Search

Odontonema strictum (Acanthaceae) leave extract was investigated for its flavonoid content. Column chromatography was used for compound isolation and mass spectrometry was performed using electrospray ionization (ESI) in the negative ion mode for compound identification. The full characterization of luteolin 7- O -[β-D-apiofuranosyl-(1 → 2)- O -β-D-ribofuranoside], a flavone glycoside, was achieved using tandem mass spectrometry and high resolution 1D and 2D Nuclear Magnetic Resonance (NMR). Among the 10 flavonoids glycosides detected in the ethanol extract, beside the isolated one, 3 flavone glycosides with luteolin or apigenin aglycone were tentatively identified., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Yvonne L Bonzi Coulibaly reports financial support was provided by International Science Programme (ISP)., (© 2024 The Authors. Published by Elsevier Ltd.)

Aims: Diets and parasites influence the gut bacterial symbionts of bumble bees, but potential interactive effects remain overlooked. The main objective of this study was to assess the isolated and interactive effects of sunflower pollen, its phenolamides, and the widespread trypanosomatid Crithidia sp. on the gut bacterial symbionts of Bombus terrestris males., Methods and Results: Bumble bee males emerged in microcolonies fed on either (i) willow pollen (control), (ii) sunflower pollen, or (iii) willow pollen spiked with phenolamide extracts from sunflower pollen. These microcolonies were infected by Crithidia sp. or were pathogen-free. Using 16S rRNA amplicon sequencing (V3-V4 region), we observed a significant alteration of the beta diversity but not of the alpha diversity in the gut microbial communities of males fed on sunflower pollen compared to males fed on control pollen. Similarly, infection by the gut parasite Crithidia sp. altered the beta diversity but not the alpha diversity in the gut microbial communities of males, irrespective of the diet. By contrast, we did not observe any significant alteration of the beta or alpha diversity in the gut microbial communities of males fed on phenolamide-enriched pollen compared to males fed on control pollen. Changes in the beta diversity indicate significant dissimilarities of the bacterial taxa between the treatment groups, while the lack of difference in alpha diversity demonstrates no significant changes within each treatment group., Conclusions: Bumble bees harbour consistent gut microbiota worldwide, but our results suggest that the gut bacterial communities of bumble bees are somewhat shaped by their diets and gut parasites as well as by the interaction of these two factors. This study confirms that bumble bees are suitable biological surrogates to assess the effect of diet and parasite infections on gut microbial communities., (© The Author(s) 2023. Published by Oxford University Press on behalf of Applied Microbiology International.)

Phenolamides are abundant specialized metabolites found in nature and consist of hydroxycinnamic acids mono- or polyconjugated with polyamines. Their participation in flower development is well-documented, and their presence in pollen raises the question of their role in pollen/pollinator interactions. The structural characterization of phenolamides is complicated by the presence of positional isomers and stereoisomers. Liquid chromatography coupled to tandem mass spectrometry in the positive ionization mode is becoming very popular in phenolamide structural characterization. However, collision-induced transamidation processes that cause the swapping of side chains have been detected, making it difficult to distinguish regioisomers with this technique. In the present report, we explore the dissociation processes undergone by the [M - H] - ions of spermidine-based phenolamides as model compounds. We describe two original competitive dissociation routes, namely, the phenolate and imidate pathways, to account for the observed fragmentation reactions undergone by collisional activated standard phenolamide anions. Whereas the phenolate pathway is regioselective at the central position for spermidine, the imidate pathway, requiring a deprotonated amide, only occurs at the extremities. Tandem mass spectrometry experiments on negatively charged phenolamide ions may then outperform their positive ionization mode counterparts for the distinction between phenolamide regioisomers and globally for the identification of phenolamides in natural extracts.

Specific floral resources may help bees to face environmental challenges such as parasite infection, as recently shown for sunflower pollen. Whereas this pollen diet is known to be unsuitable for the larval development of bumble bees, it has been shown to reduce the load of a trypanosomatid parasite ( Crithidia bombi ) in the bumble bee gut. Recent studies suggested it could be due to phenolamides, a group of compounds commonly found in flowering plants. We, therefore, decided to assess separately the impacts of sunflower pollen and its phenolamides on a bumble bee and its gut parasite. We fed Crithidia -infected and -uninfected microcolonies of Bombus terrestris either with a diet of willow pollen (control), a diet of sunflower pollen (natural diet) or a diet of willow pollen supplemented with sunflower phenolamides (supplemented diet). We measured several parameters at both microcolony (i.e., food collection, parasite load, brood development and stress responses) and individual (i.e., fat body content and phenotypic variation) levels. As expected, the natural diet had detrimental effects on bumble bees but surprisingly, we did not observe any reduction in parasite load, probably because of bee species-specific outcomes. The supplemented diet also induced detrimental effects but by contrast to our a priori hypothesis, it led to an increase in parasite load in infected microcolonies. We hypothesised that it could be due to physiological distress or gut microbiota alteration induced by phenolamide bioactivities. We further challenged the definition of medicinal effects and questioned the way to assess them in controlled conditions, underlining the necessity to clearly define the experimental framework in this research field.