Acute and sub-chronic toxicity of HPLC fingerprinted extract of Conyza sumatrensis (Retz.) E.H. Walker in rodents.

BACKGROUND

Conyza sumatrensis (CS) is an extensively used medicinal herb in the tropics for varied ailments related to pain, inflammation and malaria. Though in constant folkloric use, scientific validations are proving valuable.

OBJECTIVE

Evaluate the safety profile of methanol extract from CS in mice and rats through acute and sub-chronic toxicity studies respectively.

METHODS

Acute toxicity study involved the single oral administration of CS at 1000, 2000 and 3000mg/kg in mice, while the sub chronic toxicity was carried upon in rats at doses 250, 500 and 1000mg/kg/day for 28 days. Besides body weight, general behaviour and mortality, serum biochemical parameters and liver histology were assessed after 7 and 28 days for acute and sub-chronic study respectively. The parameters were again checked on days 14 and 56 in order to assess the recovery from damage, if any. HPLC fingerprinting of the aqueous and methanol extract was performed through C18 column using water: acetonitrile as mobile phase with observations at 240nm.

RESULTS

In the acute toxicity test, single oral dose of 1000, 2000 and 3000mg/kg of CS did not result in any behavioural changes or mortality, indicating non toxicity. In sub-chronic toxicity studies in rats, no mortality was observed at 250, 500 and 1000mg/kg/day when administered orally for a period of 28 days. Except Serum Glutamate Pyruvate Transaminase (SGPT) level in acute study and Alkaline Phosphatase (ALP), SGPT and Serum Glutamate Oxaloacetate Transaminase (SGOT) level in sub-chronic study, all the observational, haematological and biochemical parameters studied showed non-significant changes. Histological examination of liver did not reveal any treatment-related effects in any of the studies. Moreover, haematological and biochemical changes orchestrated by CS got normalised after 14 and 56 days post-treatment in acute and sub-chronic toxicity respectively. The HPLC fingerprint could resolve 11 and 28 peaks from aqueous and methanol extracts respectively.

CONCLUSIONS

The experiments indicate the methanol extract to be safe even at high and repeated doses in pre-clinical studies even though the constituents are more than in aqueous extract.