Potent Anti-Inflammatory and Antiadipogenic Properties of Bamboo (Sasa coreana Nakai) Leaves Extract and Its Major Constituent Flavonoids

The pro-inflammatory response and recruitment of macrophages into adipose tissue contribute to metabolic dysfunction. Here, we reported the anti-inflammatory and antiadipogenic effects of the methanol (MeOH) extract and ethyl acetate (EtOAc) fraction of bamboo leaf and its molecular mechanism in RAW264.7 cells and 3T3-L1 adipocytes, respectively. Functional macrophage migration assays also were performed. Surprisingly, the EtOAc fraction of MeOH extracts from native Korean plant species Sasa coreana Nakai (SCN) has shown potent anti-inflammatory properties; SCN pretreatment inhibited nitric oxide (NO) production (p < 0.01) and inducible nitric oxide synthase (iNOS) expression in lipopolysaccharide (LPS)-stimulated macrophages. Inflammatory genes induced by LPS, including TNFα, IL-1β, and IL-6, were significantly attenuated by SCN (p < 0.01). Pretreatment with SCN antagonized NF-κB nuclear translocation and the simultaneous degradation of inhibitory κB protein. Furthermore, SCN selectively inhibited the LPS-induced phosphorylation of JNK (p < 0.01) and p38 (p < 0.05) but not ERK (p > 0.05). Similar to leaf extracts of other bamboo species, we identified that SCN contained several flavonoids including orientin, isoorientin, and vitexin; these compounds inhibited LPS-induced NO production (p < 0.05) and iNOS expression. In addition, SCN inhibited adipocyte differentiation in a dose-dependent manner, as demonstrated by Oil Red O staining and the protein expression of mature adipogenic marker genes. Treatment with the major flavonoids of SCN also inhibited adipogenesis. Furthermore, conditioned medium obtained from adipocytes stimulated macrophage chemotaxis, whereas medium from adipocytes treated with SCN significantly inhibited macrophage migration. Therefore, SCN is a potential therapeutic agent for the prevention of inflammation and obesity.