Optimization of Microwave-Assisted Extraction of Astaxanthin from Haematococcus Pluvialis by Response Surface Methodology and Antioxidant Activities of the Extracts

Abstract

Microwave-assisted extraction (MAE) was applied for the extraction of astaxanthin from Haematococcus pluvialis and response surface methodology (RSM) was used to optimize extraction parameters to the content of astaxanthin. Four independent variables such as microwave power (W), extraction time (sec), solvent volume (mL), and the number of extraction were optimized in this paper. The optimal conditions were determined and tri-dimensional response surfaces were plotted from the mathematical models. The F-test and p-value indicated that microwave power, extraction time, the number of extraction, and their quadratic had a highly significant effect on the response value (p <0.01), then the solvent volume and the interaction effects of microwave power and the number of extraction also displayed significant effect (p <0.05). Considering the extraction efficiency, the optimized conditions of MAE were as follows: microwave power was 141 W, extraction time 83 sec, solvent volume 9.8 mL, the number of extraction four times. About 594 ± 3.02 µg astaxanthin was extracted from Haematococcus pluvialis the dried powders (100 mg) under the optimal conditions, and it close to the predicted contents (592 µg). The antioxidant activities of the extracts obtained under optimal conditions were analyzed, and the results showed that the extracts presented strong ability of inhibiting the peroxidantion of linoleic acid, exhibited strong radical-scavenging properties against the DPPH, as well as strong reducing power.     

Antioxidant and Antibacterial Activity of Nutraceutical Compounds from Chlorella vulgaris Extracted in Hydrothermal Condition

Abstract

Water in hydrothermal condition has been used for extraction of nutraceutical compounds from Chlorella vulgaris. Hydrothermal extraction was carried out in a semi-batch and a batch extractor at various temperatures (120–200°C), pressures (2–10 MPa), and extraction times (30–300 min) to extract antioxidant and antibacterial compounds. The effect of extraction condition on the yield of extract was investigated. The antioxidant and antibacterial activity of extracts obtained by hydrothermal extraction were examined. The increasing extraction temperature resulted in higher antioxidant activity, but lower antimicrobial activity. As comparison with hot water extraction, the antioxidant activity of extract obtained by hydrothermal extraction was higher than that obtained by hot water extraction, but the antibacterial activity of the extract obtained by hydrothermal extraction was lower.     

Optimization of Ultrasound-Assisted Extraction of Artemisinin from Artemisia annua L. by Response Surface Methodology

Artemisinin is a compound extracted from Artemisia annua L. with a remarkable curative effect against malaria. It can be extracted using ultrasound-assisted extraction (UAE) and then detected via HPLC. In this study, response surface methodology (RSM) was used to optimize UAE conditions for obtaining the maximum yield of artemisinin. Three independent variables (ratio of solvent to material, extraction temperature, and ultrasonic power) were evaluated using the Box-Behnken experimental design, with the yield of artemisinin as a response variable. Experimental data were highly fitted to a mathematical-regression model using multiple linear regression (MLR). Based on response surface plots, the three independent variables exhibited interactive effects on the yield of artemisinin. The optimal extraction conditions were as follows: 42.71 mL/g ratio of solvent to material, 41.86°C extraction temperature and 120 W ultrasonic power. The predicted yield of artemisinin by model was 0.7848%, whereas the actual yield in the extracts was 0.7826% ± 0.0790% in adjusted optimal conditions, with a relative error of 0.28%. The results undoubtedly demonstrated that RSM could be used to explore the optimum conditions of artemisinin extraction.     

Fatty acid composition,cytotoxicity and anti-inflammatory evaluation of melon (Cucumis melo L. Inodorus) seed oil extracted by supercritical carbon dioxide

ABSTRACT

Melon seed oil has been extracted by Soxhlet (hexane) and by supercritical CO₂ operating to various pressures and temperatures. Linoleic acid (67.06–68.22%) was the most abundant followed by oleic acid (21.63–22.45%), palmitic acid (5.57–6.23%) and stearic acid (2.98–3.67%). The highest inhibition of inflammation was 18.8% at 50 µg/mL for hexane and SC-CO₂ extracts obtained under 55 MPa and 70°C. The largest inhibition of IGROV and OVAR tumor cell lines were 29.9% and 21.6%, respectively, at 50 µg/mL for the ethanol extract. These results of biological activities indicate that melon seed oils can be dedicated to nutrition.     

The Anti-Adherent Activity of Plant Extracts on Penicillium Commune Spores Causing Cedar Wood Decay: An ESEM Analysis

Decay and deterioration of wood by bacteria and fungi are becoming very serious problems because of the resistance of microorganisms to antimicrobial agents. Thus, this study was aimed at investigating the anti-adhesion effect of Myrtus communis and Thymus vulgaris extracts obtained by classical and ultrasonic extraction, against of Penicillium commune spores isolated from fez Medina cedar wood. According to environmental scanning electron microscopy (ESEM) analysis, the results showed that all extracts tested have proven their ability to inhibit the adhesion of the fungal spores studied. In addition, the extract of each plant obtained by ultrasonication showed a low percentage (47% and 33%) of fungal spores adherent to a wood substrate compared to those recovered by maceration (68%). Furthermore, M. communis extracts have shown outstanding anti-adhesive activity, similar to that demonstrated by those of T. vulgaris. Finally, the treatment of wood by M. communis extracts obtained by ultrasonication showed a very important anti-adhesive activity at a concentration of 20 mg/mL compared to that at 5 mg/mL. Therefore, these extracts can be considered a potential source of bioactive metabolites acting as anti-adhesion molecules in novel formulations for the cedar wood preservation.     

不同萃取技术获得的Artemisia sp的甲醇提取物其抗氧化和抗菌活性的比较

The polyphenol content,antioxidant and antimicrobial activities of the extracts obtained by classical, ultrasonic and Soxhlet extractions from dry aerial parts of two Artemisia species(Artemisia vulgaris and Artemisia campestris)were compared.Ultrasound positively affected the yield of extractive substance and the kinetics of extraction,but the extract obtained by the classical extraction showed the highest antioxidant activities and contained higher total contents of phenolic compounds and flavonoids than the extracts obtained by two other extraction techniques.Both flavonoid aglycones(apigenin,quercetin,quercetin 3,3′-dimethyl ether)and flavonoid glycosides(rutin,hyperoside and kaempferol 3-rhamnoside)were identified by thin layer chromatograph(TLC)analysis in the extracts from both species.A.campestris extracts were richer in quercetin than A.vulgaris and its antimicrobial activity was also better than A.vulgaris.Extracts obtained from both species were found to be more effective on the tested yeasts than bacteria.The kinetics of the total extractive substances,such as phenolic,flavonoids and quercetin extraction,was successfully described by the model of unsteady-state diffusion.     

Antioxidant and Antimicrobial Activities of Echinacea (Echinacea purpurea L.) Extracts Obtained by Classical and Ultrasound Extraction

Antioxidant and antimicrobial activities of Echinacea purpurea L. (Asteraceae) extracts obtained by classical and ultrasound solvent extraction were compared. The dry aerial part of plant was extracted by 70% ethanol at a solid-to-liquid ratio of 1:10 (m/v) and 25°C. The extract obtained by classical solvent extraction contained 29% larger amounts of phenolic compounds and 20% higher content of flavonoids. 2,2-diphenyl-1-picril hydrazyl radical (DPPH) scavenging reached 93.6% and the values of EC50 were (34.16±0.65) μg·ml⁻¹ and (65.48±1.12) μg·ml⁻¹ for the extracts obtained by the classical and ultrasound extractions, respectively. The extracts, independent of the extraction technique applied, showed a considerable growth inhibition on Candida albicans and Saccharomyces cerevisiae, while no growth inhibition zones were observed for Aspergillus niger. The diameters of inhibition zone observed for all the microorganisms were larger for extracts obtained by classical extraction than those by ultrasound extraction.     

Synthesis,Characterization, and Exploration of Antimicrobial Activity of Copper Complex of Diamide Derivative of p-tert-butylcalix[4]arene

Calixarenes are a versatile class of compounds, which possesses wide applications in various fields including biological as well as pharmaceutical sciences. In the present study, amide derivative of calix[4]arene (3) was synthesized and characterized by modern analytical techniques such as elemental analysis and Fourier transform infrared spectroscopy (FT-IR). Complexation property of 3 with essential metals was explored by UV-Vis spectroscopy. The results revealed that 3 shows good selectivity toward Cu²⁺. Job's plot analysis suggests that 3 forms complex with Cu²⁺ in 1:2 stoichiometric ratio. Antimicrobial activity of 3 and its Cu²⁺ complex was also determined and it was observed that 3 is more efficient against R. stolonifer as compared to its action against bacteria, because for fungus it shows “Minimum Inhibitory Concentration” (MIC) value equal to 1.5 µg/mL, while for bacteria MIC is 3 µg/mL. However, it was found that complex is more efficient in action than 3. Oxidation state of metal, overtone concept, and Tweedy's chelation theory justifies the increased activity of metal complex. Cu²⁺ complex shows higher antimicrobial activity toward Escherichia coli (E. coli) (Gram-negative) bacteria by showing MIC value 0.37 µg/mL. While for Staphylococcus albus (S. albus) (Gram-positive) bacteria and Rhizopus stolonifer (R. stolonifer) fungal species, it shows MIC value equal to 0.75 µg/mL.     

Enrichment of antibacterial compound from the stem bark of Stereospermum fimbriatum using supercritical carbon dioxide extraction

ABSTRACT

Supercritical carbon dioxide (sc-CO₂) extraction was carried out on Stereospermum fimbriatum’s stem bark in order to obtain an enriched extract containing the targeted active compound. The recovery of its active compound, C1, was compared with the most active Soxhlet’s extract of dichloromethane. A minimum inhibitory concentration (MIC) assay was done to examine the antibacterial activity of extracts against methicillin-resistant Staphylococcus aureus. The optimum condition for an enriched extract of sc-CO₂ to have a maximum recovery of C1 at MIC value of 400 µg/mL was suggested to be operated at 40°C and pressure at 30 MPa, with addition of 6% co-solvent.     

Chemometric analysis of selective polyphenolic groups in Asparagus racemosus (Shatavar) root extracts by traditional and supercritical fluid (CO2) based extractions

ABSTRACT

Asparagus racemosus root extracts were prepared by supercritical fluid (CO₂), soxhlet, and maceration-based methods also with various pretreatments. Thereafter, these root extracts were analyzed by High-Performance Liquid Chromatography, along with the chemometric study of the disparate phenolic groups. Among these, supercritical fluid (CO₂) based extract has a larger number of polar compounds and the antioxidant activity (98.54 ± 0.22 µM Trolox equivalent mg^?1). It also has the best cell viability (94.37 ± 1.12%) and insulin release (0.82 ± 1.12 ng mL^?1) on β-pancreatic RINm-5F cells whereas, the best extractive yield (75.80 ± 3.44% w/w) was observed for pretreated aqueous soxhlet-based extract.     

Functional Gelatin-Carbon Nanotubes Nanohybrids With Enhanced Antibacterial Activity

Hybrid materials with enhanced antibacterial activity were prepared by incorporation of carbon nanotubes within gelatin-fluoroquinolones bioconjugates. Gelatin bioconjugates were characterized by UV-Vis, FT-IR, and calorimetric analyses, nanohybrids by morphological analyses. Biocompatibility was evaluated on human mesenchymal stem cells, and antibacterial performance against Klebsiella pneumoniae and Escherichia coli. Minimun inhibitory concentrations from 0.025 to 0.05 µg mL^?1 and from 0.025 to 0.10 µg mL^?1, and MBC from 0.025 to 0.10 µg mL^?1 and from 0.05 to 0.20 µg mL^?1 were detected for Escherichia coli and Klebsiella pneumoniae, respectively, showing that nanotubes increase antimicrobial activity comparing to both free and gelatin-conjugated drugs.     

QUANTIFICATION OF GALLIC ACID AND ELLAGIC ACID FROM THE SEED OF CORNUS OFFICINALIS BY UHPLC METHOD AND THEIR ANTIOXIDANT ACTIVITY

Gallic acid and ellagic acid have been identified in the seed of Cornus officinalis by the use of an ultrahigh performance liquid chromatography (UHPLC) method coupled with a diode array detector (DAD). The water extract of C. officinalis seed contained the highest gallic acid content (3.03 ± 0.10 mg/g seed), which was followed by aqueous methanol extract (2.43 ± 0.10 mg/g seed) and aqueous ethanol extract (1.53 ± 0.25 mg/g seed). But a higher concentration (12.32 ± 0.45 mg/g seed) of ellagic acid was obtained from extraction with aqueous methanol than with aqueous ethanol (11.03 ± 0.42 mg/g seed) and water (7.28 ± 0.16 mg/g seed). After heat treatment and acid hydrolysis, C. officinalis seed had higher concentrations of gallic acid and ellagic acid, contributing to more potent antioxidant activity. The results demonstrated a rich source of gallic acid and ellagic acid in C. officinalis seed, which might provide a novel source of these natural antioxidants.     

Bio-Wax Latex-Modified Paper as Antimicrobial and Water-Vapor-Resistant Packaging Material

Beeswax and carnauba wax latex particles grafted with antimicrobial agents polyhexamethylene guanidine hydrochloride and polyhexanide were prepared by coupling reaction using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride as a coupling reagent. As a bifunctional agent for the surface treatment of paper the modified bio-wax latex improved the property of water-vapor resistance and antimicrobial activities of paper significantly after coating. Compared with the control sample the water vapor transmission rate (WVTR) of the paper with coating weight of 12 g/m² was reduced significantly from 2788.8 g/m²/d to 222.0 g/m²/d (BW-Gly-PHGH) thus demonstrating excellent water vapor barrier performance. The shaking flask method was utilized to investigate the antimicrobial activity against E. coli. The results showed that antimicrobial performance was improved substantially when the amount of added modified bio-wax particles was higher than 20 mg/g fiber. The bacterial inhibition ring test indicated that the antimicrobial mode of the modified bio-wax particles was likely based on the contact mode.     

Structure Elucidation and Evaluation of Antioxidant and Tyrosinase Inhibitory Effect and Mechanism of Proanthocyanidins from Leaf and Fruit of Leucaena Leucocephala

This study aimed to investigate the structural features, antioxidant activity, tyrosinase inhibitory effect, and mechanism of proanthocyanidins from leaf and fruit of Leucaena leucocephala. MALDI-TOF-MS, thiolysis coupled with HPLC-ESI-MS, and ¹³C-NMR confirmed that these proanthocyanidins were complex mixtures of propelargonidins, procyanidins, and prodelphinidins. (Epi)catechin, (epi)gallocatechin, (epi)catechin gallate, and (epi)gallocatechin gallate were the main constitutive units. The findings obtained from enzyme analysis revealed that the proanthocyanidins had inhibitory effects on both monophenolase and diphenolase of tyrosinase. The IC₅₀ values of leaf and fruit proanthocyanidins were 73.5?±?2.7 and 52.3?±?3.5 µg/mL for monophenolase activity, and 27.2?±?1.4 and 16.1?±?1.1 µg/mL for diphenolase activity, respectively. The inhibition of diphenolase by proanthocyanidins were proved to be reversible and mixed type. In addition, it was also found from various antioxidant methods that the proanthocyanidins in leaf and fruit possessed potent DPPH radical scavenging activity with IC₅₀ values of 103.4?±?0.8 and 87.8?±?1.1 µg/mL, ABTS radical scavenging activity with IC₅₀ values of 72.9?±?0.4 and 65.7?±?0.9 µg/mL, and ferric reducing antioxidant power with FRAP values of 3.74?±?0.03 and 4.02?±?0.15?mmol AAE/g, respectively. The results obtained suggested that the proanthocyanidins from leaf and fruit of L. leucocephala might have the potential to be exploited as natural tyrosinase inhibitors and antioxidants.     

Optimization of Microwave-Assisted Extraction of Cherry Laurel Fruit

Response surface methodology was used to optimize the influence of microwave power (300–600 W), plant material-to-solvent ratio (0.05–0.2 g/cm³), and extraction time (10–30 min) on the efficiency of microwave-assisted extraction of the cherry laurel (Prunus laurocerasus L.) fruit. From experimental data, a quadratic polynomial mathematical model (R² = 0.9949) was developed to predict the extract yield. All considered factors were statistically significant for extraction efficiency, while the most important factor was extraction time. Microwave power of 550 W, plant material-to-solvent ratio of 0.05 g/cm³, and time of 25 min were determined as optimal conditions with a maximum yield of 9.36 g/100 g fresh plant material, which was confirmed through laboratory experiments (9.12 ± 0.61 g/100 g fresh plant material). An economic condition for simultaneous maximum extract yield (7.58 g/100 g fresh plant material) with minimal energy and solvent consumption was determined by the desirability function method (18.2 min, 300 W, and 0.2 g/cm³). Additionally, the total phenol and flavonoid quantification and antioxidant activity of both extracts were tested. There is no statistically significant difference in the total flavonoid content in the extracts obtained under both proposed conditions, while the total phenolic content and antioxidant activity of the extract obtained under economic conditions were slightly lower.     

Supercritical CO2 extraction of ucuúba (Virola surinamensis) seed oil: global yield,kinetic data,fatty acid profile,and antimicrobial activities

Virola surinamensis is an abundant floodplain tree, popularly known as ucuúba, that grows in the Amazon. In this study, ucuúba seed oil was obtained by supercritical fluid extraction under different operating conditions, as well as Soxhlet extraction. The operating conditions for supercritical extraction were an extraction temperature of 40, 60, or 80?°C, a pressure of 350?bar, and a CO₂ mass flow of 7.9?×?10^?5 kg/s. The supercritical extraction curves were fitted to mass transfer models, and the fatty acid profiles of the extracts were determined by gas chromatography. The antimicrobial activity was assessed against Candida albicans, Staphylococcus aureus, and Escherichia coli. The highest yield obtained using supercritical CO₂ was 64.39% and the lowest was 59.21%. The phytochemical analysis showed the presence of steroids, terpenes, coumarins, and phenolic compounds. All ucuúba oil samples showed antioxidant activity. Regarding the antimicrobial activity, ucuúba oil only showed activity against S. aureus.     

Extraction Kinetics and Anethole Content of Fennel (Foeniculum vulgare) and Anise Seed (Pimpinella anisum) Extracts Obtained by Soxhlet,Ultrasound, Percolation,Centrifugation, and Steam Distillation

Foeniculum vulgare (fennel) and Pimpinella anisum (anise) extracts were obtained by Soxhlet, cold percolation, ultrasound assisted extraction, and centrifugal extraction using ethanol as solvent; anise extracts were also obtained by steam distillation. Soxhlet presented the highest yields for both fennel and anise seed (16.8% and 23.3%, respectively). The highest anethole content among ethanolic extracts was obtained for centrifugal extraction (6.8 mg/g and 143 mg/g for fennel and anise extracts, respectively). Steam distillation presented low yield (0.26%), but high anethole content (68–98%, area). Anise ethanolic extracts also tested positive for flavonoids.     

A highly efficient method for concentrating DNA from river water by combined coagulation and foam separation

ABSTRACT

Both Escherichia coli and Enterococci were collected in foam within 7 min from 500 mL of bacteria-spiked water by coagulation and foam separation using ferric chloride and milk casein. These bacterial DNA isolated in the 100 µL of extract from the foam more than 87.5% recovery using the DNeasy PowerWater® Kit. To test this method with water from three natural rivers, 0.67–2.70 µg of DNA were concentrated in 100 µL of extract from 1,000 mL of river water. When the DNA extract was subjected to 16S rRNA gene sequencing analysis, information on the bacterial flora could be obtained.     

Extraction of Total Phenolics of Sour Cherry Pomace by High Pressure Solvent and Subcritical Fluid and Determination of the Antioxidant Activities of the Extracts

Abstract

High pressure liquid extraction (HPE) and subcritical fluid (CO₂+ethanol) extraction (SCE) were used for the extraction of total phenolic compounds (TPC) from sour cherry pomace. Antiradical efficiency (AE) of the extracts was also determined. Ethanol was the solvent for HPE and co‐solvent for SCE. Combinations of pressure (50, 125, 200 MPa), temperature (20, 40, 60°C), solid/solvent ratio (0.05, 0.15, 0.25 g/ml) and extraction time (10, 25, 40 min) were variables for HPE according to the Box‐Behnken experimental design. The variables used for SCE were pressure (20, 40, 60 MPa), temperature (40, 50, 60°C), ethanol concentration (14, 17, 20 wt%) and extraction time (10, 25, 40 min). For HPE, TPC, and AE at the optimum conditions (176–193 MPa, 60°C, 0.06–0.07 g solid/ml solvent, 25 min) were found as 3.80 mg gae/g sample and 22 mg DPPH^?/g sample, respectively. TPC and AE at the optimum conditions (54.8–59 MPa, 50.6–54.4°C, 20 wt% ethanol, 40 min) for SCE were determined as 0.60 mg gae/g sample and 2.30 mg DPPH^?/g sample for sour cherry pomace, respectively.     

Antimicrobial Activity of Ozone against Pathogenic Oral Microorganisms on Different Denture Base Resins

ABSTRACT

The present study aimed to evaluate the antimicrobial effect of gaseous ozone against specific oral pathogens on denture base resins. 1080 round samples were prepared (10mm-diameter, 2mm-thickness). Candida albicans, Streptococcus mutans, Streptococcus gordonii, and Aggregatibacter actinomycetemcomitans, polyamide-Deflex, heat-cured polymethyl-methacrylate (PMMA)-QC-20, and cold-cured-PMMA-Meliodent. The doses and durations: 25, 50 and 100µg/ml, 5, 10, 20, 30 minutes. For Cell viability (CV) MTT was used. 100µg/ml was most effective dose for C. albicans, S .gordonii, and A. actinomycetemcomitans were in heat-cured-PMMA and polyamide for S.mutans. For polyamide, lowest CV was 43% in S.mutans and A.actinomycetemcomitans. CV of heat-cure and cold-cure PMMA were 31% and 32% in S.gordonii, respectively. CV was similar for all resins and durations in S.mutans and A.actinomycetemcomitans and for polyamide for C.albicans and for heat-cure PMMA for S.gordonii. 30-min ozone application killed 80% of all microorganisms in all resins except for C.albicans in polyamide (65% cell death) and cold-cure PMMA (57% cell death). Optimal dose/duration combination was 100 µg/ml-10 min. Gaseous ozone can be considered as an effective cleansing agent for denture base resins.