Protoberberine Alkaloids Research Articles

Characterization of two methylenedioxy bridge-forming cytochrome P450-dependent enzymes of alkaloid formation in the Mexican prickly poppy Argemone mexicana

Formation of the methylenedioxy bridge is an integral step in the biosynthesis of benzo[ c]phenanthridine and protoberberine alkaloids in the Papaveraceae family of plants. This reaction in plants is catalyzed by cytochrome P450-dependent enzymes. Two cDNAs that encode cytochrome P450 enzymes belonging to the CYP719 family were identified upon interrogation of an EST dataset prepared from 2-month-old plantlets of the Mexican prickly poppy Argemone mexicana that accumulated the benzo[ c]phenanthridine alkaloid sanguinarine and the protoberberine alkaloid berberine. CYP719A13 and CYP719A14 are 58% identical to each other and 77% and 60% identical, respectively, to stylopine synthase CYP719A2 of benzo[ c]phenanthridine biosynthesis in Eschscholzia californica. Functional heterologous expression of CYP719A14 and CYP719A13 in Spodoptera frugiperda Sf9 cells produced recombinant enzymes that catalyzed the formation of the methylenedioxy bridge of ( S)-cheilanthifoline from ( S)-scoulerine and of ( S)-stylopine from ( S)-cheilanthifoline, respectively. Twenty-seven potential substrates were tested with each enzyme. Whereas CYP719A14 transformed only ( S)-scoulerine to ( S)-cheilanthifoline ( K m 1.9 ± 0.3; k cat / K m 1.7), CYP719A13 converted ( S)-tetrahydrocolumbamine to ( S)-canadine ( K m 2.7 ± 1.3; k cat / K m 12.8), ( S)-cheilanthifoline to ( S)-stylopine ( K m 5.2 ± 3.0; k cat / K m 2.6) and ( S)-scoulerine to ( S)-nandinine ( K m 8.1 ± 1.9; k cat / K m 0.7). These results indicate that although CYP719A14 participates in only sanguinarine biosynthesis, CYP719A13 can be involved in both sanguinarine and berberine formation in A. mexicana.

Structural study of 8-azole derivatives of protoberberine alkaloids: experimental and quantum chemical approach

New derivatives of protoberberine alkaloids were prepared by nucleophilic addition of some azoles (differing in bulkiness) to the iminium functionality of the quaternary protoberberine alkaloids. Compounds were structurally characterized mainly by 1H and 13C NMR spectroscopy, and the structure of 8-carbazol-1-yl-7,8-dihydroberberine was determined using single-crystal X-ray diffraction. Additionally, conformational behaviors of five derivatives varying in bulkiness of the azole moiety have been investigated by low temperature NMR spectroscopy and quantum chemical calculations. Ring current effects of pyrrole and carbazole moieties on selected 1H NMR resonances have been characterized, visualized, and discussed.

The new shortcut synthesis of 8-oxocoptisine

8-Oxocoptisine 1, a natural protoberberine alkaloid, can be more easily achieved starting from readily available and inexpensive berberine hydrochlorate 2. The structure of the target compound 1 was confirmed by melting point, 1H NMR, IR, MS and elemental analysis.

Preliminary Studies Toward Identification of Sources of Protoberberine Alkaloids used as Yellow Dyes in Asian Objects of Historical Interest

The protoberberines bright yellow alkaloids that have been used for centuries in Chinese and other traditional medicines and also as dyes for textiles and paper. The most frequently cited source for protoberberine dyes is the Amur cork tree (phellodendron amurense). However, many plants contain protoberberines, and, as shown here, the analysis of dyed objects often permits identification of plant types, which sheds light on the resources available to early dyers. In this study, representatives of five genera (Berberis, coptis, Fibraurea, Mahonia, phellodendron) of protoberberine-yielding plants were analyzed, all of which have been reported as having been used in Asia as sources of yellow colorants, using high-performance liquid chromatography (HPLC) with diode array and mass spectrometric detection. It is shown that their contents of berberine, palmatine, jatrorrhizine and other protoberberines are distinctive enough to allow them to be distinguished from one another. As a result, analysis of the dyes used in several historical objects allows conclusions to be drawn as to the plant source of the dye. Knowledge of the type of colorant used in an object is important for its conservation because the protoberberine alkaloids, as a class, are both very water-soluble and relatively unstable (among yellow dyes) to light.

A new and weakly antispasmodic protoberberine alkaloid from Rhizoma Coptidis

A new protoberberine alkaloid, 3-hydroxy-2-methoxy-9,10-methylenedioxy-8-oxo-protoberberine, along with three known compounds, was isolated from Rhizoma Coptidis. The new compound displayed weak antispasmodic activity against acetylcholine-induced contraction in isolated guinea-pig ileum with an IC50 of 83.7 microm.

ChemInform Abstract: A Novel Oxidation Stage in the Chemistry of Protoberberine Alkaloids. Synthesis of 7,8-Dehydroberbines.

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Metabolites of Protoberberine Alkaloids in Human Urine following Oral Administration of Coptidis Rhizoma Decoction

Coptidis Rhizoma has been used as a traditional Chinese herbal medicine to treat typhoid, pharyngolaryngitis, diabetes mellitus, gastroenteritis and secretory diarrhea for more than a thousand years in China. However, there is little information on the IN VIVO chemical constituents of Coptidis Rhizoma following oral administration. In this paper, the alkaloid constituents in urine were studied in humans following oral administration of Coptidis Rhizoma decoction. Using macroporous adsorption resin chromatography, open ODS column chromatography, and preparative high-performance liquid chromatography, twelve protoberberine alkaloid constituents were isolated. Their structures were elucidated by chemical evidence, enzymatic deconjugation and analyses of mass, (1)H-NMR and NOESY spectra. The identified alkaloid constituents include berberine ( P1), groenlandicine 3-O- β-D-glucuronide (M1), dehydrocheilanthifoline 2-O-β-D-glucuronide (M2), thalifendine 10-O-β-D-glucuronide (M3), jatrorrhizine 3-O-β-D-glucuronide (M4), columbamine 2-O-β-D-glucuronide (M5), berberrubine 9-O-β-D-glucuronide (M6), jatrorrhizine 3-O-sulfate (M7), demethyleneberberine 2-O-sulfate (M8), dehydrocorydalmine 10-O-sulfate (M9), 3,10-demethylpalmatine 10-O-sulfate (M10) and 2,3,10-trihydroxyberberine 2-O-sulfate ( M11). No other parent protoberberine alkaloids from Coptidis Rhizoma except for a trace of berberine were found in the urine. These findings suggested that the protoberberine alkaloids, which were absorbed in vivo following oral administration of Coptidis Rhizoma decoction, were mainly conjugated with glucuronic acid or sulfuric acid to form phase II metabolites directly or after biotransformation to phase I metabolites, and finally excreted in urine.

ChemInform Abstract: Structure-Activity Relationships of Quaternary Protoberberine Alkaloids Having an Antimalarial Activity.

Abstract Seventeen quaternary protoberberine alkaloids related to berberine 1 were tested for antimalarial activity in vitro against Plasmodium falciparum and structure-activity relationships are proposed. The activity of the protoberberine alkaloids was influenced by the type of the oxygen substituents on rings A, C and D and the position of the oxygen functions on ring D. The position of the oxygen functions on ring D and the type of the oxygen substituents at the C-13 position (ring C) strongly influenced the activity. Shifting the oxygen functions at C-9 and C-10 to C-10 and C-11 on ring D resulted in a significant increase in the activity. Compounds bearing a methylenedioxy function at C-2 and C-3 (ring A) or C-9 and C-10 (ring D) showed higher activity than those which have methoxy groups at the same positions. Introduction of a methoxy group into the C-1 position (ring A) decreased the activity. Replacement of a hydroxy group at C-2 or C-3 (ring A) by a methoxy group led to a reduction in the activity. Displacement of a hydroxy function at C-13 (ring C) by the oxygen substituents such as OMe, OEt, OCOOEt, and OCON(Me) 2 reduced the activity. In the same replacement at C-9 (ring D), the activity depended upon the type of the oxygen function. Six protoberberines displayed more potent activity than berberine 1 . The activity decreased in the order: 10 , 11 , 17 and 18 > 7 and 8 > 1 .

ChemInform Abstract: Convenient Synthesis of 2,3,9,10-Tetraoxygenated Protoberberine Alkaloids and Their 13-Methyl Alkaloids.

New and convenient synthesis of 2,3,9,10-tetraoxygenated protoberberine alkaloids and their 13-methyl alkaloids through the same intermediates was developed. Acylation of the brominated benzylphenethylamine (13) with alpha-chloro-alpha-(methylthio)acetyl chloride, followed by cyclization with stannic chloride, furnished the key intermediates 4-methylthio-3-phenethylisoquinolin-3-ones (14), which were methylated to provide their methyl derivatives (17). Both isoquinolin-3-ones (14, 17) were easily transformed into protoberberine alkaloids (16) and their 13-methyl alkaloids (21) in good yield.

Characterization of Aromatase Binding Agents from the Dichloromethane Extract of Corydalis yanhusuo Using Ultrafiltration and Liquid Chromatography Tandem Mass Spectrometry

Aromatase represents an important target for the treatment of hormone-dependent breast cancer. In the present study, nine alkaloids from the dichloromethane extract of Corydalis yanhusuo were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS) and tested for their aromatase binding activities using an ultrafiltration LC-MS method by investigating the differences of peak areas of compounds before and after incubations with aromatase. It was demonstrated that the quaternary protoberberine alkaloids and the tertiary protoberberine alkaloids exhibited potent aromatase binding activities. The quaternary ammonium group and the methyl group at C-13 position of tertiary protoberberine alkaloids might be necessary for the activity. The findings should provide guidance for the discovery of potential aromatase inhibitors from natural products.

Synthesis, structure and DNA cleavage studies of coumarin analogues of tetrahydroisoquinoline and protoberberine alkaloids

Novel molecular matrices have been derived from coumarin-4-acetic acids and β-phenylethylamines using the Bischler–Napieralski protocol which has led to the synthesis of analogues of tetrahydropapaverine in which the dimethoxybenzene moiety has been replaced by substituted coumarins. One carbon homologation has led to cyclization at the C3 position of coumarin generating the protoberberine skeleton. Structures have been confirmed by diffraction studies. The results showed that compounds 6e, 6f, 7e and 7f were found to be very effective against DNA samples of Gram positive bacterium Staphylococcus aureus and fungus Aspergillus niger.

Alkaloids from Roots ofStephania rotundaand Their Cholinesterase Inhibitory Activity

In the course of screening plants used in folk medicine as memory enhancers, a 70% ethanolic extract of Stephania rotunda roots showed significant AChE inhibitory activity. Repeated column chromatography led to the isolation of a new protoberberine alkaloid, which we named stepharotudine (1), and seven known compounds (2-8). The chemical structures of the isolated compounds were elucidated based on extensive 1D and 2D NMR spectroscopic data. Compounds 1-8 were investigated in vitro for their anticholinesterase activity using a rat cortex AChE enzyme.

Acetylcholinesterase inhibitors from Stephania venosa tuber

Acetylcholinesterase (AChE) inhibitors have lately gained interest as potential drugs in the treatment of Alzheimer's disease. Three AChE inhibitors were isolated from tubers of a Thai medicinal plant, Stephania venosa (Bl) Spreng. They were identified as quaternary protoberberine alkaloids, stepharanine, cyclanoline and N-methyl stepholidine. They expressed inhibitory activity on AChE with IC50 values (concentration that caused 50% inhibition of activity) of 14.10 +/- 0.81, 9.23 +/- 3.47 and 31.30 +/- 3.67 microM, respectively. The AChE inhibitory activity of these compounds was compared with those of the related compounds, palmatine, jatrorrhizine and berberine, as well as tertiary protoberberine alkaloids isolated from the same plant, stepholidine and corydalmine. The results suggest that the positive charge at the nitrogen of the tetrahydroisoquinoline portion, steric substitution at the nitrogen, planarity of the molecule or substitutions at C-2, -3, -9, and -10 affect the AChE inhibitory activity of protoberberine alkaloids.

Effect of berberine on proliferation, cell cycle and apoptosis in HeLa and L1210 cells.

Previous studies on the anticancer activity of protoberberine alkaloids against a variety of cancer cell lines were extended to human tumour HeLa and murine leukemia L1210 cell lines. An attempt was also made to investigate the relationship between the cytotoxic activity of berberine and its molecular mechanism of action. Cytotoxicity was measured in-vitro using a primary biochemical screening according to Oyama and Eagle, and the growth inhibition assay. The in-vitro cytotoxic techniques were complemented by cell cycle analysis and determination of apoptotic DNA fragmentation in L1210 cells. Berberine acted cytotoxically on both tumour cell lines. The sensitivity of leukemia L1210 cells to the berberine was higher than that of HeLa cells. The IC(100) was below 100 microg mL(-1) for HeLa cells and approached a 10 microg mL(-1) limit for the leukemia L1210 cells. For both cell lines the IC(50) was found to be less than 4 microg mL(-1), a limit put forward by the National Cancer Institute (NCI) for classification of the compound as a potential anticancer drug. In L1210 cells treated with 10-50 microg mL(-1) berberine, G(0)/G(1) cell cycle arrest was observed. Furthermore, a concentration-dependent decrease of cells in S phase and increase in G(2)/M phase was detected. In addition, apoptosis detected as sub-G(0) cell population in cell cycle measurement was proved in 25-100 microg mL(-1) berberine-treated cells by monitoring the apoptotic DNA fragmentation (DNA ladder) using agarose gel electrophoresis.

Considerable Change of Fluorescence Properties upon Multiple Binding of Coralyne to 4-Sulfonatocalixarenes

The interaction of coralyne, an analogue of natural protoberberine alkaloids, with 4-sulfonatocalixarenes (SCXn) was studied in aqueous solution at pH 2 to reveal the major factors determining the stability, stoichiometry, and fluorescent properties of the species formed. Addition of SCXn to coralyne solution brought about remarkable fluorescence intensity diminution and hypochromism in the 300-440 nm absorption domain. SCXn hosts were capable of binding as many coralyne molecules as the number of their hydroxybenzenesulfonate units. The SCXn-promoted interaction among coralyne molecules was evidenced by the appearance of a long-lived fluorescence component. In dilute alkaloid solution, 1:1 and 1:2 coralyne/4-sulfonatocalix[4]arene complexes were formed, but only 1:1 association occurred with 4-sulfonatocalix[8]arene. Time-resolved fluorescence measurements demonstrated that photoinduced electron transfer from a hydroxybenzenesulfonate moiety to the singlet-excited coralyne can compete efficiently with the other deactivation processes.

Increased Plasma Exposures of Five Protoberberine Alkaloids from Coptidis Rhizoma in Streptozotocin-Induced Diabetic Rats: Is P‐GP Involved?

Our previous study showed a higher exposure of berberine, palmatine, coptisine, epiberberine and jatrorrhizine in 6-week streptozotocin (STZ)-induced diabetic rats, after oral administration of Coptidis Rhizoma extract. The aim of the present study was to investigate whether the function and expression of intestinal P-glycoprotein (P-GP) was downregulated in STZ-induced diabetic rats and if the impairment of P-GP function and expression contributed to the exposure increase of the five protoberberine alkaloids. Plasma concentration-time profiles of the drugs in the portal vein were obtained after oral administration of Coptidis Rhizoma extract. The effective permeability of the drug across duodenum and ileum were measured using in situ single-pass intestine perfusion. P-GP function in the rat intestine was assessed by measuring the absorption of rhodamine 123 (Rho123). P-GP levels were evaluated using Western blots. It was found that the C(max) and AUC(0-8) values of five alkaloids in the portal vein of diabetic rats were significantly higher than those in the control rats. Diabetic rats also exhibitd a higher level of Rho123 in the portal vein, which showed impairment of P-GP function. A higher effective permeability of the tested drug was found in the duodenum of diabetic rats using in situ single-pass intestine perfusion, indicating that berberine and Rho123 transported more easily across the intestinal barrier of diabetic rats. A lower level of P-GP protein was found in the duodenum, jejunum and ileum of the diabetic rats as compared with age-matched control rats. All these results suggested that the function and expression of P-GP were impaired in the intestine of STZ-induced diabetic rats which, at least partly, contributed to the exposure increase of the five protoberberine alkaloids.

A new benzylisoquinoline alkaloid from Argemone mexicana

A new benzylisoquinoline alkaloid, argemexirine, together with two known protoberberine alkaloids, dl-tetrahydrocoptisine and dihydrocoptisine, have been isolated from the methanolic extract of the whole plant of Argemone mexicana L. The compounds were identified by spectral and chemical evidence. This is the first report of these alkaloids in this plant species.

Molecular recognition of poly(A) targeting by protoberberinealkaloids: in vitro biophysical studies and biological perspectives

The use of small molecules to specifically control important cellular functions through binding to nucleic acids is an area of major current interest at the interface of chemical biology and medicinal chemistry. The polyadenylic acid [poly(A)] tail of mRNA has been recently established as a potential drug target due to its significant role in the initiation of translation, maturation and stability of mRNA as well as in the production of alternate proteins in eukaryotic cells. Very recently some small molecule alkaloids of the isoquinoline group have been found to bind poly(A) with remarkably high affinity leading to self-structure formation. Plant alkaloids are small molecules known to have important traditional roles in medicinal chemistry due to their extensive biological activity. Especially, noteworthy are the protoberberine alkaloids that are widely distributed in several botanical families exhibiting myriad therapeutic applications. This review focuses on the structural and biological significance of poly(A) and interaction of protoberberine alkaloids with this RNA structure for the development of new small molecule alkaloids targeted to poly(A) structures as futuristic therapeutic agents.

Anti-Helicobacter pylori Activity and Structure-Activity Relationships of Berberine Derivatives

and urease, which play important roles in pathogenesis of gastric ulcers. Nine synthetic protoberberine alkaloids (four 8-alkyl-dihydro-berberines, two 8-alkyl-berberines, and three 12-bromo-8-alkyl- berberines) (Scheme 1), including three unreported analogs, and natural berberine and palmatine were tested for elucidation of both their activity and their structure-activity relationships. The effect of growth inhibition by berberine (

Quantitative Determination of Protoberberine Alkaloids in Tinospora cordifolia by RP-LC-DAD

Tinospora cordifolia, known as Guduchi in Ayurveda, is a medicinal plant popular mainly for immunomodulatory activity. Its therapeutic activity may be attributed to protoberberine alkaloids such as jatrorrhizine, palmatine and berberine. A new, simple RP-LC-DAD method has been developed for separation, simultaneous identification and quantitative estimation of these protoberberine alkaloids in T. cordifolia extracts and formulations. The developed method was validated based on ICH-Q2B guidelines and was found to be accurate, precise and linear over a relatively wide range of concentrations (0.65–83.33 μg mL−1). This method can serve as a useful quality control tool for T. cordifolia and its formulations.