Chemical composition and in vitro investigation of biological activities of Hemizygia bracteosa (Benth.) Briq leaves

Hemizygia bracteosa (Benth.) Briq (Lamiaceae) is used in the treatment of mental disease, memory loss, HIV, malaria and had antimicrobial and hypoglycemic properties. To the authors’ knowledge, no scientific study has been done on these properties except antimicrobial and hypoglycemic properties. The phytochemical investigation focused on the quantification of phenolic compounds, flavonoids, tannins, anthocyanins and reducing sugars. Gas chromatography-mass spectrometry (GC-MS) analysis was performed on derivatized and non-derivatized extracts for the determination of chemical composition. Phytochemical composition evaluation  shows phenolics content between 9.3 and 24.8 mg eq GA/g, a flavonoids content of 9 to 10.5 mg eq Q/g, an anthocyanins content of 0.0005 to 0.0025 mg eq C3G/g, a reducing sugar content of 126.1 to 123.7 mg eq G/kg, and undetected tannin content. GC-MS results revealed the presence of sugars, alcohols, acids, sesquiterpenes, amino acids, ester, lactone, phenolic. It also revealed that acetylcholinesterase inhibition was between 16.9 and 36.5%; xanthine oxidase inhibition between 3.8 and 60.2% ; ii-amylase inhibition between 6.1 and 8.7%, anti-inflammatory activity between 4.7 and 8.1%, anti-cancer activity between 24 and 96.4% for MCF7 ; 33.1 and 96.8% for HCT116 ; antioxidant activity between 2.1 and 13.2%. The results of acetylcholinesterase inhibition of ethyl acetate and methanolic extracts may justify the use of the plant in the treatment of mental illnesses and memory loss. But H. bracteosa should be used with caution because of its very high anti-cancer activity that could induce cytotoxicity.   Key words: Hemizygia bracteosa, chemical composition, antioxidant, acetylcholinesterase, inflammation, xanthine oxidase, ii-amylase, cancer.