American mistletoes as a promising source of bioactive compounds

Mistletoe, associated with Christmas traditions and ancient mythology, is a hemiparasite plant displaying a broad host range. Mistletoe has been used in traditional medicine for several purposes, such as treating pain, wounds, and cancer symptoms. Loranthaceae and Viscaceae are the two most studied families of the five comprising the mistletoe group. These two families have worldwide distribution. Phoradendron is the largest American endemic genus of Viscaceae, and preclinical studies have confirmed their pharmacological activities. Furthermore, some species of the genus Psittacanthus have significant ethnopharmacological importance. Despite the traditional uses of these plants, bioactive compounds, including pentacyclic triterpenic acids, polyphenols, and small proteins known as thoinins, have been isolated and showed antidiabetic, antiHIV-1, anticancer, and vasorelaxant activities. However, most of these American mistletoes lack scientific evidence about their biological activities and chemical composition. In this regard, the less investigated American mistletoe also provides an immense opportunity to discover novel natural products with promising therapeutic applications. In this review, we summarized the isolated compounds obtained from American mistletoe and described their biological activities.