Crude Drugs for Clearing Heat Contain Compounds Exhibiting Anti-Inflammatory Effects in Interleukin-1β-Treated Rat Hepatocytes

Traditional Japanese medicines, i.e., Kampo medicines, consist of crude drugs (mostly plants) that have empirical pharmacological functions (‘<i>Yakuno</i>’ in Japanese), such as clearing heat. Crude drugs with cold properties, such as <i>Phellodendron</i> bark, have the empi...

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Main Authors: Airi Fujii, Saki Onishi, Nodoka Watanabe, Mizuki Kajimura, Kentaro Ito, Keita Minamisaka, Yuto Nishidono, Saki Shirako, Yukinobu Ikeya, Mikio Nishizawa
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/2/416
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Summary:Traditional Japanese medicines, i.e., Kampo medicines, consist of crude drugs (mostly plants) that have empirical pharmacological functions (‘<i>Yakuno</i>’ in Japanese), such as clearing heat. Crude drugs with cold properties, such as <i>Phellodendron</i> bark, have the empirical function of clearing heat as they cool the body. Because we found that anti-inflammatory compounds were present in several crude drugs for clearing heat, it is speculated that the empirical function of clearing heat may be linked to anti-inflammatory activities. When 10 typical crude drugs were selected from 22 herbal crude drugs for clearing heat, we identified anti-inflammatory compounds in five crude drugs, including <i>Phellodendron</i> bark. In this study, the other crude drugs were extracted and partitioned with ethyl acetate (EtOAc) and <i>n</i>-butanol to obtain three crude fractions. All the EtOAc-soluble fractions, except that from <i>Forsythia</i> fruits, inhibited interleukin (IL)-1β-induced nitric oxide (NO) production in primary-cultured rat hepatocytes. Anti-inflammatory compounds were identified from these EtOAc-soluble fractions: baicalein from <i>Scutellaria</i> roots, (−)-nyasol from <i>Anemarrhena</i> rhizomes, and loniflavone from <i>Lonicera</i> leaves and stems. (+)-Phillygenin was purified from <i>Forsythia</i> fruits by removing cytotoxic oleanolic and betulinic acids. These compounds suppressed the production of NO and cytokines in hepatocytes. Anti-inflammatory compounds were not purified from the EtOAc-soluble fraction of <i>Rehmannia</i> roots because of their low abundance. Collectively, these findings indicate that anti-inflammatory compounds are present in all 10 crude drugs for clearing heat, confirming that these anti-inflammatory compounds in crude drugs provide the empirical functions for clearing heat. Other empirical functions of Kampo medicine can also be explained by modern pharmacological activities.
ISSN:1420-3049