLC and potential effects on inflammatory Cytokines produced during bacterial infections. Food & Function. https://doi.org/10.1021/acsfoodscitech.3c00599.
DOI: https://doi.org/10.1021/acsfoodscitech.3c00599

Interpretive Summary: Coffee is one of the most popular drinks consumed worldwide. For years, its consumption has been reported to have beneficial health effects on several human diseases including diabetes and fatty liver disease. Among coffee compounds, caffeine has been considered as a main anti-inflammatory compound in coffee. However, there is a proceeding question about caffeine’s anti-inflammatory activity. Interestingly, interleukin-6 (IL-6) is a key inflammatory cytokine deeply involved in the immune functions, and a high level of IL-6 has been reported to be significantly associated with clinical phenomena of severe type COVID-19 patients. However, there is not much information about the potential effect of coffee on IL-6, particularly related to caffeine. Therefore, in this study, sixteen coffee products (regular and decaf ground/instant coffees) were used to investigate caffeine’s capacity to inhibit IL-6 in human peripheral blood mononuclear cells (PBMCs). Our study showed that coffee products in the market (both regular and decaf coffee products) can inhibit IL-6 significantly, but caffeine may have no effect on IL-6 inhibition in PBMCs. This study provides new information that commonly consumed coffee products may have potentials to inhibit IL-6 production, but caffeine may not play a significant role in the inhibition.

Technical Abstract: The effect of coffee on inflammatory cytokine IL-6 has not been fully investigated, particularly related to caffeine. Therefore, in this paper, sixteen coffee products (eight ground coffees (GC: regular (n=4) and decaf (n=4)) and eight instant coffees (IC; regular (n=4) and decaf (n=4)) were used to investigate the potential role of caffeine in IL-6 inhibition. First, the amounts of caffeine in coffee products were analyzed by HPLC. Then, their effects on IL-6 were investigated in human peripheral blood mononuclear cells (PBMCs). Both regular and decaf GC (n=8) significantly inhibited IL-6 production in PBMCs (P < 0.05). However, caffeine did not inhibit IL-6 production in PBMCs. Similarly, both regular and decaf IC (n=8) could inhibit IL-6 significantly in PBMCs (P < 0.05), suggesting that both regular/decaf coffees can inhibit IL-6 production and caffeine may not play a significant role in the inhibition in PBMCs. To confirm the data, regular and decaf coffee samples (n=2) were prepared from the regular and decaf GC (n=8) and IC (n=8) samples, and their effects on mRNA and protein productions of IL-6 were further investigated at 0, 2, 4, 6, 10, and 24 h in PBMCs. Both coffee samples significantly inhibited IL-6 mRNA production at 2, 4, and 6 h in PBMCs (P < 0.05), despite little caffeine’s effects at these time points. Likewise, both regular/decaf coffee samples inhibited the production of IL-6 protein at 4, 6, 10, and 24 h. Particularly, there was no additional increase in IL-6 production after 6 h. Because of caffeine’s incapacity to inhibit IL-6, potential effects of other coffee compounds (chlorogenic acid and javamide-I/-II) on IL-6 were additionally investigated, and javamide-I/-II were found to have some inhibitory effects on IL-6 in PBMCs. Altogether, the data suggest that regular and decaf ground/instant coffee coffees are equally potent in inhibiting IL-6 in PBMCs, and caffeine may not be a major contributing factor to the inhibition.