Malabar Nut Tree Leaf Extract, derived from Justicia adhatoda (also known as Vasaka), has a long history of use in traditional Ayurvedic and Unani medicine for the management of respiratory conditions, including bronchitis. The primary bioactive compounds, vasicine and vasicinone, have been shown in preclinical studies to possess bronchodilatory, expectorant, and anti-inflammatory effects. Several in vitro and animal studies demonstrate that these alkaloids help to relax bronchial smooth muscles, facilitate the clearance of mucus, and exhibit mild antimicrobial activity against respiratory pathogens.

There are also a few small clinical studies and pilot trials suggesting that standardized extracts or formulations containing Justicia adhatoda may improve symptoms such as cough and sputum production in patients with bronchitis or other respiratory ailments. However, the clinical evidence is limited by small sample sizes, short durations, and methodological weaknesses. Most modern pharmacological reviews acknowledge that while the traditional use is strong and preclinical data are promising, rigorous large-scale clinical trials are lacking.

Overall, the use of Malabar Nut Tree Leaf Extract for bronchitis is justified by both traditional use and moderate scientific evidence, primarily from animal and laboratory research, with some supportive early human data. The evidence level is rated 3 out of 5 due to the lack of robust, high-quality clinical trials.