New phenylalkanoids from the rhizome of Cnidium officinalis Makino

Cnidium officinalis rhizomes were immersed in 80% MeOH. The extract was fractionated to water, n-butanol, and ethyl acetate fractions (Fr). Open column chromatography was repeatedly carried out on n-butanol and ethyl acetate Fr using silica gel, octadecyl silica gel, and Sephadex LH-20 as the stationary phase affording five phenyl alkanoids 1–5 including two new ones. The molecular structures including stereochemistry were decided based on spectroscopic interpretation of nuclear magnetic resonance, mass spectrometry, and infrared spectroscopy as well as chemical reaction. Three known compounds, coniferyl alcohol methyl ether (1), vanillin (2), and coniferyl aldehyde (3), were reported in the beginning for this plant by authors. Two new phenyl alkanoids were named, 7-methoxyeugenol and cnidiumoside.


Introduction
Cnidium officinalis Makino (Umbelliferae) is a perennially grown herb either semi-shaded or not shaded in moist soil. It originates from China but is now extensively cultivated in Korea, Japan, and China [1]. The ground parts have been used as a medicinal, conspicuous aroma, and as condiment materials in beverages, baking, cosmetics, and the pharmaceutical industry [1]. The dried rhizomes (Cnidii Rhizoma) have been especially utilized in East-Asia countries for the treatment of female menstrual disorders and headaches through a decrease in inflammation and an improvement in blood circulation [2,3]. Many studies have also reported the rhizomes as having anti-cancer [4], analgesic [5], antibacterial [6], anticonvulsive [7], anti-inflammatory [4,5], febrifuge, hypotensive [8], sedative [9], and vasodilator [10] effects. The major constituents of the rhizomes were revealed to be phthalides, alkaloids, ceramides, polyphenols, and flavonoids [1]. Phthalides in particular are the most important constituents copiously contained in the essential oil [6]. Many reported biological activities of C. officinalis rhizomes are due to the presence of phthalides [6]. Phenols are also major constituents of rhizomes and are reported to have various pharmacological activities [11]. However, phenyl alkanoids of this plant are rarely studied. The authors isolated five phenyl alkanoids from C. officinalis rhizomes in this study. Among them, two compounds were revealed to be new and three others have never been reported for C. officinalis. This paper describes the isolation procedure for phenyl alkanoids and the structure determination including stereostructures.

Plant materials
Cnidium officinalis rhizomes were provided and identified by Dr. J. T. Jeong, Department of Herbal Crop Research, RDA, Korea. A standard sample (NPCL-20200023) was put up at NPCL Laboratory, KyungHee University, Yongin, Korea.

General experimental procedures
The instruments and materials used for the isolation and identification of the phenyl alkanoids were the same as those in literatures [12]. The silica gel and the octadecyl silica gel (ODS) resins used for column chromatography (CC) were Kiesel gel 60 (Merck, Darmstadt, Germany) and the Lichroprep RP-18 (40-60 mµ , Merck) respectively. Sephadex LH-20 was purchased from Amersham Biosciences (Uppsala, Sweden). Thin layer chromatography (TLC) was carried out using Kiesel gel 60 F 254 and RP-18 F 254S (Merck) TLC plates, and the spots were detected using a UV lamp Spectroline Model ENF-240 C/F (Spectronics Corporation, Westbury, NY, USA) and a 10% H 2 SO 4 solution. Deuterium solvents were purchased from Merck Co. Ltd and Sigma Aldrich Co. Ltd (St. Louis, MO, USA). Nuclear magnetic resonance (NMR) spectra were recorded on a 600 MHz FT-NMR spectrometer (Bruker AVANCE 600, Billerica, MA, USA). Infrared (IR) spectra were obtained using a Perkin Elmer Spectrum One FT-IR spectrometer (Buckinghamshire, England). The specific rotation value was measured with JASCO P-1010 digital polarimeter (Tokyo, Japan). ESIMS spectra were recorded on a AB SCIEX Q-TOF 5600 (Framingham, MA, USA). Solvents were supplied by Burdick & Jackson (Muskegon, MI, USA).

Isolation of phenyl alkanoids from Cnidium officinalis rhizomes
C. officinalis rhizomes were dried at room temperature and 10 kg of dried materials were powdered and soaked overnight in ethanol (70%, 54 L × 2) at room temperature. The obtained solution was evaporated using rotary vacuum evaporator at 40℃ affording a brownish extract (2.1 kg). The residue was divided using systemic solvent fractionation using polarity as ethyl acetate (COE, 280 g), n-butanol (COB, 125 g), and water (COW, 1.695 kg) Fr. The column chromatography (CC) for COE (270 g) and COB (120 g) was performed as seen in Figs

Acid hydrolysis of cnidiumoside (5)
The solution of 10 mg of 5 in 5 mL of 1N HCl was refluxed for 2 hrs. 15