*2.3. Anti-Inflammatory Properties*

Inflammation represents the first physiological response against injuries caused by physical agents, poisons, and others. [5,77–79]. The defense system, the so-called primary inflammation, neutralizes infectious microorganisms, removes irritation, and maintains ordinary physiological functions [80]. The phlogosis is triggered by various chemical and biological agents, including pro-inflammatory enzymes and cytokines, such as eicosanoids or degradation products of inflamed tissue.

According to recent reports, pomegranate exhibited potential as an anti-inflammatory medicine in both in vitro and in vivo studies. Some extracts of pomegranate, especially the cold-pressed seed extract, decrease the action of cyclooxygenase and lipoxygenase enzymes in vitro. Cyclooxygenases are useful enzymes for the degradation of arachidonic acid into prostaglandins, key mediators of inflammation. Lipoxygenase, on the other hand, mediates the transformation of arachidonic acid into leukotrienes and it is reduced by extracts of pomegranate seeds [81,82].

Bousetta et al. [83] report that punicic acid (12), a fatty acid contained in pomegranate seed oil, has an anti-inflammatory activity due to the inhibition of neutrophil activation, and therefore limits lipid peroxidation.

Lee et al. [80] analyzed some hydrolyzable tannins, including punicalagin (9) and punicalin (13), isolated from pomegranate by fractionation. Following in vitro studies, each of these compounds exerted a dose-dependent inhibitory effect on nitric oxide synthesis with an important anti-inflammatory effect [84].

De Nigris et al. [85] have shown that the dietary inclusion of pomegranate fruit extract caused an important reduction in expression of the markers of vascular inflammation, thrombospondin, and cytokine transforming growth factor (TGF-β1) in obese Zucker rats, a model of metabolic syndrome.

Larossa et al. [86] indicated that pomegranate composition could prevent colon inflammation before and during the disease process. They assessed the consequences of pomegranate intake and its main microbiota-derived metabolite urolithin-A (UROA) on colon inflammation. Results suggested that URO-A could represent the most powerful anti-inflammatory compound derived from pomegranate ingestion in healthy subjects, whereas in colon inflammation, the e ffects could be caused by the nonmetabolized ellagitannin-related fraction. Additionally, pomegranate extract supplementation has been shown to lead to decreased levels of prostaglandin E2 in the colon mucosa due to reduced cyclooxygenase-2 (COX-2) overexpression and diminished levels of prostaglandin synthetase E (PTGES) due to high ellagic acid (8) content [87].

Park et al. analyzed the e ffects of pomegranate peel extract (PPE) on THP-1 monocytic cells exposed to PM10, air-borne particulate matter with a diameter of <10 μM (PM10) that are known to induce cytotoxicity and ROS production and also to increase the expression and secretion of inflammatory cytokines, such as TNFα, IL-1β. This study demonstrated that PPE at 10–100 μgmL−<sup>1</sup> is able to lower the production of ROS and the expression of TNFα, IL-1β, MCP-1, and ICAM-1 thus preventing inflammatory events due to particulate matter [88].

A recent study by Xu et al. explore the inflammation effects of pomegranate flower (PFE) ethanol extract in lipopolysaccharide (LPS) -induced RAW264.7 cells. LPS is a component of the Gram-negative bacteria cell wall that has been often used in inflammatory response because it can activate macrophages. Their findings sugges<sup>t</sup> that PFE is able to suppress the production of NO, PGE-2, and pro-inflammatory cytokines (TNFα, IL-6, IL-1β), as well as the protein expression of iNOS and COX-2 in LPS-stimulated RAW264.7 macrophages. Furthermore, PFE treatment markedly inhibited LPS-induced NF-kB activation through blocking nuclear translocation of NF-kB and IkB α degradation and PFE treatment also inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) [89].

Kim et al. demonstrated the advantageous protective outcomes of pomegranate beverages, in comparison with those of mango in a preclinical model of colitis. The results obtained suggested that extracts rich in gallo- and ellagitannins work on several molecular targets in the protection against ulcerative colitis. Mango polyphenols inhibited the IGF-1R- AKT/mTOR via, and pomegranate polyphenols downregulated the mTOR downstream pathway, decreasing the ERK1/2 expression [90].

The systemic e ffects of PE on the formalin-induced nociceptive behavior and against gastric injury generated by non-steroidal anti-inflammatory drugs and ethanol in mice have been investigated. PE provide antinociceptive and anti-inflammatory activities without damaging the stomach and even displaying gastroprotection, possibly by modulation at central and peripheral levels [91].

The topical anti-inflammatory e ffect of a standardized pomegranate rind extract (SPRE), toward a mouse model of contact dermatitis has been evaluated, in relation to its marker compound ellagic acid, by Mo et al. The results highlighted the powerful anti-inflammatory activity of topical application of SPRE, ellagic acid being responsible for the extract activity as its major antioxidant constituent. The study suggests the topical formulation of SPRE as a promising therapy for contact dermatitis and as an alternative therapy for cutaneous disorders [92].

All these researches highlight the ability of the di fferent components present throughout the pomegranate fruit to act as anti-inflammatory agent. However, further studies are required to completely exploit pomegranate's preventive and therapeutic potential in vivo.
