title: Bioguided isolation of pentacyclic triterpenes from the leaves of Alstonia scholaris (Linn.) R. Br. growing in Egypt.
abstract: Ethanolic and aqueous extracts of the leaves and flowers of Alstonia scholaris were evaluated for their antioxidant activity by investigating their effect on blood glutathione levels in alloxan-induced diabetic rats. The ethanolic extract of the leaves was the most active; therefore, its cytotoxicity against HepG2 cells was also tested. Promising GI₅₀ values of 1.96, 4.34 and 4.65 µg mL⁻¹ were observed for the extract, its chloroform and ethyl acetate fractions, respectively. The chloroform active subfraction I (GI₅₀ = 2.97 µg mL⁻¹) yielded betulin (1), betulinic acid (2) and ursolic acid (3) upon purification. Compounds 1-3 were identified using spectroscopic techniques and by comparison with reported data. GLC of unsaponifiable and saponifiable fractions of the hexane extract revealed β-sitosterol (7.37%) and n-tetracosane (54.4%) to be the major sterol and hydrocarbon components, respectively. Linoleic acid (48.89%) was the predominant fatty acid.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt. helaskary@hotmail.com
authors.forename: Hesham I
authors.initials: HI
authors.lastname: El-Askary
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: El-Olemy
authors.forename: Maha M
authors.initials: MM
authors.lastname: Salama
authors.forename: Amany A
authors.initials: AA
authors.lastname: Sleem
authors.forename: Mahetab H
authors.initials: MH
authors.lastname: Amer
mesh_terms: D031051:Alstonia / Q000737:chemistry*; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D004534:Egypt; D056945:Hep G2 Cells; D006801:Humans; D008297:Male; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014315:Triterpenes / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D014315:Triterpenes