Abstract:
Verbascoside is found in many medicinal plant families such as Verbenaceae. Important
biological activities have been ascribed to verbascoside. Investigated in this study is the potential
of verbascoside as an adjuvant during tuberculosis treatment. The present study reports on the
in vitro metabolism in human hepatic microsomes and cytosol incubations as well as the presence and
quantity of verbascoside within Lippia scaberrima. Additionally, studied are the inhibitory properties
on human hepatic CYP enzymes together with antioxidant and cytotoxic properties. The results
yielded no metabolites in the hydrolysis or cytochrome P450 (CYP) oxidation incubations. However,
five different methylated conjugates of verbascoside could be found in S-adenosylmethionine
incubation, three different sulphate conjugates with 30
-phosphoadenosine 50
-phosphosulfate (PAPS)
incubation with human liver samples, and very low levels of glucuronide metabolites after incubation
with recombinant human uridine 5’-diphospho-glucuronosyltransferase (UGT) 1A7, UGT1A8, and
UGT1A10. Additionally, verbascoside showed weak inhibitory potency against CYP1A2 and
CYP1B1 with IC50 values of 83 µM and 86 µM, respectively. Potent antioxidant and low cytotoxic
potential were observed. Based on these data, verbascoside does not possess any clinically relevant
CYP-mediated interaction potential, but it has effective biological activity. Therefore, verbascoside
could be considered as a lead compound for further drug development and as an adjuvant during
tuberculosis treatment.
