João Benhur Mokochinski

Comparative Study of Chemical Composition and Biological Activity of Yellow, Green, Brown, and Red Brazilian Propolis

The chemical composition and biological activity of a sample of yellow propolis from Mato Grosso do Sul, Brazil (EEP-Y MS), were investigated for the first time and compared with green, brown, and red types of Brazilian propolis and with a sample of yellow propolis from Cuba. Overall, EEP-Y MS had different qualitative chemical profiles, as well as different cytotoxic and antimicrobial activities when compared to the other types of propolis assessed in this study and it is a different chemotype of Brazilian propolis. Absence of phenolic compounds and the presence of mixtures of aliphatic compounds in yellow propolis were determined by analysing 1H-NMR spectra and fifteen terpenes were identified by GC-MS. EEP-Y MS showed cytotoxic activity against human tumour strain OVCAR-8 but was not active against Gram-negative or Gram-positive bacteria. Our results confirm the difficulty of establishing a uniform quality standard for propolis from diverse geographical origins. The most appropriate pharmacological applications of yellow types of propolis must be further investigated.

Drought tolerance of sugarcane is improved by previous exposure to water deficit

Under field conditions, plants are exposed to cycles of dehydration and rehydration during their lifespan. In this study, we hypothesized that sugarcane plants previously exposed to cycles of water deficits will perform better than plants that have never faced water deficits when both are subjected to low water availability. Sugarcane plants were grown in a nutrient solution and exposed to one (1WD), two (2WD) or three (3WD) water deficit cycles. As the reference, plants were grown in a nutrient solution without adding polyethylene glycol. Under water deficits, leaf gas exchange was significantly reduced in 1WD and 2WD plants. However, 3WD plants showed similar CO2 assimilation and lower stomatal conductance compared to the reference plants, with increases in intrinsic water-use efficiency. Abscisic acid concentrations were lower in 3WD plants than in 1WD plants. Our data revealed root H2O2 concentration as an important chemical signal, with the highest root H2O2 concentrations found in 3WD plants. These plants presented higher root dry matter and root:shoot ratios compared to the reference plants, as well as higher biomass production when water was available. Our data suggest that sugarcane plants were able to store information from previous stressful events, with plant performance improving under water deficits. In addition, our findings provide a new perspective for increasing drought tolerance in sugarcane plants under nursery conditions.

Photoacoustic spectroscopy applied to the direct detection of bioactive compounds in Agaricus brasiliensis mycelium

This paper describes the application of the photoacoustic spectroscopic (PAS) for detection of bioactive compounds in Agaricus brasiliensis mycelium. The mycelium was cultivated by solid-state fermentation and by submerged fermentation. Vegetal residues from food industry were used as substrates for fermentation: apple pomace (Malus domestica), wheat (Triticum aestivum), peel and pomace of pineapple (Ananas comosus), malt (Hordeum vulgare) and grape pomace (Vitis vinifera). Dry and ground samples of biomass were directly put into the PA cell. The optical absorption spectra indicated the existence of three main absorption bands: one around 280 nm related to phytosterols (ergosterol), phenolic acids, flavonoids and aromatic amino acids, another at 340 nm, due to phenolic and flavonoid compounds, and the third one at around 550 nm associated with anthocyanins and anthocyanidins. A correlation between the PA signal and the total phenolic content was satisfactory, as well as for the analyzed spectrum region (270 nm up to 1000 nm), using multivariate methods. Our results indicated that PA technique may be considered as an analytical tool to quickly detect bioactive compounds in mushrooms without the need of sample pretreatment.

An integrated analysis of mRNA and sRNA transcriptional profiles in Coffea arabica L. roots: insights on nitrogen starvation responses

Coffea arabica L. is an important agricultural commodity, accounting for 60% of traded coffee worldwide. Nitrogen (N) is a macronutrient that is usually limiting to plant yield; however, molecular mechanisms of plant acclimation to N limitation remain largely unknown in tropical woody crops. In this study, we investigated the transcriptome of coffee roots under N starvation, analyzing poly-A+ libraries and small RNAs. We also evaluated the concentration of selected amino acids and N-source preferences in roots. Ammonium was preferentially taken up over nitrate, and asparagine and glutamate were the most abundant amino acids observed in coffee roots. We obtained 34,654 assembled contigs by mRNA sequencing, and validated the transcriptional profile of 12 genes by RT-qPCR. Illumina small RNA sequencing yielded 8,524,332 non-redundant reads, resulting in the identification of 86 microRNA families targeting 253 genes. The transcriptional pattern of eight miRNA families was also validated. To our knowledge, this is the first catalog of differentially regulated amino acids, N sources, mRNAs, and sRNAs in Arabica coffee roots.

Chemical Variability of Geopropolis from Jataí, Mandaçaia and Mandurí Stingless Bees

Stingless bees (meliponinae) are popularly known as native bees and are important pollinators of many crops. Honey from these insects has a palatable flavor and is sold at higher values than Apis mellifera honey. In addition, beehives from stingless bees are marketed with ornamental and environmental purposes. Despite the economic growth of meliponiculture, studies with meliponinae beehive products are scarce. Stingless bees produce geopropolis which consists of plant resins mixed with soil or clay. In the current study the chemical, qualitative and quantitative composition and the antiradical activity of geopropolis produced by different Meliponinae species occurring in Prudentópolis, Paraná were compared. Antiradical activity, as well as total phenolic and flavonoid contents were determined. Spectral profiles by UV-Vis Spectroscopy and Mass Spectrometry with Electrospray Ionization (ESI-MS) were compared as well. The effect of the native bee species (Tetragonisca angustula (Latreille), Melipona quadrifasciata quadrifasciata (Lepeletier) e Melipona marginata (Lepeletier)) and the harvest period on the chemical variability of geopropolis was assessed by statistical tools such as analysis of variance (ANOVA) and multivariate analysis (Principal Component Analysis, PCA). It was observed that both investigated effects, bee species and harvest period, significantly affected the levels of total phenolics and flavonoids and the antiradical activity. Additionally, 12 components of geopropolis were identified by UPLCMS/MS. PCA grouped geopropolis as function of the bee species, indicating that, for the same geographic region, the overall chemical composition of geopropolis is mainly determined by the stingless bee species.