A Study on Justicia flava (Forssk.) Vahl.: Pharmacognostic Characterization and Antiplasmodial and Anti-Inflammatory Properties of the Leaves

Justiciaflava (Acanthaceae) is utilized in folk medicine for treating malaria, inflammatory conditions, and respiratory infections. In this study, the antiplasmodial and anti-inflammatory activities of the 70% hydroalcoholic leaf extract of J. flava (JFE) were investigated. The antiplasmodial activity was assessed by the suppressive test and Rane’s curative test. The carrageenan-induced paw oedema assay in chicks was used to assess the anti-inflammatory activity. In Rane’s curative test, JFE significantly suppressed the parasitaemia level ( $p$  < 0.0001) by 56.85%, 63.85%, and 77.85% at 30, 100, and 300 mg·kg−1, respectively. The highest suppression of parasitaemia in the suppressive test was 51.31% at 300 mg·kg−1. The extract prolonged the survival time of infected mice significantly and prevented weight loss and hypothermia which are cardinal signs of P. berghei-induced infection. JFE inhibited foot oedema in chicks with a maximum percentage inhibition of 54.00 ± 5.20%. Pharmacognostic characterization of J. flava revealed it to have simple, petiolate, oppositely arranged leaves which are broadly lanceolate in shape with entire to slightly crenate margins. Microscopy of the leaf showed wavy-walled epidermal cells, diallelocytic stomata, abundant clothing and secretory trichomes, pitted vessels, collateral conjoint vascular bundles, cystoliths, and prismatic calcium oxalate crystals. Flavonoids, tannins, phytosterols, triterpenoids, coumarins, alkaloids, and saponins were detected in the plant. This study has provided important parameters for the correct identification of J. flava and given the scientific credence to its antimalarial and anti-inflammatory effects in traditional medicine. J. flava is a potential source of new antimalarial and anti-inflammatory compounds.