13-Methylberberine (13-MB) (chloride) is a 13-methyl-substituted derivative of berberine . Berberine is a widely distributed berberidaceaen alkaloid found in plant tissues that has antibacterial, anti-inflammatory, antitumor, anti-obesity, and hypercholesterolemic activity. 13-MB has improved antibacterial activity against S. aureus (MIC = 125 μg/ml) and improved antitumor activity with a mean GI50 value of 11.7 μM, as compared to berberine. 13-MB also induces down-regulation of adipocyte differentiation transcription factors, reduces de novo lipid synthesis, and accumulates in murine 3T3-L1 adipocytes at higher levels than berberine, suggesting improved anti-obesity activity.