Tocolytic activity assessment of the methanol leaf extract of Justicia flava Vahl (Acanthaceae) on mouse myometrial contractility and preliminary mass spectrometric determination of secondary metabolites

Ethnopharmacological relevance: The leaves of Justicia flava are traditionally used in the South of Nigeria to prevent preterm births. Aim of the study: In this study, the activity of the methanol leaf extract of J. flava (JF) was investigated on uterine contractility in non-pregnant and pregnant isolated mouse tissues. Material and methods: The effects on spontaneous, oxytocin, and KCl-induced contractions were determined. The effects in calcium-free media were also determined. Possible mechanisms of activity were investigated using receptor and channel modulators. Mass spectrometric analysis was additionally performed on the leaf extract to identify secondary metabolites. Results: JF was observed to inhibit spontaneous, oxytocin and high KCl-induced uterine contractility. JF also inhibited contractions in Ca²⁺-free media. JF was found to exert its inhibitory effect via interaction with inositol triphosphate and ryanodine receptors and also through modulation of K⁺- channels. Lignans and alkaloids were identified with the lignans being the most abundant in JF. Conclusion: JF has been shown to potently inhibit uterine contractions in non-pregnant and pregnant isolated mouse uterus. The inhibitory activity of JF has been shown to occur via blockade of extracellular and intracellular calcium entry and these effects may be due to the lignans identified in - JF. JF has therefore been shown in this study to be a lead plant in the discovery of new drugs with uterine inhibitory activity.