Abstract
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.
Key words
NQO1 - traditional healers - Saudi Arabian medicinal plants - chemoprotection
