Objective To investigate the chemical constituents of Mallotus repandus. Methods The compounds were separated and purified using a variety of chromatographic techniques, including silica gel and ODS column chromatography, as well as semi-preparative HPLC. Their structures were established by NMR and mass spectroscopy analysis. The antimicrobial activities of these isolates were evaluated by the broth microdilution method. Results Twenty-nine compounds were obtained from the dichloromethane extract of the twigs and leaves of M. repandus and identified as 3-O-cis-caffeoyl betulinic acid (1) , ergosta-4,6,8(14),22-tetraen-3-one (2), β-sitostenone (3), 5,8-epidioxyergosta-6,9(11),22-trien-3-ol (4), N(N'-benzoyl-S^*-phenylalaninyl)-S^*-phenylalaninolbenzoate (5), aurantiamide acetate (6), isoechinulin A (7), 6-geranylnaringenin (8), questin (9), 1,3,8-trihydroxy-6-methyl-9,10-anthracenedione (10), flavoglaucin (11), isodihydroauroglaucin (12), isoaspergin (13), 5'-cis-isotetrahydroauroglaucin (14), (E)-6-hydroxy-7-(3-methyl-2-butenyl)-2-(3-oxobut-1-enyl)chroman-5-carbaldehyde (15), camellia chlorophyllide Ⅱ (16), 13²(R)-hydroxypheophorbide-a ethyl ester (17), ethyl pheophorbide a (18), ligulariaphytin A (19), (−)-α-tocospirone (20), α-tocospiro B (21), δ-tocopherol (22), α-tocopherolquinone (23), 5-methoxypinosylvin (24), dehydroabietic acid (25), (5E,7E)-9-oxooctadeca-5,7-dienoicacid (26), (10E,12E)-ethyl-9-oxo-octadeca-10,12-dienoate (27), (10E,12Z)-9-hydroxy-10,12-octadecadienoic acid (28) and palmitic acid (29), respectively. Compound 13 has a minimum inhibitory concentration (MIC) of 128 μg/mL against Enterococcus faecalis, 16 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA), and 4 μg/mL against Cryptococcus neoformans. Compound 15 has an MIC of 128 μg/mL against E. faecalis, 64 μg/mL against MRSA, and 8 μg/mL against C. neoformans.Conclusion Compounds 2, 4, 8, 9, 11—19, and 24—28 were reported from Euphorbiaceae plants for the first time, compounds 1, 3, 5, 7, 20, 21, and 23 were reported from the genus Mallotus for the first time, and compounds 6, 10, and 22 were reported from M. repandus for the first time. Compounds 13 and 15 have notable inhibitory effects on E. faecalis, MRSA, and C. neoformans.

Mallotus repandus (Willd.) Müll.Arg.  /  Euphorbiaceae  /  antimicrobial activities  /  ergosta-4,6,8(14),22-tetraen-3-one  /  aurantiamide acetate  /  bonannione A  /  questin  /  isoaspergin