Below are some PubMed articles on the safety and effectiveness of
grapefruit seed extract.

Antimicrobial activity of grapefruit seed and pulp ethanolic
extract.Cvetnic Z, Vladimir-Knezevic S.
Department of Microbiology, Faculty of Pharmacy and Biochemistry,
University of Zagreb, Croatia.

Antibacterial and antifungal activity of ethanolic extract of
grapefruit (Citrus paradisi Macf., Rutaceae) seed and pulp was examined
against 20 bacterial and 10 yeast strains. The level of antimicrobial
effects was established using an in vitro agar assay and standard broth
dilution susceptibility test. The contents of 3.92% of total
polyphenols and 0.11% of flavonoids were determined spectrometrically
in crude ethanolic extract. The presence of flavanones naringin and
hesperidin in the extract was confirmed by TLC analysis. Ethanolic
extract exibited the strongest antimicrobial effect against Salmonella
enteritidis (MIC 2.06%, m/V). Other tested bacteria and yeasts were
sensitive to extract concentrations ranging from 4.13% to 16.50% (m/V).

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Krajewska-Kulak E, Lukaszuk C, Niczyporuk W.
Zaklad Teorii Pielegniarstwa Akademii Medycznej w Bialystoku, 15-096
Bialystok, ul. M. C. Sklodowskiej 7a.

Grapefruit seed extract was discovered by Jacob Harich an american
immunologist in 1980. Assessment of the influence of grapefruit extract
on the yeast-like fungi strains--Candida albicans growth. Material used
in this investigation was ATCC test Candida albicans strains no 10231,
200 of Candida albicans strains, 5 of Candida sp. strains isolated from
patients with candidiasis symptoms from different ontocenosis and 12 of
dermatophytes and moulds isolated from patients. The susceptibility of
the Candida was determined by serial dilution method. It seems that 33%
grapefruit extract exert a potent antifungal activity against the yeast
like fungi strains and had low activity against dermatophytes and
moulds. Further studies in vitro and in vivo on greater number of the
yeast-like fungi strains and other fungi species are needed.

PMID: 16886437 [PubMed - indexed for MEDLINE]

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Cvetnic Z, Vladimir-Knezevic S.
Department of Microbiology, Faculty of Pharmacy and Biochemistry,
University of Zagreb, Croatia.

Antibacterial and antifungal activity of ethanolic extract of
grapefruit (Citrus paradisi Macf., Rutaceae) seed and pulp was examined
against 20 bacterial and 10 yeast strains. The level of antimicrobial
effects was established using an in vitro agar assay and standard broth
dilution susceptibility test. The contents of 3.92% of total
polyphenols and 0.11% of flavonoids were determined spectrometrically
in crude ethanolic extract. The presence of flavanones naringin and
hesperidin in the extract was confirmed by TLC analysis. Ethanolic
extract exibited the strongest antimicrobial effect against Salmonella
enteritidis (MIC 2.06%, m/V). Other tested bacteria and yeasts were
sensitive to extract concentrations ranging from 4.13% to 16.50% (m/V).

PMID: 15610620 [PubMed - indexed for MEDLINE]

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Heggers JP, Cottingham J, Gusman J, Reagor L, McCoy L, Carino E, Cox R,
Zhao JG.
Department of Surgery (Plastic), School of Medicine, University of
Texas Medical Branch, Galveston, USA.

OBJECTIVES: Recent testimonials report grapefruit-seed extract, or GSE
(Citricidal) to be effective against more than 800 bacterial and viral
strains, 100 strains of fungus, and a large number of single and
multicelled parasites. This study investigated GSE for antibacterial
activity at varying time intervals and concentration levels and tissue
toxicity at varying concentrations in an effort to determine if a
concentration existed that was both microbicidal and nontoxic and in
what period of time. DESIGN: Gram-negative and gram-positive isolates
were introduced into graduated dilutions of GSE (twofold concentrations
ranging from 1:1, through 1:512) for determination of bacterial
activity. In vitro assays with human skin fibroblast cells were also
performed at the same dilutions to determine toxicity. RESULTS: These
tests indicated that from the 1:1 through the 1:128 concentrations, GSE
remained toxic as well as bactericidal. However, test results indicated
that at the 1:512 dilution, GSE remained bactericidal, but completely
nontoxic. CONCLUSIONS: The initial data shows GSE to have antimicrobial
properties against a wide range of gram-negative and gram-positive
organisms at dilutions found to be safe. With the aid of scanning
transmission electron microscopy (STEM), the mechanism of GSE's
antibacterial activity was revealed. It was evident that GSE disrupts
the bacterial membrane and liberates the cytoplasmic contents within 15
minutes after contact even at more dilute concentrations.

PMID: 12165191 [PubMed - indexed for MEDLINE]

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Reagor L, Gusman J, McCoy L, Carino E, Heggers JP.
School of Medicine, University of Texas, Medical Branch, Galveston,
USA.

OBJECTIVES: Grapefruit-seed extract (GSE) Citricidal has, in recent
reports, been reported to be successful in combating a variety of
common infectious agents. In our study, drops of concentrated
grapefruit-seed extract were tested for antibacterial properties
against a number of gram-positive and gram-negative organisms. DESIGN:
Sixty-seven (67) distinct biotypes were tested for their
susceptibilities to the GSE as well as to 5 other topical
antibacterials (Silvadene, Sulfamylon, Bactroban, Nitrofurazone, and
Silvadene, Nystatin). Wells were punched into Mueller-Hinton agar
plates, which were then inoculated with the organism to be tested; each
well was then inoculated with one of the antibacterial agents. After an
overnight incubation period, the plates were checked for zones of
bacterial susceptibility around the individual wells, with a measured
susceptibility zone diameter of 10 mm or more considered a positive
result. RESULTS: The GSE was consistently antibacterial against all of
the biotypes tested, with susceptibility zone diameters equal to or
greater than 15 mm in each case. CONCLUSIONS: Our preliminary data thus
suggest an antibacterial characteristic to GSE that is comparable to
that of proven topical antibacterials. Although the GSE appeared to
have a somewhat greater inhibitory effect on gram-positive organisms
than on gram-negative organisms, its comparative effectiveness against
a wide range of bacterial biotypes is significant.

PMID: 12165190 [PubMed - indexed for MEDLINE]

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Lopez L, Romero J, Ureta F.
Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chile,
Santiago de Chile.

There is a wide offer of disinfectant products, for the food industry,
available in the market, such as chlorine, iodine and quaternary
ammonium compounds and their respective derivatives. However, new
alternative products have emerged, for instance grapefruit seed
extract, and peracetic and lactic acids. The present study was carried
out in order to analyze in vitro the germicide effect, from the
grapefruit seed extract (400 ppm), peracetic acid (2000 ppm) and lactic
acid (20,000 ppm) at the manufacturer recommended action time, and
other additional times. The germicide effect was tested against
microorganisms such as Escherichia coli, Staphylococcus aureus,
Streptococcus faecalis and Pseudomonas aeruginosa. In each case, the
death kinetic was determined through the evaluation of the germicide
effect (%), specific death rate (t-1) and the decimal reduction time
(min). From the evaluated products, the best germicidal effect at the
manufacturer conditions was reached by peracetic acid (2000 ppm) at 1
min, which presented the lower decimal reduction times compared with
the other tested microorganisms. Generally speaking, Gram positive
microorganisms showed a greater sensibility to the disinfectant action.

PMID: 12214551 [PubMed - indexed for MEDLINE]

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Dembinski A, Warzecha Z, Konturek SJ, Ceranowicz P, Dembinski M, Pawlik
WW, Kusnierz-Cabala B, Naskalski JW.
Department of Physiology, Jagiellonian University Medical School, 16
Grzegorzecka Street, 31-531 Cracow, Poland.

Grapefruit seed extract (GSE) has been shown to exert antibacterial,
antifungal and antioxidant activity possibly due to the presence of
naringenin, the flavonoid with cytoprotective action on the gastric
mucosa. No study so far has been undertaken to determine whether this
GSE is also capable of preventing acute pancreatic damage induced by
ischemia/reperfusion (I/R), which is known to result from reduction of
anti-oxidative capability of pancreatic tissue, and whether its
possible preventive effect involves an antioxidative action of this
biocomponent. In this study carried out on rats with acute hemorrhagic
pancreatitis induced by 30 min partial pancreatic ischemia followed by
6 h of reperfusion, the GSE or vehicle (vegetable glycerin) was applied
intragastrically in gradually increasing amounts (50-500 microl) 30 min
before I/R. Pretreatment with GSE decreased the extent of pancreatitis
with maximal protective effect of GSE at the dose 250 microl. GSE
reduced the pancreatitis-evoked increase in serum lipase and poly-C
specific ribonuclease activity, and attenuated the marked fall in
pancreatic blood flow and pancreatic DNA synthesis. GSE administered
alone increased significantly pancreatic tissue content of lipid
peroxidation products, malondialdehyde and 4-hydroxyalkens, and when
administered before I/R, GSE reduced the pancreatitis-induced lipid
peroxidation. We conclude that GSE exerts protective activity against
I/R-induced pancreatitis probably due to the activation of
antioxidative mechanisms in the pancreas and the improvement of
pancreatic blood flow.

PMID: 15613745 [PubMed - indexed for MEDLINE]

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