Abstract
Citrus plants contain large amounts of flavonoids with beneficial effects on human health. In the present study, the antioxidant and anti-inflammatory potential of bioavailable polyphenols from Citrus sinensis was evaluated in vitro and ex vivo, using the murine macrophages cell line J774A.1 and primary peritoneal macrophages. Following simulated gastro-intestinal digestion, the in vitro bioavailability of Citrus sinensis polyphenolic extract was assessed using the human cell line Caco-2 grown as monolayers on a transwell membrane. Data demonstrated a relative permeation of its compounds (8.3%). Thus, the antioxidant and anti-inflammatory effect of polyphenolic Citrus sinensis fraction (Cs) was compared to the bioavailable one (CsB). Results revealed that Citrus extract were able to reduce macrophages pro-inflammatory mediators, including nitric oxide, iNOS, COX-2 and different cytokines. Moreover, the effect of Citrus sinensis polyphenols was associated with antioxidant effects, such as a reduction of reactive oxygen species (ROS) and heme-oxygenase-1 (HO-1) increased expression. Our results provide evidence that the bioavailable polyphenolic constituents of the Citrus sinensis extract accumulate prevalently at intestinal level and could reach systemic circulation exerting their effect. The bioavailable fraction showed a higher anti-inflammatory and antioxidant potential compared to the initial extract, thus highlighting its potential nutraceutical value.
Highlights
Inflammation is a biological process mainly supported by the immune cells to protect the host from microbial infection or tissue injury
We investigated the antioxidant and anti-inflammatory effect of bioavailable flavonoids from Citrus sinensis extract
Data highlighted how most of the flavonoids are already bioavailable after the salivary and gastric stages, whereas the intestinal environment is mainly responsible for their degradation, in accordance with previous studies [23]
Summary
Inflammation is a biological process mainly supported by the immune cells to protect the host from microbial infection or tissue injury. Synthetic antioxidants are known to have free radical inhibition properties in the human body, but these compounds could prove toxic and hazardous to the human body [4]. In this regard, the area of natural products is of great interest. Different studies have observed the inverse correlation existing between the risk of cardiovascular diseases and polyphenols intake [8]. Most of these effects have been highlighted by the use of in vitro screening methods. Gastrointestinal (GI) digestion conditions may result in drastic structural changes that could affect the stability and bioactivity of food constituents [9]
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