Alstonia scholaris (L.) R. Br., an evergreen tropical plant rich in
indole alkaloids with significant physiological activity, is traditionally used to treat
respiratory diseases in China. This study was conducted to establish the toxicity profile of the
alkaloid extract (TA) of A. scholaris leaves in non-rodents. After
oral administration of a single dose (4 g/kg.bw), a number of transient symptoms, such as
unsteady gait,
drooling,
emesis, and reddening of peri-oral mucosa, were observed, but no treatment-related mortality. A sub-chronic toxicity study with a range of doses of TA (20, 60 and 120 mg/kg.bw) was conducted for a 13-week treatment period, followed by 4-week recovery observation. Except for
emesis and
drooling in majority of animals in 120 mg/kg.bw treatment group, no clinical changes were observed in TA-treated animals. Data from electrocardiography, bone marrow, urine, fecal, hematology and clinical chemistry analyses were comparable between TA-treated and control animals. No significant differences in the relative organ weights and histopathological characteristics were evident between the TA-treated and control groups. Accordingly, the non-observed-adverse-effect-level (NOAEL) of TA was established as 120 mg/kg.bw. Our results add further knowledge to the safety database for
indole alkaloid extracts from A. scholaris with potential utility as novel
drug candidates.