Safety evaluation of Parijata (Nyctanthes arbor-tristis L.) flower extract through single- and repeated-dose oral toxicity study in experimental animals

Background: Parijata ( Nyctanthes arbor-tristis L.) is widely used in Ayurvedic medicine for its immunomodulatory, antipyretic, anti-inflammatory, and antifertility properties. However, systematic toxicological data on its hydroalcoholic flower extract are lacking. Objective: The objective of the study is to evaluate the safety profile of hydroalcoholic extract of N. arbor-tristis flowers through single-dose and 28-day repeated-dose oral toxicity studies in experimental animals. Materials and Methods: For the single-dose acute oral toxicity study, 36 Swiss albino mice were administered the hydroalcoholic extract of Parijata flowers orally at doses of 250–2000 mg/kg body weight and observed for 14 days. For the 28-day repeated-dose oral toxicity study, 48 Wistar rats were randomly assigned to four groups and administered the extract orally at 180, 900, or 1800 mg/kg/day for 28 consecutive days, while the control group received 0.2% w/v carboxymethylcellulose as the vehicle. Parameters evaluated included mortality, clinical signs of toxicity, body weight, feed and water consumption, hematological indices, serum biochemical parameters, organ weights, gross pathological, and histopathological examination. Results: No mortality or treatment-related clinical signs were observed at any dose in either species. In the single-dose study, the No Observed Effect Level (NOEL) was established at 2000 mg/kg. In the 28-day study, high-dose male rats exhibited a significant reduction in body weight gain from Week 2 onwards; however, no corresponding histopathological abnormalities were observed. Hematological and serum biochemical parameters showed statistically significant changes in some treated groups; however, all values remained within normal limits and lacked a dose-dependent pattern. Moreover, no treatment-related gross or histopathological abnormalities were observed in any organ or tissue. Conclusion: The No Observed Adverse Effect Level (NOAEL) was established at 1800 mg/kg/day and the NOEL at 900 mg/kg/day following 28 consecutive days of oral administration. The findings demonstrated a favorable safety profile of Parijata flower extract and support its further investigation for therapeutic potential.