Phytochemical screening, gossypol content and toxicological assessment of Thespesia populnea extracts

The cotton plant (Gossypium) is one of the most popular plants that contains gossypol, a yellow pigment described in the literature as a phytoalexin. Thespesia populnea (Family: Malvaceae) a neighboring plant, is closely related to Gossypium and other genera such as Cienfuegosia and Thurberia and is also described to contain gossypol as a natural product. Widely used in the Togolese pharmacopeia, Thespesia populnea is a medicinal plant not endemic but imported into Togo. The present work intends to study the phytochemical screening and toxicity of T. populnea leaves and bark. In addition to the phytochemical screening, free radical scavenging activity, gossypol extraction, and acute and sub-chronic toxicity were carried out. Results show that the bark contains more compounds than the leaves. Similarly, ethanolic extract of bark gave a much higher free radical scavenging activity (IC50 77.45 mg EQ/g ES) than leaves (158.22 mg EQ/g ES). Gossypol’s content evaluated from each organ was 0.12% and 0.42% for leaves and bark respectively. The LD50 of the extracts is greater than 5000 mg/kg. In addition, the ethanolic extract of bark at repeated doses of 500 mg/kg and 1000 mg/kg caused congestion lesions in the liver and kidneys of over 60% of the animals. This study shows that T. populnea should be used sparingly.