A toxicological investigation of a celery seed extract having anti-inflammatory activity

An extract of the seed from celery (Apium graviolens) (CSE), and fractions thereof, have been found to possess anti-inflammatory activity, gastro-protective activity, and anti-Helicobacter pylori activity. In view of the potential for employing these extracts for therapeutic use, toxicological investigations were undertaken with an alcoholic extract (A-CSE) which has previously been shown to have the above pharmacological activities.

A 28-day toxicity study was performed in rats according to Good Laboratory Practice (GLP) conditions. Eighteen adult male and 18 adult female rats were randomly assigned to 3 treatment groups of 6 rats/sex/group and were dosed orally with A-CSE of 0, 150 or 5,000 mg/kg per day. Daily observations of vital signs and body weights were recorded and ophthalmological investigations were performed. At autopsy, the principal organs were weighed and sections collected for histological analysis. Serum and urine samples were collected at termination for routine clinical chemistry. Under non-GLP conditions alpha-2-μ-globulin immunohistochemistry was performed on kidney tissues and hepatic cytochrome P450 protein was determined, as well as, the enzymatic activities of the principal isoforms.

All animals survived treatments with no visible or behavioral signs of toxicity being observed during the study. There were no statistically significant differences in body weight gains, body weight gains per day or cumulative absolute body weight gains, for either sex, in any treatment groups when compared with controls. Slightly increased liver weight and liver to body and brain weight ratios were observed in female rats and in liver to body weight ratios in male rats given high dose A-CSE which was a test article effect, but the absence of any microscopic correlates for the liver weight increases suggests that these were not toxicologically significant. Treatment related macroscopic changes were not observed at necropsy and microscopic findings were limited to minimal increases in gastric eosinophils in several male and female rats in the 5,000 mg/kg per day treatment groups. Minimal focal degeneration of renal tubules was observed sporadically in both sexes assigned to all treatment groups including control and was consistent with early spontaneous nephropathy of laboratory rats and thus was not considered to represent a pathologic change associated with the test article. Increased serum globulin and phosphorus levels were observed in male rats given 5,000 mg/kg per day A-CSE and decreased serum triglycerides levels in female animals given 150 or 5,000 mg/kg per day A-CSE. The increase in serum globulin and phosphorus in male animals was small in magnitude and not considered toxicologically significant. The mechanism for the decrease in serum triglycerides in female rats was not apparent. Changes in urinalysis parameters were limited to small decreases in urine pH in female animals in the 150 and 5,000 mg/kg per day groups and were not deemed toxicologically significant. Alpha-2-μ-globulin immunohistochemistry was performed on kidney tissues from all animals and found to be within normal physiologic limits. Minor corneal mineralization occurred in some animals from all treatment groups. Cataracts were observed in one in the control and one in an animal that had 5,000 mg/kg per day but since the cataracts occurred in the metabolically inactive region of the lens, these were not considered indicative of test article related lesions. There were no changes in total hepatic microsomal protein or in total cytochrome P450 protein. Although male rats appeared to have to higher levels of total microsomal protein than female rats, there appeared to be no treatment effect in either male or female animals. As regards the activity of the various isoforms tested (CYP2B1/2, CYP1A1/2, CYP3A1/2), with the large range of activities detected for each P450 isoform, no clear change in activity or protein were observed, however, these data were not statistically analyzed.

These results suggest that there are no toxicologically significant sub-chronic effects of oral A-CSE in rats. The no adverse effect level for systemic toxicity would appear to be 5,000 mg/kg per day.