Our earlier, preliminary work (Neto et al., 2002) had identified
P. galioides as inhibiting the growth of S. aureus and
S. epidermidis. Using the microplate bioassay we found that
a crude methanolic extract of P. galioides inhibited growth
of both bacteria completely at concentrations of less than
1 mg/mL. Fractionation of this extract produced fractions
containing grifolic acid, which inhibited both S. aureus and S.
epidermidis at 31g/mL and a fraction containing grifolin,
which was specific for S. epidermidis. Grifolin and grifolic
acid were previously isolated fromP. galioides(Mahiou et al.,
1995), however, this is their first identification as the antibacterial
principles in this species. Grifolin isolated from Grifola
confluens was reported active against S. aureus (Hirata and
Nakanishi, 1950) and grifolic acid from Albatrellus cristatus
was reported active against Bacillus subtilis (Zechlin et al.,
1981).