Chemotaxonomic investigation of Apocynaceae for retronecine-type pyrrolizidine alkaloids using HPLC-MS/MS

Pyrrolizidine alkaloids are synthesized and accumulated in flower of Myosotis scorpioides

Pyrrolizidine alkaloids (PAs) are specialized metabolites that are produced by various plant families that act as defense compounds against herbivores. On the other hand, certain lepidopteran insects uptake and utilize these PAs as defense compounds against their predators and as precursors of their sex pheromones. Adult males of Parantica sita, a danaine butterfly, convert PAs into their sex pheromones. In early summer, P. sita swarms over the flowers of Myosotis scorpioides, which belongs to the family Boraginaceae. M. scorpioides produces PAs, but the organs in which PAs are produced and whether P. sita utilizes PAs in M. scorpioides are largely unknown. In the present study, we clarified that M. scorpioides accumulates retronecine-core PAs in N-oxide form in all organs, including flowers. We also identified two M. scorpioides genes encoding homospermidine synthase (HSS), a key enzyme in the PA biosynthetic pathway, and clarified that these genes are expressed in all organs where PAs accumulate. Phylogenetic analysis suggested that these two HSS genes were originated from gene duplication of deoxyhypusine synthase gene like other HSS genes in PA-producing plants. These results suggest that PAs are synthesized and accumulated in the flower of M. scorpioides and provide a possibility for a PA-mediated interaction between P. sita and M. scorpioides.

High-performance liquid chromatography analysis of alkaloids in various parts of lotus extracts with ion mobility spectrometry and mass spectrometry dual detection

Using high-performance liquid chromatography coupled with electrospray ionization-ion mobility spectrometry and mass spectrometry, we proposed a dual-detection method for the identification and profiling of alkaloids in various lotus parts including leaf, plumule, stem, seed epicarp, and receptacle. The eluent from high-performance liquid chromatography was split and conducted to electrospray ionization-ion mobility spectrometry and time-of-flight mass spectrometry separately to facilitate the compound identification. In total, 23 kinds of alkaloids were identified based on m/z, drift time, and retention time, including alkaloid isomers such as lirinidine, N-nornuciferine, and O-nornuciferine with identical m/z that are difficult to differentiate using mass spectrometry alone. Using this method, we investigated the changing dynamics of alkaloid accumulation in lotus leaves and lotus stems at different harvesting periods. The total alkaloid content showed an increasing trend with the growth and development of leave and stem. Overall, the developed dual detection method has the advantages of high peak capacity and high sensitivity compared with the conventional detection method and facilitates the identification of detected compounds.

Pyrrolizidine Alkaloids-Pros and Cons for Pharmaceutical and Medical Applications

Heterocyclic organic compounds named pyrrolizidine alkaloids (PAs) belong to a group of alkaloids and are synthesized by either plants or microorganisms. Therefore, they are naturally occurring secondary metabolites. They are found in species applied in the pharmaceutical and food industries, thus a thorough knowledge of their pharmacological properties and toxicology to humans is of great importance for their further safe employment. This review is original because it synthesizes knowledge of plant and microbial PAs, which is unusual in the scientific literature. We have focused on the Boraginaceae family, which is unique due to the exceptional richness and diversity of its PAs in plant species. We have also presented the microbial sources of PAs, both from fungi and bacteria. The structure and metabolism of PAs have been discussed. Our main aim was to summarize the effects of PAs on humans, including both negative, toxic ones, mainly concerning hepatotoxicity and carcinogenicity, as well as potentially positive ones for pharmacological and medical applications. We have collected the results of studies on the anticancer activity of PAs from plant and microbial sources (mainly Streptomyces strains) and on the antimicrobial activity of PAs on different strains of microorganisms (bacteria and fungi). Finally, we have suggested potential applications and future perspectives.

Phytochemical and Biological Study of Trophic Interaction between Pseudosphinx Tetrio L. Larvae and Allamanda Cathartica L

In this article, we propose to explore the chemical interaction between Pseudosphinx tetrio L. and Allamanda cathartica L. using different analytical methods, including an innovative electrochemical approach (called electrochemical ecology) and multivariate analysis, and we investigate the potential antimicrobial effects (antibacterial and antifungal activities) of this interaction in order to gain a better understanding of their specific interaction. The analytical study presents a similar chemical profile between the leaves of healthy and herbivorous A. cathartica and the excretions of the caterpillars. The similar analytical profile of the leaves of A. cathartica and the excretions of P. tetrio, and the difference with the caterpillar bodies, suggests a selective excretion of compounds by the caterpillar. The measured antimicrobial activities support the physicochemical tests. The natural products found selectively in the excretions (rather than in the body) could explain the ability of P. tetrio to feed on this toxic Apocynaceae species.

Comparative in vivo antimalarial activities of aqueous and methanol extracts of MAMA powder - A herbal antimalarial preparation

ETHNOPHARMACOLOGICAL RELEVANCE

The choice of extraction solvent is a significant consideration in ethnomedicine as optimal extraction could influence the bioactivity of the herbal medicinal product.

AIM OF STUDY

This study investigated the possible influence of the choice of solvents (methanol and water) for extracting MAMA Powder (MP) against Plasmodium berghei-infected mice to optimize its antimalarial activity and for developing other pharmaceutical dosage forms.

MATERIALS AND METHODS

Aqueous and methanol extracts of MP, obtained through the decoction and soxhlet methods, respectively, were subjected to liquid chromatography-mass spectroscopy (LC-MS) for their respective fingerprints. The antimalarial activities of the methanol and aqueous extracts (12.5-100 mg/kg) were evaluated orally using the chemosuppressive test model on chloroquine-sensitive Plasmodium berghei-infected mice. The methanol extract was subjected to the established infection and prophylactic antimalarial tests with chloroquine (10 mg/kg) and pyrimethamine (1.25 mg/kg) as positive controls, respectively. The aqueous extract was investigated in chloroquine-resistant P. berghei using the chemosuppressive (12.5-800 mg/kg) and established infection (25-400 mg/kg) antimalarial models.

RESULTS

The LC-MS fingerprints of both aqueous and methanol extracts revealed similar indole alkaloid contents. Chemosuppressive activity of the aqueous extract (75.3%) was significantly (p < 0.05) higher than the methanol extract (67.6%). In the chloroquine-resistant P. berghei infection experiments, the aqueous extract (400 mg/kg) exhibited significant parasite clearance (72%).

CONCLUSION

The study concluded that the water extract with higher antimalarial activity could be optimized for chloroquine-resistant malaria and can thus facilitate the production of liquid and solid dosage forms.