The antioxidant potential of parsley and its constituents.

The use of parsley as a meaningful source of dietary antioxidants has been overlooked due to the more common practice of using this herb as a garnish for improving the organoleptic qualities of foods. Notwithstanding this however, is the fact that parsley is comprised of a unique makeup of bioactive flavonoids, which includes both flavones (e.g. apigenin) and essential oil components (e.g. myristicin and apiol). Information on the antioxidant activity of parsley has been evaluated using a variety of chemical and cell-based antioxidant assays, and on a variety of parsley samples derived from different solvent extracts and originating from different anatomic parts of the herb. Studies have shown parsley to contain both bioactive phytochemical constituents that possess antioxidant activity, while also containing other components that have a carryover effect that yields defined chemopreventative activity in cell systems that are exposed to oxidative stress. For example, apigenin, the primary flavone characteristic to parsley exhibits weak reducing and free-radical scavenging activity, albeit that it also has a strong affinity to sequester free metal ions that otherwise could be involved in Fenton-reaction-induced free-radical generation. Alternatively, this flavone can stimulate the induction of reactive oxygen species (ROS), while concomitantly inducing apoptosis in cultured cancer cell lines, thereby suggesting a strong chemoprevention activity rather than acting purely as an antioxidant. On the other hand, essential oil recovered from parsley leaves exhibits notable antioxidant capacity in assays designed to measure reducing power and free-radical scavenging activity. Apiol is a stronger antioxidant than myristicin, and a primary contributor to the antioxidant activity found in parsley essential oil. The objective of this review is to assess the data derived from <i>in vitro</i>-chemical- and cell-based and <i>in vivo</i> studies that have shown potential antioxidant activity of parsley and its constituents; relevant to both improving food quality as well as having a carryover effect that can enhance human health.