PMID- 20209160
OWN - NLM
STAT- In-Process
DA  - 20100308 
IS  - 1932-6203 (Electronic)
VI  - 5
IP  - 3
DP  - 2010
TI  - pH-Dependent metal ion toxicity influences the antibacterial activity of two
      natural mineral mixtures.
PG  - e9456
AB  - BACKGROUND: Recent studies have demonstrated that several mineral products sold
      for medicinal purposes demonstrate antimicrobial activity, but little is known
      about the physicochemical properties involved in antibacterial activity.
      METHODOLOGY/PRINCIPAL FINDINGS: Using in vitro mineral suspension testing, we
      have identified two natural mineral mixtures, arbitrarily designated BY07 and
      CB07, with antibacterial activity against a broad-spectrum of bacterial
      pathogens. Mineral-derived aqueous leachates also exhibited antibacterial
      activity, revealing that chemical, not physical, mineral characteristics were
      responsible for the observed activity. The chemical properties essential for
      bactericidal activity against Escherichia coli were probed by testing
      antibacterial activity in the presence of metal chelators, the hydroxyl radical
      scavenger, thiourea, and varying pH levels. Chelation of the BY07 minerals with
      EDTA or desferrioxamine eliminated or reduced BY07 toxicity, respectively,
      suggesting a role of an acid-soluble metal species, particularly Fe(3+) or other
      sequestered metal cations, in mineral toxicity. This conclusion was supported by
      NMR relaxation data, which indicated that BY07 and CB07 leachates contained
      higher concentrations of chemically accessible metal ions than leachates from
      non-bactericidal mineral samples. CONCLUSIONS/SIGNIFICANCE: We conclude that the
      acidic environment of the hydrated minerals significantly contributes to
      antibacterial activity by increasing the availability and toxicity of metal
      ions. These findings provide impetus for further investigation of the
      physiological effects of mineral products and their applications in
      complementary antibacterial therapies.
AD  - School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America.
FAU - Cunningham Tanya M 
AU  - Cunningham TM 
FAU - Koehl Jennifer L 
AU  - Koehl JL 
FAU - Summers Jack S 
AU  - Summers JS 
FAU - Haydel Shelley E
AU  - Haydel SE
LA  - eng
GR  - AT003618 / AT / NCCAM NIH HHS / United States
GR  - AT004690 / AT / NCCAM NIH HHS / United States
GR  - Howard Hughes Medical Institute / United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
DEP - 20100301
PL  - United States
TA  - PLoS One
JT  - PloS one
JID - 101285081
SB  - IM
PMC - PMC2830476
OID - NLM:PMC2830476
EDAT- 2010/03/09 06:00
MHDA- 2010/03/09 06:00
CRDT- 2010/03/09 06:00
PHST- 2009/11/02 00:00[received]
PHST- 2010/02/02 00:00[accepted]
PHST- 2010/03/01 00:00[epublish]
AID - 10.1371/journal.pone.0009456[doi]
PST - epublish
SO  - PLoS ONE. 2010 ; 5(3):e9456.