Osteoporosis, a disease characterized by low bone density that poses a high risk of bone fractures, is associated with aging, diet, and menopause. Despite the various known therapeutic methods for osteoporosis treatment, the development of a new therapeutic agent without side effects in long-term use is required. Cinnamic acid (CA) is a phytochemical found in cinnamon. In this study, we evaluated the effect of CA on osteoporosis and demonstrated its mechanism in MC3T3E1 preosteoblasts and ovariectomized mice. CA treatment induced osteoblast differentiation with elevation of osteogenic markers both in vitro and in vivo. CA treatment ameliorated bone loss resulting in better bone indices, increased gut microbial diversity, and recovered changes in the gut microbial composition induced by ovariectomy. These changes were accompanied by an increase in BMP/TGFβ/Smad signaling. Therefore, CA has the potential to suppress the progress of bone loss via the enhancement of bone density through the regulation of gut microbiota.

Nonalcoholic fatty liver disease (NAFLD) ranges in severity from hepatic steatosis to cirrhosis. Lemon balm and its major constituent, rosmarinic acid (RA), effectively improve the liver injury and obesity; however, their therapeutic effects on nonalcoholic steatohepatitis (NASH) are unknown. In this study, we investigated the effects of RA and a lemon balm extract (LBE) on NAFLD and liver fibrosis and elucidated their mechanisms. Palmitic acid (PA)-exposed HepG2 cells and db/db mice fed a methionine- and choline-deficient (MCD) diet were utilized to exhibit symptoms of human NASH. LBE and RA treatments alleviated the oxidative stress by increasing antioxidant enzymes and modulated lipid metabolism-related gene expression by the activation of adenosine monophosphate-activated protein kinase (AMPK) in vitro and in vivo. LBE and RA treatments inhibited the expression of genes involved in hepatic fibrosis and inflammation in vitro and in vivo. Together, LBE and RA could improve liver damage by non-alcoholic lipid accumulation and may be promising medications to treat NASH.