A traditional Japanese medicine used for obesity may offer additional benefits beyond weight loss, according to researchers at the University of Osaka working with Kobayashi Pharmaceutical Co., Ltd., as reported on Aug. 2. The team investigated whether Bofutsushosan, a Kampo medicine containing 18 crude-drug ingredients, could protect aging tissues from fibrosis—a buildup of scar-like tissue that can stiffen organs and impair function. Their findings were published in Phytomedicine.
The study involved feeding 63-week-old male mice a high-fat diet with or without 2% Bofutsushosan for eight weeks. Mice receiving the medicine weighed 14.8% less than untreated mice by the end of the study, ate less food, had smaller fat deposits, showed reduced fat accumulation in the liver, and exhibited fewer fibrosis-related changes in both fat tissue and liver.
To determine if Bofutsushosan's effects extended beyond weight loss, researchers also treated cultured fat-cell precursors with the medicine. In these cells, Bofutsushosan reduced several signals related to fibrosis and partly suppressed activity in the TGF-β/SMAD2/3 pathway—a key driver of scar-like tissue formation.
Testing each ingredient separately revealed that Forsythiae Fructus, Zingiberis Rhizoma, Rhei Rhizoma, and Scutellariae Radix demonstrated strong anti-fibrotic activity in cell cultures. Some mineral ingredients such as Sal Mirabilis had opposite effects under these conditions; however, researchers cautioned that this might be specific to cell culture and does not indicate harm during clinical use. Increasing amounts of candidate anti-fibrotic ingredients—either alone or excluding Sal Mirabilis—produced stronger suppression of some fibrosis markers in cultured cells but have not yet been tested in animals or humans.
Lead author Ayano Onishi said, "Bofutsushosan is best known for its effects on obesity. Our findings suggest that it may also act on fibrosis associated with aging and obesity. Understanding the role of each ingredient could help guide future research into Kampo medicines, but human studies will be needed before the findings can be applied to treatment." The results are preclinical; further animal and human studies are required before any changes to treatment approaches can be considered.
