Isoleojaponin, a new Halimane diterpene isolated from Leonurus japonicus.

Hankui Wu,Sensheng Wang,Yan E,Shanshan Sun,Zhiyong Xu,Yunfeng Shi,Liping Zhang,Haijuan Liu,Xuelin Dong,Jinjin Wang,Yanyan Lv,Gang Li

doi:10.3390/molecules20010839

Hankui Wu, Sensheng Wang + Show 10 more

Open Access

https://doi.org/10.3390/molecules20010839

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Journal: Molecules (Basel, Switzerland)	Publication Date: Jan 7, 2015
Citations: 21	License type: CC BY 4.0

Affiliation: Anyang Normal University

Abstract

Leojaponin (2), a labdane diterpene, was isolated from the EtOH extract of the herb of Leonurus japonicus together with a new halimane diterpene named isoleojaponin (1). Isoleojaponin has a new diterpene skeleton with a unique cross-conjugated α,β-unsaturated ketone system, Their structures were elucidated by physical and spectroscopic analysis, and the relative configuration of the chiral C-9 carbon was determined by a computational method, and analysis of its possible biogenesis pathways.

Highlights

Leonurus japonics Houtt. (Lamiaceae) is an annual or biennial herbaceous plant widely distributed and cultivated in China
Correlations of H3-20/C-8, C-9, C-10, and C-11; H-11/C-8, C-9, C-10, C-12, C-20; H2-12/C-9, C-11, C-13, C-14 and C-16 suggested Me-20 was connected to a quaternary carbon which linked to two β-olefinic carbons of the cross conjugated α, â-unsaturated ketone and linked to an ethyl group bearing a monosubstituted furanyl ring at its end (Figure 2c)
It would be reasonable to deduce from the biogenesis pathways of the co-isolation of compound 1 and 2, a stereospecific 1,2-Me migration might result in the formation of 1 as shown (Figure 5), and this type of reaction was observed by biomimetic rearrangements of simplified labdane diterpenoids [14]

Summary

Introduction

Leonurus japonics Houtt. (Lamiaceae) is an annual or biennial herbaceous plant widely distributed and cultivated in China. Phytochemical studies on this plant have been reported [2,3,4,5,6,7,8,9,10]. Our previous investigation on two plants of the family of Lamiaceae resulted in the isolation of a number of new labdane diterpenes [11,12]. One of them was identified as leojaponin by comparison of the NMR data with those reported [2]. The other one was elucidated as its isomer and named isoleojaponin (1), it has transformed structure skeleton compared with a labdane-type compound such as leojaponin, the methyl group (Me-20) connected to C-10 has shifted to link with C-9, and the double bonds of ring-B were rearranged correspondingly. This paper describes the isolation and structure elucidation of these isolates (Figure 1)

Results and Discussion

General

Plant Material

Extraction and Isolation

Conclusions