A New Dimeric Carbazole Alkaloid from Murraya Koenigii (L.) Leaves with Α-Amylase and Α-Glucosidase Inhibitory Activities

A new dimeric carbazole alkaloid, 3,3 ',5,5 ',8-pentamethyl-3,3 '-bis(4-methylpent-3-en-1-yl)-3,3 ',11,11 '-tetrahy-dro-10,10 '-bipyrano[3,2-a]carbazole, was isolated from the hexane extract of leaves of Murraya koenigii (L.) Sprengel. (Family: Rutaceae). The structure was elucidated based on 13C and 1H NMR, High-Resolution Mass Spectrometry (HRMS), and 2D NMR data. The in vitro antidiabetic activity of the new dimer was investigated in terms of alpha-amylase and alpha-glucosidase enzyme inhibition assays. The dimer exhibited significant alpha-amylase inhibitory activity (IC50 = 30.32 +/- 0.34 ppm) and alpha-glucosidase inhibitory activity (IC50 = 30.91 +/- 0.36 ppm).