Chemical composition and acaricidal activity of essential oils from two species of the genus Bauhinia that occur in the Cerrado biome in Brazil

Volatile profile and micropropagation conditions of Bauhinia forficata Link

Bauhinia forficata Link. is a native South American plant, which possesses volatile compounds with pharmaceutical and medicinal properties such as antidiabetic and anti-inflammatory effects. However, the conservation and propagation of this plant are complicated by its recalcitrant seeds and delayed flowering transition. Hence, tissue culture is employed for the safe and efficient propagation of B. forficata. However, the optimal conditions for the in vitro cultivation of B. forficata remain unknown. Thus, this study aimed to characterize the volatile profile of adult B. forficata field plants and evaluate the effects of different light intensities (43 and 70 μmol m-2 s-1), gas exchange rates (14 and 25 µL L-1 s-1), and exogenous sucrose concentrations (0, 20, and 30 g L-1) on their in vitro development. The results showed that β-caryophyllene is the major volatile compound produced by B. forficata. Moreover, culturing in a medium containing 30 g L-1 of sucrose and flasks with membranes that allow CO2 exchange at the rate of 25 µL L-1 s-1 produced vigorous and hardened plants with high survival rates independent of irradiance. This study is the first to report the optimal in vitro culture conditions for B. forficata as a reference for future studies on micropropagation and secondary metabolite production using this species.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03634-8.

The use of pracaxi oil collector in the selective flotation of xenotime from silicates

Rare earth elements have played a key role in technological advancement, attracting great visibility in the global commodity market. Xenotime, a heavy rare earth resource (YPO₄), can be found associated with granitic rocks, as in the Pitinga deposit, located in the Brazilian Amazon region, where the main gangue minerals are quartz, microcline and albite. This research investigates the application of a new collector produced from pracaxi oil, an Amazon oil abundant in Brazil, in the selective flotation between xenotime and its main gangue minerals. The study conducted the synthesis and characterization of the collector, the chemical, mineralogical and surface characterization of minerals, as well as the evaluation of collector adsorption and flotability via microflotation tests, zeta potential measurements, surface tension determination and XRD, WDXRF, ICP-MS, FTIR and XPS analyses. The pracaxi collector was found to be mainly composed of oleic acid (56.2%), linoleic acid (14.1%) and behenic acid (10.6%), in addition to exhibiting a critical micelle concentration (CMC) of approximately 150 mg/L. Microflotation tests indicated that the best condition for selective recovery of xenotime occur at alkaline condition (pH 9.0), presenting selectivity of approximately 90% with collector concentration of 10.0 mg/L. The zeta potential data confirmed a selective adsorption of pracaxi collector onto xenotime, with an increase in the surface charge from -30 mV to -68 mV, whereas no significant changes were detected in the silicates. The FTIR spectra showed the appearance of a band at 1545 cm^-1 on the surface of the xenotime after collector adsorption, which indicates, along with the zeta potential data, the chemical nature of the adsorption. The presence of small amounts of iron in the lattice structure of silicate gangues can act as an activator, and therefore, may be responsible for the small flotability of these minerals. The performance of the pracaxi oil collector presented in this study indicates the great potential of this Amazonian oil for application in the selective flotation of xenotime ores found in the region.

Application of essential oils as natural biopesticides; recent advances

There is an urgent need for the development of sustainable and eco-friendly pesticide formulations since common synthetic pesticides result in many adverse effects on human health and the environment. Essential oils (EOs) are a mixture of volatile oils produced as a secondary metabolite in medicinal plants, and show activities against pests, insects, and pathogenic fungi. Their chemical composition is affected by several factors such as plant species or cultivar, geographical origin, environmental conditions, agricultural practices, and extraction method. The growing number of studies related to the herbicidal, insecticidal, acaricidal, nematicidal, and antimicrobial effects of EOs demonstrate their effectiveness and suitability as sustainable and environment-friendly biopesticides. EOs can biodegrade into nontoxic compounds; at the same time, their harmful and detrimental effects on non-target organisms are low. However, few biopesticide formulations based on EOs have been turned into commercial practice upto day. Several challenges including the reduced stability and efficiency of EOs under environmental conditions need to be addressed before EOs are widely applied as commercial biopesticides. This work is an overview of the current research on the application of EOs as biopesticides. Findings of recent studies focusing on the challenges related to the use of EOs as biopesticides are also discussed.

Plant Natural Sources of the Endocannabinoid (E)-β-Caryophyllene: A Systematic Quantitative Analysis of Published Literature

(E)-β-caryophyllene (BCP) is a natural sesquiterpene hydrocarbon present in hundreds of plant species. BCP possesses several important pharmacological activities, ranging from pain treatment to neurological and metabolic disorders. These are mainly due to its ability to interact with the cannabinoid receptor 2 (CB2) and the complete lack of interaction with the brain CB1. A systematic analysis of plant species with essential oils containing a BCP percentage > 10% provided almost 300 entries with species belonging to 51 families. The essential oils were found to be extracted from 13 plant parts and samples originated from 56 countries worldwide. Statistical analyses included the evaluation of variability in BCP% and yield% as well as the statistical linkage between families, plant parts and countries of origin by cluster analysis. Identified species were also grouped according to their presence in the Belfrit list. The survey evidences the importance of essential oil yield evaluation in support of the chemical analysis. The results provide a comprehensive picture of the species with the highest BCP and yield percentages.