Citrus Peel Flavonoids as Potential Cancer Prevention Agents

Abstract

Citrus fruit and in particular flavonoid compounds from citrus peel have been identified as agents with utility in the treatment of cancer. This review provides a background and overview regarding the compounds found within citrus peel with putative anticancer potential as well as the associated in vitro and in vivo studies. Historical studies have identified a number of cellular processes that can be modulated by citrus peel flavonoids including cell proliferation, cell cycle regulation, apoptosis, metastasis, and angiogenesis. More recently, molecular studies have started to elucidate the underlying cell signaling pathways that are responsible for the flavonoids’ mechanism of action. These growing data support further research into the chemopreventative potential of citrus peel extracts, and purified flavonoids in particular. This critical review highlights new research in the field and synthesizes the pathways modulated by flavonoids and other polyphenolic compounds into a generalized schema.

Beneficial Effects of Citrus-Derived Polymethoxylated Flavones for Central Nervous System Disorders

“…Citrus peels and/or extract have been reported to have various beneficial effects on humans, e.g., body weight control [ 171 ], promote cardiovascular health [ 172 ], improve hepatic steatosis [ 173 ] and cancer prevention [ 174 , 175 ]. Although consisting of only a few cases, one clinical study has demonstrated that PMF-rich citrus peel extract prevents the progression of cognitive dysfunction in AD patients on donepezil therapy [ 176 ].…”

Flavonoids in Lemon and Grapefruit IntegroPectin

“…It is also of relevance to this account the growing evidence, recently emphasized by Valtchev and co-workers reviewing citrus peel flavonoid anti-cancer properties [9], of synergy between these bioactive molecules, with citrus peel whole extracts showing higher activity than the fractionated extracts or isolated single compounds. Finally, citrus peel extracts obtained from freeze-dried peel, due to enhanced rupture of the cell vacuoles and release of phenolic compounds accumulating therein, have >50% higher concentrations of total phenolic and total flavonoid compounds when compared to extracts obtained from the fresh peel [10].…”

“…Citrus flavonoids contained in large amount in citrus processing waste are the target of specific extraction procedures [8], as they are increasingly added to several new nutraceutical products and food supplements. It is now well known, indeed, that the broad-scope biological activity of these flavonoids, including anti-inflammatory, antiproliferation, anti-angiogenesis and cell cycle regulation effects are due not only to their free radical scavenging activity, but also to their ability to act as modulators of several key molecular events implicated in cell survival and apoptosis [9]. Scheme 1.…”

Effects of Lipid-Based Encapsulation on the Bioaccessibility and Bioavailability of Phenolic Compounds

“…The skin and colon carcinogenesis as well as the tumor size and volume of mice suffering from prostate cancer was significantly reduced in treated animals. In addition to the health-improving effects of a phenolic-enriched extract, the specific effects of each individual phenolic compound can also be allocated; such as an anti-inflammatory potential of tangeretin and sinensetin or the suitability of hesperidin as an antioxidant [14].…”