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Lycopersicon esculentum (tomato) is a plant widely used in Africa like food and to solve many health problems. The methanol crude extract of tomato recently demonstrated a good antiproliferative effect on many human cancer cell lines. The aim of this research was to evaluate the acute toxicity and subacute oral toxicity of methanolic extract from leaves of this plant. These toxicities were evaluated based on the OECD (Organization for Economic Cooperation and Development) guidelines. The assay of acute toxicity was performed using a total of 3 female rats, which received a single dose of 5000 mg/kg of methanolic extract via oral gavage. For the subacute toxicity study, 32 Wistar rats (males and females) were used. The groups were treated with three different doses of Lycopersicon esculentum methanolic extract (250, 500, and 1000 mg/kg b.w.) for 28 days and the control group received distilled water. The hematological, biochemical, and histopathological studies were performed after the sacrifice. Single dose of tomato extract caused no toxicity up to a dose of 5000 mg/kg body weight; hence, the median lethal dose (DL50) of leaves of this plant was greater than this value. However, lower toxic effects could be manifested in the long-term treatment at the highest dose (1000 mg/kg) because urea level and total serum proteins significantly increased at a dose of 1000 mg/kg with respect to control. The microscopic observation showed no remarkable pathological changes on all organs in the treated groups compared with the control groups of female and male rats. These results demonstrate that single dose of tomato extract leaves is relatively nontoxic at a dose of 5000 mg/kg b.w. and prolonged use of lower doses (250 and 500 mg/kg) of L. esculentum orally should be encouraged, whereas highest dose (1000 mg/kg) should be avoided.

In order to contribute to the fight against infectious diseases, the in vitro antibacterial activity and the antibiotic-potentiating effects of Tristemma hirtum and five other Cameroonian edible plants have been evaluated against Gram-negative multidrug-resistant (MDR) phenotypes. The microdilution method was used to evaluate the bacterial susceptibility of the extracts and their combination to common antibiotics. The phytochemical screening of the extracts was carried out according to standard methods. Phytochemical analysis of the extracts revealed the presence of alkaloids, triterpenes, steroids, and polyphenols, including flavonoids in most of the tested extracts. The entire tested extracts showed moderate (512 μg/mL ≤ MIC ≤ 2048 μg/mL) to weak (MIC > 2048 μg/mL) antibacterial activities against the tested bacteria. Furthermore, extracts of leaf of Tristemma hirtum and pericarps of Raphia hookeri (at their MIC/2 and MIC/4) strongly potentiated the activities of all antibiotics used in the study, especially those of chloramphenicol (CHL), ciprofloxacin (CIP), kanamycin (KAN), and tetracycline (TET) against 70% (7/10) to 100% (10/10) of the tested MDR bacteria, with the modulating factors ranging from 2 to 128. The results of this study suggest that extracts from leaves of Tristemma hirtum and pericarps of Raphia hookeri can be sources of plant-derived products with antibiotic modifying activity.

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