Optimization of ultrasound- and enzymatic-assisted extractions of polyphenols from dried red onion peels and evaluation of their antioxidant activities.

There is a recognized need for exploring new natural antioxidants that have high antioxidant potential. Thus, the aim of this study was to optimize the extraction process of onion peels using ultrasound- and enzymatic-assisted extractions (UAE and EAE) methods to utilize the optimal extracts as natural antioxidants. Box-Behnken Design (BBD) was implemented to reach the optimal extracts with the highest simultaneous content of total phenolic content (TPC) and total flavonoid content (TFC). The optimal UAE and EAE extracts were subjected to High Performance Liquid Chromatography (HPLC) analysis to identify their chemical profile. The antioxidant activities of optimal extracts obtained by UAE and EAE were evaluated in vitro using DPPH and FRAP assays and their abilities to increase the oxidative stability of sunflower oil were studied using Rancimat test. The optimal conditions for UAE were 34.02 W, 26.87 mL/g solid, and 45.43 min, meanwhile they were 30.00 mL/g solid, 45.43 min at enzyme concentration of 0.52% for EAE method. DPPH and FRAP assays results revealed that EAE optimal extract show superior antioxidant activity over UAE optimal extract. The protection factor of optimal EAE extract against sunflower oil oxidation was close to that of butylated hydroxytoluene (BHT).

Extraction of essential oil from methyl cinnamate basil (Ocimum canum Sims) with high yield in a short time using enzyme pretreatment.

This research was carried out to evaluate the effect of viscozyme pre-treatment followed by hydrodistillation (E-HD) on extraction yield, extraction time and quality of methyl cinnamate basil (O. canum) oil. The viscozyme, as a multienzyme acting on cell wall, was used at different concentrations (0.5% and 1%, v/w) for 30, 60 and 90 min at 50 °C and pH 5 before hydrodistillation (HD). Oxygenated monoterpenes/monoterpene hydrocarbons ratio was used as a quality index for the obtained essential oil. Enzymatic pretreatment at 1% enzyme concentration for 90 min followed by HD increased yield of essential oil by 44.5% with high quality index and decreased HD time from 180 to 30 min. Thirty-nine volatile compounds, comprising > 99% of the essential oil were identified and quantified by Gas Chromatography Mass Spectrum (GC-MS). The major components of essential oil were (E)-methyl cinnamate, camphor, trans-ß-caryophyllene and 1,8-cineole. Results confirm the effectiveness of the enzyme pretreatment, which enhance extraction of O. canum essential oil in a short time, with a high quality.

Optimization of the extraction of polyphenols and antioxidant activity from Malva parviflora L. leaves using Box-Behnken design.

Box-Behnken Design (BBD) was used to optimize the extraction conditions of polyphenols from Malva (Malva parviflora L.) leaves. The effect of ethanol concentration (20-80%), solvent/leaf powder ratio (10:1 to 30:1, v/w) and extraction time (5-45 min) on the polyphenols yield and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the obtained extracts were investigated. Quadratic models fit well. The optimal conditions (53.40% ethanol, solvent/leaf powder ratio 20:1 (v/w), and 15 min) resulted in an extract with a maximum yield of polyphenols (1098.4 mg GAE/100 g leaf powder) and high inhibition percentage of DPPH radical (33.31%) with desirability 0.742. High Performance Liquid Chromatography (HPLC) analysis indicated that the major identified polyphenol compounds extracted at the optimal conditions were naringenin, ρ-coumaric acid, apigenin-7-glucoside, luteolin, and cinnamic acid. These findings indicate that M. parviflora leaf extracts possess DPPH radical scavenging activity and could be used as a natural source for bioactive products.

Hypolipidemic Effect of Moringa oleifera Lam Leaf Powder and its Extract in Diet-Induced Hypercholesterolemic Rats.

The leaves of Moringa oleifera Lam possess some potential medicinal value. The aim of this study was to evaluate the protective effect of M. oleifera leaf powder and its extract against hyperlipidemia in rats. Adult male albino rats were divided into six groups. The first group was fed on a basal diet that served as a negative control, whereas the others were fed on a high-fat diet (HFD) containing moringa leaf powder at 0.737% or 1.475% or administered daily with 200 or 400 mg dry moringa leaf extract/kg bw for 60 days. A positive control group was fed on the HFD. Serum indices related to lipid profile, oxidative status, and liver function were analyzed. Feeding rats on an HFD containing moringa leaf powder at 0.737% or an oral dose of its dry extract at 400 mg/kg bw alleviated the harmful elevation of cholesterol, triglycerides, low-density lipoprotein cholesterol, malondialdehyde, and the activities of alanine aminotransferase and aspartate aminotransferase in serum that were induced by the HFD. This is the first study demonstrating the hypocholesterolemic effect of M. oleifera leaf powder.

A comparative study of nutmeg (Myristica fragrans Houtt.) oleoresins obtained by conventional and green extraction techniques.

This study evaluated the effect of conventional maceration and ultrasound assisted extraction techniques on the extraction yield, chemical composition and sensory characteristics of nutmeg oleoresins. Extraction was performed using material: absolute ethanol ratio 1:4, at room temperature. The volatile components of the oleoresin were identified by gas chromatography-mass spectrometry. The results of the study showed that the yield ranged from 4.55 to 9.63 %. Fifty-three compounds in the nutmeg oleoresin have been identified to account for >90 % of the total oil content. Sabinene, myristicin, elemicin, α-pinene, ß-pinene, limonene, terpinen-4-ol and myristic acid were found as major compounds of all the nutmeg oleoresins obtained by different techniques. The sensory characteristics of the oleoresin were strongly influenced by the ultrasonic intensity and duration of extraction. The experimental results showed that ultrasound assisted extraction technique at 40 % of the maximal output power and 10 min produced superior quality nutmeg oleoresin with a remarkable yield.