Berberine, and its salts (e.g. berberine chloride dihydrate, BCD) are yellow crystalline materials that are used in Chinese herbal medicine, and in the United States as dietary supplements. In addition, berberine is a component of goldenseal, another popular herbal dietary supplement. This study was performed as a follow-up research study to a previously conducted developmental toxicity evaluation of berberine chloride dihydrate, administered in the feed to Sprague-Dawley (CD®) rats on gestational days (gd) 6 to 20 (NTP, 2001b). In that study, administration of 14500 ppm BCD in the feed (corresponding to 1000 mg/kg/day BCD) was associated with an apparent palatability problem that rendered BCD intake data inaccurate. Thus, the present study seeks to define the maternal and developmental effects of 1000 mg/kg/day BCD when administered by gavage (a more accurate oral route of exposure) on gd 6 through 19.
In this study, twenty-five timed-mated rats were assigned to the control and BCD-treated groups. Dams were monitored in-life for clinical signs of toxicity, feed and water intake, and body weight. At necropsy (gd 20), the following determinations were made: maternal clinical condition; body, liver, and gravid uterine weights; pregnancy status; and the number of corpora lutea. In the gravid uterus, the numbers of resorbed, dead, and live fetuses were recorded. Live fetuses were weighed, sexed, and examined for external, visceral, and skeletal morphological anomalies. Analysis of the dose formulation indicated that dams were exposed to 1125-1155 mg BCD/kg/day.
No maternal mortality was observed in this study. Yellow discoloration of the feces was noted in the treated group, and was considered to be due to ingestion of the colored test chemical (yellow powder with an orange cast). There were no other remarkable clinical signs related to BCD exposure.
BCD exposure was associated with small, but statistically significant decreases (4%) in maternal body weight on gd 9 and 15. Maternal body weight on gd 20 was equivalent for the two groups. The BCD-treated group gained less weight than the vehicle control group on gd 6 to 9, just after initiation of dosing, but weight gain for the two groups throughout the rest of the study was comparable. Corrected maternal body weight gain was decreased (77% of the control value) in the BCD-treated group compared to the control group.
Maternal liver weight (absolute and relative) was reduced in BCD-treated animals. Gravid uterine weight was not adversely affected.
In the treated group maternal relative feed consumption (g/kg/day) decreased on gd 6 to 9 and 9 to 12, and was significantly decreased for the treatment period (gd 6 to 20) and the gestational period (gd 0 to 20). Maternal relative water intake (g/kg/day) increased during the middle and latter portions of the treatment period (gd 12 to 15, 15 to 18, 18 to 19, and 19 to 20), and was increased for the treatment period (gd 6 to 20), but not for the gestational period (gd 0 to 20).
At scheduled necropsy, pregnancy was confirmed in 25 (100%) control animals and 22 (92%) treated animals. Prenatal mortality was unaffected by treatment, and average live litter size was actually greater in the BCD-treated group compared to control animals. In addition, the incidence of fetal morphological anomalies (external, visceral or skeletal malformations or variations) was unaffected.
In summary, CD® rats were dosed by gavage with BCD (0 or ~1000 mg/kg/day) in 0.5% aqueous methylcellulose from gd 6 through 19. Maternal toxicity was found (decreased corrected maternal body weight gain, decreased feed consumption, and decreased relative maternal liver weight) and was noted at 1000 mg/kg/day, in the absence of any adverse effects on the fetus. Live litter size was increased in the BCD-treated group, and fetal body weight per litter was comparable. The maternal data for this study is consistent with, although less striking than, that observed in the previously conducted feed study (NTP, 2001b). However, the absence of a significant effect of BCD administered by gavage on any measure of developmental toxicity suggests that the effects observed on fetal body weight in the feed study may have been secondary to reduced corrected maternal body weight. Thus, the maternal toxicity LOAEL remains at 531 mg/kg/day BCD or 420 mg/kg/day berberine chloride, as suggested by the feed study. The developmental toxicity NOAEL can be raised from 531 mg BCD/kg/day or 420 mg berberine chloride/kg/day as suggested by the feed study, to approximately 1100 mg/kg/day BCD or 96.5 mg/kg/day berberine chloride, based on the absence of developmental effects in the present study.