Alkaloids of Aconitum barbatum

Chemical components of Aconitum barbatum var. puberulum and their cytotoxic and antibacterial activities

Nineteen compounds, including seventeen alkaloids O-methylarmepavine (1), (S)-6-methoxy-1-(4-methoxybenzyl)-2-methyl -1,2,3,4-tetrahydroisoquinolin-7-ol (2), (+)-(IR,laR)-lahydroxymagnocurarin (3), (6R,6aS,P)-(+)-corydine (4), (+)-N-methyllaurotetanine (5), magnoflorine (6), 3-hydroxy-1,2-dimethoxy-5-methyl-5H-dibenzoindol-4-one (7), imperialine (8), crispine B (9), (S)-1-(3-methoxyphenyl)-N-methylpropan-2-amine (10), methyl 2- (acetamino)benzoate (11), 2-carboxyoxanilic acid methylester (12), 4-[2-(methoxycarbonyl) anilino]-4-oxobutanoic acid methyl ester (13), N-methylcorydaldine (14), N-methyl-6,7- dimethoxyisoquinolone (15), (5S,6R,7S,8R)-5-amino-(2Z,4Z)-1,2,3-trihybuta-2,4-dienyloxypentane- 6,7,8,9-tetraol (16), nicotinic acid (17), and two megastigmane type compounds, S(+)- dehydrovomifoliol (18) and megastigmane (19), were isolated from the Aconitum barbatum var. puberulum Ledeb. Compounds 1-3 and 5-19 were isolated from this plant for the first time, of which compound 11 was isolated from natural source for the first time. Cytotoxicity evaluation revealed that compound 5 displayed mild cytotoxicity against the Hela cell lines (IC50 13.69 ± 0.036 μM). Antibacterial activity evaluation revealed that compounds 1 and 6 showed strong antibacterial activity against the Gram-positive bacterium, S. aureus.

The diterpenoid alkaloids

The diterpenoid alkaloids are a family of extremely important natural products that have long been a research hotspot due to their myriad of intricate structures and diverse biological properties. This chapter systematically summarizes the past 11 years (2009-2019) of studies on the diterpenoid alkaloids, including the "so-called" atypical ones, covering the classification and biogenetic relationships, phytochemistry together with 444 new alkaloids covering 32 novel skeletons and the corrected structures, chemical reactions including conversion toward toxoids, synthetic studies, as well as biological activities. It should be noted that the synthetic studies, especially the total syntheses of various diterpenoid alkaloids, are for the first time reviewed in this treatise. This chapter, in combination with our four previous reviews in volumes 42, 59, 67, and 69, will present to the readers a more completed and updated profile of the diterpenoid alkaloids.

C18-diterpenoid alkaloids in tribe Delphineae (Ranunculaceae): phytochemistry, chemotaxonomy, and bioactivities

This review systematically summarizes the C18-diterpenoid alkaloid (DA) compositions isolated from the genera Aconitum and Delphinium in the Delphineae tribe (Ranunculaceae). A total of 117 distinct C18-DA components have been reported, including 58 lappaconitine-type DAs, 54 ranaconitine-type DAs, and five rearranged-type DAs. These components mainly originated from plants from the subgenus Lycoctonum in the genus Aconitum or less frequently from plants within the genus Delphinium. Natural C18-DAs have exhibited a wide range of bioactivities, including analgesic, antiarrhythmic, anti-inflammatory, anti-tumor, and insecticidal activities, which are closely related to their chemical structures. The high chemical and biological diversities among the reported C18-DA constituents in Delphineae plants indicated their potential as a vast resource for drug discovery. Additionally, the Delphineae plant C18-DAs exhibited chemotaxonomic values and showed a high regularity of distribution at different taxonomic levels; therefore, the Delphineae plant C18-DAs can serve as good chemical molecular markers in the taxonomic treatment of plants within this tribe, especially in the infrageneric division.

Diterpenoid alkaloids from Aconitum barbatum var. puberulum Ledeb

Seven previously undescribed diterpenoid alkaloids, including five C₂₀-diterpenoid alkaloids, barpuberudine, barpubesines A-D, and two C₁₈-diterpenoid alkaloids, barpubenines A-B, along with 11 known diterpenoid alkaloids were isolated from the whole plant of Aconitum barbatum var. puberulum Ledeb. (Ranunculaceae). Barpuberudine is an unprecedented carbon skeleton of C₂₀-diterpenoid alkaloid, while barpubenines A-B are the first example of rearranged types in C₁₈-diterpenoid alkaloids. Their structures were elucidated based on a comprehensive spectroscopic data analysis. The probable pathway of biogenesis of barpuberudine and barpubenines A-B were discussed. Additionally, the antiarrhythmic, cytotoxic and antimicrobial activities of isolates were also evaluated.

Puberunine and puberudine, two new C18-diterpenoid alkaloids from Aconitum barbatum var. puberulum

Two C(18)-diterpenoid alkaloids, puberunine (1) and puberudine (2), together with four other new alkaloids, including the first examples having β-oriented substitution at C-3 and a rare chloro-substituent were isolated from Aconitum barbatum var. puberulum. Their structures were elucidated by spectroscopic methods. Puberunine and puberudine, which possess a unique rearranged E ring and an opened A ring, respectively, represent new subtypes of the C(18)-diterpenoid alkaloids. A plausible biosynthetic pathway of 1 and 2 was proposed.

Two new 18-carbon norditerpenoid alkaloids from Aconitum sinomontanum

Two new 18-carbon norditerpenoid alkaloids, sinaconitines A (1) and B (2), together with two known alkaloids, ranaconitine (3) and lappaconitine (4), were isolated from the roots of Aconitum sinomontanum. Their structures were elucidated on the basis of spectral evidences and X-ray crystallographic analysis for 1. Furthermore, the reversed 13C NMR assignments for C-10 and C-13 of 3, 4, puberanine, puberanidine and demethyllappaconitine were revised. Compounds 1-4 were evaluated for cyclooxygenase-2 (COX-2) enzyme inhibitory activity. However, they did not show any inhibition at 10 microM.

Alkaloids of Aconitum laeve and their anti-inflammatory antioxidant and tyrosinase inhibition activities

A lycoctonine-type norditerpenoid alkaloid, swatinine (1), along with four known norditerpenoid alkaloids, delphatine (3), lappaconitine (4), puberanine (5), and N-acetylsepaconitine (6), and were isolated from the aerial parts of Aconitum laeve Royle. Compound 2 has been isolated for the first time from a natural source. The structure of compound 1 was deduced on the basis of spectral data. The anti-inflammatory, antioxidant and tyrosinase inhibition studies on all six compounds have also been carried out.

Isolation of a multidrug resistance inhibitor from Aconitum pseudo-laeve var. erectum

To overcome multidrug resistance (MDR) in cancer chemotherapy, we prepared various plant extracts and searched for a component which is effective for inhibition of MDR. MDR inhibition activity was determined by measuring cytotoxicity to MDR cells using multidrug resistant human fibrocarcinoma KB V20C, which is resistant to 20 nM vincristine and expresses high level of mdr1 gene. Of various plant extracts, the MeOH extract of the root of Aconitum pseudo-laeve var. erectum was found to have potent inhibitory activity on MDR. The bioassay-guided fractionation of the MeOH extract of the plant led to the isolation of an alkaloid, lycaconitine, as an active principle. And the IC50 of lycaconitine for KB V20C cells was 74 micrograms/ml.