Research of Bioactive Chemical Markers in Trunk Bark Extracts of Anogeissus leiocarpa , a Traditional Herbal Remedy for Hypertension

High blood pressure or hypertension is a public health problem in Burkina Faso. According to official statistics, its prevalence rate is estimated at 20%. The management of this disease is long-term with chronic treatments. This leads the population to resort to efficient, accessible and cheaper herbal medicines. Anogeissus leiocarpa is one of the plants used in traditional medicine for the treatment of hypertension in Burkina Faso. Earlier preclinical studies have proved the efficacy and safety of trunk bark extract. In this investigation, bioactive chemical marker phytocompounds are sought for the development, quality control and standardization of the antihypertensive drug based on this plant. The extracts of this plant are prepared by decoction from trunk bark powder and then fractionated successively with solvents in order of increasing polarity (n-hexane, dichloromethane, ethyl acetate and 1-butanol). The fractions obtained are subjected to phytochemical screening. The antioxidant properties of the different extracts have also been studied since the chemical species known as free radicals, which cause oxidative stress, are related to hypertension. The evaluation of the contents of total phenolic compounds and total flavonoids, which would have antihypertensive properties, was carried out according to the method using Folin-Ciocalteu. The highest total phenolic and total flavonoid contents were obtained with the ethyl acetate fraction (89.52 mg tannic acid equivalent/g dry extract and 70.87 mg quercetin equivalent/g dry extract for flavonoids). The best antioxidant power is also obtained with the ethyl acetate fraction (IC50: 6.93µg /mL). Standardization tests using analytical methods have identified three compounds A, B and C whose structure determination is in progress. These compounds could be used as markers for quality control of the prototype antihypertensive phytodrugs developed.