Brazilian Journal of Science

Determination of the environmental impacts of gold mining within the scope of the circular economy: Applications of the new economic model of the European Union

Edip Avşar — 2024-11-19

Following the Industrial Revolution wastes generated in the production and consumption processes have emerged as disruptive elements to ecosystems and threats to the safety of future generations. Resources are finite, limiting the ability to sustain the cycle for a sustainable future. With increasing population and industrial development, the single-use lifestyle of “take, use, discard” has become a significant problem in direct economic strategies. The European Union has led the way in waste management with its circular economy strategy, aiming to 'do more with less' as a long-term approach to economic growth. Today, companies in various industries must set an example for environmental awareness, lifestyle, and consumption habits in society to shift positively. This study focuses on the gold mining sector. Its objective is to examine and evaluate the impact of cyanide used in the purification process on groundwater and surface water resources. A sample facility was selected for analysis. Monthly environmental reports from 2015-2016 were obtained for this facility, allowing the study to examine the effects of cyanide on water sources by comparing available analysis results with the relevant national legislation. As a result, it was found that the cyanide levels at the treatment plant outlet and waste storage facility did not exceed the committed limits, and continuous pollution was not observed in the monitoring wells drilled to assess groundwater contamination.

Phytochemical prospecting, vitamins, total phenolics and flavonoids, and antioxidant and acetylcholinesterase activities of Scleroderma citrinum Persoon (Sc) mushroom extract

Paulo Cesar Barbosa Neto — 2024-11-08

Scleroderma is a genus of Gasteromycetes and Basidiomycota mushrooms in tropical and subtropical regions. This study aimed to evaluate the ethanolic extract of the mushroom Scleroderma citrinum regarding phytochemical prospecting, vitamin, phenolic, and total flavonoid content, and antioxidant (FRAP and DPPH) and acetylcholinesterase (AChE) inhibition activities. Fruiting bodies of S. citrinum were collected and the ethanolic extract was produced by maceration. Phytochemical prospecting was performed for several phytochemical groups using colorimetric means; the content of vitamins A, B, C, D, and E was obtained qualitatively by colorimetric methods, the content of phenolic and flavonoids by the colorimetric method and quantification by spectrophotometry. The spectrophotometric method performed the antioxidant activity in reducing FRAP and DPPH radicals by spectrophotometry and the acetylcholinesterase inhibition activity. Seventeen positive phytochemical groups were observed, the qualitative presence of vitamins of the A, B, and D complexes, 195.03 mg GAE g^-1 of total phenolics, 93.10 mg QE g^-1 of total flavonoids, FRAP reduction of 3.941 µM TE g^-1, DPPH reduction of 127.78 µg mL^-1 and AChE inhibition of 55.6%. The extract of the mushroom Scleroderma citrinum proved to be rich in phytocompounds, vitamins, and important biological antioxidant and acetylcholinesterase inhibition effects.

Seasonal chemical composition and antioxidant activity of the essential oil from Cinnamomum zeylanicum Nees leaves in a Brazilian Cerrado region

Lorena Gonçalves Lima — 2024-11-27

Cinnamomum zeylanicum is an aromatic species with essential oil in its leaves, stems, and roots, widely used in traditional medicine and culinary applications. The essential oil of C. zeylanicum exhibits various biological activities, such as antioxidant and antifungal properties. This study aimed to evaluate the essential oil extracted from the leaves of C. zeylanicum collected during two seasonal periods in the Brazilian Cerrado, focusing on its volatile chemical profile, and antioxidant, and antifungal activities. Leaves of C. zeylanicum were collected in July and December 2023. The essential oil was extracted through hydro distillation. The volatile chemical profile was determined by gas chromatography-mass spectrometry (GC-MS), antioxidant activity was assessed by DPPH free radical reduction, and antifungal activity was evaluated based on the inhibition of Sclerotinia sclerotiorum, Colletotrichum gloeosporioides, and C. acutatum. Two major compounds were identified: eugenol (72% and 63%) and eugenyl acetate (9% and 15%) for the dry and hot seasons (July) and the wet and hot seasons (December), respectively. DPPH free radical reduction showed maximum inhibition of 89% and 65% for July and December, respectively. Antifungal activity demonstrated maximum inhibition rates of 65% and 53% for S. sclerotiorum, 82% and 71% for C. gloeosporioides, and 56% and 27% for C. acutatum during the same periods. This study highlights seasonal variations in the major compounds of essential oil, which influenced its production, DPPH radical scavenging activity, and inhibition of the evaluated fungal strains.

First report, phytochemical screening, and antioxidant and acetylcholinesterase inhibition activities of Macrolepiota mastoidea (Fr.) Singer mushroom extract in the Southwest region of Brazil

Hugner Vicente da Silva — 2024-11-25

The Agaricales family is rich in species of edible macrofungi. Macrolepiota mastoidea is a representative of this group, found in various regions of the world, including Brazil. It is an edible species with several recorded biological activities. This study aimed to report the first findings on M. mastoidea and its phytochemical screening, as well as its antioxidant activity and acetylcholinesterase inhibition in a 70% (v/v) hydroethanolic extract from fresh mushrooms. M. mastoidea was collected from a Cerrado area in the Southwest of Goiás, Brazil. The hydroethanolic extract was produced, and the phytochemical screening was conducted for various phytochemical groups. Antioxidant activity was assessed using the DPPH free radical model, and acetylcholinesterase inhibition activity was determined using Electrophorus electricus type VI. The results showed the presence of various phytochemical groups such as alkaloids, sugars, flavonoids, and tannins. The DPPH reduction activity was IC₅₀ 305.16 µg mL^-1, and acetylcholinesterase inhibition was 72%. Macrolepiota mastoidea demonstrated potential for further pharmacological studies with promising biological activities.

Enhanced degradation of methylene blue dye using hydrothermally synthesized Nickel-doped Strontium oxide catalysts

Jehangir Shah — 2024-11-11

Methylene blue is an organic contaminant that is produced by the plastic, textile, and dye industries. Many studies have been undertaken to investigate the cleanup of methylene blue from industrial effluents. SrO nanoparticles are now being utilized to remove methylene blue colours from water. We used a hydrothermal technique to create strontium oxide nanoparticles for photocatalytic MB breakdown under light conditions. To enhance the solar light activity and avoid charge recombination, we employed a hydrothermal technique to add Ni as a dopant in strontium oxide nanoparticles. Strong base NaOH, nickel nitrate, and strontium nitrate were used as precursors. The nanoparticles were crushed into powder and calcined at 450 °C in a muffle furnace to produce SrO and Ni-doped SrO nanoparticles. The nanoparticles were analyzed using several analytical methods to determine their morphological and structural properties. At 309, 312, and 317 nm, UV-Vis spectroscopy showed absorbance values of SrO doped with varied nickel concentrations. The Ni–O stretching peak was identified in the FTIR analysis of strontium oxide nanoparticles at 402 cm^-1 and 581 cm^-1, whereas the Sr–O bond gave a signal at 854.84 cm^-1. SEM images of Ni-doped SrO nanoparticles were created at various magnifications. The nanostrips are hexagonal and cylindrical. Sherrer's equation was used to compute the average crystalline structure, which showed that the diameters of pure and Ni-doped SrO (2 percent, 3 percent, and 4 percent) nanoparticles were 45.54 nm, 36.14 nm, 42.93 nm, and 41.21 nm, respectively. According to the EDX examination, the relative concentration of Ni-doped SrO is about 72 percent Sr and oxygen, with around 1.34 percent Ni. The resulting sample was tested for photocatalytic degradation of organic pollutants in aqueous solution, such as methylene blue, and the completion of the reaction was monitored using UV-visible spectroscopy to measure the % photocatalytic degradation during light illumination. According to the UV-visible spectra, 90% of the dye was effectively destroyed.