Antimicrobial, antioxidant, and anti-inflammatory activities of Justicia adhatoda L. leaf extract

Justicia adhatoda, popularly known as Malabar nut, is a medicinal plant widely used in traditional medicinal systems like Ayurveda and Unani. In the present study, phytochemicals extracted from the leaf samples of J. adhatoda were subjected to qualitative phytochemical characterisation and evaluated for their antimicrobial, antioxidant, and anti-inflammatory activities. In addition, the extracts were examined for cytotoxicity using a brine shrimp lethality bioassay. Further, essential oils were extracted from the leaves and their antimicrobial activities were assessed. The extraction yields were 35.76%, 17.58%, 7.54% and 2.6% for water, methanol, ethanol, and n-hexane, respectively. The extracts and essential oils showed potential antimicrobial activities against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas fluorescens. All extracts inhibited soybean lipoxygenase with a potency comparable to that of the standard inhibitor vanillin. The inhibitory activity decreased in the following order: n-hexane > water > methanol > ethanol. The lethality of the extracts on brine shrimp nauplii decreased in the following order: n-hexane > methanol > ethanol > water. These results indicated that the extracts may contain potential metabolites with biological activities and could be exploited for drug development studies.