Extracts of Sideritis scardica as triple monoamine reuptake inhibitors

Sideritis species are traditionally used within the Mediterranean area as teas, flavouring agents or for therapeutical purposes. The aim of this study was to investigate the effects of Sideritis scardica extracts on the monoamine transporters and to derive and explain possible medicinal applications from the pharmacological profile of the extracts. We have studied the effect of various S. scardica extracts on serotonin, noradrenaline and dopamine uptake in rat brain synaptosomes and serotonin uptake in human JAR cells. All extracts inhibited the uptake of all three monoamines into rat brain synaptosomes by their respective transporters, the alcoholic extracts being more effective than the water extract. EC₅₀ values were in the range of 30–40 μg/ml. Inhibition of the human serotonin transporter by the methanol extract was even more effective (EC₅₀ 1.4 μg/ml). Combining Sideritis ethanol extract and fluvoxamine resulted in a leftward shift of the fluvoxamine concentration–response curve. The pharmacological profile of S. scardica extracts as triple monoamine reuptake inhibitors suggests their use in the phytochemical therapy of mental disorders associated with a malfunctioning monoaminergic neurotransmission, such as anxiety disorders, major depression, attention-deficit hyperactivity disorder, mental impairment or neurodegenerative diseases.