Objective: In general, antiallergic drugs, steroids, and autonomic drugs are administered for patients with allergic diseases, but the chronic administration of these medicines may occasionally induce side effects. As such, several complementary and alternative medicine (CAM) are used, even though their effectiveness has not been established by a significant amount of evidence. Health food, herbal medicines, herbal tea, and aromatherapy, etc., are used for the treatment of allergic rhinitis (AR) as CAM. Rosmarinic acid is a type of polyphenol, and is reported to have antiallergic, antioxydative and anti-inflammatory properties. Rosmarinic acid is included in Perilla Herbs, which are used in health foods and herbal medicines (Kampo medicines), Rosemary and Lemon balm, which are used as herbal teas and essential oils of aromatherapy. This study was performed to evaluate the effect of rosmarinic acid on AR using AR model rats.
Methods: Six-week-old male Sprague-Dawley rats were sensitized with toluene 2,4-diisocyanate (TDI) to induce AR. Rosmarinic acid (1 mg/kg i.p. or 3 mg/kg i.p.) is administrated for 21 days. On day 22, the symptom of nasal allergy was evaluated by counting the number of sneezes within 10 minutes. Substance P (SP), calcitonin gene-related peptide (CGRP) and nerve growth factor (NGF) in the nasal lavage fluids were also measured.
Result: SP and CGRP take part in the exacerbation of rhinitis symptoms, and are secreted from the nerve ending following nerve stimulation by chemical mediators such as histamine. The administration of Rosmarinic acid had no effect on NGF, but significantly suppressed increases of sneezes, SP and CGRP dose-relatedly. Conclusion: Rosmarinic acid could control the symptom of nasal allergy, and one of the mechanisms was suppressing of the secretion of SP and CGRP.