Protective Effect of Prunella vulgaris L. Whole 
Plant or Spicas Water Extracts on Hyperthyroidism with Liver-yang Hyperactivity Syndrome

Abstract

Background: Prunella vulgaris L. (Lamiaceae) is a perennial medicinal plant commonly used to treat thyroid dysfunction, infectious hepatitis, and mastitis in north-east Asia and Europe. In China, there has been a historical change in the medicinal use of P. vulgaris from the use of whole plants to the use of the spicas. Purpose: This study aimed to evaluate the protective effects of whole plant P. vulgaris water extracts and spicas on hyperthyroidism with liver-yang hyperactivity syndrome and to preliminarily explain the mechanism of action of these water extracts. Methods: Rats were induced with aconite decoction and levothyroxine and treated with P. vulgaris whole plant and spicas water extract for 28 days at the same time. Body weight, food intake, and rectal temperature were monitored. The serum thyroid function indicators thyroid stimulating hormone (TSH), thyroid hormone-free triiodothyronine (FT3) and free thyroxine (FT4), liver function index alanine aminotransferase (ALT) and aspartate aminotransferase (AST), oxidative damage index malondialdehyde (MDA), and superoxide dismutase (SOD) were detected. Liver and thyroid tissues were taken for sectioning and observation. The liver inflammatory factors human tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected by immunohistochemistry, and the expression levels of the apoptotic proteins caspase-3 and B-cell lymphoma-2 (Bcl-2) were detected. Results: Both P. vulgaris whole plant and spica water extract groups exhibited markedly reduced FT3 and FT4 contents, increased the TSH content, and decreased ALT and AST activities. Furthermore, these agents improve thyroid and liver lesion tissue; reduce MDA content; increase SOD activity; reduce IL-6, TNF-α, and caspase-3 expression; and increase Bcl-2 expression. Conclusion: The whole plant and spicas water extracts of P. vulgaris have obvious protective effects on hyperthyroidism and hyperactivity in liver yang, and the protective effect of the water extract of spicas is greater than that of the whole plant water extract.