Antimicrobial Activity of Mahonia aquifolium Crude Extract and its Major Isolated Alkaloids

The genus Mahonia comprises several species, of which Mahonia aquifolium (Pursh) Nutt. has long been used in traditional medicine for various skin conditions, and berberine, the main alkaloid of this bush, is used in Asian medicine as a drug due to its antimicrobial activity (Kim et al., 2002). Berberine seems to be active against a number of pathogenic and potentially pathogenic microorganisms, including bacteria, fungi, protozoa and viruses, as indicated by several in vitro studies (Kaneda et al., 1998; Lampert and Shaffner, 1995). As to the molecular basis of the biological activity of isoquinoline alkaloids, berberine has been reported to be able to interact with DNA by intercalation with AT base pair preferences (Iwasa et al., 2001). This binding affinity may cause inhibition of replicational and/or transcriptional activity of the target cells. Moreover, the crude extract of plants containing berberine and other protoberberines was found to display differential inhibitory effects on both sterol and cell wall chitin biosynthesis in Candida albicans (Park et al., 1999). In previous studies of the stem bark of M. aquifolium the inhibitory effect of the crude extract and the isolated protoberberine alkaloids – berberine, palmatine and jatrorrhizine – on a variety of dermatophytes and two Candida species of human origin have been detected (Volleková et al., 2003).

The present communication reports on the in vitro study of the antimicrobial activity of berberine and jatrorrhizine (Fig. 1) and a crude extract from the stem bark of Mahonia aquifolium against 20 strains of coagulase-negative staphylococci (14 strains of S. epidermidis, three strains of S. hominis, one strain of S. warneri, S. lentus and S. hyicus), 20 strains of Propionibacterium acnes, and 20 strains of Candida sp. (17 strains of C. albicans, two strains of C. glabrata and one strain of C. tropicalis).