Dammarane and Apotirucallane Triterpenoids from the Stem Bark of Melia Toosendan and Their Antibacterial Activities

Abstract

Eight previously undescribed triterpenoids, including four dammarane-type triterpenoids, named meliasenans A−D ( 1 − 4 ), four apotirucallane-type triterpenoids, named meliasenans E−H ( 5 − 8 ), along with nine known analogues ( 9 − 17 ) have been isolated from the stem bark of Melia toosendan . The structures of the new compounds were elucidated by IR, HRESIMS, 1D, 2D NMR, as well as electronic circular dichroism (ECD) analyses. The results of bioassay showed that the new compounds 7 and 8 exhibited potential antibacterial effect on Pseudomonas solanacearum and Bacillus gasoformans, with MIC values of 117.2 µg·mL -1 and 118 µg·mL -1 , respectively. Moreover, 8 and 11 showed apparent antibacterial activities against Bacillus subtilis (ATCC 6051) with MIC values of 118 µg·mL -1 and 92.1µg·mL -1 , respectively.

Keywords: Melia toosendan, dammarane, apotirucallane, triterpenoids, antibacterial activity