Essential oil composition, <i>in vitro</i> antidiabetic, cytotoxicity, antimicrobial, antioxidant activity, and <i>in silico</i> molecular modeling analysis of secondary metabolites from <i>Justicia schimperiana</i>

<i>Justicia schimperiana</i>, known as "Dhumuugaa" in Afan Oromo and "Sensel" or "Smiza" in Amharic, is traditionally used to treat ailments such as scabies, fever, asthma, diarrhea, malaria, and more. This study explored the chemical composition and biological activity of its extracts and isolated compounds. The essential oils were extracted using the hydrodistillation method, and their chemical composition was evaluated using GC-MS. GC-MS analysis identified 54 and 52 chemical components in the essential oils (EOs) from roots and leaves, respectively. The structures of the isolated compounds have been identified using 1D and 2D-NMR techniques. Six compounds - β-sitosterol (<b>1</b>), 5-methoxy durmillone (<b>2</b>), <i>trans</i>-resveratrol (<b>3</b>), tricuspidatol A (<b>4</b>), kaempferol-3-O-α-rhamnopyranoside (<b>5</b>), and kaempferol-3-O-rutinoside (<b>6</b>) - were isolated from the root extracts and reported for the first time in this species. The antimicrobial activity was evaluated using the broth microdilution technique. EOs extracts showed significant antibacterial activity, particularly against <i>Staphylococcus aureus</i>, <i>Streptococcus agalactiae</i>, while compound <b>6</b> showed potent activity with an MIC of 0.25 μg/mL. The antioxidant activity revealed strong radical scavenging for compounds <b>5</b> and <b>6</b>, with extracts also demonstrating significant α-amylase inhibitory effects and moderate cytotoxicity against the MCF-7 cell line. Molecular docking and ADMET analysis highlighted compounds <b>5</b> and <b>6</b> as promising therapeutic agent. These findings highlight the medicinal potential of <i>J. schimperiana</i> roots, warranting further exploration.