Optimization of Ultrasound-Assisted Extraction of Verbascum sinaiticum Leaves: Maximal Phenolic Yield and Antioxidant Capacity.

Verbascum sinaiticum (Qetetina or yeahya Joro) is a medicinal plant with secondary metabolites such as phenolics, flavonoids, glycosides, saponins, and alkaloids. This study was designed to optimize the ultrasonic-assisted extraction (UAE) parameters to enhance the phenolic content and characterize the phenolic compounds using ultra-high-performance liquid chromatography, coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC-ESI-QTOF-MS/MS), and antioxidant activities in Verbascum sinaiticum extract. Extraction time, sample-to-solvent ratio, and extraction temperature were considered for UAE optimization. It was found that UAE generated the highest extraction yield (21.6%), total phenolic content (179.8 GAE mg/g), total flavonoid content (64.49 CE mg/g), DPPH (61.85 µg/mL), and ABTS (38.89 µg/mL) when compared to maceration extraction. Metabolite analysis in this study showed the detection of 17 phenolic compounds, confirming antioxidant capacities. The optimization parameters have significant effects on phenolic compounds. Scanning electron microscopy showed the presence of structural changes when UAE was used over the maceration method. The optimized UAE parameters for extraction temperature (41.43 °C), sample-to-solvent ratio (36.32 g/mL), and extraction time (33.22 min) for TPC were obtained. This study shows the potential application for UAE of Verbascum sinaiticum leaves in the development of pharmaceutical and nutraceutical products.

Cereal- and Fruit-Based Ethiopian Traditional Fermented Alcoholic Beverages.

Traditional fermented alcoholic beverages are drinks produced locally using indigenous knowledge, and consumed near the vicinity of production. In Ethiopia, preparation and consumption of cereal- and fruit-based traditional fermented alcoholic beverages is very common. Tella, Borde, Shamita, Korefe, Cheka, Tej, Ogol, Booka, and Keribo are among the popular alcoholic beverages in the country. These beverages have equal market share with commercially produced alcoholic beverages. Fermentation of Ethiopian alcoholic beverages is spontaneous, natural and uncontrolled. Consequently, achieving consistent quality in the final product is the major challenge. Yeasts and lactic acid bacteria are the predominate microorganisms encountered during the fermentation of these traditional alcoholic beverages. In this paper, we undertake a review in order to elucidate the physicochemical properties, indigenous processing methods, nutritional values, functional properties, fermenting microorganisms and fermentation microbial dynamics of Ethiopian traditional alcoholic beverages. Further research will be needed in order to move these traditional beverages into large-scale production.

Effect of Ultrasound-Assisted Extraction of Moringa stenopetala Leaves on Bioactive Compounds and Their Antioxidant Activity.

Moringa stenopetala is a multipurpose plant having high nutritional and medicinal values. The aim of this study is to evaluate the effect of time and temperature of ultrasound-assisted extraction on bioactive compounds and antioxidant activities of M. stenopetala leaf extract. The ultrasound-assisted extraction took place at each of 30, 40 and 50 °C for 10, 20 and 30 min. The study also included the analysis of the interaction effects of time and temperature on the total phenolic content, total flavonoid content, antioxidant activity (ABTS and DPPH assay), FRAP and chelating activity. The highest total phenolic content, expressed in mg gallic acid equivalents per g dry mass, was 46.6 and total flavonoid content, expressed in mg catechin equivalents per g dry mass, was 20.4 at 40 °C for 20 min. Under the same conditions, the highest antioxidant activities evaluated by DPPH, ABTS and FRAP, expressed in mg Trolox equivalents per g dry mass, were 336.5, 581.8 and 133.3 respectively, and chelating activity, expressed in mg EDTA equivalents per g dry mass, was 28.4. The lowest amounts of bioactive compounds and antioxidant activities were observable when the extraction occurred at 50 °C for 30 min, followed by the extraction at lower temperature (30 °C) for shorter time (10 min). The morphological analysis of the residues obtained after extraction using scanning electron microscope indicated that there was a higher ultrasonic destruction of the structural components of the sample at longer extraction time. Therefore, ultrasound-assisted extraction at a temperature of 40 °C for 20 min is the best time-temperature combination to extract bioactive compounds from M. stenopetala leaves.