Chemical Constituents of Plants from Tribe Chelidonieae and their Bioactivities

Fluorescence, Absorption, Chromatography and Structural Transformation of Chelerythrine and Ethoxychelerythrine in Protic Solvents: A Comparative Study

Chelerythrine (CH) and ethoxychelerythrine (ECH) are chemical reference substances for quality control of Chinese herbal medicines, and ECH is the dihydrogen derivative of CH. In this study, their fluorescence and absorption spectra, as well as their structural changes in different protic solvents were compared. It was observed that their emission fluorescence spectra in methanol were almost the same (both emitted at 400 nm), which may be attributed to the nucleophilic and exchange reactions of CH and ECH with methanol molecules with the common product of 6-methoxy-5,6-dihydrochelerythrine (MCH). When diluted with water, MCH was converted into CH, which mainly existed in the form of positively charged CH⁺ under acidic and near-neutral conditions with the fluorescence emission at 550 nm. With the increase of pH value of the aqueous solution, CH⁺ converted to 6-hydroxy-5,6-dihydrochelerythrine (CHOH) with the fluorescence emission at 410 nm. The fluorescence quantum yields of MCH and CHOH were 0.13 and 0.15, respectively, and both the fluorescence intensities were much stronger than that of CH⁺. It is concluded that CH and ECH can substitute each other in the same protic solvent, which was further verified by high-performance liquid chromatography. This study will help in the investigation of structural changes of benzophenanthridine alkaloids and will provide the possibility for the mutual substitution of standard substances in relevant drug testing.

Anti-TMV activity and mode of action of three alkaloids isolated from Chelidonium majus

BACKGROUND

Plant viral diseases are difficult to control and have caused serious damage to the agricultural industry. Recently, botanical biopesticides characterized by environment friendly, safe to non-target organism and not as susceptible to produce drug resistance, have exhibited great potential to be developed as antiviral agents. To screen the natural products with antiviral effect, three alkaloids possessed anti-tobacco mosaic virus (TMV) activity were isolated from Chelidonium majus and the modes of action were investigated.

RESULT

The anti-TMV effect of crude extracts at 10 mg mL^-1 was 51.73%. Bioassay-guided fractionation and isolation of the compounds with anti-TMV activity were performed on the methanol extract of C. majus yielding three bioactive alkaloids namely: chelerythrine (1), chelidonine (2), and sanguinarine (3). The results of bioassay showed that chelerythrine exhibited great inactivation, proliferation inhibition and protection effects against TMV at 0.5 mg mL^-1 with the efficiency of 72.67%, 77.52% and 59.34%, respectively. Chelidonine at 0.1 mg mL^-1 can provide 54.90% and 64.45% inhibitions on TMV through inducing resistance in two kinds of tobacco. Sanguinarine showed a weaker protection for resisting TMV in comparison to chelerythrine and chelidonine.

CONCLUSION

Chelerythrine and chelidonine displayed significant inhibitions on TMV with different modes of action. These results provided important evidence that the extracts in C. majus might be a potential source of new drugs in controlling virus disease agriculturally.

New aporphine alkaloids with selective cytotoxicity against glioma stem cells from Thalictrum foetidum

Seven new isoquinoline alkaloids, 9-(2'-formyl-5', 6'-dimethoxyphenoxy)-1, 2, 3, 10-tetramethoxy dehydroaporphine (1), 9-(2'-formyl-5', 6'-dimethoxyphenoxy)-1, 2, 3, 10-tetramethoxy oxoaporphine (2), 3-methoxy-2'-formyl oxohernandalin (3), (-)-9-(2'-methoxycarbonyl-5', 6'-dimethoxyphenoxy)-1, 2, 3, 10-tetramethoxy aporphine (4), (-)-2'-methoxycarbonyl thaliadin (5), (-)-9-(2'-methoxyethyl-5', 6'-dimethoxyphenoxy)-1, 2, 3, 10-tetramethoxy aporphine (6), (-)-3-methoxy hydroxyhernandalinol (7), together with six known isoquinoline alkaloids (8-13) were isolated from the roots of Thalictrum foetidum. Their structures were elucidated by extensive spectroscopic measurements. Compounds 1 and 2 showed significant selective cytotoxicity against glioma stem cells (GSC-3^# and GSC-18^#) with IC₅₀ values ranging from 2.36 to 5.37 μg·mL^-1.

Hybrid isoquinolines from Thalictrum foetidum: a new type of aporphine inhibiting Staphylococcus aureus by combined mechanisms

Thalfoetines A–D (1–4), unique hybrid aporphine alkaloids with a C-7 aromatic unit formed by a new C–C bond linking two building blocks, were isolated from Thalictrum foetidum.

In silico target fishing and pharmacological profiling for the isoquinoline alkaloids of Macleaya cordata (Bo Luo Hui)

Background

Some isoquinoline alkaloids from Macleaya cordata (Willd). R. Br. (Bo Luo Hui) exhibited antibacterial, antiparasitic, antitumor, and analgesic effects. The targets of these isoquinoline alkaloids are undefined. This study aims to investigate the compound–target interaction network and potential pharmacological actions of isoquinoline alkaloids of M. cordata by reverse pharmacophore database screening.

Methods

The targets of 26 isoquinoline alkaloids identified from M. cordata were predicted by a pharmacophore-based target fishing approach. Discovery Studio 3.5 and two pharmacophore databases (PharmaDB and HypoDB) were employed for the target profiling. A compound–target interaction network of M. cordata was constructed and analyzed by Cytoscape 3.0.

Results

Thirteen of the 65 predicted targets identified by PharmaDB were confirmed as targets by HypoDB screening. The targets in the interaction network of M. cordata were involved in cancer (31 targets), microorganisms (12 targets), neurodegeneration (10 targets), inflammation and autoimmunity (8 targets), parasitosis (5 targets), injury (4 targets), and pain (3 targets). Dihydrochelerythrine (C6) was found to hit 23 fitting targets. Macrophage migration inhibitory factor (MIF) hits 15 alkaloids (C1–2, C11–16, C19–25) was the most promising target related to cancer.

Conclusion

Through in silico target fishing, the anticancer, anti-inflammatory, and analgesic effects of M. cordata were the most significant among many possible activities. The possible anticancer effects were mainly contributed by the isoquinoline alkaloids as active components.