Efficacy of Liriope platyphylla extract on improving respiratory function: A CONSORT-randomized, double-blind, placebo-controlled pilot trial.

BACKGROUND: The respiratory system is the first line of defense against outside pollutants. Recently, respiratory health has been receiving increasing attention due to the increase in fine dust, which reduces respiratory function and increases incidence of chronic obstructive pulmonary disease, and in coronavirus pandemic, which can cause severe acute respiratory syndrome. METHODS: This clinical pilot trial was designed to secure evidence for a main clinical trial and to confirm the efficacy and safety of Liriope platyphylla (LP) extract for improving respiratory function. We conducted a double-blind randomized placebo-controlled trial with 22 participants from June 30, 2021, to August 25, 2021. The primary outcome was Breathlessness, Cough, and Sputum Scale score. Secondary outcomes included forced vital capacity, forced expiratory volume at 1 second (FEV1), forced expiratory volume at 1 s/forced vital capacity ratio, cough assessment test score, chronic obstructive pulmonary disease assessment test score, peripheral blood mononuclear cell counts (white blood cells, eosinophils, T cells, and B cells), high-sensitivity C-reactive protein level, erythrocyte sedimentation rate, cytokine (interleukin-1ß, interleukin-4, tumor necrosis factor-α, interleukin-6, interleukin-8, interferon-γ, and immunoglobulin E) levels, antioxidant (glutathione peroxidase and superoxide dismutase) levels, and nitric oxide level. RESULTS: A total of 22 participants were randomly assigned to 2 groups: the LP group (n = 11), who took 1000 mg of LP extract per day, and the placebo group, who took 1000 mg of dextrin per day. Participants took 1 capsule twice a day for 4 weeks. For the Breathlessness, Cough, and Sputum Scale, the interaction between group and visit was statistically significant in a blend of analyses of variance. interleukin-8, tumor necrosis factor-α, and interferon-γ levels decreased more in the LP group than in the placebo group. The sample size required for large-scale clinical trials in the future was 50. There were no side effects. CONCLUSION: LP extract can enhance respiratory function. The detailed data we obtained support conducting the future main large-scale clinical trial.

Efficacy of liriope platyphylla extract for improving respiratory functions: Study protocol for a randomized, double-blinded, placebo-controlled pilot trial.

BACKGROUND: Respiratory disease has emerged as a global issue due to COVID-19. In particular, there has been an increased frequency of occurrence of symptoms such as cough, sputum, and dyspnea, which commonly accompany chronic obstructive pulmonary disease (COPD). Liriope platyphylla (LP) extract is known to improve respiratory function. LP extract ameliorates the symptoms commonly seen in bronchitis, asthma, and COPD and enhances immunity, as it has anti-inflammatory properties. In a previous study in rats, LP effectively improved respiratory inflammation levels. However, few randomized controlled trials have verified the effects of LP in respiratory disease and there have been no studies to determine the appropriate dose and duration to make it a more convenient functional health product. Based on previous studies, we would like to proceed with this clinical trial under the assumption that LP will help improve respiratory function and produce anti-inflammatory effects. METHODS: This will be a single-center, randomized, double-blind, placebo-controlled pilot trial. Participants will randomly be allocated to receive either 1000 mg LP or placebo. The total duration of the clinical trial will be 4 to 6 weeks. A follow-up assessment will be conducted 4 weeks after screening, and the effect and safety of LP application will be assessed at this second visit. The primary outcome will be the breathlessness, cough, and sputum scale score. Secondary outcomes will include pulmonary function, clinical symptoms of cough and sputum (reported through a questionnaire), changes in immune cells, changes in immune factors used to analyze allergic inflammation in bronchi, antioxidant enzyme activity, nitric oxide level, and COPD assessment test score. DISCUSSION: This study has limited inclusion and exclusion criteria and the intervention will be well-controlled. This will be the first randomized controlled trial to assess the efficacy and safety of LP extract in adults with cough and sputum. This study will provide insight into the mechanisms of the anti-inflammatory effects and improvement of respiratory function of LP.