Medicinal plants are a rich source of biologically-active
phytochemicals and have been used in
traditional medicine for centuries. Specific
phytochemicals and extracts of their plant sources have the ability to reduce the risk for chronic degenerative diseases by induction of
enzymes involved in
xenobiotic metabolism, many of which also have
antioxidant and anti-inflammatory functions. One such multifunctional cytoprotective
enzyme is
NAD(P)H :
quinone oxidoreductase. In this study, we prepared extracts of 27 Saudi Arabian medicinal plants which belong to 18 different plant families and tested their ability to induce
NAD(P)H :
quinone oxidoreductase in murine
hepatoma cells grown in microtiter plate wells. In addition to the Brassicaceae, a known source of
NAD(P)H :
quinone oxidoreductase inducer activity, we found substantial inducer activity in extracts from the Apiaceae, Apocynaceae, and the Asteraceae families. Five out of a total of eight active extracts are from plants which belong to the Asteraceae family. We further show that
artemisinin, an agent which is used clinically for the treatment of
malaria, contributes but does not fully account for the inducer activity of the extract of Artemisia monosperma. In contrast to
artemisinin,
deoxyartemisinin is inactive in this assay, demonstrating the critical role of the endoperoxide moiety of
artemisinin for inducer activity. Thus, the
NAD(P)H :
quinone oxidoreductase inducer activity of extracts of some Saudi Arabian medicinal plants indicates the presence of specific
phytochemicals which have the potential to protect against chronic degenerative diseases.