Chemical constituents from the leaves of Cinnamomum burmannii

Abstract

Cinnamomum burmannii Blume (Lauraceae) is a source of Indonesian cinnamon and is widely used as a spice in Indonesia [1]. The chemical constituents of the leaves of this plant have not yet been reported. Recently, we reported a new amide, cinnabutamine, along with five known amides from the stems of C. burmannii [2]. In the course of screening for biologically and chemically novel agents from Formosan plants in the family Lauraceae [3–12], C. burmannii was chosen for further phytochemical investigation. In this study, the MeOH extract of its leaves was subjected to solvent partitioning and chromatographic separation to afford 11 pure substances. The chemical constituents of the leaves of C. burmannii were separated by column chromatography. Eleven compounds, including squalene (1) [13], ficaprenol-10 (2) [14], methyl vanillate (3) [15], coumarin (4) [16], -sitostenone (5) [17], -sitosterol (6) [17], vanillic acid (7) [15], syringic acid (8) [15], (+)-abscisic acid (9) [18], p-hydroxybenzoic acid (10) [15], and kaempferol-3-O-rhamnoside (11) [19], were isolated from the leaves of C. burmannii. Compounds 1–3, 5–8, 10, and 11 were found for the first time from this plant. The specimen of C. burmannii was collected from Chiayi County, Taiwan in January 2009. A voucher specimen (Cinnamo. 10) was identified by Dr. Fu-Yuan Lu (Department of Forestry and Natural Resources College of Agriculture, National Chiayi University) and deposited in the Department of Medical Laboratory Sciences and Biotechnology, School of Medical and Heath Science, Fooyin University, Kaohsiung, Taiwan. The air-dried leaves of C. burmannii (4.7 kg) were extracted with MeOH (80 L 4) at room temperature, and a MeOH extract (186.4 g) was obtained upon concentration under reduced pressure. The MeOH extract was placed on a silica gel column and eluted with CH2Cl2 gradually enriched with MeOH to afford five fractions. Part of fraction 2 (9.52 g) was subjected to silica gel chromatography by eluting with n-hexane–EtOAc (100:1) and enriched with EtOAc to furnish four further fractions (2-1–2-4). Fractions 2-1 (3.05 g) eluted with n-hexane– EtOAc (60:1) was further purified by silica gel column chromatography using the same solvent system to give squalene (1) (12 mg) and ficaprenol-10 (2) (15 mg). Fractions 2-2 (2.57 g) and 2-3 (1.62 g) eluting with n-hexane–EtOAc (30:1) were further separated by silica gel chromatography to give methyl vanillate (3) (5 mg), and purified by preparative TLC (n-hexane– acetone, 20:1) to give coumarin (4) (19 mg) and -sitostenone (5) (12 mg), respectively. A part of fraction 3 (21.07 g) was subjected to silica gel chromatography by eluting with CH2Cl2–MeOH (100:1) and enriched with MeOH to furnish four further fractions (3-1–3-4). Fraction 3-1 (6.52 g) eluted with CH2Cl2–MeOH (80:1) was further purified by silica gel column chromatography using n-hexane–acetone (10:1) to give -sitosterol (6) (10 mg). Fraction 3-2 (8.73 g) eluting with CH2Cl2– MeOH (60:1) was further purified by silica gel column chromatography using the same solvent system and preparative TLC (n-hexane–acetone, 4:1) to give vanillic acid (7) (6 mg) and syringic acid (8) (5 mg). Fraction 3-3 (0.43 g) was further purified by another silica gel column using n-hexane–acetone (3:1) to obtain (+)-abscisic acid (9) (9 mg). A part of fraction 4 (15.33 g) was subjected to silica gel chromatography eluting with CH2Cl2–MeOH (40:1) and enriched gradually with MeOH to give three fractions (4-1–4-3). Fraction 4-2 (8.21 g) was further separated by silica gel column chromatography using the same solvent system and purified by preparative TLC (CH2Cl2–MeOH, 20:1) to yield p-hydroxybenzoic acid (10) (6 mg). Kaempferol3-O-rhamnoside (11) (8 mg) was further purified on a silica gel column using CH2Cl2–MeOH (10:1) from fraction 4-3.