Assessment of acute, 14-day, and 13-week repeated oral dose toxicity of Tiglium seed extract in rats.

BACKGROUND: Seed of mature Croton tiglium Linne, also known as Tiglium seed (TS), has been widely used as a natural product due to its several health beneficial properties including anti-tumor and antifungal activities. Despite its ethnomedicinal beneficial properties, toxicological information regarding TS extract, especially its long-term toxicity, is currently limited. Therefore, the objective of the present study was to evaluate acute and subchronic toxicity of TS extract in rats after oral administration following test guidelines of the Organization for Economic Cooperation and Development (OECD). METHODS: Toxicological properties of TS extract were evaluated by toxicity assays to determine its single-dose acute toxicity (125, 250, 500, 1000, or 2000 mg/kg), 14-day repeated-dose toxicity (125, 250, 500, 1000, or 2000 mg/kg) and 13-week repeated-dose toxicity (31.25, 62.5, 125, 250, and 500 mg/kg) in Sprague-Dawley rats and F344 rats. Hematological, serum biochemical, and histopathological parameters were analyzed to determine its median lethal dose (LD50) and no-observed-adverse-effect-level (NOAEL). RESULTS: Oral single dose up to 2000 mg/kg of TS extract resulted in no mortalities or abnormal clinical signs. In 13-week toxicity study, TS extract exhibited no dose-related changes (mortality, body weight, food/water consumption, hematology, clinical biochemistry, organ weight, or histopathology) at dose up to 500 mg/kg, the highest dosage level suggested based on 14-day repeat-dose oral toxicity study. CONCLUSION: Acute oral LD50 of TS extract in rats was estimated to be greater than 2000 mg/kg. NOAEL of TS extract administered orally was determined to be 500 mg/kg/day in both male and female rats. Results from these acute and subchronic toxicity assessments of TS extract under Good Laboratory Practice regulations indicate that TS extract appears to be safe for human consumption.

Mutagenicity and tumor-promoting effects of Tiglium seed extract via PKC and MAPK signaling pathways.

Tiglium seed is a seed of mature Croton Tiglium Linne containing croton oils, which have been traditionally used as laxative or purgative. As it contains phorbol derivatives, we investigated the mutagenicity and tumor-promoting activity of Tiglium seed. Tiglium seed extract produced the mutagenic responses in five Salmonella typhimurium strains in Ames assay, whereas it did not alter the frequencies of chromosomal aberrations or micronuclei, indicating that it exerted the mutagenic potential, not clastogenicity. Accompanied with phosphorylation of connexin43 (Cx43) and extracellular signal-regulated kinases 1/2 (ERK1/2), Tiglium seed extract inhibited gap junctional intercellular communication (GJIC) associated with tumor-promoting potential. Importantly, these effects were blocked by a protein kinase C (PKC) inhibitor or mitogen-activated protein kinase (MAPKs) inhibitors, suggesting that Tiglium seed-induced GJIC inhibition was regulated by phosphorylation of Cx43 via PKC and MAPKs signaling. In conclusion, Tiglium seed has mutagenicity, possibly linking to tumor-promoting potential through the dysfunction of GJIC.