Elsevier

Phytochemistry

Volume 119, November 2015, Pages 26-31
Phytochemistry

neo-Clerodane diterpenoids from the aerial parts of Teucrium fruticans cultivated in China

https://doi.org/10.1016/j.phytochem.2015.09.011Get rights and content

Highlights

  • First phytochemical research of Teucrium fruticans cultivated in China.

  • Seven neo-clerodane diterpenes were isolated from Teucrium fruticans.

  • neo-Clerodane diterpenes are potential chemotaxonomic markers of Teucrium genus.

Abstract

Seven neo-clerodane diterpenes, teufruintins A–G (17), together with eight known compounds (815) were isolated from the CHCl3-soluble fraction of the aerial parts of Teucrium fruticans cultivated in China. The chemical structures of the isolated compounds were elucidated using different spectroscopic methods. All of the isolated diterpenes were evaluated for their cytotoxic activities on three human cancer cell lines, and for their ability to inhibit LPS-induced nitric oxide production in RAW 264.7 macrophages. None of the compounds displayed cytotoxic activities on the cancer cell lines, and only 15 showed weak NO inhibitory activity.

Graphical abstract

Seven neo-clerodane diterpenes, teufruintin A–G (17), were isolated from Teucrium fruticans cultivated in China. neo-Clerodane diterpenes are potential chemotaxonomic markers of Teucrium genus.

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Introduction

The genus Teucrium (Lamiaceae), which consists of approximately 300 species worldwide, is primarily distributed in the Mediterranean area. Many Teucrium species are widely used in folk medicine as diuretics, diaphoretics, antipyretics, and for the treatment of stomach pain, diabetes and traumatic injuries (Ardestani et al., 2008, Barrachina et al., 1995, Hao et al., 2013, Pourmotabbed et al., 2010). Teucrium fruticans, native to the western Mediterranean, is a spreading evergreen shrub with arching velvety white shoots, glossy aromatic leaves and pale blue flowers in summer. It was reported that European T. fruticans contains neo-clerodane diterpenes (Bruno et al., 1992, Coll and Tandrón, 2005, Coll and Tandrón, 2004, Savona et al., 1978) and abietane diterpenes (Bruno et al., 1990, Cuadrado et al., 1992), but no information on T. fruticans introduced in other areas has been reported. Having a strong adverse environmental tolerance, T. fruticans was introduced from New Zealand to China in 2004, and commonly used as a background for flower borders (Chen et al., 2012). The difference in the growth environments of T. fruticans between the Mediterranean area and China may lead to the diversification of metabolites in the plant. However, to date no phytochemical investigation was carried out on T. fruticans cultivated in China. Aiming to determine whether metabolites changed after the plant’s introduction in China, the methanol extract of the aerial parts of T. fruticans cultivated in China was investigated. Seven new (17) and eight known (815) neo-clerodane diterpenes were obtained. Herein, described are the isolation, structural elucidation, and bioactivity investigation results.

Section snippets

Results and discussion

Air-dried aerial parts of T. fruticans were ultrasonically extracted with MeOH, and the crude extract was partitioned with CH2Cl2, EtOAc, and H2O. Repeated column chromatography and preparative HPLC of the CH2Cl2 fraction resulted in the isolation of compounds 115. The structures of the new compounds (17, Fig. 1) were elucidated based on extensive spectroscopic analyses. In addition to the seven new compounds, eight known compounds were identified, namely, fruticolone (8), isofruticolone (9) (

Concluding remarks

neo-Clerodane diterpenes are the primary chemical constituents of the Teucrium species (Bruno et al., 2004, Fiorentino et al., 2011, Fiorentino et al., 2009), which is consistent with the results of this study on T. fruticans. To the best of our knowledge, eleven neo-clerodane diterpenes had been previously reported from European T. fruticans (Bruno et al., 1992, Coll and Tandrón, 2005, Coll and Tandrón, 2004, Savona et al., 1978), and this paper added 9 neo-clerodane diterpenes (17, 10, and 14

General experimental procedures

Optical rotations were measured using a JASCO P-1020 polarimeter (Jasco Tokyo Japan). UV spectra were recorded using a UV-2450 UV–visible spectrophotometer (Shimadzu, Tokyo, Japan). NMR spectra were acquired on a Bruker AV-500 NMR instrument (1H: 500 MHz, 13C: 125 MHz), with TMS as an internal standard. HRESIMS were measured with an Agilent 6520B Q-TOF mass instrument (Agilent Technologies, Santa Clara, CA, USA). The extracts were subjected to silica gel (Qingdao Marine Chemical Co., Ltd.,

Acknowledgments

This research was supported by the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), New Century Excellent Talents in University (NCET-12-09-77), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT1193).

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