Acute and sub-acute toxicity studies of roselle leaves

Roselle leaves are widely used in traditional medicine but have not previously been
studied for their safety through standard in vivo toxicity studies. This study aimed to
evaluate the safety of roselle leaves extract through acute and sub-acute oral toxicity
studies in Sprague Dawley (SD) rats. An acute toxicity study was carried out using a
single high dose of roselle leaves extract at 3000 mg/kg and toxic signs were observed
within 14 days. While sub-acute toxicological study was carried out using 28-days
repeated doses of 0 mg/kg (control), 1000 mg/kg, 2000 mg/kg, and 5000 mg/kg of roselle
leaves extract. Bodyweight changes were recorded throughout the experimental period.
On day 29, blood was withdrawn and analysed for haematology and clinical biochemistry
values. During the 14-day acute toxicity study, there were no significant changes in body
weight increment, adverse clinical signs and mortality. In the sub-acute toxicity study,
there were also no toxicology significant changes in haematology and clinical
biochemistry except a slight decrease in triglyceride (TG) and glucose level (p < 0.05)
which is attributed to roselle leaves aqueous extract administration. However, the results
were within the normal reference range of SD rats. Therefore, the acute and sub-acute
toxicity studies in SD rats showed that roselle leaves aqueous extract is non-toxic and
could be classified as a no-observed-adverse-effect level (NOAEL).