IJT - CIR - February 2024 - 18S

18S
International Journal of Toxicology 43(Supplement 1)
addition of purified water-soluble fractions from defatted
Humulus lupulus (hops) extract to the culture medium reduced
the estrogen E2 released from the ovarian cells with a probably
related decrease in cyclic adenosine monophosphate (cAMP)
release.49
A Humulus lupulus (hops) extract activated the estrogen
response element (ERE) in Ishikawa cells and induced EREluciferase
expression in MCF-7 cells. In the MCF-7 cell line,
progesterone receptor (PR) mRNA was significantly upregulated
by Humulus lupulus (hops) extract with an EC50 of
1.1 μg/mL.93 Humulus lupulus (hops) consisted of a chloroform
partition of a methanolic extract from a previously
SFE-CO2-extracted Nugget Humulus lupulus (hops) cultivar;
the individual constituents included prenylated flavanones and
isoflavonoids. The estrogenic activity proved to be considerably
greater than that of established phytoestrogens such as
coumestrol (present in red clover) and genistein and daidzein
(present in soy).
Dermal Irritation and Sensitization Studies
Irritation
Human
Humulus Lupulus (Hops) Extract. In a 2-week cumulative
irritation test (n = 26) of a formulation containing Humulus
Lupulus (Hops) Extract (.125%), the test formulation did not
demonstrate a significant irritation potential in human
subjects.94
A formulation containing Humulus Lupulus (Hops) Extract
(.6 to 1.2%; 20 µL) was patch tested (n = 12) at 10% (final
concentration .06 to .12%) using 8-mm aluminum cups
covering 50 mm2 skin.95,96 The patches were administered to
the upper back for 24 h. Controls were water and sodium
lauryl sulfate (1%). The test sites were examined 30 min to 1 h
and 24 h after patch removal. One subject had a reaction at the
site of the negative control and was not included in the final
analysis of the results. No reactions to the test material were
observed in 9 subjects; two subjects showed very slight erythema.
The controls had the expected results in the rest ofthe
subjects. The irritation index was .04 (out of 5) and the test
article was rated a non-irritant.
A patch test (n = 12) was conducted on a product mixture
that contained Humulus Lupulus (Hops) Extract (approximately
.18% in caprylic/capric triglyceride).37 The test substance
was applied to the skin on the back under a patch for
48 h. No adverse reactions were observed. It was concluded
that the test substance had good cutaneous compatibility.
Sensitization
Humulus lupulus (hops) extract. In a human maximization test
(n = 26) of a product containing Humulus Lupulus (Hops)
Extract (.125%), the test product did not demonstrate contact
sensitization potential.94 No further information was provided.
Ocular Irritation Studies
In Vitro
Products and product mixtures containing Humulus Lupulus
(Hops) Extract were assayed at up to .5% (Table 13). Humulus
Lupulus (Hops) Extract was predicted to be a slight ocular
irritant in hen's egg test-chorion-allantoic membrane (HETCAM)
and cornea fibroblast (CFIO) assays and a non-irritant
in an EpiOcular assay.95,96,98 Another Humulus Lupulus
(Hops) Extract was predicted to be non-irritating in an HETCAM
assay and to SIRC fibroblastic cells.37
Human
In a 4-week use study (n = 48) ofan eye cream that contained
Humulus Lupulus (Hops) Extract (.125%), the test material
did not demonstrate a potential to cause eye irritation.94
Clinical Studies
Occupational Exposure
Dermal. The causative agents of Humulus lupulus (hops)
plant-induced contact skin reactions have not been
established.99,100 Both irritant and allergic effects have been
described. In Humulus lupulus (hops) harvesters, dermatitis
has been attributed to mechanical abrasion by the rough hairs
on the climbing stem. It has also been suggested that lupulin,
the yellow powdery secretion of the glandular hairs on the
scales of the strobiles, may be responsible for the irritation.
A human repeated insult patch test (HRIPT; n = 52) of
Humulus Lupulus (Hops) Extract (10%; extracted with butylene
glycol) had negative results.36 No further information
was provided.
An HRIPT (n = 102) was conducted of a product mixture
that contained Humulus Lupulus (Hops) Extract (approximately
.18% in caprylic/capric triglyceride).37 The test substance
was applied to the same site three times per week for 9
applications. The challenge was applied two weeks after the
last induction application. All patches were in place for 48 h.
Patch sites were examined for reactions when patches were
removed and at 72 and 96 h. No reactions were observed.
An HRIPT (n = 102) was conducted of a product mixture
that contained Humulus Lupulus (Hops) Extract (approximately
5% in glycerin/water).97 The induction and challenge
phases were conducted at 10% (.5% Humulus Lupulus (Hops)
Extract). Induction and challenge patches were in place for
24 h. The test sites were observed before the application ofthe
next patch and at 24 and 72 h after the application of the
challenge patch. There were no signs of irritation or sensitization
at any time during the test period; there was no indication
of a potential to cause dermal irritation or contact
sensitization.

IJT - CIR - February 2024

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IJT - CIR - February 2024 - Cover3
IJT - CIR - February 2024 - Cover4
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