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The present work was designed to investigate the effect of maceration, ultra-sound, and microwave-assisted extraction on free, esterified, and bound phenolics of Tulaipanji rice (Oryza sativa L.) flour. Antioxidant activity was measured by DPPH, ABTS, SOD, and reducing power assays. HPTLC analysis was performed for identification and quantification of phenolics in different extracts. Total phenolic (TPC) and total flavonoid contents (TFC) were found significantly high (p < 0.05) in microwave-assisted extraction of bound phenolics compared with other methods. Microwave-assisted extracts showed highest DPPH radicals, ABTS radicals, SOD, and reducing power activity. Further, Pearson's correlation study exhibited a significant positive correlation within % yield, TPC, and TFC. Significant negative correlation was found within % yield, TPC, TFC, and antioxidant activity. The study found that extractive value, antioxidant activity, and phenolic contents varied with the extraction methods. Microwave-assisted extraction technique showed the best performance for extraction as compared to other methods. [ABSTRACT FROM AUTHOR]

Black rice ( Oryza sativa L.) is a rich source of phenolics and anthocyanins. It was aimed to investigate the effect of different extraction methods such as conventional solvent extraction, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) on antioxidant activity and phenolic profiling of black rice free, esterified, and bound phenolics fractions. Spectrophotometric methods were used to evaluate antioxidant activity and HPTLC was used for phenolics profiling. The highest content of % yield, total anthocyanin (TAC), total phenolic (TPC), and total flavonoid (TFC) contents were detected in MAE. It was also observed that antioxidant activity based on DPPH, ABTS, superoxide radical-scavenging and ferric reducing antioxidant power (FRAP) assays showed highest activity in MAE. Eight phenolic compounds were identified and quantified by a validated HPTLC method. MAE showed most abundant phenolic compounds. A significant positive correlation was established between % yield, total phenolic content, and total flavonoid content ( p  < 0.05) where a significant negative correlation was established between % yield, TPC, and TFC with IC 50 of antioxidant activity ( p  < 0.05). Diverse phenolic contents and antioxidant activity were studied with different forms of phenolics with the different extraction methods. It designates that the extraction techniques had effects on the bioactive compounds as well biological properties., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

The green synthesis of metallic nanoparticles has tremendous impacts in various fields as found in recent years due to their low cost, easy and environmentally friendly synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using an aqueous Eupatorium adenophorum ( E. adenophorum ) leaf extract as a bioreductant. Interestingly, Fourier transform infrared (FTIR) spectroscopy analysis established that the E. adenophorum extract not only served as a bioreductant but also acted as a capping agent to stabilize the nanoparticles by functionalizing the surfaces. Various characterization techniques were adopted, such as X-ray powder diffraction (XRD), FTIR, ultraviolet-visible absorption (UV-Vis) spectroscopy, dynamic light scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) to analyze the biosynthesized AgNPs. Biosynthesized nanoparticles were also explored for antioxidant, antibacterial and photocatalytic activities. The AgNPs showed improved free radical scavenging activity (IC 50 48.96 ± 0.84 µg/mL) and bacterial inhibitory effects against both gram-positive ( Staphylococcus aureus ; 64.5 µg/mL) and gram-negative ( Escherichia coli ; 82.5 µg/mL) bacteria. Photocatalytic investigation showed AgNPs were effective at degrading rhodamine dye (78.69% in 90 min) when exposed to sunlight. These findings collectively suggest that E. adenophorum AgNPs were successfully prepared without the involvement of any hazardous chemical and it may be an effective antibacterial, antioxidant and promising agent for the removal of hazardous dye from waste water produced by industrial dyeing processes., Competing Interests: Conflict of interestThe authors declare that they have no competing interests., (© Institute of Chemistry, Slovak Academy of Sciences 2023, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Different parts of Camellia sinensis (L.) were extracted with solvents according to polarity, and the extracts' phytochemical profiling and biological activities were examined. The total phenolic (TPC) and total flavonoid (TFC) contents increased with the increasing polarity of the solvent which met its maximum in polar solvents. The increasing antioxidant, anti-inflammatory and antidiabetic activities were recorded with increasing polarity of solvents which showed hydroalcoholic as best solvent. The strong and significant correlation was among the TPC, TFC, DPPH, anti-inflammatory and antidiabetic activities for different parts of tea. HPTLC study of individual phenolic acids, epigallocatechin gallate, gallocatechin and theaflavin met their maximum level of content with polar solvents like hydroalcohol, methanol and water mostly in mainly tea leaves. Our finding suggested that the polar solvents and young leaves of tea were beneficial for obtaining extracts. On the other hand, phenolics were found to be potent antioxidant, anti-inflammatory and antidiabetic agent., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)