Quaternary Protoberberine Alkaloids Research Articles

Synthesis and Cytotoxicity Assessment against Human Colorectal Cancer Cell Lines of Quaternary 8-Dichloromethyl Protoberberine Alkaloids.

Twenty-two quaternary 8-dichloromethylprotoberberine alkaloids were synthesized from unmodified quaternary protoberberine alkaloids (QPAs) to improve their physical and chemical properties and to obtain selectively anticancer derivatives. The synthesized derivatives showed more appropriate octanol/water partition coefficients by up to values 3-4 compared to unmodified QPA substrates. In addition, these compounds exhibited significant antiproliferative activity against colorectal cancer cells and lower toxicity on normal cells, resulting in more significant selectivity indices than unmodified QPA compounds in vitro. The IC50 values of antiproliferative activity of quaternary 8-dichloromethyl-pseudoberberine 4-chlorobenzenesulfonate and quaternary 8-dichloromethyl-pseudopalmatine methanesulfonate against colorectal cancer cells are 0.31 μM and 0.41 μM, respectively, significantly stronger than those of other compounds and positive control 5-fluorouracil. These findings suggest that 8-dichloromethylation can be used as one of the modification strategies to guide the structural modification and subsequent investigation of anticancer drugs for CRC based on QPAs.

Natural protoberberine alkaloid–montmorillonite nanocomposite powders with AIE features for visualizing high-resolution latent fingerprints

Real-time and in-situ fluorescence visualization technologies have attention to in the forensic analysis of latent fingerprints (LFPs). The fingerprint powders with high performance and biocompatibility are essential for imaging LFPs with high definition and safety. In this work, five quaternary protoberberine alkaloid (QPA) derivatives were analyzed with reorganization energy and four-point calculations to explain the relationship between the substituent effect and luminescent properties and further resolve the luminous behaviors of four QPA-based natural products in solution. Thanks to the restriction of the intramolecular motions mechanism, aggregation-induced emission (AIE) active BBC nanoaggregates could sensitively detect explosive analog, 2,4,6-trinitrophenol, at a nanomolar level (9.8 nM of detection limit). Combined with natural montmorillonite (MMT) mineral powders, three levels of details for fingerprints were successfully imaged with solid-luminous BBC/MMT nanocomposites. The insight into the substituted effect of alkoxy groups on the QPA framework not only provides a new concept to design rotor-free AIE luminogens but also expands natural products and their nanocomposites into LFP and detection applications.

Chemoproteomics Reveals That Quaternary Protoberberine Alkaloids Inhibit Telomerase Activity Oncologically by Binding to PES1.

Natural QPAs have anti-cancer property. The prodrugs of QPAs synthesized in our work with significantly improved solubility showed significantly stronger activity in animal experiments. Nevertheless, the mechanism of action of QPAs for treating cancers remains poorly understood. Here, a chemoproteomic study reveals that QPAs non-covalently and multivalently bind to PES1 in CRC cells, which impinges on the direct interaction between hTERT and hTR in the assembly of the telomerase complex, downregulates telomerase activity, and so promotes the aging process of CRC cells. This study is beneficial for us to conduct extensively the pharmaceutical chemistry research of QPAs.

Antiplasmodial and antimalarial evaluation of a Nigerian hepta-herbal Agbo-iba decoction: Identification of magic bullets and possible facilitators of drug action

Ethnopharmacological relevanceMalaria remains one of the most important pathogenic infectious diseases. Although Africa suffers the greatest brunt, a sizeable proportion of her population still relies on herbal medicines for reasons of cost as well as the belief etched in the minds of consumers that herbal medicines are safer and more efficacious than Modern medicines. Agbo-iba; a concoction of two or more than two plants is commonly used for the management of malaria in Nigeria. Aim of the studyThis study assessed the safety and efficacy of a hepta-herbal Agbo-iba (HHA) antimalarial decoction used for the management of malaria in Benin city, Nigeria. Materials and methodsAssessment was done against malaria parasite in culture as well as in vivo in pre-clinical murine model of malaria. ResultsHHA (IC50Pf3D7 50 μg/ml) was moderately potent and only one of its constituent plants Annickia affinis (IC50Pf3D7 1.49 μg/ml) was far more potent, while all others were moderately active to inactive against the parasite in vitro. HHA showed good selectivity in vitro and was safe at 2 g/kg in mice. However, at 100 mg/kg oral dose, while HHA suppressed parasite growth by 56.76%, the suppression caused by A.affinis was only 32.46% in mice malaria suggesting the existence of synergistic partner(s) in the herbal formula. LCMS revealed the presence of quaternary protoberberine alkaloids (QPAs) in A.affinis and HHA. ConclusionsAlthough QPAs have strong in vitro antiplasmodial activity, their in vivo antimalarial activity is undermined by being substrates of Permeability glycoprotein (Pgp) efflux pump. Our study suggests that inhibitor(s) of Pgp in HHA could improve the bioavailability of QPAs in mice fed the herbal combo. Further, molecules from other HHA constituent plants may also contribute to the better potency observed for the polyherbal in vivo. These possibilities were validated by the curative antimalarial study at 100 mg/kg, where A.affinis was inactive but the HHA suppressed parasite growth by 44.45%.

1297-P: Berberine Derivatives as Novel Antidiabetes Agents Targeting Intestinal AMPK and Antimicrobial Peptide-Controlled Gut Microbiome

Mammalian 5′-AMP-activated protein kinase (AMPK) is a key nutrient sensor for maintaining cellular energy status and a known therapeutic target for glucose control in type 2 diabetes (T2D) . Despite current understandings of its well-established roles in regulating glucose metabolism in various tissues, AMPK functions in the intestine, the first-line organ for nutrient processing, remains largely elusive. We have uncovered a novel link between intestinal AMPK activation and brown adipose tissue (BAT) thermogenic regulation through modulating the anti-microbial peptide (AMP) -controlled gut microbiota and their metabolites. Therefore, the intestinal AMPK-AMP-microbiota-BAT axis is a potential target for the treatment of T2D. Berberine, a quaternary ammonium protoberberine alkaloid with an isoquinoline scaffold isolated from medicinal herbs, has been used to treat T2D in animal models as well as human trials, while offsetting renal, cardiovascular, hepatic, and respiratory risks. However, its poor bioavailability severely limits its application and development. As such, there is a dire need to explore structural modifications of berberine to obtain better pharmacological properties and elucidate its underlying mechanisms of action. Berberine can activate AMPK indirectly by inhibition of mitochondrial respiration in the adipocyte, myotubes and liver; however, its effects on intestinal AMPK are still unknown. We have successfully synthesized natural and non-natural novel berberine derivatives. We will determine their antidiabetes effects and elucidate the underlying mechanisms of action in targeting the intestinal AMPK-AMP pathways for T2D treatment. Moreover, our study will provide a better structure-activity relationship to guide the future design of berberine derivatives with higher potency and improved bioavailability. Disclosure E.Zhang: None.

Alkaloid Escholidine and Its Interaction with DNA Structures.

Simple SummaryEscholidine is a rare protoberberine alkaloid present in trace amounts in roots of Eschscholtzia californica and in the aerial parts of Hunnemannia fumariaefolia. Due to the characteristic charged structure, it can interact with various forms of nucleic acids, including non-canonical structures. A series of spectroscopic experiments have shown notable melting stabilization of antiparallel G-quadruplex sequence DL40 induced by escholidine (ΔTm = 5.2 °C). Interaction stoichiometry calculated from fluorescence titration curves was estimated to be 4:1 or 5:1 (alkaloid:DNA). Nuclear Magnetic Resonance (NMR) experiments have confirmed that an external loop binding is likely responsible for this stabilization. The three-dimensional model of the complex between escholidine and DL40, obtained as a result of the molecular docking experiment, implies the preferred orientation of escholidine to the quadruplex structure. Since the stabilization of telomeric G-quadruplex structures by small ligands is often used as a strategy in anti-cancer therapy, alkaloid escholidine seems to be an interesting agent from a medicinal point of view.Berberine, the most known quaternary protoberberine alkaloid (QPA), has been reported to inhibit the SIK3 protein connected with breast cancer. Berberine also appears to reduce the bcl-2 and XIAP expression-proteins responsible for the inhibition of apoptosis. As some problems in the therapy with berberine arose, we studied the DNA binding properties of escholidine, another QPA alkaloid. CD, fluorescence, and NMR examined models of i-motif and G-quadruplex sequences present in the n-myc gene and the c-kit gene. We provide evidence that escholidine does not induce stabilization of the i-motif sequences, while the interaction with G-quadruplex structures appears to be more significant.

Divergent total syntheses of pseudoberberine and nitidine through C[sbnd]H vinylation and switchable 6π electrocyclizations

Quaternary protoberberine alkaloids and quaternary benzophenanthridine alkaloids are two biosynthetically related natural product families of biological importance. Although significant advances have been achieved in the synthetic chemistry of these alkaloids, a unified approach to these tetracyclic pyridinium-contained alkaloids remains elusive until our recent report. Herein, we report a concise, modular, divergent approach to two of them, pseudoberberine and nitidine, based on our newly developed strategy in five and seven steps. The key transformations include an Ag-promoted annulation, an isoquinoline-directed CH vinylation, and switchable aza-6π- or all-carbon-6π-electrocyclization.

(+)- and (–)-Corydecumbenines A and B, two pairs of novel quaternary protoberberine alkaloid cycloadduct enantiomers with anti-neuroinflammatory and neuroprotective activities from the rhizomes of Corydalis decumbens

Two novel Diels-Alder [4 + 2] cycloadducts of quaternary protoberberine alkaloids and fumaric acid monoanion, corydecumbenines A and B (1 and 2), and six known isoquinoline analogues (3–8) were isolated from the rhizomes of Corydalis decumbens. The planar structures of 1 and 2 were elucidated by extensive spectroscopic analysis including UV, IR, HRESIMS, 1D and 2D NMR. Chiral chromatography of 1 and 2 afforded two pairs of enantiomers (+)-corydecumbenine A (1a), (–)-corydecumbenine A (1b), (+)-corydecumbenine B (2a), and (–)-corydecumbenine B (2b), respectively, and their absolute configurations were determined by single-crystal X-ray crystallography and comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1b and 2b exhibited significant nitric oxide (NO) inhibitory activities in lipopolysaccharide (LPS)-stimulated BV-2 cells with IC50 values of 11.6 and 16.2 μM, respectively, comparable to the positive control indomethacin (IC50 = 10.3 μM), and they could also decrease the level of interleukin (IL)-1β in BV-2 cells in a dose-dependent manner. Most of the isolates showed neuroprotective effects against the injury of OGD/R-induced PC12 cells at 20 μM.

Quaternary protoberberine alkaloids and their interactions with DNA

The G-quadruplex DNA is commonly present in several protooncogenic-DNA promoters and participates in many important biological processes such as replication, transcription, and translation. Because of their supposed role in cancer, G-quadruplex DNA is often studied as a target for anti-cancer drugs. Quaternary protoberberine and tetrahydroprotoberberine alkaloids (corysamine, coptisine, stylopine), which are supposed to selectively bind these structures, have been compared in terms of stability with selected types of DNA. Influence of selected alkaloids on the stability of double-stranded DNA and non-canonical forms of DNA was observed by determining association constants of alkaloid–DNA complexes using spectroscopic methods—molecular absorption spectrometry, fluorescence spectrometry, and mass spectrometry. Furthermore, the effect of given alkaloids on the melting temperature of these DNA structures was determined using CD spectrometry. Competitive dialysis and electrospray mass spectrometry were performed for affinity comparison of certain alkaloids to different DNA structures including G-quadruplexes. These experiments have proven that corysamine and coptisine prefer interaction with G-quadruplexes in comparison to dsDNA and ssDNA, whereas tetrahydroprotoberberine alkaloid stylopine does not interact with any DNA whatsoever.

A new dimeric protoberberine alkaloid and other compounds from the tubers of Tinospora dentata

A new dimeric quaternary protoberberine alkaloid, bispalmatrubine (1), and thirteen known compounds (2-14) were purified from the tubers of Tinospora dentata. Their structures were determined by spectroscopic and spectrometric analytical methods. Among the isolates, eight compounds were examined for their in vitro anti-inflammatory potential and several tested alkaloids displayed moderate inhibitory effects of N-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLP/CB)-induced superoxide anion generation and elastase release.

Evaluation of anti-onchocercal activity of pseudopalmatine, a quaternary protoberberine alkaloid of Enantia chlorantha (Syn. <i>Annickia chlorantha</i>)

As part of our efforts towards identifying and subsequently developing lead compounds from medicinal plants of Cameroon to combat neglected tropical diseases, we embarked to phytochemically investigate Enantia chlorantha (Syn. Annickia chlorantha). The rationale for choosing this plant is its numerous uses in folk medicine in Cameroon and other parts of Africa. In Cameroon the quaternary protoberberine alkaloids, columbamine (2), palmatine (3) and jatrorrizine (4) have been isolated from the stem back and combined to produce a phytomedicine (HEPAZOR®) used in the treatment of viral hepatitis. An alkaloidal extraction of the methanolic extract of the stem bark of the plant was carried-out and this afforded yellow amorphous solids whose structure was obtained using routine nuclear magnetic resonance spectroscopy (NMR), high pressure liquid chromatography coupled to an electrospray mass spectrometer (HPLC-ESI-MS) and comparison with literature. The compound was identified as pseudopalmatine (1), a quaternary protoberberine alkaloid. Preliminary screening of the compound on both adult and juvenile worms of Onchocerca ochengi, a close relative of Onchocerca volvulus, the parasite responsible for human onchocerciasis (river blindness), showed that compound (1) was inactive at a concentration of 500 μg/mL on the adult worms, but inhibited microfilariae motility completely at this same concentration and by 50 % at 250 μg/mL and was thus considered active. While this work to the best of our knowledge constitutes the first report on the anti-onchocercal activity of quaternary protoberberine alkaloids in general and pseudopalmatine (1) in particular isolated from E. Chlorantha, it has however opened a window for further investigation of the anti-onchoceral activity of this class of compounds. Key words: anti-onchocercal, pseudopalmatine, alkaloid, Enantia chlorantha

Elucidation of Compatibility Interactions of Traditional Chinese Medicines: In Vitro Absorptions Across Caco-2 Monolayer of Coptidis Rhizoma and Euodiae Fructus in Zuojin and Fanzuojin Formulas as A Case.

Traditional Chinese medicines are often combined as formulae and interact with each other. As for Coptidis Rhizoma (CR) and Euodiae Fructus (EF), the most classical compatibilities were Zuojin (ZJF) and Fanzuojin formulas (FZJF) with reverse mixture ratios and opposite effects. To compare in vitro absorption interactions between CR and EF, bidirectional transports across Caco-2 cell monolayer of extracts of two formulas and equivalent single herbs were studied. Eighteen alkaloids from CR and EF were determined by liquid chromatography coupled to tandem mass spectrometry. Parameter apparent permeability coefficient (Papp ) and efflux rate (ER) values showed that most alkaloids were well or moderately absorbed and six quaternary protoberberine alkaloids from CR had obvious efflux. ZJF compatibilities reduced both Papp BL→AP and ER values of three indole alkaloids, and increased ER values of two quinolone alkaloids from EF. FZJF compatibilities obviously affected the bidirectional Papp values of CR alkaloids, weakened ERs of five protoberberines from CR and enlarged ERs of two quinolones from EF. Conclusions were drawn that different compatibility ratios of CR and EF led to different interactions on the in vitro absorption of alkaloids. The results may provide a good reference for interaction studies on the compatibilities of traditional Chinese medicines. Copyright © 2017 John Wiley & Sons, Ltd.

Pharmacokinetics Studies of 12 Alkaloids in Rat Plasma after Oral Administration of Zuojin and Fan-Zuojin Formulas.

Zuojin formula (ZJ) is a traditional Chinese medicine (TCM) prescription consisted of Coptidis Rhizoma (CR) and Euodiae Fructus (EF), and has been used to treat gastrointestinal (GI) disease for more than 700 years. Fan-Zuojin formula (FZJ) is a related TCM prescription also consisted of CR and EF with the opposite proportion. In recent years, ZJ was getting more attention for its antitumor potential, but the indeterminate pharmacokinetic (PK) behavior restricted its clinical applications, and the PK differences between ZJ and FZJ were also largely unknown. Consequently it is necessary to carry out a full-scale PK study to demonstrate the physiological disposition of ZJ, as well as the comparative PK study between ZJ and FZJ to illustrate the compatibility dose effects. Therefore a liquid chromatographic–tandem mass spectrometry (LC–MS/MS) method was established and validated for the determinations of coptisine, epiberberine, palmatine, berberine, 8-oxocoptisine, 8-oxoepiberberine, noroxyhydrastinine, corydaldine, dehydroevodiamine, evodiamine, wuchuyuamide-I, and evocarpine in rat plasma. PK characteristics of 12 alkaloids after oral administration of ZJ and FZJ were compared, and the result was analyzed and discussed with the help of an in silico study. Then an integrated PK study was carried out with the AUC-based weighting method and the total drug concentration method. The established method has been successfully applied to reveal the PK profiles of the 12 alkaloids in rat plasma after oral administration of ZJ and FZJ. The results showed that: (1) double peaks were observed in the plasma concentration-time (C–T) curves of the alkaloids after ZJ administration; but the C–T curves approximately matched the two-compartment model after FZJ administration; (2) There were wide variations in the absorption levels of these alkaloids; and even for a certain alkaloid, the dose modified systemic exposure levels and elimination rate also varied significantly after administration of ZJ and FZJ extracts. The results could be interpreted as follows: firstly, inhibition effect on GI motility caused by the high content CR alkaloids (especially berberine) in ZJ could delay the Tmax, and increase the absorption and systemic exposure levels of the other alkaloids, and also lead to the double peak phenomenon of these alkaloids. However, for quaternary protoberberine alkaloids (QPA), double peaks were primarily caused by the different Ka value in two intestinal absorption sites; Secondly, absorption was the major obstacle to the systemic exposure level of the alkaloids from CR and EF. In silico and PK studies suggested that the absorption of these alkaloids, except QPAs, mainly depended on their solubility rather than permeability; Thirdly, EF could promote the absorption and accelerate the elimination of QPAs, and had a greater influence on the former than the latter. At last the integrated PK analysis suggested that berberine and dehydroevodiamine could be regarded as the representative components to reflect the PK behaviors of CR and EF alkaloids after administration of ZJ and FZJ. In conclusion, the absorption, elimination and systemic exposure level of these alkaloids were mainly influenced by the proportion of EF and CR, the pharmacological effect on GI motility, and the physicochemical property of these alkaloids. These findings would be helpful for a better understanding of the activities and clinical applications of ZJ, FZJ and other related TCM prescriptions.

Acetylcholinesterase Inhibitory Activity of Alkaloids Isolated from Stephania venosa

Stephania venosa (Blume) Spreng or "Sa-Bu-Leud" is a Thai medicinal plant used for treatment of cancer and diabetes, and as a blood-tonic and aphrodisiac. This plant .ontains alkaloids as its major components and has been of interest for its acetylcholinesterase (AChE) inhibitory activity. Phytochemical screening - of S. venosa was made using HPLC analysis and showed the chemical variation between the same species from different provenances. Fractionation of .S..venosa extract yielded three alkaloids, namely, dicentrine, crebanine, and tetrahydropalmatine. AChE inhibitory potential of the isolated alkaloids was evaluated using Ellman's AChE inhibition assay. Dicentrine, crebanine, and tetrahydropalmatine inhibited-AChE activity with IC(50) values of 93.5, 86.6, and 168.6 μg/mL, respectively. The AChE inhibitory activity of the tertiary protoberberine alkaloid, tetrahydropalriiatine, was lower than that of the aporphine alkaloids, dicentrine and crebanine, whereas the quaternary protoberberine alkaloid, berberine, showed a higher AChE inhibitory effect than the others.

New synthetic method of 8-oxocoptisine starting from natural quaternary coptisine as anti-ulcerative colitis agent

Quaternary coptisine (1), a natural bioactive quaternary protoberberine alkaloid (QPA), was treated with potassium ferricyanide in aqueous solution of 5 N sodium hydroxide leading to the acquisition of 8-oxocoptisine (2) with much higher yield than reported in the literature. This is the first report of the oxidation of a natural QPA by applying potassium ferricyanide as an oxidant. 8-Oxocoptisine showed significant anti-ulcerative colitis efficacy in vitro with EC50 value being 8.12 × 10− 8 M.

A new quaternary protoberberine alkaloid isolated from Dicranostigma leptopodum (Maxim) Fedde

Phytochemical investigation of the whole plants of Dicranostigma leptopodum (Maxim) Fedde has led to the isolation of two quaternary protoberberine alkaloids 5-hydroxy-coptisine (1) and berberrubine (2). This type of alkaloids was isolated from the genus Dicranostigma for the first time and the new compound structure (1) was elucidated by various spectroscopic methods including 2D NMR techniques (gCOSY, HMQC and HMBC) and HR-ESI-MS.

Inhibitory Effect of Extract from Twelve Chinese Medical Herbs and Two Active Quaternary Protoberberine Alkaloid from Coptis chinensis Franch

Inhibitory Effect of Extract from Twelve Chinese Medical Herbs and Two Active Quaternary Protoberberine Alkaloid from Coptis chinensis Franch

Two new quaternary protoberberine alkaloids from Corydalis yanhusuo

Two new quaternary protoberberine alkaloids, namely corydayanine (1) and yanhusuine (2), were isolated from the tubers of Corydalis yanhusuo. On the basis of extensive chemical and spectroscopic evidences, especially 1D and 2D NMR and HRMS experiments, their structures were elucidated as 5,6-dihydro-3,9-dihydroxy-2,10-dimethoxy-13-methyl-dibenzo[a,g] quinolizinium alkaloid and 5,6-dihydro-12-hydroxy-2,3,9-trimethoxy-13-methyl-dibenzo[a,g] quinolizinium alkaloid, respectively.

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.

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 .