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Abstract
The paper presented a systematic study on the chemical constituents and biological activity of Leucosceptrum, from which more than sixty constituents were extracted out, including sesterterpenoids, flavonoids, phenylethanoid glycosides, acyl glycosides and phenols, etc. Among them some sesterterpenes showed a variety of activities, such as antifeedant, antifungal, inhibiting PEP and antiangiogenesis. Therefore, to carry out the studies of Leucosceptrum plants will be of great significance to discovering new medicinal components.
Key words L. canum Smith; Chemical constituents; Bioactivity
1 Introduction
Leucosceptrum, a type of shrub and arbor in family Lamiaceae, grows mostly in Bhutan, Nepal, India, Laos, Vietnam as well as Yunnan and Sichuan Provinces in China[1]. L. canum Smith is a species of nectariferous plant whose root and leaves show great medicinal values, and the yellow pigment extracted from its flowers can also be widely used as a type of safe food dye[ 21. During recent years, some medicinal constituents with novel structures and strong biological activities were found out after a series of systematic studies. In order to comprehensively understand the present research situation of L. canum Smith, the paper reviewed the latest studies on its chemical constituents and biological activities so as to provide references for its further study and development.
2 Chemical components
Sixty chemical components have already been isolated from the Leucosceptrum plant till now, including sesterterpenoids, flavonoids, dianabol, acyl glycosides and phenols, among which the sesterterpenoids and flavonoids were dominant structural types.
2.1 Terpenoids
2.1.1 Sesterterpenes. Luo Shi-Hong, from the villi on the surface of L. canum Smith leaves collected from Southwest China, isolated four novel-structured and highly oxidized sesterterpenes, which were leucosceptroids A - D (1 -4) [3"4] ; all the four constituents were structured with A cyclopentane, B cyclohexanone, and C tetrahydrofuran. What makes the great difference between constituents 3, 4 and 1,2 lies in that the furan ring at D changes into cyclopentenone. Muhammad separated five compounds from the L. canum produced in Nepal, which were eucosceptrine (5) , 17a-hydroxyleucosceptrine (6), leucosesterterpenone (7), 14ßmethylleucosesterterpenone ( 8 ) and leucosesterlactone ( 9 ) , whose structures were totally different from that of the sesterterpenes separated by Luo Shi-Hong15~7]. Compounds 5-9 belong to a new type of sesterterpenes known as leucosesterterpene, which is typically characterized...