Biology Reference
In-Depth Information
ursi
leaves, also lowered the MICs of oxacillin, and the effect of the
combination of corilagin (
8
) and oxacillin on MRSA was bactericidal
(Shimizu
et al
., 2001).
The production of penicillin-binding protein 2a (PBP2a) and drug-
inactivating β-lactamase in the bacteria are regarded as important factors
participating in the antibiotic-resistance mechanism of MRSA. The
hydrolyzable tannins were found to decrease the production of PBP2a, to
inactivate PBP2a and to suppress the β-lactamase activity (Shiota
et al
.,
2004). The macrocyclic ellagitannin dimer oenothein B (
115
), which was
isolated from
Oenothera erythrosepala
(
Onagraceae
) (Hatano
et al
.,
1990c), similarly suppressed the
antibiotic resistance of MRSA (Hatano
et al
., 2006). A survey of the
compounds possessing synergistic
effects with antibiotics against MRSA
and some other bacteria with antibiotic
resistance has revealed that
ellagitannins, condensed tannins, and
some other polyphenolics are effective
agents. The sustainability of the effect
against the antibiotic resistance and the
differences in the mode of action
(bactericidal or bacteriostatic) were
found to be dependent on the
polyphenolic structure. Further research to develop polyphenol-based
candidates for new medicines effective against drug-resistant bacteria or
drug resistance itself is expected.
OH
HO
O
HO
HO
O
OH
O
OH
O
O
OH
O
HO
O
OH
O
O
O
OH
O
HO
OH
OH
O
O
HO
O
OH
OH
O
O
HO
O
O
O
HO
OH
OH
OH
HO
OH
OH
Oenothein B (
115
)
2.4.4 Effects on
Leishmania donovani
In addition to the antibacterial and antifungal activities of ellagitannins,
the antiparasitic effects of various hydrolyzable tannins against the
extracellular promastigotes and intercellular amastigotes of
Leishmania
donovani
were assessed (Kolodziej
et al
., 2001). In an
in vitro
infection
model of leishmaniasis using macrophage-like RAW 264.7 cells infected
