Method Development for Purification of γ-oryzanol from Hydrolyzed Rice Bran Acid Oil by Semi-preparative Chromatography.

The objective of this study was to develop a method for isolation and purification of γ-oryzanol from hydrolyzed rice bran acid oil (RBAO) using semi-preparative chromatography by first applying silica coated-thin layer chromatography (TLC) to determine the suitable mobile phase. Subsequently, column chromatography was carried out to determine the effects of purification conditions such as the amount of and particle sizes of the sample silica gel, and elution modes, on the percentage of γ-oryzanol yield and recovery. The results from the TLC suggested that 75:25 (v/v) hexane to ethyl acetate mixture was a suitable mobile phase. The semi-chromatographic results indicated that the column containing 10 g of 25-40 µm silica gel with isocratic elution gave the highest yield (84%) of purified γ-oryzanol (> 95% purity). Further application of a step-gradient elution with 85:15 (v/v), followed by 75:25 (v/v) hexane to ethyl acetate mixture increased chromatographic resolution (Rs), resulting in enhanced separation efficiency, which in turn led to a higher yield of purified γ-oryzanol of 90%.

High Levels of Policosanols and Phytosterols from Sugar Mill Waste by Subcritical Liquefied Dimethyl Ether.

Extracting nutraceuticals with high value from bagasse, filter mud, and sugarcane leaves discarded as sugar mill by-products, is crucial for the development of a sustainable bio-economy. These by-products are important sources of policosanols and phytosterols, which have a cholesterol-lowering effect. This research focused on using a promising green technology, subcritical liquefied dimethyl ether extraction, with a low pressure of 0.8 MPa, to extract policosanols and phytosterols and on application of pretreatments to increase their contents. For direct extraction by subcritical liquefied dimethyl ether without sample pretreatment, the highest extraction yield (7.4%) and policosanol content were found in sugarcane leaves at 2888 mg/100 g, while the highest and lowest phytosterol contents were found in filter mud at 20,878.75 mg/100 g and sugarcane leaves at 10,147.75 mg/100 g, respectively. Pretreatment of filter mud by ultrasonication in hexane solution together with transesterification before the second subcritical liquefied dimethyl ether extraction successfully increased the policosanol content, with an extract purity of 60%, but failed to increase the phytosterol content.

Phenanthrene-enriched extract from Eulophia macrobulbon using subcritical dimethyl ether for phosphodiesterase-5A1 inhibition.

Eulophia macrobulbon (E.C.Parish & Rchb.f.) Hook.f. contains a natural PDE5A1 inhibitor, phenanthrene, 1-(4'-hydroxybenzyl)-4,8- dimethoxyphenanthrene-2,7-diol (HDP), a potential agent for the treatment of erectile dysfunction. The aim of this study was to improve the extraction efficiency of HDP from E. macrobulbon by using a more environmentally friendly extraction method, subcritical liquid dimethyl ether extraction (sDME), instead of classical solvent extraction (CSE) and ultrasound-assisted extraction (UAE). The efficiency and quality of the extracts obtained were evaluated using the following criteria: %process yield; solvent amount; extraction time; temperature; %HDP content by LC-MS, bioactivity as inhibition of phosphodiesterase-5A1 (PDE5A1) by radio-enzymatic assay; and chemical profiles by LC-QTOF-MS. sDME provided the highest content of HDP in the extract at 4.47%, much higher than the use of ethanol (0.4-0.5%), ethyl acetate (1.2-1.7%), or dichloromethane (0.7-1.4%). The process yield for sDME (1.5-2.7%) was similar to or lower than the other solvents (0.9-17%), but as long as the process yield is not prohibitively low, the concentration is a more important measure for clinical use. The optimal conditions for sDME extraction were: Extraction time, 40 min; 200% water as co-solvent; sample-to-solvent ratio of 1:8; temperature, 35 °C. Phenanthrene aglycone and glycoside derivatives were the major constituents of the sDME extracts and lesser amounts of phenolic compounds and sugars. The inhibition of PDE5A1 by sDME (IC50 0.67 ± 0.22 µg/ml) was tenfold more potent than ethanolic extract and other extraction methods, suggesting a high probability of clinical efficacy. Thus, sDME was a more efficient, faster, solvent-saving and environmentally friendly extraction method and more selective for phenanthrene when extracted from E. macrobulbon.

Subcritical dimethyl ether extraction as a simple method to extract nutraceuticals from byproducts from rice bran oil manufacture.

The byproducts of rice bran oil processes are a good source of fat-soluble nutraceuticals, including γ-oryzanol, phytosterol, and policosanols. This study aimed to investigate the effects of green technology with low pressure as the subcritical fluid extraction with dimethyl ether (SUBFDME) on the amount of γ-oryzanol, phytosterol, and policosanol extracted from the byproducts and to increase the purity of policosanols. The SUBFDME extraction apparatus was operated under pressures below 1 MPa. Compared to the chemical extraction method, SUBFDME gave the highest content of γ-oryzanol at 924.51 mg/100 g from defatted rice bran, followed by 829.88 mg/100 g from the filter cake, while the highest phytosterol content was 367.54 mg/100 g. Transesterification gave the highest extraction yield of 43.71% with the highest policosanol content (30,787 mg/100 g), and the SUBFDME method increased the policosanol level from transesterified rice bran wax to 84,913.14 mg/100 g. The results indicate that the SUBFDME method is a promising tool to extract γ-oryzanol and phytosterol and a simple and effective technique to increase the purity of policosanol. The study presented a novel technique for the potential use of SUBSFDME as an alternative low-pressure and low-temperature technique to extract γ-oryzanol and phytosterol. The combination of transesterification and the SUBFDME technique is a potential simple two-step method to extract and purify policosanol, which is beneficial for the manufacture of dietary supplements, functional foods and pharmaceutical products.

Synergizing Sulfonated Hydrothermal Carbon and Microwave Irradiation for Intensified Esterification Reaction.

The synergy of sulfonated hydrothermal carbon and microwave (MW) irradiation was applied for the esterification of oleic acid with methanol (MeOH) to produce biodiesel. The effects of temperature, reaction time, ratio of oleic acid to methanol, and catalyst loading were investigated at a fixed MW power of 400 W. The addition of hexane, serving as a co-solvent and separator, was also investigated. The optimum conditions for the proposed process were oleic acid-to-methanol molar ratio of 1:5 and hexane-to-methanol ratio of 0.5 (v/v) in the presence of a 5 wt % catalyst, at 100 °C for 60 min, obtaining a 97% yield of oleic acid methyl ester. The addition of slight amounts of hexane resulted into an eightfold reduction in the amount of MeOH needed to obtain a yield above 90%, which normally required a MeOH-to-oil ratio of 40:1. This proposed novel approach could provide a more cost-effective method for the esterification of oil to produce biodiesel, that is, reactive separation utilizing carbon-based catalysts under MW irradiation.