nutrients and heavy metals in flowers and corms of the saffron crocus crocus sativus l

We used ICP mass spectrometry and gas chromatography to examine the nutritional properties of the flower organs of saffron crocus grown in two cultivation fields. The pollenkitt consisted of a variety of mainly unsaturated fatty acids of dietary value, and fats of the same type were also on the anther wall. Microelements important for the human body were at concentrations allowable in both pollen and anther wall cells. Lead and mercury were below allowable levels, unlike arsenic which in pollen of the Field A was 1.70 μg/g, and cadmium which in the Field B was 0.29 μg/g in pollen and 0.43 μg/g in the anther wall cells. The contamination of the stamens was associated with the high concentration of heavy metals found in the soil. Phosphorus, magnesium and calcium were high and sodium low in both pollen and anther wall cells, regardless of the cultivation fields. Styles and corms were rich in macroelements and not contamined by heavy metals. If on one hand pollen and anthers of saffron deserve attention as dietary supplements, on the other it must be taken into due account their tendency to absorb toxic metals from the soil

Assessing chemical mechanisms underlying the effects of sunflower pollen on a gut pathogen in bumble bees

Many pollinator species are declining due to a variety of interacting stressors including pathogens, sparking interest in understanding factors that could mitigate these outcomes. Diet can affect host-pathogen interactions by changing nutritional reserves or providing bioactive secondary chemicals. Recent work found that sunflower pollen (Helianthus annuus) dramatically reduced cell counts of the gut pathogen Crithidia bombi in bumble bee workers (Bombus impatiens), but the mechanism underlying this effect is unknown. Here we analyzed methanolic extracts of sunflower pollen by LC-MS and identified triscoumaroyl spermidines as the major secondary metabolite components, along with a flavonoid quercetin-3-O-hexoside and a quercetin-3-O-(6-O-malonyl)-hexoside. We then tested the effect of triscoumaroyl spermidine and rutin (as a proxy for quercetin glycosides) on Crithidia infection in B. impatiens, compared to buckwheat pollen (Fagopyrum esculentum) as a negative control and sunflower pollen as a positive control. In addition, we tested the effect of nine fatty acids from sunflower pollen individually and in combination using similar methods. Although sunflower pollen consistently reduced Crithidia relative to control pollen, none of the compounds we tested had significant effects. In addition, diet treatments did not affect mortality, or sucrose or pollen consumption. Thus, the mechanisms underlying the medicinal effect of sunflower are still unknown; future work could use bioactivity-guided fractionation to more efficiently target compounds of interest, and explore non-chemical mechanisms. Ultimately, identifying the mechanism underlying the effect of sunflower pollen on pathogens will open up new avenues for managing bee health