Acute and Sub-Acute Toxicity Evaluation of Ethanolic Halimeda gracilis Extract (Kadarpassi Chooranam): Advancing Preclinical Safety Data for Marine-Based Therapeutics in Wistar Rats

Abstract

Background:
Marine-derived algae are recognised as a promising source of compounds with medicinal properties and therapeutic potential. However, the limited toxicological data available restrict their translational applications. Halimeda gracilis, a green alga traditionally utilised in Siddha medicine as kadarpassi chooranam, has demonstrated diverse pharmacological activities. This study aimed to evaluate the acute and sub-acute oral toxicity of the ethanolic extract of Halimeda gracilis (Kadarpassi Chooranam) in Wistar rats, providing foundational safety data to support its potential pharmaceutical applications.

Methods:
Acute toxicity was assessed following OECD Test Guideline 423 at a single dose of 2000 mg/kg of Ethanolic Extract of Kadarpassi Chooranam (EEKPC). Sub-acute toxicity (28 days) was evaluated following OECD Guideline 407 using daily doses of 250, 500, and 1000 mg/kg. Hematological, biochemical, gross pathological, and histopathological parameters were evaluated.

Results:
No mortality or treatment-related abnormalities were observed at any dose of EEKPC. The LD50 exceeded 2000 mg/kg, and the NOAEL was 1000 mg/kg/day. All physiological, biochemical, and histopathological findings were within normal limits.

Conclusion:
These findings indicate that the EEKPC is well-tolerated under experimental conditions, supporting its safe use as a potential phytopharmaceutical or nutraceutical ingredient. Further chronic toxicity and mechanistic studies are warranted to confirm its long-term safety.