Antiplasmodial anthraquinones and hemisynthetic derivatives from the leaves of Tectona grandis (Verbenaceae)

• Published in: Phytochemistry letters Vol. 8; pp. 41 - 45
• Main Authors: Kopa, Theodora K., Tchinda, Alembert T., Tala, Michel F., Zofou, Denis, Jumbam, Ransom, Wabo, Hippolyte K., Titanji, Vincent P.K., Frédérich, Michel, Tan, Ning-Hua, Tane, Pierre
• Format: Journal Article Web Resource
• Language: English
• Published: Elsevier Ltd 01.05.2014; Elsevier
• Subjects: Anthraquinone; Antiplasmodial activity; Human health sciences; Napthoquinone; Pharmacie, pharmacologie & toxicologie; Pharmacy, pharmacology & toxicology; Plasmodium falciparum; Sciences de la santé humaine; Tectona; Tectona grandis; Verbenaceae; Antiplasmodial activity; Anthraquinone; Tectona grandis; Napthoquinone; Verbenaceae
• ISSN: 1874-3900; 1876-7486; 1876-7486
• DOI: 10.1016/j.phytol.2014.01.010

•Isolation and structural elucidation of a new anthraquinone of Tectona grandis.•Two new hemisynthetic derivatives were obtained.•Structures of compounds were determined by means of spectroscopic methods.•Compound 3 showed prominent antiplasmodial activity. Chemical investigation of the methanol extract of the leaves of Tectona grandis led to the isolation of one new anthraquinone derivative, grandiquinone A (3-acetoxy-8-hydroxy-2-methylanthraquinone) (1), along with nine known compounds: 5,8-dihydroxy-2-methylanthraquinone (2), hydroxysesamone (3), 3-hydroxy-2-methylanthraquinone (4), quinizarine (5), betulinic acid (6), ursolic acid (7), tectograndone (8), corosolic acid (9) and sitosterol 3-O-β-d-glucopyranoside (10). Compounds 2 and 3 were isolated for the first time from the leaves of this plant, while 5 has never been reported from the genus Tectona. Hydroxysesamone (3) and tectograndone (8) were subjected to cyclisation and acetylation reactions to afford two hemisynthetic derivatives, 6,9-dihydroxy-2,2-(dimethyldihydropyrano)-3,4-dihydro-2H-benzo[g]chromene-5,10-dione (11) and acetyltectograndone (12) respectively, which are reported here for the first time. The ethyl acetate-soluble portion, some of the isolated compounds and hemisynthetic derivatives were evaluated for their antiplasmodial activity against the multidrug-resistant Dd2 strain of Plasmodium falciparum. Compound 3 showed a prominent activity, while 2, 8, 9, 11 and 12 showed significant in vitro anti-malarial activity. Compound 1 was weakly active in this test. The structures of the compounds were elucidated by spectroscopic methods and comparison of the data with the literature.