Effect of Extracts from Indigowood Root (Isatis indigotica Fort.) on Immune Responses in Radiation-Induced Mucositis

Objectives: To evaluate the effect of indigowood root (Isatis indigotica Fort.) on acute mucositis induced by radiation. Design: The objective severity of mucositis, anorexia, and swallowing difficulty were measured before and after the treatment. Settings: Patients with head and neck cancer receiving radiotherapy at Tian Sheng Memorial Hospital, Taiwan were recruited for this trial. Subjects: Twenty (20) patients were randomized into two groups. Group 1 served as controls with only normal saline, and group 2 as the indigowood root (IR) group. Interventions: Prophylactic application of IR consisted of gargling and then swallowing the IR preparation on the irradiated oral mucosa. Outcome measures: Patients' characteristic distribution of gender, age, diagnosis, and mean radiation dose between the two arms were calculated by Fisher's exact test. We compared the mean of grade 1-4 mucositis, anorexia, difficulty in swallowing, and body weight change with the Mann-Whitney U test. p values less than 0.05 indicated statistical significance. Results: The clinical trial showed that application of IR can reduce the severity of radiation mucositis (p=0.01), anorexia (p=0.002), and swallowing difficulty (p=0.002). Although patients' resting days did not show a significant difference (p=0.06), complete radiotherapy was done without rest for 4 of 11 patients in the IR group versus 2 of 9 in controls. Hemoglobin level between both groups showed no significant difference. Serum interleukin-6 was significantly lower in the IR group during the first, fifth, and seventh weeks. Conclusions: We confirmed that indigowood root has anti-inflammatory ability to reduce the mucosal damage caused by radiation. We postulate that indirubin may play a pharmaceutical role in improvement of radiation mucositis, anorexia, and difficulty in swallowing in our clinical trial. However, the exact mechanisms and pathways still need further analysis.