Efficient one-pot synthesis of anti-HIV and anti-tumour β-carbolines

Design and Synthesis of Fluorescent 1,3-Diaryl-β-carbolines and 1,3-Diaryl-3,4-dihydro-β-carbolines

The 1,3-diaryl-β-carboline derivatives, including 3,4-dihydro variants, were synthesized via a multiple-step approach. These compounds possess rigid and twisted configurations, which are expected to exhibit unique optical properties. The absorption and fluorescence properties of the newly synthesized compounds were investigated. These synthetic 1,3-diaryl-β-carbolines displayed strong emission in the range of 387-409 nm and exhibited absolute photoluminescence quantum yields of up to 74%. Density functional theory calculations were performed to better elucidate the geometric, electronic, and optical properties of these novel 1,3-diaryl-β-carbolines.

Selectivity-tunable oxidation of tetrahydro-β-carboline over an OMS-2 composite catalyst: preparation and catalytic performance

Controlling the reaction selectivity of organic transformations without losing high conversion is always a challenge in catalytic processes. In this work, a H3PO4·12WO3/OMS-2 nanocomposite catalyst ([PW]-OMS-2) was prepared through the oxidation of a Mn(ii) salt with sodium phosphotungstate by KMnO4. Comprehensive characterization indicates that different Mn2+ precursors significantly affected the crystalline phase and morphology of the as-synthesized catalysts and only MnSO4·H2O as the precursor could lead to a cryptomelane phase. Moreover, [PW]-OMS-2 demonstrated excellent catalytic activity toward aerobic oxidative dehydrogenation of tetrahydro-β-carbolines due to mixed crystalline phases, enhanced surface areas, rich surface oxygen vacancies and labile lattice oxygen species. In particular, β-carbolines and 3,4-dihydro-β-carbolines could be obtained from tetrahydro-β-carbolines with very high selectivity (up to 99%) over [PW]-OMS-2 via tuning the reaction solvent and temperature. Under the present catalytic system, scalable synthesis of a β-carboline was achieved and the composite catalyst showed good stability and recyclability. This work not only clarified the structure-activity relationship of the catalyst, but also provided a practical pathway to achieve flexible, controllable synthesis of functional N-heterocycles.

β-carboline alkaloids attenuate bleomycin induced pulmonary fibrosis in mice through inhibiting NF-kb/p65 phosphorylation and epithelial-mesenchymal transition

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Arenaria kansuensis is used in traditional medicine to treat lung inflammation for a long time. However, the anti-pulmonary fibrosis effect and its corresponding bioactive constituents of this plant have not been studied extensively.

AIM OF THE STUDY

The purpose of this study was to investigate the anti-pulmonary fibrosis effect and its corresponding bioactive constituents of A. kansuensis and its possible mechanism.

MATERIALS AND METHODS

In vivo experiment, the anti-pulmonary fibrosis effects of the fraction (Part1) enriched from ethyl acetate extracts of the whole plant A. kansuensis were evaluated through bleomycin (BLM)-induced pulmonary fibrosis mice (five groups, n = 10) daily at doses of 50, 100 and 150 mg/kg for 15 days. In vitro experiment, the anti-inflammation and reversed epithelial-mesenchymal transition (EMT) effect of 12 β-carboline alkaloids isolated from Part1 were evaluated through lipopolysaccharide (LPS)-induced RAW264.7 inflammatory cell model and TGF-β1 induced A549 cell model.

RESULTS

In this study, a fraction named Part1 extracted from Arenaria kansuensis presented strong anti-pulmonary fibrosis effect at the dose of 150 mg/kg. Vivo experiments showed that the survival rate and body weight of mice significantly increased after Part1 treatment. Part1 could significantly inhibit the initial of inflammation, deposition of collagen and expression of TGF-β1 and α-SMA, moreover, the expression of E-cadherin was significantly elevated after administration of Part1. All the cure effects of Part1 were in dose dependent manner. A total of 12 β-carboline alkaloids were identified in Part1 and they all showed suppressive effect on inflammatory cytokines including MCP-1, TNF-α, IL-6 and IL-1β through inhibition of NF-kb/p65 phosphorylation, and that epithelial-mesenchymal transition (EMT) process was reversed by different compounds in different levels. The expression of indicators of EMT including α-SMA, vimentin and E-cadherin was significantly improved after given different β-carboline alkaloids.

CONCLUSIONS

This study showed that antifibrogenic effect of β-carboline alkaloids was due to inhibiting the initial of inflammation through NF-kb/p65 pathway and reversing the process of EMT.

Direct Biomimetic Synthesis of β-Carboline Alkaloids from Two Amino Acids

The increasing importance of enzyme mimics in organic synthesis inspired us to design a novel biomimetic synthesis of β-carboline alkaloids directly from tryptophan and a second amino acid. This novel one-pot protocol utilizes abundant and readily available starting materials and thus presents a green and user-friendly alternative to conventional methods that rely on stepwise synthesis. Driven by molecular iodine and TFA, decarboxylation, deamination, Pictet-Spengler reaction, and oxidation reactions proceeded sequentially, transforming biomass amino acids into value-added alkaloid motifs.

A review on traditional uses, phytochemistry, pharmacology, pharmacokinetics and toxicology of the genus Peganum

ETHNOPHARMACOLOGICAL RELEVANCE

The plants of the genus Peganum have a long history as a Chinese traditional medicine for the treatment of cough, hypertension, diabetes, asthma, jaundice, colic, lumbago, and many other human ailments. Additionally, the plants can be used as an amulet against evil-eye, dye and so on, which have become increasingly popular in Asia, Iran, Northwest India, and North Africa.

AIM OF THE REVIEW

The present paper reviewed the ethnopharmacology, phytochemistry, analytical methods, biological activities, metabolism, pharmacokinetics, toxicology, and drug interaction of the genus Peganum in order to assess the ethnopharmacological use and to explore therapeutic potentials and future opportunities for research.

MATERIALS AND METHODS

Information on studies of the genus Peganum was gathered via the Internet (using Google Scholar, Baidu Scholar, Elsevier, ACS, Pudmed, Web of Science, CNKI and EMBASE) and libraries. Additionally, information was also obtained from some local books, PhD and MS's dissertations.

RESULTS

The genus Peganum has played an important role in traditional Chinese medicine. The main bioactive metabolites of the genus include alkaloids, flavonoids, volatile oils, etc. Scientific studies on extracts and formulations revealed a wide range of pharmacological activities, such as cholinesterase and monoamine oxidase inhibitory activities, antitumor, anti-hypertension, anticoagulant, antidiabetic, antimicrobial, insecticidal, antiparasidal, anti-leishmaniasis, antioxidant, and anti-inflammatory.

CONCLUSIONS

Based on this review, there is some evidence for extracts' pharmacological effects on Alzheimer's and Parkinson's diseases, cancer, diabetes, hypertension. Some indications from ethnomedicine have been confirmed by pharmacological effects, such as the cholinesterase, monoamine oxidase and DNA topoisomerase inhibitory activities, hypoglycemic and vasodilation effects of this genus. The available literature showed that most of the activities of the genus Peganum can be attributed to the active alkaloids. Data regarding many aspects of the genus such as mechanisms of actions, metabolism, pharmacokinetics, toxicology, potential drug interactions with standard-of-care medications is still limited which call for additional studies particularly in humans. Further assessments and clinical trials should be performed before it can be integrated into medicinal practices.

C3-Selective alkenylation of N-acylindoles with unactivated internal alkynes by cooperative nickel/aluminium catalysis

Highly regio- and stereoselective alkenylation of N-acylindoles with unactivated internal alkynes has been accomplished by cooperative nickel/aluminium catalysis to afford C3-alkenylated indoles.

Palladium-catalyzed oxidative cyclization of aniline-tethered alkylidenecyclopropanes with O2: a facile protocol to selectively synthesize 2- and 3-vinylindoles

A facile and versatile palladium catalyzed oxidative cyclization of aniline-tethered alkylidenecyclopropanes with O₂ to selectively construct important synthetic intermediates 2- and 3-vinylindoles in moderate to good yields has been developed.

Potent AChE and BChE inhibitors isolated from seeds of Peganum harmala Linn by a bioassay-guided fractionation

ETHNOPHARMACOLOGICAL RELEVANCE

Seeds of Peganum harmala Linn are traditionally used as folk medical herb in Uighur medicine in China to treat disorders of hemiplegia and amnesia. Previously studies have proved that dominating alkaloids in P. harmala show significant inhibitory activities on the cholinesterase.

AIM OF THE STUDY

The aim of the present study is to isolate trace ingredients from seeds of P. harmala and evaluate its inhibitory activities on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).

MATERIALS AND METHODS

For sake of screening effective cholinesterase inhibitors, trace compounds were isolated from seeds of P. harmala through a bioassay-guided fractionation and their structures were determined via detailed spectral analysis. The inhibitory activities on AChE and BChE were assessed using an improved Ellman method by UPLC-ESI-MS/MS to determine the common final product choline.

RESULTS

The activity-guided fractionation led to the isolation of two new alkaloids 2-aldehyde-tetrahydroharmine (10), 2-carboxyl-3,4-dihydroquinazoline (19), one syringin structure analog 1-O-β-D-xylopyranose sinapyl alcohol (22), and along with 19 known compounds. Compounds acetylnorharmine (6), harmic acid methy ester (7), harmine N-oxide (13), 6-methoxyindoline (14), syringin (21) were first found from genus Peganum and compounds 3-hydroxylated harmine (4), 1-hydroxy-7-methoxy-β-carboline (5) were new natural products. The results showed that the 2-aldehyde-tetrahydroharmine (10) has a potential inbibitive effect on both AChE and BChE with IC50 values of 12.35 ± 0.24 and 5.51 ± 0.33 µM, respectively. Deoxyvasicine (15) and vasicine (16) showed the strongest BChE inhibitory activity with IC50 values of 0.04 ± 0.01 and 0.1 ± 0.01 µM. The analysis of the structure-activity relationship indicated that the saturation of pyridine ring and the presence of substitution at indole ring, C-1, C-3, C-7 and N-2, for β-carbolines, were essential for effective inhibition of both AChE and BChE and the five-membered ring between C-2 and N-3 as well as the substituent groups sited at C-4 and C-9, for quinazolines, were important to both the AChE/BChE-inhibitory activity.

CONCLUSIONS

Bioassay-guided fractionation has led to the isolation of AChE and BChE inhibitors from the seeds of P. harmala. These results are in agreement with the traditional uses of the seeds of P. harmala.

Synthesis and antiviral and fungicidal activity evaluation of β-carboline, dihydro-β-carboline, tetrahydro-β-carboline alkaloids, and their derivatives

Six known β-carboline, dihydro-β-carboline, and tetrahydro-β-carboline alkaloids and a series of their derivatives were designed, synthesized, and evaluated for their anti-tobacco mosaic virus (TMV) and fungicidal activities for the first time. All of the alkaloids and some of their derivatives (compounds 3, 4, 14, and 19) exhibited higher anti-TMV activity than the commercial antiviral agent Ribavirin both in vitro and in vivo. Especially, the inactivation, curative, and protection activities of alkaloids Harmalan (62.3, 55.1, and 60.3% at 500 μg/mL) and tetrahydroharmane (64.2, 57.2, and 59.5% at 500 μg/mL) in vivo were much higher than those of Ribavirin (37.4, 36.2, and 38.5% at 500 μg/mL). A new derivative, 14, with optimized physicochemical properties, obviously exhibited higher activities in vivo (50.4, 43.9, and 47.9% at 500 μg/mL) than Ribavirin and other derivatives; therefore, 14 can be used as a new lead structure for the development of anti-TMV drugs. Moreover, most of these compounds exhibited good fungicidal activity against 14 kinds of fungi, especially compounds 4, 7, and 11.

An efficient, mild and solvent-free synthesis of benzene ring acylated harmalines

A facile synthesis of a series of benzene ring acylated analogues of harmaline has been achieved by Friedel-Crafts acylation under solvent-free conditions at room temperature using acyl halides/acid anhydrides and AlCl₃. The reaction afforded 10- and 12-acyl analogues of harmaline in good yield, along with minor quantities of N-acyl-tryptamines and 8-acyl analogues of N-acyltryptamines.

A simple, rapid and mild one pot synthesis of benzene ring acylated and demethylated analogues of harmine under solvent-free conditions

A simple, rapid, solvent-free, room temperature one pot synthesis of benzene ring acylated and demethylated analogues of harmine using acyl halides/acid anhydrides and AlCl₃ has been developed. Eight different acyl halides/acid anhydrides were used in the synthesis. The resulting mixture of products was separated by column chromatography to afford 10- and 12-monoacyl analogues, along with 10,12-diacyl-11-hydroxy products. In five cases the corresponding 10-acyl-11-hydroxy analogues were also obtained. Yields from the eight syntheses (29 products in total) were in the 6-34% range and all compounds were fully characterized.

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit from the beginning up to the end of 2004. Newly isolated alkaloids, structure determinations, total synthesis and biological activities are included.