Studies on the Alkaloids of the Bark of Magnolia officinalis: Isolation and On-line Analysis by HPLC-ESI-MSn

Abstract

Abstract:The bark of Magnolia officinalis is a well-known Traditional Chinese Medicine. In the present study, two new alkaloids, named (S)-4-keto-magnoflorine (6) and (R)-3,4-dehydromagnocurarine (11), together with seven known alkaloids: (S)-magnoflorine (5), trans/cis N-feruloylputrescine (7/8), (R)-magnocurarine (10), (S)-tembetarine (12), (R)-oblongine (14), and (R)-asimilobine (17) were isolated and their structures elucidated by spectroscopic methods, including 1D, 2D NMR, and HRESI-MS. The absolute configurations of the isoquinoline alkaloids 5, 6, 10-12, 14, and 17 were determined by CD. In vitro inhibitory activities against aldose reductase, lipase, α-glucosidase, DPP-IV and three cancer cell lines (A549, Bel-7402, and HCT-8) were evaluated for all isolated compounds. However, all compounds showed weak activities in all tests at the same concentration as the positive control drugs. An HPLC-ESI-MS n method has been established for screening of alkaloids in the bark of M. officinalis. A total of 23 alkaloids were identified or tentatively characterized; including 13 aporphines, eight benzylisoquinolines and two amides. Plausible fragmentation pathways of the representative compounds 6, 7/8, 11, and 17 were proposed in the present study.

Antifungals and acetylcholinesterase inhibitors from the stem bark of Croton heliotropiifolius

“…The absolute configuration of C-1 could not be assigned. Indeed the optical rotation value obtained for 1 was very close to 0 (+4.18) and contradictory information about C-1 stereochemistry were reported for closely related compounds (Chrisey and Brossi, 1990;Reddy and Cook, 1994;Roszkowski et al, 2005;Yan et al, 2013). It was not possible based on literature comparison to deduce unambiguously C-1 stereochemistry and 1 might occur as partial racemic mixture as this was also reported for 1,2,3,4-tetrahydroroeharmine (Reddy and Cook, 1994).…”

Tissue‐specific metabolite profiling of benzylisoquinoline alkaloids in the root of Macleaya cordata by combining laser microdissection with ultra‐high‐performance liquid chromatography/tandem mass spectrometry

“…4(c)) with those reported in the literature, compound 2 was identified as magnocurarine. [33][34][35] Similarly, compounds 3, 5, 14 and 18 were identified as N-methylcoclaurine, 2-methylmagnocurarine, colletine and N-demethylcolletine, respectively. [33][34][35] The MS and MS 2 data and proposed fragmentation pathways are shown in Supplementary Figs.…”

“…S10(B), see Supporting Information) with those reported in the literature, compound 1 was identified as 10-demethylmagnoflorine. [32,33] For type III, V and VI alkaloids, the product ions appear mostly below m/z 230 and result from retro-Diels-Alder (RDA) reaction, which is the typical fragmentation pattern for these three types of alkaloid. [32] The loss of H 2 O from the [M + H] + ion distinguishes the fragmentation behavior of type VI alkaloids from that of type III and V alkaloids.…”

Biological activity and toxicity of the Chinese herb Magnolia officinalis Rehder & E. Wilson (Houpo) and its constituents

“…As well as these well-known lignans magnolol and honokiol, alkaloids are a group of interesting secondary metabolites of this species, which produces mainly isoquinoline-type alkaloids, the majority of which are aporphine and benzylisoquinoline derivatives (Yan et al, 2013). Magnolia bark also contains volatile oils, the major constituents of which are the sesquiterpenoid alcohols, α-, β-, and γ-eudesmol (about 95% of the essential oil).…”

“…From the bark of M. officinalis, different tertiary and quaternary alkaloids have been isolated and structurally elucidated (Yan et al, 2013), including (1) the aporphine alkaloids N-methylcoxylonine, (S)-magnoflorine, magnofficine, (R)-asimilobine, corytubérine, anonaine, liriodenine and (2) the benzyltetrahydroisoquinoline alkaloids (R)-magnocurarine, (S)-tembetarine, lotusine, (R)-oblongine, reticuline (Guo et al, 2011;Yan et al, 2013). Magnoflorine and magnocurarine are considered as the major and most potent of Magnolia bark alkaloids (Dharmananda, 2002) (Tables 4 and 5).…”