Berberine and its more biologically available derivative, dihydroberberine, inhibit mitochondrial respiratory complex I: a mechanism for the action of berberine to activate AMP-activated protein kinase and improve insulin action - Turner, N; Li, J Y; Gosby, A; To, S W; Cheng, Z; Miyoshi, H; Taketo, M M; Cooney, G J; Kraegen, E W; James, D E; Hu, L H; Li, J; Ye, J M (Diabetes, 2008)