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Avicennia africana is an important ethnomedicinal plant that has long been used to treat malaria and several other diseases. Despite the plant’s antimalarial and other therapeutic properties, there is limited evidence-based data on its potential toxicity. Hence, the purpose of the current study was to assess the safety of A. africana leaf ethanolic extract (AAE). The study was designed to ascertain the cytotoxic effects of the crude extract on red blood cells (RBCs) as well as the acute and subacute toxicity in Wistar albino rats in accordance with Organization for Economic Co-operation and Development (OECD) guidelines “Test No. 423” and CPMW/SWP/1042/99. The pulverized, shade-dried plant leaves were sequentially macerated with 70% ethanol to obtain the crude extract (AAE). The extract’s cytotoxic activity (CC50) against the uninfected human red blood cells (RBCs) was determined using the 3-(4,5-Dimethylythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. For the acute toxicity studies, the rats (male and female) were divided randomly into six groups of five rats (n = 5) and dosed orally once with the following dose levels: 100, 300, 1000, 3000, and 5000 mgkg−1, p.o. of the extracted AAE, with the control group receiving only the vehicle. In the repeated dose toxicity studies, the rats (both sexes) were orally administered daily with AAE at 100, 300, and 1000 mgkg−1 for 14 days. Rat body weights were measured, and blood samples were tested for haematological and biochemical markers. Internal organs like the heart, kidney, liver, and spleen were collected, inspected, and weighed, and histological examinations were performed. The median lethal dose (LD50) value is greater than 5000 mgkg−1 body weight, with no significant change in bodyweight or relative organ weight (ROWs) of the extract-treated groups or control group. The extract showed greater cytotoxicity activity (CC50), which was >100 μg/mL, compared to the reference drug (artesunate).The dosage groups of 100 and 300 mgkg−1bwt had neutrophilia and lymphocytopenia ( p < 0.05 ). However, changes in these haematological parameters may not be dose dependent and could be stress related. All the serum biochemical markers studied in rats given AAE did not show any significant change ( p > 0.05 ). Histopathological examination of internal organs of AAE-treated rats did not show any significant abnormalities resulting from the extract treatment compared to the control group. Based on the findings in the present study, the LD50 value of AAE was found to exceed 5000 mgkg−1 in the acute toxicity test, while the no observed adverse effect level (NOAEL) in rats was 1000 mgkg−1 p.o. In the sub-acute toxicity tests. Histopathological analysis revealed no morphological abnormalities in the vital organs.

Background. The present study aimed at validating the traditional use and toxicity profile of a methanolic extract of the aerial parts of Psychotria ankasensis in alleviating depression and anxiety disorders. Method. The antidepressant effect of methanolic extract of Psychotria ankasensis (PAE 30, 100, and 300 mg/kg, p.o.) was assessed in mice using the forced swim test (FST) and the tail suspension test (TST). The plant's anxiolytic potential was also evaluated in mice using the elevated plus-maze (EPM) and the open field tests (OFT). The subchronic toxicity was assessed via oral administration of PAE at doses of 100, 300, and 1000 mg/kg in rats for 28 days. Results. PAE 100 and 300 mg/kg showed antidepressant-like properties by significantly (at least p < 0.05 ) decreasing the frequency and duration of immobility in FST and TST. PAE (100 and 300 mg/kg) also showed a significant (at least p < 0.05 ) anxiolytic effect in both EPM and OFT. In the EPM test, Emax for PAE and diazepam were 92.52 ± 40.11% and 85.95 ± 45.92%, respectively, whereas Emax was approximately 100% for both test drugs in the OFT. Subchronic administration of PAE did not reveal any toxic effects with respect to organ weight index, haematological, serum biochemical, and histopathological parameters. Conclusions. Methanolic extract of P. ankasensis exhibited antidepressant-like and anxiolytic-like effects devoid of significant toxicity at the doses tested in murine models.