Running title: Lemon Balm Poorly Influences Rat Fundus Motility Acta facultatis medicae Naissensis 2023; 40(1): 80-89 80 ACTA FACULTATIS MEDICAE NAISSENSIS UDC: 615.322:582.943.13]:612.32 DOI: 10.5937/afmnai40-38933 Original article Lemon Balm (Melissa officinalis L.) Hydrolate Poorly Influences Isolated Rat Gastric Fundus Motility Nikola M. Stojanović 1 , Sara Mladenović 2 , Bogdan Stojiljković 2 , Aleksandar Marković 2 , Dragana Pavlović 3 , Pavle Randjelović 1 , Jelena Zvezdanović 4 , Ljiljana Stanojević 4 1 University of Niš, Faculty of Medicine, Department of Physiology, Niš, Serbia 2 University of Niš, Faculty of Medicine, Niš, Serbia 3 University of Niš, Faculty of Medicine, Department of Pharmacy, Niš, Serbia 4 University of Niš, Faculty of Technology, Leskovac, Serbia SUMMARY Introduction. Lemon balm has been used for centuries due to its strong sedative, antimicrobial and spasmolytic effects. Besides different types of extracts and essential oils, hydrolates (by-products obtained during essential oil extraction) are preparations of aromatic medicinal plants with potential pharmacological activity. Aim. To estimate Melissa officinalis leaves hydrolate effects on gastric motility. Methods. The influence of the hydrolate was tested in vitro in a tissue bath in the rat fundus spontaneous contraction experimental model. Increasing volumes of sample (making the final concentration span 0.5 – 500 µl/ml) were successively added to the tissue bath. Results. Lower doses of the hydrolate did not produce any significant changes in the contraction patterns, while the higher ones led to a statistically significant increase in basal tone of the stomach fundus. Yet, these changes in basal tonus were still modest. Phytochemical qualitative characterization, done by liquid chromatography with ultra-high performances, showed that rosmarinic acid was dominant compound of M. officinalis hydrolate. Conclusion. Although the tested hydrolate poorly influences isolated rat gastric fundus motility, further studies could clarify its pharmacological activity and potential future application of this by-product of M. officinalis hydrodestilation. Keywords: Melissa officinalis, hydrolate, gastric fundus, contractions Corresponding author: Nikola M Stojanović e-mail: nikola.st90@yahoo.com