Alkaloids from the Delphinium Flexuosum Bieb. and Their Pharmacological Activity

Abstract

Background: The aerial and underground parts of D. flexuosum Beeb. have been studied regarding the content of diterpene alkaloids, and a preliminary estimation of their pharmacological potency has been conducted. Diterpenoid alkaloids from larkspur species are claimed to have diverse pharmacological activity, including analgesic, anticonvulsant, muscle relaxant, etc. In this regard, searching for additional natural resources rich in alkaloids within larkspur species growing in Georgia seems reasonable. Objectives: This study aims to comprehensively investigate the diterpene alkaloid content and pharmacological potency of D. flexuosum M. Bieb's aerial and underground parts, which have yet to be sufficiently explored in previous research. Methods: Alkaloid fractions from aerial and underground parts of D. flexuosum were isolated using the polybuffer separation method with citrate-phosphate buffers (pH 8.0 → 2.0). The antinociceptive activity was evaluated using the hot plate test, a standard method for assessing analgesics with central mechanisms. In contrast, the anticonvulsant activity was examined using the pentylenetetrazol (PTZ) induced seizures test. Results: The composition of 8 alkaloid fractions (4 each for aerial and underground parts) has been studied, revealing six dominant alkaloids. Diterpene bases methyllycaconitin, anthranoyllycoctonine, delcosine, and lycoctonine predominate in both aerial and underground organs of D. flexuosum, while the underground organs additionally contain alkaloids songorine, norsongoramine, and delectin. Pharmacological tests revealed that three fractions from the ground and two from the underground parts exhibited a short-time analgesic activity. In contrast, none of the studied fractions appeared to have notable anticonvulsant activity. Conclusions: The observed activity of the investigated alkaloids is based on central rather than peripheral mechanisms of analgesia by breaking impulse conductivity at different stages of passing through nociceptive pathways.