Comparative evaluation of classical and modified Tamra Bhasma: Acute oral toxicity, antimicrobial, and antioxidant profiles

Abstract

Background

Tamra Bhasma, a traditional Ayurvedic copper-based formulation, has been used for its antimicrobial and therapeutic benefits. However, its complex preparation and the risk of toxicity when not made according to classical methods have limited its broader clinical use. Recent efforts aim to simplify its preparation and scientifically validate its safety and efficacy.

Objective

The present study aimed to evaluate and compare the acute oral toxicity of two Tamra Bhasma preparations viz. Classical Tamra Bhasma I (CTB I) and a chemically processed form (CTB II) in comparison with synthetic copper oxides (A-CuO and S-CuO). The antimicrobial and antioxidant profiles are also compared between CTB I and CTB II.

Materials and methods

CTB I and CTB II were prepared using standard Ayurvedic protocols with different raw materials. Acute oral toxicity was tested in female rats using OECD guideline 425 at a limit dose of 2000 mg/kg, followed by a two-week observation period. Hematological, biochemical, and histopathological analyses were performed. Antimicrobial activity was assessed against Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae using the disk diffusion method. Antioxidant activity was measured by DPPH radical scavenging assay.

Results

No mortality, behavioral abnormalities, or significant weight changes were observed at the test dose. Hematological and biochemical parameters remained within normal ranges. Histopathological findings showed mild liver congestion in the CTB I group and increased sinusoidal space in the S-CuO group, with normal architecture in other organs. CTB I exhibited stronger antibacterial activity against Gram-positive bacteria, whereas CTB II was more effective against Gram-negative strains. CTB I also showed higher antioxidant activity than CTB II, though less potent than ascorbic acid.

Conclusion

CTB I and CTB II have LD₅₀ more than 2000 mg/kg and demonstrate differing antimicrobial and antioxidant effects depending on preparation methods. These results support further investigation into their therapeutic mechanisms and potential applications.