A Scoping Review of Genus Viscum: Biological and Chemical Aspects of Alcoholic Extracts

The genus Viscum comprises a large number of semi-parasitic shrubs popularly known as Mistletoe. The Viscum species grow in many countries of Europe, Africa and Asia with different popular uses in ornamentation, foods and medicine. Many studies about Viscum have been done over the last years focusing on biological activities and chemical composition of the aqueous extracts, mainly related to anthroposophical medicines. However, it is known that non-aqueous preparations, as alcoholic extracts, have demonstrated different biological activities that are species—and host tree—dependent. Considering the potential of these alcoholic extracts, a scoping review was conducted using data from three online databases: PubMed, Scopus and Embase. Inclusion criteria consisted of the in vitro, in vivo, ex vivo, clinical and chemical studies of alcoholic extracts from Viscum species. The present review summarized 124 original publications about fourteen Viscum species. Viscum album, Viscum articulatum and Viscum coloratum were the main studied species. Alcoholic extracts demonstrated hypotensive, anticancer, antimicrobial, analgesic and anti-inflammatory capabilities, among other biological activities. Flavonoids, phenolic acids and terpenoids represented 48%, 24% and 11% of the total identified compounds, respectively. This review contributes to the knowledge of alcoholic preparations of the Viscum species and points out the lack of clinical studies concerning these different extracts.