Two new alkaloids from Pachysandra terminalis and their antibacterial activity assessment

Abstract

• One alkaloid with a novel skeleton and one new pregnane-type alkaloid were isolated and identified. • All of the compounds were evaluated for their antibacterial activities. • Compound 2 could be considered as bactericidal to multidrug-resistant strains (MRSE, MRSA and LAC). Phytochemical investigation of a 90 % ethanol extract of Pachysandra terminalis Sieb. Et Zucc led to the isolation of a novel alkaloid, terminamine T ( 1 ); a new pregnane-type alkaloid, terminamine U ( 2 ); and four known pregnane-type alkaloids ( 3 - 6 ). The structures of these compounds were elucidated on the basis of nuclear magnetic resonance spectra, mass spectrometry data, single-crystal X-ray diffraction, and by a comparison with data from the literature. All compounds were evaluated for their antibacterial activities against gram-positive ( S. aureus, ATCC 29213) and gram-negative ( E. coli , ATCC 25922) bacteria. Compounds 2 - 6 exhibited generally modest to poor antibiotic properties. Furthermore, compound 2 showed antibacterial activity against methicillin-resistant Staphylococcus epidermidis (MRSE), methicillin-resistant Staphylococcus aureus (MRSA), and methicillin-resistant Staphylococcus aureus USA300 (LAC) with a minimal inhibitory concentration (MIC) value of 32 μg/mL (75 μM) and minimum bactericidal concentration (MBC) values of 64, 128, and 128 μg/mL (150, 300, and 300 μM), respectively.