Total phenolic and flavonoid contents of Cola acuminata extract and evaluation of sub-acute toxicity on the hematological parameters of Wistar rat

Cola acuminata, also known as kola nut, is a West African evergreen tree with notable medicinal properties. Traditionally, its seeds have been used for their therapeutic effects, including antioxidant activity. 
In this study, Cola acuminata leaves were collected, dried, and extracted using a cold maceration method with methanol. To assess the extract's safety, a subacute toxicity test was conducted on 24 Wistar rats over 14 days. The rats were divided into four groups and given varying doses of the extract: control (distilled water), low (250 mg/kg), medium (500 mg/kg), and high (1000 mg/kg). After the test period, the rats were fasted and euthanized, and blood samples were analyzed for toxicity through a full blood count test. The antioxidant properties of the extract were evaluated by measuring total phenolic and flavonoid contents. The total phenolic content was determined using the Folin-Ciocalteu reagent method, with results expressed as gallic acid equivalents (GAE) per milliliter, while flavonoid content was measured using the aluminum chloride colorimetric method with quercetin as the standard and expressed as quercetin equivalents (QE) per milliliter. 
Results indicated that the Cola acuminata leave extract was non-toxic at all tested doses compared to the control. It exhibited a low total phenolic content of 28.48 GAE mg/mL but a high total flavonoid content of 146.67 QE mg/mL, suggesting potential antioxidant property. Thus, Cola acuminata leaves extract is non-toxic and demonstrates strong potential antioxidant property.