Honey is a rich source of carbohydrates, while minor compounds such as amino acids and polyphenols contribute to its health-promoting effects. Honey is one of the oldest traditional remedies applied for microbial infections, due to its antibacterial, anti-inflammatory, and antioxidant properties. The aim of this study was to investigate the antibacterial and antibiofilm effects of Hungarian black locust, linden, and sunflower honeys against the most common biofilm-forming respiratory tract pathogens Haemophilus spp., Pseudomonas aeruginosa, and Streptococcus pneumoniae. The unifloral character of all three honey types was confirmed by melissopalynological analysis. The antibacterial activity of each honey sample against each bacterium strain was proven with agar well diffusion assay and thin layer chromatography—direct bioautography. Kinetics and mechanisms of antibacterial action were clarified with time-kill assay and membrane degradation study. The anti-biofilm activity was evidenced using crystal violet assay. In each assay, linden honey was the most effective, followed by sunflower and black locust honey. In addition, each honey sample had greater potential to suppress respiratory tract bacteria, compared to major sugar components. In conclusion, honey in general and linden honey in particular, can have a role in the treatment of respiratory tract infections caused by biofilm-forming bacteria.

Floral rewards such as nectar and pollen have a major influence on successful pollination and fruit-set, even in selffertile Rubus sp. (Rosaceae), which include most cultivated raspberries and blackberries. A 2-year study was designed to examine the diurnal dynamics of nectar secretion and pollen shedding in the raspberry cultivars ‘Autumn Bliss’ and ‘Malling Exploit’, and in the blackberry cultivars ‘Arapaho’ and ‘Hull’, in order to establish the effect of these traits on floral attractiveness to various insect visitors. The volume of nectar secreted per flower was measured using calibrated capillaries, and the concentrations of sugars in the nectar were measured using a hand-held refractometer. The four Rubus cultivars differed in their patterns of nectar and pollen presentation. Volumes of nectar and concentrations of sugars were influenced by year, cultivar, age of the flower, and time of sampling. The four cultivars exhibited different patterns of nectar secretion over the 2 years. In year-1, an early morning peak in nectar volume was followed by a rapid decline, while the concentrations of sugars increased during the day. In year-2, both the volume of nectar and the concentrations of sugars increased from the morning to the afternoon. The patterns of pollen presentation were similar in both years of study. Anther dehiscence took only 3 - 8 h per flower in the poorest nectar producer, ‘Arapaho’; while, in cultivars with higher nectar yields, pollen shedding lasted for 6 - 10 h. Pollen-shedding flowers secreted significantly higher volumes of nectar, with significantly lower concentrations of sugars, compared to pre-pollen-shedding flowers in year-1. The concentrations of sugars in the nectar were higher in both raspberry cultivars than in the blackberry cultivars, but both blackberry cultivars were as attractive to bees due to their more appealing nectar sugar composition. Bees were more attracted to flowers of cultivars which simultaneously offered ample nectar and some pollen (i.e., ‘Autumn Bliss’, ‘Malling Exploit’, and ‘Hull’) than to flowers with a rapid rate of pollen shedding, but a low nectar yield (i.e., ‘Arapaho’). Higher rates of bee-mediated cross-pollination may provide economically important increases in fruit yields and better quality fruit.

The goal of the study was to evaluate the pollen spectrum, antioxidant capacity and mineral content of four Hungarian honey types, using multivariate statistical analysis. The light colored honeys were represented by milkweed honey and a multifloral (MF) honey with dominant pollen frequency of linden (MF-Tilia); the darker ones were goldenrod honey and a multifloral honey with Lamiaceae pollen majority (MF-Lamiaceae). The pollen spectrum of the samples was established with melissopalynological analysis. The absorbance of the honeys positively correlated with the antioxidant capacity determined with three of the used methods (TRC, TEAC, DPPH), but not with ORAC. The latter method correlated negatively also with other antioxidant methods and with most of the mineral values. MF-Tilia had high ORAC value, K and Na content. The MF-Lamiaceae had the highest K, Mg, P, S, Cu and Zn content, the last five elements showing strict correlation with the TRC method. The darker goldenrod honey had higher SET values and total mineral content, than the milkweed honey. The above character-sets facilitate identification of each honey type and serve as indicators of variety. The antioxidant levels and mineral content of honeys allowed their clear separation by principal component analysis (PCA).

Lutein and its cis-isomers occur in a lot of plants, including a variety of flowers. In this study, lutein isomers were produced via iodine-catalyzed isomerization, and four cis-isomers (9Z-, 9′Z-, 13Z-, and 13Z′) were isolated by means of column chromatography and semipreparative HPLC. The structures of the 9′Z- and 13′Z-isomers were elucidated via NMR measurements. These compounds were used as standards for the HPLC-DAD-MS determination of the carotenoid composition of the flowers of 20 plant species, in which lutein and its geometrical isomers are the main components. The flowers showed great variation in their cis- and trans-lutein content, and also in the presence or absence of other carotenoids, such as violaxanthin, neoxanthin, β-cryptoxanthin, and β-carotene. Some of the investigated flowers were found to be rich sources of lutein without zeaxanthin.