Antioxidant phytochemicals of Opuntia ficus-indica (L.) Mill. cladodes with potential anti-spasmodic activity

Background: Opuntia ficus-indica (OFI) (L.) Mill. (Cactaceae), a plant widespread in dry regions of the world, shows interesting biological activities (cicatrizant, antiulcer, anti-inflammatory, and hypolipidemic) and is widely used in traditional medicine. Objectives: Phytochemical analysis and antispasmodic effect of wild OFI cladodes were carried out. Material and Methods: Polyphenols and Vitamin E occurrence, in antioxidant pool of OFI cladodes, were quantified by high-performance liquid chromatography. The antispasmodic effect of OFI cladodes was assessed in isolated rabbit smooth muscle tissues. The experiments were carried out with preparations of rabbit jejunum and uterus with the spontaneous contractile activity, to evaluate the effect of cumulative concentrations of the extract on basal tone, amplitude, and frequency of contractions. Results: Catechin, quercetin, kaempferol, isorhamnetin and chlorogenic, ferulic, and p-coumaric acid were identified. α -, β -, and γ -tocopherols have been highlighted and α -tocopherol is the major component. OFI cladodes contain significant amount of polyphenols and tocopherols that are effective radical scavengers and inhibited ethanol 1,1-diphenyl-2-picrylhydrazyl formation by 50%. OFI cladodes caused a light inhibition of amplitude and frequency of spontaneous contractions and a marked decrease in muscle basal tone of rabbit jejunum preparations. On spontaneously contracting uterus preparations, the addition of increasing concentrations of cladode extract caused uterine muscle relaxation. Conclusion: The contraction of smooth muscle preparations depends on an increase in cytoplasmic free calcium ion concentration, which activates the contractile elements. The flavonoids may suppress the contractility of smooth myocytes, by an inhibition of availability of Ca²⁺ for muscle contraction.