Leaf and fruit from Mediterranean Sicilian sumac (Rhus coriaria L.) show promising antioxidant and anti-inflammatory activities in gastrointestinal epithelial cells

Sumac (Rhus coriaria L.) is gaining attention as a rich source of polyphenols with health properties, including anti-inflammatory and antioxidants. Most of the available literature was generated on its traditional use in the Middle East, but the plant has also been historically propagated in the Mediterranean region. The fruit is consumed as spice, whereas both fruit and leaf are considered as empirical remedies for gastrointestinal disorders. Unexpectedly, the biological activity at this level is still poorly investigated. We previously reported that fruit extracts from Iranian sumac may counteract Helicobacter pylori related gastritis (PMID: 35565724).

Here, we investigated the antioxidant and anti-inflammatory properties of fruit and leaf from Sicilian sumac (Sicily, Italy) in human gastric (GES-1) and intestinal (CaCo-2) cells.

Traditional methods of extraction, such as hot water infusion and hydroalcoholic maceration, allowed to obtain dry extracts rich in gallic acid, flavonoids and gallotannins (up to 73% GA eq. in leaf). Polyphenols and antioxidant capacity (ORAC) remained elevated after simulated gastrointestinal digestion. Both fruit (1 – 60 μg/mL) and leaf (0.01 – 20 μg/mL) extracts inhibited the release of chemokines (IL-8 and MCP-1) in epithelial cells. The mechanism was related to the NF-κB impairment in gastric cells. At same concentrations, fruit and leaf extracts reduced the level of ROS in intestinal, but not in gastric cells ([Fig. 1]).

Fig. 1 Rhus coriaria L. workflow

The overall data valorise the potential role of Sicilian sumac in gut inflammation and oxidative stress, highlighting the properties of leaf extracts.