Preparation of Hydroxytyrosol by Acid Hydrolysis from Olive Leaves

Hydroxytyrosol (HT) is the main bioactive compound in olive leaves. However, olive leaves contain a lower level of HT and the extraction process of HT was rarely optimized. In this study, compared with two extraction methods, ultrasound was found to have a positive effect on improving the yield of HT. Therefore, ultrasound was used to assist hydrolysis of hydrochloric acid to extract HT from olive leaves. Response surface method and macroporous resins were applied to optimize the extraction process as well as enrichment of HT. The results showed that ultrasonic extraction time had a significant effect on the yield and the optimal extraction conditions were obtained: ultrasonic time was 120 min, hydrochloric acid concentration was 1.60 mol/L and the liquid-to-material ratio was 60.00 mL/g. Under the optimal extraction condition, the yield of HT was 14.11 ± 0.12 mg/g. NKA-Ⅱ macroporous resin was proved to be a suitable resin to enrich HT from extraction solution. The optimal condition for enriching HY was 250 mL of loading solution at the flow rate of 1.5 mL/min with 40 mL volume of 75% ethanol–eluent at a flow rate of 1.0 mL/min. The concentration of HT changed from 2.27% to 9.25% after enrichment by macroporous resin.

Microwave-assisted extraction of phenolic compounds from coffee (Coffea robusta L. Linden) bee pollen

Summary Introduction: Coffee bee pollen contains some precious bioactive compounds, especially phenolic compounds. This material is easily found in many regions in Vietnam and is quite useful for human health. Objective: The main aim of this study was to determine the best extraction conditions for the total polyphenol content (TPC) and antioxidant capacity (AC) of coffee (Coffea robusta L. Linden) bee pollen with microwave-assisted extraction (MAE). Methods: TPC and AC of extract of coffee (C. robusta) bee pollen were determined using Folin-Ciocalteu (FC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, respectively. In addition, micromorphology of sample was observed using scanning electron micrographs (SEM). Results: The findings showed that all factors strongly affected the efficiency of the extraction process. The best extraction conditions obtained were ethanol concentration of 60% (v/v), solid to solvent ratio of 1/30 (w/v), extraction time of 7 min, and a microwave power of 314 W. Conclusion: The highest TPC and AC obtained were 13.73 mg GAE/g DW and 10.08 µmol TE/g DW with aqueous ethanol as the solvent at the optimal extraction condition. In addition, the microstructures of the material changed insignificantly under microwave irradiation.

Optimized Extraction Method for Kleeb Bua Daeng Formula with the Aid of the Experimental Design

Kleeb Bua Daeng formula is one of the popular remedies sold in Chao Phya Abhaibhubejhr Hospital, Thailand. This formula contains Piper nigrum L., Nelumbo nucifera Gaertn., and Centella asiatica L. as active components. Owing to getting the highest content of its phytochemical compounds, the conditions of solvent extraction for this formula were optimized. The type of solvent, number of extraction times, and ratio between the material and solvent were varied in this study using the Box–Behnken design. The important phytochemical constituents (total phenolics, flavonoids, carotenoids, and anthocyanins) were also determined. From the result of this study, it was found that the highest content of each total active compound was obtained from different conditions such as the optimal extraction condition of phenolic content was obtained using methanol as solvent, one time of extraction, and the ratio of powder and solvent was 1 : 6. Thus, the variation of solvent extraction condition could affect the phytochemical content. Further studies about the herbal formula involving the extraction process should concern the variation of extraction conditions to get the highest content of the active compound.

Highland Barley and Its By-Products Enriched with Phenolic Compounds for Inhibition of Pyrraline Formation by Scavenging α-Dicarbonyl Compounds

Pyrraline, a typical kind of advanced glycation end product, has been found to contribute to the development of pathologies associated with ageing and diabetes mellitus. In the study, phenolic compounds extracted from highland barley whole grain (HBWG) and vinasse (HBVN) were used to inhibit pyrraline formation in a simulated food. The optimal extraction condition for HBWG and HBVN was using 8 mL of 50% acetone solution at 50 °C for 60 min. The extraction and identification of phenolic compounds from HBWG and HBVN were performed by UPLC–PAD–MS/MS. The inhibitory effects of pyrraline in the simulated food were 52.03% and 49.22% by HBVN and HBWG, respectively. The diphenyl picrylhydrazyl radical- and ferric-reducing ability of plasma assays was used to evaluate the antioxidant activity of the extracts. The main inhibition pathways and molecular mechanism of phenolic compounds on pyrraline regulation were explored by scavenging α-dicarbonyl compounds. The study demonstrated that highland barley and its by-products can potentially be used as a functional food to regulate pyrraline formation during food processing.

Optimization of total flavonoid content of ethanolic extract of Persicaria pulchra (Bl.) Soják for the inhibition of α-glucosidase enzyme

Objectives. There has been a rapid increase in the number of diabetic patients since the past few decades in developed and developing countries. This rapid increase is accompanied by alarming costs of treatment. α-Glucosidase inhibitors are one of the most effective drugs employed for the reduction of postprandial hyperglycemia to manage Type 2 diabetes mellitus. Additionally, flavonoids, a group of natural substances, which are widely distributed in plants and possess variable phenolic structures, exhibit outstanding hypoglycemic activity and are considered as potential α-glucosidase inhibitors. In Vietnam, Persicaria pulchra (Bl.) Soják (P. pulchra) is employed in traditional medications. It possesses high flavonoid contents and its anti-diabetes ability has been hypothesized, although it has attracted less attention for investigation. Hence, the aim of this study is to optimize the condition of the P. pulchra extract to obtain the highest total flavonoid content and measure the bioactivities of P. pulchra, such as the anti-α-glucosidase and antioxidant activities.Methods. The effects of the extracting conditions, including the temperature, extraction time, liquid-to-solid ratio (LSR), and ethanol (C2H5OH) concentration, on the total flavonoid content are investigated via experiments and analyzed by the response surface methodology (RSM). Concurrently, the optimal extraction also determines the anti-α-glucosidase and antioxidant activities.Results. The optimal extraction condition for the highest flavonoid content (530 mg quercetin/g) is determined in 60 min, at 53°C, with LSR of 9.46 g/g and C2H5OH concentration of 62%. Moreover, the optimal plant extract exhibits good α-glucosidase inhibition with a half-maximal inhibitory concentration (IC50) of 22.67 mg/mL, compared to the positive control (acarbose −7.77 g/mL). Additionally, P. pulchra is proposed to be a potential antioxidant with an IC50 of ~12.68 µg/mL.Conclusions. The study confirmed the optimal extraction condition of P. pulchra that will obtain the highest total flavonoid content and revealed the potentials of P. pulchra in α-glucosidase inhibition and antioxidation.

Determination of Curcuma longa L. (Turmeric) Leaf Extraction Conditions Using Response Surface Methodology to Optimize Extraction Yield and Antioxidant Content

Curcuma longa L. (turmeric) has been used as a functional food material, but other parts of it such as leaves are wasted as a byproduct. This work concentrated on developing turmeric leaves as a functional food material by establishing its optimal extraction condition. Response surface methodology was applied to optimize turmeric leaf extraction conditions. Turmeric leaves were pulled out with water and ethanol (10, 30, and 50%). Then, total phenolic compound content, total flavonoid content, and radical-scavenging activity of each extract were quantified to confirm the optimal extracting solvent. According to the results, water was the most efficient solvent to extract antioxidant contents such as total phenolic compounds (3.65 ± 0.02 mg GAE/g) and flavonoids (4.99 ± 0.17 mg QCE/g) content. Radical-scavenging activity was also higher in water extract compared with others such as DPPH (51.10 ± 2.29%), H2O2 (25.39 ± 2.69%), and ABTS (91.08 ± 0.15%). Central composite design was applied to confirm the effect of independent variables such as temperature (X1) and time (X2) to the yield (Y1). After conducting experiments, the extraction condition was established as 150 min with 1 : 25 ratio at 85°C with a 15.58% yield. Proximate compositions of the extract were determined to suggest background data for further research. In conclusion, this study confirmed the antioxidant property of turmeric leaves and developed the optimal extraction condition of the leaves to promote its application in food industry as a new food source.

Extraction of Essential Oils from Vietnam’s Orange (Citrus sinensis) Peels by Hydrodistillation: Modeling and Process Optimization

In this study, extraction of essential oil from orange peels was investigated by hydrodistillation method and combine technology software to optimize the process. By using the response surface methodology (RSM) based on Box-Behnken surface statistical design, the effect of parameters such as water-to-material ratio (2-4 mL/g), extraction time (45-75 min), and temperature (120-140 ºC) on the extraction of essential oil process from orange (Citrus sinensis) peels was examined . All factors were significantly affected to the extraction yield of essential orange peel oil. Optimum conditions for extraction oil yield including the ratio of water to material, temperature, extraction time achieved 3.19 mL/g, 130.08 ºC, 74.31 min, respectively. Below the optimal extraction condition, the maximum yield of orange oil of 3.21 % was obtained. Using gas chromatography/mass spectrometry (GC/MS), the results revealed that the essential orange peels oil is extremely rich in limonene (98.343 %).

Equilibrium of chiral extraction of 4-nitro-d,l-phenylalanine with BINAP metal complexes

The enantioselective extraction of 4-nitro-phenylalanine (Nphy) was studied with metal-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) complexes as the chiral selector. The complex with palladium (BINAP-Pd) exhibits the highest selectivity out of the selectors studied, which is solubilised in the organic phase and preferentially extracts d-Nphy from the aqueous phase. Efficiency of extraction depends, often substantially, on a number of process variables, including types of organic solvents and metal precursors, concentration of ligand, pH, and temperature. A reactive extraction model was established to interpret the experimental data. The equilibrium formation constants and other important parameters required by the model were determined experimentally. The equilibrium formation constants were 6.73 and 1.93 for d-Nphy and l-Nphy. By way of modelling and experiment, an optimal extraction condition with pH of 7 and BINAP-Pd concentration of 1 mmol L−1 was obtained with enantioselectivity (α) of 3.37, which was close to the maximum of 3.48, and a performance factor (pf) of 0.195. The model was verified experimentally with excellent results.

Hemicelluloses extraction from giant bamboo (Bambusa balcooa Roxburgh) prior to kraft or soda-AQ pulping and its effect on pulp physical properties

The alkaline and acid preextraction of giant bamboo (Bambusa balcooa Roxburgh), grown in South Africa, before kraft and soda-anthraquinone (AQ) pulping was in focus and the effects of NaOH concentration, temperature, and time on hemicelluloses extraction were studied by means of a statistical experimental design. The NaOH concentration exerted the strongest influence, solubilizing up to 20.4% of the available xylan with 2.0 M NaOH at 90°C for 240 min. The optimal extraction condition was achieved with 1 M NaOH at 90°C for 240 min, in the course of which 13.6% of the xylan was removed; the screened pulp yield was 50.4% without viscosity reduction, whereas the burst index of the handsheets was even improved. In the case of dilute acid preextraction before soda-AQ pulping, 11.3% xylan could be removed without affecting the pulp quality. The viscosity of the pulp was even better than that of pulps from nonextracted bamboo. The biorefinery approach, alkaline preextraction in combination with kraft pulping, is superior to the approach, acid prehydrolysis/soda-AQ pulping.

Process Optimization of Ultrasonic-Assisted Extraction of Arabinogalactan from Dihydroquercetin Extracted Residues by Response Surface Methodology and Evaluation of Its Antioxidant Activity

Ultrasound was used for the extraction of larch arabinogalactan fromLarix gmelinii. The optimal conditions for ultrasound extraction were determined by response surface methodology. Specifically, the Box-Behnken design was employed to evaluate the effects of three independent variables: ultrasound time, temperature, and liquid-solid ratio. The highest arabinogalactan yield (11.18%) was obtained under the optimal extraction condition (extraction temperature 41.5°C, extraction time 24.3 min, and liquid-solid ratio 40 mL/g). In addition, the antioxidant activity of arabinogalactan that was extracted from dihydroquercetin extraction residues exhibited a moderate and concentration-dependent hydroxyl radical-scavenging capacity, ferric-reducing power, and reducing power. The wood material was characterized before and after processing by scanning electron microscopy and Fourier-transform infrared spectroscopy.