Vitexin with its Derivatives is Responsible for the Cholinomimetic Properties of Penianthus longifolius Extract which Stimulates Muscarinic Receptors

摘要

Background: Alzheimer's disease is a neurodegenerative disease that affects about 47.5 million people worldwide, a number that is expected to double every 20 years. Availablejreatments are only palliative because none of the cholinomimetic agents is curative or preventive and they mostly come with severe side effects. The discovery of safer and more effective medications is an unmet healthcare need. Penianthus longifolius is an herbal medicine with strong cholinomimetic activity. Objectives: The purpose of this research was to identify the bioactive components responsible for the observed activities. Method: Aqueous extract of the leaves of P. longifolius was subjected to liquid-liquid fractionation and was tested for cholinomimetic properties in an organ bath experiment and for free radical scavenging properties using 2,2-diphenyl-l-picrylhydrazyl method. The aqueous fraction was further fractionated using HP20 and the HP20 fractions were analyzed using HPLC-DAD. The components were identified by dereplication. Results: Results showed that the extracts had a dose dependent response antioxidant activity in addition to the cholinomimetic property which had been reported. The dereplication analysis showed that the compounds responsible for the activities observed were vitexin, isovitexin and other apigenin glycosides. Conclusion: With the antioxidant activity and cholinomimetic activity mediated through muscarinic receptors, P. longifolius leaf extract deserves further attention as a potential source of anti-Alzheimer's medication.