Acutuminine, a new alkaloid from the leaves of Menispermum dauricum DC

Eleven undescribed alkaloids from the rhizomes of Sinomenium acutum and their IDO1 and TDO inhibitory activities

Eleven previously undescribed alkaloids, named sinometumines A-K, along with three known alkaloids, were isolated from the rhizomes of Sinomenium acutum. The chemical structures of these unreported compounds were established using extensive spectroscopic methods (IR, UV, HRESIMS, and NMR), and their absolute configurations were determined by single crystal X-ray diffraction analyses and calculated electronic circular dichroism spectroscopy (ECD). Sinometumine D was the first aporphine-type derived alkaloid inner salt with a rearranged dibenzofuran ring backbone. Sinometumine E was a rare protoberberine-type alkaloid with a complex 6/6/6/6/6/6 hexacyclic skeleton. This was the first report of alkaloids with these two skeletons isolated from S. acutum. All isolates were evaluated for their inhibitory activities against indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO). Lysicamine possessed noteworthy inhibitory activities as an IDO1/TDO dual inhibitor with IC₅₀ values of 6.22 ± 0.26 μM and 23.76 ± 2.93 μM, respectively, and liriodenine revealed moderate dual inhibition with IC₅₀ values of 31.65 ± 4.44 μM and 15.64 ± 0.26 μM. The intermolecular interactions and binding modes between lysicamine and IDO1/TDO were elaborated by molecular docking studies.

Enantioselective Synthesis of (-)-10-Hydroxyacutuminine

An enantioselective synthesis of (-)-10-hydroxyacutuminine is reported. Central to our strategy is a photochemical [2+2] cycloaddition that forges two of the quaternary stereocenters present in the acutumine alkaloids. A subsequent retro-aldol/Dieckmann sequence furnishes the spirocyclic cyclopentenone. Efforts to chlorinate the acutumine scaffold at C10 under heterolytic or radical deoxychlorination conditions led to the synthesis of an unexpected cyclopropane-containing pentacycle.

Alkaloids from the stems and rhizomes of Sinomenium acutum from the Qinling Mountains, China

Thirteen undescribed alkaloids (sinotumines A-M), including five oxoisoaporphine, a benzo[h]quinoline, an aporphine, two protoberberine, two hasubanane, and two proaporphine alkaloids, and 50 known analogues were isolated from the 95% aqueous EtOH extract of the stems and rhizomes of Sinomenium acutum. The structures and absolute configurations of the isolates were elucidated on the basis of comprehensive analysis of 1D and 2D NMR, HRMS, single-crystal X-ray diffraction, and comparison of the experimental and calculated electronic circular dichroism (ECD) data. Sinotumine F, a rare benzo[h]quinoline alkaloid, was speculated as an oxidation product of the oxoisoaporphine alkaloid, and its putative biosynthetic pathway is proposed. Sinotumines L and M are the first samples of proaporphine-based heterodimers coupled with 1-heptanone and coniferol alcohol moiety, respectively. The T-cell suppression and NO inhibition effects of the isolates were evaluated.

The Hasubanan and Acutumine Alkaloids

Research in the hasubanan and acutumine alkaloid fields up to 1970 was discussed under "morphine alkaloids" in Volume 13 of this chapter. Advances in the field of hasubanan alkaloids from 1971 to 1975 were reviewed in Volume 16 and from 1976 to 1986 in Volume 33. This chapter extends the information in the three preceding reviews to hasubanan alkaloid literature published from 1987 to June 2013. This chapter covers acutumine alkaloid literature since (-)-acutumine (3) was isolated in 1929. This chapter includes occurrence and physical constants, new alkaloids, synthesis, biosynthesis, and pharmacology. Section 1 introduces the foremost alkaloids, (-)-hasubanonine (1) and (-)-acutumine (3), and the numbering systems of the hasubanan (2) and acutumine (4) skeletons. Section 2 details the occurrence and physical constants of 29 new hasubanan and 15 acutumine alkaloids. The isolation and structural determination of these new alkaloids are described in Section 3. Section 4 summarizes total syntheses and synthetic studies toward hasubanan and acutumine alkaloids. Completed syntheses of the hasubanan alkaloids (+)-cepharamine (ent-71), (-)-hasubanonine (1), (-)-runanine (8), (-)-delavayine (6), (+)-periglaucine B (19), and (-)-8-demethoxyrunanine (12) are reviewed. Completed syntheses of (-)-acutumine (3) and (-)-dechloroacutumine (52) are also described. Section 5 details biosyntheses of (-)-acutumine (3) advanced by Barton, Wipf, and Sugimoto. Section 6 summarizes pharmacological studies of hasubanan and acutumine alkaloids. Opioid receptor affinity, anti-HBV activity, and antimicrobial activity of hasubanan alkaloids are reported. Antiamnesic properties, cytotoxicity, and anti-HBV activity of acutumine alkaloids are described.

Occurrence of halogenated alkaloids

Once considered to be isolation artifacts or chemical "mistakes" of nature, the number of naturally occurring organohalogen compounds has grown from a dozen in 1954 to >5000 today. Of these, at least 25% are halogenated alkaloids. This is not surprising since nitrogen-containing pyrroles, indoles, carbolines, tryptamines, tyrosines, and tyramines are excellent platforms for biohalogenation, particularly in the marine environment where both chloride and bromide are plentiful for biooxidation and subsequent incorporation into these electron-rich substrates. This review presents the occurrence of all halogenated alkaloids, with the exception of marine bromotyrosines where coverage begins where it left off in volume 61 of The Alkaloids. Whereas the biological activity of these extraordinary compounds is briefly cited for some examples, a future volume of The Alkaloids will present full coverage of this topic and will also include selected syntheses of halogenated alkaloids. Natural organohalogens of all types, especially marine and terrestrial halogenated alkaloids, comprise a rapidly expanding class of natural products, in many cases expressing powerful biological activity. This enormous proliferation has several origins: (1) a revitalization of natural product research in a search for new drugs, (2) improved compound characterization methods (multidimensional NMR, high-resolution mass spectrometry), (3) specific enzyme-based and other biological assays, (4) sophisticated collection methods (SCUBA and remote submersibles for deep ocean marine collections), (5) new separation and purification techniques (HPLC and countercurrent separation), (6) a greater appreciation of traditional folk medicine and ethobotany, and (7) marine bacteria and fungi as novel sources of natural products. Halogenated alkaloids are truly omnipresent in the environment. Indeed, one compound, Q1 (234), is ubiquitous in the marine food web and is found in the Inuit from their diet of whale blubber. Given the fact that of the 500,000 estimated marine organisms--which are the source of most halogenated alkaloids--only a small percentage have been investigated for their chemical content, it is certain that myriad new halogenated alkaloids are awaiting discovery. For example, it is estimated that nearly 4000 species of bryozoans have not been examined for their chemical content. The few species that have been studied contain some extraordinary halogenated alkaloids, such as hinckdentine A (610) and the chartellines (611-613). Of the estimated 1.5 million species of fungi, secondary metabolites have been characterized from only 5000 species. The future seems bright for the collector of halogenated alkaloids!

Conversion of dechlorodauricumine into miharumine by a cell-free preparation from cultured roots of Menispermum dauricum

Dechlorodauricumine (5) and dechloroacutumine (6) were converted to miharumine (7) and dechloroacutumidine (8), respectively, by a cell-free preparation from cultured roots of Menispermum dauricum in the presence of FAD. The structures of 7 and 8 were elucidated on the basis of spectroscopic analyses and chemical conversion.

Ideas and experiments in biosynthesis

During the past 25 years or so, there has been almost undreamed of progress in understanding the pathways by which living systems synthesize the remarkable range of substances they contain. This progress could not have been made had not isotopes of carbon, nitrogen, hydrogen and oxygen become available in quantity at a time when the intellectual climate was right for their penetrating application in biosynthetic research. It was by his generation of far-reaching ideas about biosynthesis that Sir Robert Robinson made such a major contribution to establishing this right climate. His thinking pointed the way for many studies on living systems. Several examples will be discussed which were of particular interest to Sir Robert, such as the biosynthesis of morphine and colchicine, and another topic which is currently at a fascinating stage of development, the biosynthesis of natural porphyrins. New equipment and techniques, especially 13C n.m.r. spectroscopy and high-pressure liquid chromatography, have helped in a borad study of the biochemical conversion of porphobilinogen into uroporphyrinogen-III which must be formed by some rearrangement process. It is established that a single intramolecular rearrangement occurs and that this step comes at the end of the assembly of four porphobilinogen units which forms the unrearranged bilane.

Two new alkaloids and active anti-hepatitis B virus constituents from Hypserpa nitida

Two new alkaloids, hypserpanines A and B (1, 11), together with eleven known compounds, phenolbetain (2), acutumine (3), acutumidine (4), dechloroacutumine (5), dauricumine (6), dauricumidine (7), pronuciferine (8), glaziovine (9), S-reticuline (10), magnoflorine (12) and laurifoline(13), were isolated from Hypserpa nitida Miers. (Menispermaceae) and chemically elucidated through spectral analyses. All the isolated alkaloids were evaluated for their anti-HBV activities in vitro using the HBV transfected Hep G2.2.15 cell line. The most active compound, dauricumidine (7), exhibited an IC(50) value of 0.450 mM (SI=4.13) on hepatitis B virus (HBV) surface antigen (HBsAg) secretion of the Hep G2.2.15 cell line.

Alkaloids from Menispermum dauricum

The alkaloids, dechloroacutumidine and 1-epidechloroacutumine, together with three known alkaloids, acutumidine, acutumine, and dechloroacutumine, were isolated from the rhizomes of Menispermum dauricum and their structures established by spectral and chemical methods. The cytotoxicity of each compound against the growth of human cell lines was studied, and acutumine selectively inhibited T-cell growth.