D-2-hydroxy-2-phenylacetic acid

Toxicity to reproduction: other studies

Administrative data

Endpoint:

toxicity to reproduction: other studies

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

Read across to DL-mandelic acid (90-64-2)

Adequacy of study:

other information

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Unsuitable route of exposure (rabbit study); sperm motility was examined in vitro only.

Justification for type of information:

see chapter 13 read across justification

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2020

Materials and methods

Test guideline

Qualifier:

no guideline available

GLP compliance:

not specified

Test material

Test material information

1

Reference substance name:

Mandelic acid

EC Number:

202-007-6

EC Name:

Mandelic acid

Cas Number:

90-64-2

Molecular formula:

C8H8O3

IUPAC Name:

hydroxy(phenyl)acetic acid

Test material form:

not specified

Test animals

Species:

rabbit

Strain:

not specified

Sex:

female

Administration / exposure

Route of administration:

other: rabbit vaginal epithelium

Duration of test:

All animal experiments described in this paper were approved by the animal use and welfare committees of the Shanghai Institute of Planned Parenthood Research. In the present study, sexually mature female rabbits were used. Forty rabbits were randomly assigned to five groups (n = 8). The vehicle control group received the vehicle only (a drug-free thermal gel), and three treatment groups received MA gel at 10, 20 and 40 mg/mL, respectively, and the N-9 control group received N-9 gel at 40 mg/mL

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

10 other: mg/ml

Doses / concentrations 2

Dose / conc.:

20 other: mg/ml

Doses / concentrations 3

Dose / conc.:

40 other: mg/ml

No. of animals per sex per dose:

Forty rabbits were randomly assigned to five groups (n = 8)

Control animals:

yes

Details on study design:

RVI Test:
The treatment groups received the MA gel, or N-9 gel, whereas the control group received the vehicle only. Gels were continuously administered to rabbits vaginally once per day for 7 days. Rabbits were sacrificed at the 24 h mark after the last administration, and the vaginal tissue was fixed in 10 % formaldehyde in PBS at room temperature for 24 h, dehydrated in graded series of ethanol, and then embedded in paraffin. Sections were stained with hematoxylin-eosin and observed under a light microscope (Nikon 80i, Japan). Histological assessments were performed according to the Eckstein Irritation Score. The basic criteria of the semi-quantitative scoring system include epithelial injury, leukocyte infiltration, vessel congestion and interstitial edema, and each is evaluated using a 5-point score, ranging from 0 to 4, compared with the control group. A total score of between 0 and 8 is considered acceptable, and one of 11 or over is considered unacceptable.

Statistics:

Data were shown as mean ± standard deviation of three independent experiments. Data were analyzed by one-way analysis of variance (ANOVA), followed by a t-test, and p values < 0.05 were considered as statistically significant.

Applicant's summary and conclusion

Executive summary:

DL-Mandelic acid (MA), an alpha-hydroxycarboxylic acid, has been widely used as an intermediate of pharmaceutical and fine chemicals. Here, we evaluated the sperm-immobilizing activity of MA and its safety profiles. Spermatozoon motility was assessed by computer-aided sperm analysis, the integrity of the plasma membrane and mitochondrial potential was assessed using fluorescein isothiocyanate-pisum sativum agglutinin and JC-1, respectively. The local tolerance of the MA-containing gel formulation was evaluated using a rabbit vaginal irritation test. We found that MA inhibited sperm motility and movement patterns in a concentration-dependent manner. Within 20 s, MA-induced spermatozoa immobilization occurred with a minimum effective concentration and a median effective concentration of 0.86 and 0.54 mg/mL, respectively. Plasma membrane disruptions of MA-treated spermatozoa were relatively mild, but mitochondrial depolarization occurred. Histopathological examination showed that MA exposure did not exert obvious effects on the integrity of spermatozoa membrane structures and only caused slight irritation to the rabbit vaginal epithelium. The vaginal irritation scores of the vehicle control and the nonoxynol −9 gel control groups were 1.38 ± 0.65 and 7.88 ± 1.67, respectively (p < 0.01), whereas those of the MA gel groups at 10, 20, and 40 mg/mL were 1.69 ± 1.04, 2.98 ± 0.77, and 4.35 ± 1.04 with p values of > 0.05, > 0.05, and < 0.05 (vs. vehicle control), respectively, which were within the clinically acceptable range (< 8). Therefore, our results confirmed that MA exhibited significant spermimmobilizing effects and caused mild plasma membrane injury, suggesting that it has potential for development as a future non-surfactant spermicide.