Chemical Constituents of the Roots of Morinda coreia

Abstract

The genus Morinda belongs to the Rubiaceae family and comprises 80 species [1]. Many plants belonging to the Morinda species are valuable traditional herbs in the Austronesia and oriental countries. The roots, barks, stems, leaves, and fruits of Morinda citrifolia have been used traditionally as a folk medicine for the treatment of many diseases, including diabetes, high blood pressure, and cancer [2]. Morinda coreia (Yo-Paa) is a tree distributed in the Southeast Asia region. The bark and wood are used to treat fever and as an antimalarial agent in northeastern Thai (Isarn) traditional medicine [2]. Phytochemical reports on the leaves and branches of M. coreia have revealed iridoid glycosides, phenolic glycoside, secoiridoid glucoside, and anthraquinone glycoside [3]. This is the first report on the phytochemical investigation and biological activities of M. coreia roots. The roots of M. coreia were collected from Mahasarakham Province of Thailand in July 2010 and identified by Ms. Suttira Khumkratok, a botanist at the Walai Rukhavej Botanical Research Institute, Mahasarakham University, where a voucher specimen (Khumkratok no. 1-11) is deposited. Air-dried and powdered roots of M. coreia (1.5 kg) were successively extracted in a Soxhlet apparatus with CH2Cl2, EtOAc, and MeOH. Removal of solvents from each extract under reduced pressure gave CH2Cl2 (76.58 g), EtOAc (8.48 g), and MeOH (81.46 g) crude extracts. The CH2Cl2 extract (76.58 g) was fractionated by vacuum liquid chromatography (VLC) over silica gel (Merck Art. 7730), eluting with n-hexane, CH2Cl2, EtOAc, and MeOH with increasing polarity to provide five fractions (DC1-DC5). Fraction DC2 was subjected to silica gel column chromatography (CC) and eluted with a gradient system of n-hexane–CH2Cl2, then CH2Cl2–EtOAc (from 1:0 to 0:1), to afford nordamnacanthal (1, 10 mg) [4]. Fraction DC4 was further subjected to silica gel CC (n-hexane, CH2Cl2, EtOAc, and MeOH in a gradient system) and radial chromatography (chromatotron ), using n-hexane–EtOAc (4:1) to yield damnacanthal (2, 10 mg) [4], soranjidiol (3, 20 mg) [5], 1-methoxy2-methylanthraquinone (4, 5 mg) [6], anthragallol (5, 6 mg) [7], 2-methoxy-6-methyl-1,3,5-trihydroxyanthraquinone (6, 4 mg) [8], and 1-hydroxy-5,6-dimethoxy-2-methylanthraquinone (7, 5 mg) [9], respectively.