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Coffee is one of the world's most popular beverages, and its consumption generates copious amounts of waste. The most relevant by-product of the coffee industry is the spent coffee grounds, with 6 million tons being produced worldwide per year. Although generally treated as waste, spent coffee grounds are a rich source of several bioactive compounds with applications in diverse industrial fields. The present work aimed at the analysis of spent coffee grounds from different geographical origins (Guatemala, Colombia, Brazil, Timor, and Ethiopia) for the identification of bioactive compounds with industrial interest. For this purpose, the identification and quantification of the bioactive compounds responsible for the antioxidant activity attributed to the spent coffee grounds were attempted using miniaturized solid-phase extraction (µ-SPEed), combined with ultrahigh-performance liquid chromatography with photodiode array detection (UHPLC-PDA). After validation of the µ-SPEed/UHPLC-PDA method, this allowed us to conclude that caffeine and 5-caffeoylquinic acid (5-CQA) are the most abundant bioactive compounds in all samples studied. The total phenolic content (TPC) and antioxidant activity are highest in Brazilian samples. The results obtained show that spent coffee grounds are a rich source of bioactive compounds, supporting its bioprospection based on the circular economy concept closing the loop of the coffee value chain, toward the valorization of coffee by-products. [ABSTRACT FROM AUTHOR]

Withania somnifera is endemic to Ethiopia where its leaf and root is traditionally used for the treatment of malaria in south Ethiopia. The main purpose of this study was to investigate phytochemicals and antioxidant activity of the leaf extract of Withania somnifera. The anti-oxidant potential and total antioxidant potential was determined by using reducing power determination method and phosphomolybdate method respectively. As per the phytochemical tests, the methanol extract revealed that presence of tannins, phenolics, flavonoids, saponins and, alkaloids while all are absent in hexane extract. The antioxidant capacity of methanol, acetone and hexane leaf extracts of Withania somnifera were found to be 494.088±0.230, 104.190±0.020 and 3.413±0.023 mg of ascorbic acid per 10 mg of dry weight of antioxidant in the reducing power, respectively and it's total antioxidant capacity of these extracts were 45.41±0.018, 8.70±0.004 and 0.38±0.002mg of ascorbic acid per 10 mg of dry weight of the crude extract. Thus, the results of the present investigation infer that this plant extracts possess potent antioxidant. Therefore it is strongly recommended to isolate the antioxidant components. [ABSTRACT FROM AUTHOR]