Abstract:

This study aims to investigate the secondary metabolites produced by the endophytic fungus Alternaria brassicae isolated from Salvia miltiorrhiza. Twenty-four compounds were isolated from solid fermentation products of A. brassicae by silica gel column chromatography, gel chromatography and preparative high performance liquid chromatography, and their structures were identified as 5-methoxy-6′-methyl-biphenyl-3,3′,4′-triol (1), altenusin (2), 2,5-dimethyl-7-hydroxychromone (3), altechromone A (4), 2-(9-hydroxypropyl)-5-methyl-7-hydroxychromone (5), 4′-epi-dihydroaltenuene A (6), dihydroaltenuene B (7), (+)-(4′R,5′S,7′R)-altenuene (8), 4′-epialtenuene (9), methyl nortricycloalternarate (10), tricycloalternarene L (11), cyclo-(D-Leu-L-Trp) (12), cyclo(L-Leu-L-Phe) (13), cyclo(L-Phe-L-Val) (14), cyclo(L-Phe-L-Pro) (15), perlolyrine (16), flazin (17), 3-acetyl-5-isopropylpyrrolidine-2,4-clion (18), L-tenuazonic acid (19), D-allo-tenuazonic acid (20), S-N-acetyl phenyl (21), phenethyl-8-O-β-D-(6′-O-acetyl)-glucoside (22), α-acetylorcinol (23), phenyllactic acid (24) by MS and NMR methods. Among these, compounds 1-9 are polyketide derivatives, compounds 10 and 11 are mixed-source terpenoids, compounds 12-15 are cyclic dipeptides, compounds 16-20 are alkaloids, and compounds 22-24 are benzene ring derivatives. All compounds were isolated from Alternaria brassicae for the first time, and compounds 22 and 23 were isolated from Alternaria fungi for the first time. In vitro anti-inflammatory activity tests showed that compounds 1, 2, and 19 significantly inhibited the production of NO in lipopolysaccharide -induced RAW 264.7 cells with IC₅₀ values of 19.19 ± 0.37, 28.72 ± 1.02 and 22.55 ± 1.75 μmol/L, respectively.

Key words:

Salvia miltiorrhiza, endophytic fungi, Alternaria brassicae, secondary metabolites, anti-inflammatory activity