Radical-scavenging activity of extracts from Cordia verbenacea DC obtained by different methods

The possibility of using the leaves of Cordia verbenacea as a new source of natural antioxidant compounds was investigated. In the present work, extracts from C. verbenacea were obtained using different extraction methods: supercritical fluid extraction (SFE), Soxhlet (SE), hydrodistillation and maceration, with the objective to evaluate the methods in terms of yield and antioxidant potential. The high-pressure technique was applied using pure CO₂ and CO₂ with co-solvent at different temperatures and pressures (30, 40 and 50 °C and 100, 200, and 300 bar). Organic solvents with different polarities were used to obtain extracts by low-pressure extraction processes. The extracts were evaluated according to their antioxidant activity using total phenolic content, scavenging abilities on DPPH radical, total antioxidant activities (ABTS^•+), superoxide anion radical-scavenging (O₂^•) and protection against lipid peroxidation in vitro (LPO). Ethyl acetate fraction obtained by maceration and extract isolated by SE using 25% aqueous mixture of ethanol possessed the highest scavenger activity against DPPH radical (IC₅₀ = 9.2 ± 0.4 μg/ml, IC₅₀ = 27.4 ± 0.1 μg/ml, respectively). The SFE with 8% ethanol as a co-solvent produced extracts with distinguished increase in the antioxidant activity. The Soxhlet extract with ethyl acetate exhibited a strong reduction of lipid peroxidation (IC₅₀ = 209 ± 3 μg/ml) value comparable to the standard rutin (IC₅₀ = 203 ± 2 μg/ml). The results indicate that extracts of C. verbenacea have important potential as a source of bioactive compounds with antioxidant activity.     

Essential Oil of Cymbopogon nardus (L.) Rendle: A Strategy to Combat Fungal Infections Caused by Candida Species

Background: The incidence of fungal infections, especially those caused by Candida yeasts, has increased over the last two decades. However, the indicated therapy for fungal control has limitations. Hence, medicinal plants have emerged as an alternative in the search for new antifungal agents as they present compounds, such as essential oils, with important biological effects. Published data demonstrate important pharmacological properties of the essential oil of Cymbopogon nardus (L.) Rendle; these include anti-tumor, anti-nociceptive, and antibacterial activities, and so an investigation of this compound against pathogenic fungi is interesting. Objective: The aim of this study was to evaluate the chemical composition and biological potential of essential oil (EO) obtained from the leaves of C. nardus focusing on its antifungal profile against Candida species. Methods: The EO was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Testing of the antifungal potential against standard and clinical strains was performed by determining the minimal inhibitory concentration (MIC), time-kill, inhibition of Candida albicans hyphae growth, and inhibition of mature biofilms. Additionally, the cytotoxicity was investigated by the IC₅₀ against HepG-2 (hepatic) and MRC-5 (fibroblast) cell lines. Results: According to the chemical analysis, the main compounds of the EO were the oxygen-containing monoterpenes: citronellal, geranial, geraniol, citronellol, and neral. The results showed important antifungal potential for all strains tested with MIC values ranging from 250 to 1000 μg/mL, except for two clinical isolates of C. tropicalis (MIC > 1000 μg/mL). The time-kill assay showed that the EO inhibited the growth of the yeast and inhibited hyphal formation of C. albicans strains at concentrations ranging from 15.8 to 1000 μg/mL. Inhibition of mature biofilms of strains of C. albicans, C. krusei and C. parapsilosis occurred at a concentration of 10× MIC. The values of the IC₅₀ for the EO were 96.6 μg/mL (HepG-2) and 33.1 μg/mL (MRC-5). Conclusion: As a major virulence mechanism is attributed to these types of infections, the EO is a promising compound to inhibit Candida species, especially considering its action against biofilm.     

Dual Bioactivities of Essential Oil Extracted from the Leaves of Artemisia argyi as an Antimelanogenic versus Antioxidant Agent and Chemical Composition Analysis by GC/MS

The study was aimed at investigating the antimelanogenic and antioxidant properties of essential oil when extracted from the leaves of Artemisia argyi, then analyzing the chemical composition of the essential oil. The inhibitory effect of the essential oil on melanogenesis was evaluated by a mushroom tyrosinase activity assay and B16F10 melanoma cell model. The antioxidant capacity of the essential oil was assayed by spectrophotometric analysis, and the volatile chemical composition of the essential oil was analyzed with gas chromatography-mass spectrometry (GC/MS). The results revealed that the essential oil significantly inhibits mushroom tyrosinase activity (IC₅₀ = 19.16 mg/mL), down-regulates B16F10 intracellular tyrosinase activity and decreases the amount of melanin content in a dose-dependent pattern. Furthermore, the essential oil significantly scavenged 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline- 6-sulphonic acid) ABTS radicals, showed an apparent reduction power as compared with metal-ion chelating activities. The chemicals constituents in the essential oil are ether (23.66%), alcohols (16.72%), sesquiterpenes (15.21%), esters (11.78%), monoterpenes (11.63%), ketones (6.09%), aromatic compounds (5.01%), and account for a 90.10% analysis of its chemical composition. It is predicted that eucalyptol and the other constituents, except for alcohols, in the essential oil may contribute to its antioxidant activities. The results indicated that essential oil extracted from A. argyi leaves decreased melanin production in B16F10 cells and showed potent antioxidant activity. The essential oil can thereby be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products.     

Reactive extraction and in situ esterification of Jatropha curcas L. seeds for the production of biodiesel

Jatropha curcas L. has recently been hailed as the promising feedstock for biodiesel production as it does not compete with food sources. Conventional production of biodiesel from J. curcas L. seeds involve two main processing steps; extraction of oil and subsequent esterification/transesterification to fatty acid methyl esters (FAME). In this study, the feasibility of in situ extraction, esterification and transesterification of J. curcas L. seeds to biodiesel was investigated. It was found that the size of the seed and reaction period effect the yield of FAME and amount of oil extracted significantly. Using seed with size less than 0.355 mm and n-hexane as co-solvent with the following reaction conditions; reaction temperature of 60 °C, reaction period of 24 h, methanol to seed ratio of 7.5 ml/g and 15 wt% of H₂SO₄, the oil extraction efficiency and FAME yield can reached 91.2% and 99.8%, respectively. This single step of reactive extraction process therefore can be a potential route for biodiesel production that reduces processing steps and cost.     

Pereskia aculeata Muller (Cactaceae) Leaves: Chemical Composition and Biological Activities

The aims of this work were to study the chemical composition of the essential oil from the leaves of Pereskia aculeata and to evaluate some biological activities of three leaf extracts. The phenolic content, antioxidant activity, and in vitro antimicrobial and antifungal activities were determined. The methanol extract showed antioxidant activity (EC₅₀ 7.09 mg/mL) and high polyphenols content (15.04 ± 0.31 mg gallic acid equivalents (GAE)/g). The petroleum ether extract exhibited potent antibacterial activity against Escherichia coli, whereas the chloroform extract showed inhibitory activity against Bacillus cereus and Staphylococcus aureus. The petroleum ether and methanol extracts were more effective in inhibiting the growth of Aspergillus versicolor. The possible cytotoxicity of extracts on neuroblastoma SH-SY5Y cancer cell line and the influence on adenylate cyclase (ADCY) expression was also studied. P. aculeata chloroform extract showed antiproliferative activity with an IC₅₀ value of 262.83 µg/mL. Treatments of SH-SY5Y neuroblastoma cells with 100 µg/mL of methanol extract significantly reduced ADCY1 expression.     

GC and GC/MS Analysis of Essential Oil Composition of the Endemic Soqotraen Leucas virgata Balf.f. and Its Antimicrobial and Antioxidant Activities

Leucas virgata Balf.f. (Lamiaceae) was collected from the Island Soqotra (Yemen) and its essential oil was obtained by hydrodistillation. The chemical composition of the oil was investigated by GC and GC-MS. Moreover, the essential oil was evaluated for its antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria, and one yeast species by using broth micro-dilution assay for minimum inhibitory concentrations (MIC) and antioxidant activity by measuring the scavenging activity of the DPPH radical. The investigation led to the identification of 43 constituents, representing 93.9% of the total oil. The essential oil of L. virgata was characterized by a high content of oxygenated monoterpenes (50.8%). Camphor (20.5%) exo-fenchol (3.4%), fenchon (5.4%), and borneol (3.1%) were identified as the main components. Oxygenated sesquiterpenes were found as the second major group of compounds (21.0%). β-Eudesmol (6.1%) and caryophyllene oxide (5.1%) were the major compounds among oxygenated sesquiterpenes. The results of the antimicrobial assay showed that the oil exhibited a great antibacterial activity against the tested S. aureus, B. subtilis, and E. coli. No activity was found against P. aeruginosa and C. albicans. Moreover, the DPPH-radical scavenging assay exhibited only a moderate antioxidant activity (31%) for the oil at the highest concentration tested (1 mg/mL).     

Transesterification of palm oil on KyMg1 − xZn1 + xO3 catalyst: Effect of Mg-Zn interaction

The Mg-Zn interaction effect of K_yMg_1 − xZn_1 + xO₃ heterogeneous type catalyst and its performance on transesterification of palm oil have been studied using the response surface methodology and the factorial design of experiments. The catalyst was synthesized using the co-precipitation method and the activity was assessed by transesterification of palm oil into fatty acid methyl esters. The ratio of the Mg/Zn metal interaction, temperature and time of calcination were found to have positive influence on the conversion of palm oil to fatty acid methyl ester (FAME) with the effect of metal to metal ratio and temperature of calcination being more significant. The catalytic activity was found to decrease at higher calcination temperature and the catalyst type K₂Mg_0.34Zn_1.66O₃ with Mg/Zn ratio of 4.81 gave FAME content of 73% at a catalyst loading of 1.404 wt.% of oil with molar ratio of methanol to oil being 6:1 at temperature of 150 °C in 6 h. A regression model was obtained to predict conversions to methyl esters as a function of metal interaction ratio, temperature of calcination and time. The observed activity of the synthesized catalyst was due to its synergetic structure and composition.     

Supercritical impregnation of lavandin (Lavandula hybrida) essential oil in modified starch

Lavandin (Lavandula hybrida) essential oil contains components with biocide properties that can be used as substitutes of synthetic drugs in livestock. This application requires an appropriate formulation of the essential oil. In this work, supercritical impregnation of lavandin oil has been proposed as a possible formulation process, due to the high solubility of lavandin essential oil in supercritical carbon dioxide. The polymer used in this work as carrier material was starch modified with the n-octenil succinate (OSA) group, in the form of powder with a particle size of 30 μm. The effects of operational pressure (10-12 MPa), temperature (313-323 K) and lavandin oil to starch mass ratio (0.2-1) were studied. Impregnation loads ranging from 25 to 150 mg lavandin oil/g OSA-starch were obtained. The distribution coefficient of essential oil between the starch and the supercritical phase as well as the essential oil load depended on the density of CO₂.     

Brazilian Ginseng extraction via LPSE and SFE: Global yields, extraction kinetics, chemical composition and antioxidant activity

Brazilian Ginseng extracts of two species, Pfaffia paniculata and Pfaffia glomerata, were obtained by supercritical fluid extraction (SFE) with CO₂ and by low-pressure solvent extraction (LPSE) with methanol, hexane and ethanol. The SFE assays were conducted at pressures of 100, 200 and 300 bar, and temperatures of 30 and 50 °C. The qualitative chemical compositions of the extracts were determined by thin layer chromatography (TLC). One of the active principles of interest from P. glomerata extract, β-ecdysone, was identified and quantified by HPLC. The antioxidant activities of Brazilian Ginseng extracts were determined by the coupled reaction of linolenic acid and β-carotene. For P. paniculata, the highest SFE yield was obtained at 200 bar/50 °C (0.22%, dry basis—d.b.), while the best extraction condition for P. glomerata was obtained at 200 bar/30 °C (0.18%, d.b.). The higher extract yields obtained by LPSE were 2.0% and 5.8% (w/w, d.b.) for P. paniculata and P. glomerata, respectively, both obtained with methanol as extraction solvent. From the overall extraction curve of P. glomerata, it was possible to obtain the kinetic parameters of extraction; the duration of the CER (constant extraction rate) period was determined as 134 min. The TLC plates showed the possible presence of flavonoids in the ethanolic extract for both Pfaffia species. The antioxidant activity analysis detected that LPSE extracts had higher activity than SFE extracts.     

Bactericidal and Antioxidant Activity of Essential Oils from <Emphasis Type="Italic">Myristica fragrans</Emphasis> Houtt and <Emphasis Type="Italic">Salvia microphylla</Emphasis> H.B.K

This study chemically characterizes and evaluates the bactericidal and antioxidant activities of essential oils from Myristica fragrans and Salvia microphylla. The essential oils were obtained by steam distillation and were subsequently subjected to analysis by GC–MS and GC. The agar diffusion test was employed to evaluate the bactericidal activity, while the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and β-carotene/linoleic acid tests were used to determine the antioxidant activity. Terpin-4-ol (14.95%), sabinene (13.07%) and γ-terpinene (11.22%) were found to be the major constituents in the essential oil of M. fragrans by gas chromatography, whereas (E)-caryophyllene (15.35%), α-eudesmol (14.06%), β-eudesmol (8.74%) and γ-eudesmol (7.64%) were encountered in the essential oil of S. microphylla. Both essential oils showed bactericidal activity, with the essential oil of S. microphylla being more efficient. The antioxidant activity of the essential oils from M. fragrans and S. microphylla were demonstrated by the β-carotene/linoleic acid test, with IC₅₀ 976 and IC₅₀ 770 μg/mL, respectively.     

Influence of ionic liquids on the direct electrochemistry of glucose oxidase entrapped in nanogold-N,N-dimethylformamide-ionic liquid composite film

Glucose oxidase (GOD) immobilized in nanogold particles (NAs)-N,N-dimethylformamide (DMF) composite film on glassy carbon (GC) electrode exhibits a pair of quasi-reversible and unstable peaks due to the redox of flavin adenine dinucleotide (FAD) of GOD. When ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄) or trihexyltetradecylphosphorium bis (trifluoromethylsulfony) (P_666,14 NTf₂) is introduced in the film, the peaks become small. But ILs 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆) and 1-octyl-3-methylimidazolium hexafluorophate (OMIMPF₆) make the peaks large and stable. In different composite films the formal potential (E⁰′) of GOD is different. UV-vis spectra show that the GOD dispersed in these films almost retains its native structure and there are weak interactions between ILs and GOD. Electrochemical impedance spectra display that NAs can promote the electron transfer between FAD and GC electrode; and ILs can affect the electron transfer through interacting with GOD. The thermal stability of GOD entrapped in NAs-DMF-ILs composite films is also influenced by ILs, and it follows such order as: in NAs-DMF-OMIMPF₆ > in NAs-DMF-BMIMPF₆ ≈ in NAs-DMF-BMIMBF₄ > in NAs-DMF. In addition, GOD immobilized in NAs-DMF-OMIMPF₆ and NAs-DMF-BMIMPF₆ films shows good catalytic activity to the oxidation of glucose. The I_max of H₂O₂ and the apparent K_m (Michaelis-Menten constant) for the enzymatic reaction are calculated.     

Microstructure, growth mechanism and mechanical property of Al2O3-based eutectic ceramic in situ composites

Directionally solidified Al₂O₃-based eutectic ceramic in situ composites with inherently high melting point, low density, excellent microstructure stability, outstanding resistance to creep, corrosion and oxidation at elevated temperature, have attracted significant interest as promising candidate for high-temperature application. This paper reviews the recent research progress on Al₂O₃-based eutectic ceramic in situ composites in State Key Laboratory of Solidification Processing. Al₂O₃/YAG binary eutectic and Al₂O₃/YAG/ZrO₂ ternary eutectic ceramics are prepared by laser zone melting, electron beam floating zone melting and laser direct forming, respectively. The processing control, solidification characteristic, microstructure evolution, eutectic growth mechanism, phase interface structure, mechanical property and toughening mechanism are investigated. The high thermal gradient and cooling rate during solidification lead to the refined microstructure with minimum eutectic spacing of 100 nm. Besides the typical faceted/faceted eutectic growth manner, the faceted to non-faceted growth transition is found. The room-temperature hardness H_V and fracture toughness K_IC are measured with micro-indentation method. For Al₂O₃/YAG/ZrO₂, K_IC = 8.0 ± 2.0 MPa m^1/2 while for Al₂O₃/YAG, K_IC = 3.6 ± 0.4 MPa m^1/2. It is expectable that directionally solidified Al₂O₃-based eutectic ceramics are approaching practical application with the advancement of processing theory, technique and apparatus.     

Supercritical CO2 extraction of Helichrysum italicum: Influence of CO2 density and moisture content of plant material

Kinetics and selectivity of supercritical carbon dioxide (SC CO₂) extraction of Helichrysum italicum flowers were analyzed at pressures in the range of 10-20 MPa and temperatures of 40 °C and 60 °C (density of SC CO₂ from 290 to 841 kg/m³) and also at 10 MPa and 40 °C using flowers with different moisture contents (10.5% and 28.4%). Increased moisture content of H. italicum flowers resulted in enchased solubility of solute enabling decrease of SC CO₂ consumption necessary for achieving desired extraction yield. The most abundant compounds in the supercritical extracts are sesquiterpenes and waxes while monoterpenes and sesquiterpenes are the main constituents of essential oil obtained by hydrodistillation. The optimal set of working parameters with respect to extraction yield, SC CO₂ consumption and chemical composition of extract were defined related to moisture content of raw material and SC CO₂ density.     

Chemical Composition,Antitumor Properties,and Mechanism of the Essential Oil from Plagiomnium acutum T. Kop.

Plagiomnium acutum T. Kop. (P. acutum) has been used as a traditional Chinese medicine for thousands of years to treat cancer but lacks evidence. The objective of this work was to reveal the chemical composition of P. acutum essential oil (PEO) and explore its potential antitumor activity and molecular mechanism. PEO was prepared by the simultaneous distillation–extraction method and characterized by gas chromatography/mass spectroscopy. CCK8 assay, flow cytometry, western blot, and immunofluorescence techniques were used to analyze the effects and mechanism of PEO against cancer cells. A total of 74 constituents of PEO were identified, with diterpenes (26.5%), sesquiterpenes (23.89%), and alcohols (21.81%) being the major constituents. Two terpenoids, selina-6-en-4-ol and dolabella-3,7-dien-18-ol, were detected in PEO for the first time. PEO showed significant cell growth inhibitory activity on HepG2 and A549 cells by blocking the G1 phase and inducing apoptosis, which may be attributed to its upregulation of p21^Cip1 and p27^Kip1 proteins and interference with mitochondrial membrane potential effect. Dolabella-3,7-dien-18-ol accounts for 25.5% of PEO and is one of the main active components of PEO, with IC₅₀ values in HepG2 and A549 cells of (25.820 ± 0.216) µg/mL and (23.597 ± 1.207) μg/mL, respectively. These results confirmed the antitumor medicinal value of P. acutum and showed great application potential in the pharmaceutical industry.     

SFE from Bidens pilosa Linné to obtain extracts rich in cytotoxic polyacetylenes with antitumor activity

Bidens pilosa L. is a plant considered medicinal by some South American cultures. It contains polyacetylenes which may be the constituents responsible for its antitumor activity. Extracts obtained by hydroethanol maceration (HCE) and supercritical fluid extraction (SFE) were monitored for antitumor activity and the presence of polyacetylenes in the constitution. Both extracts killed concentration-dependently the MCF-7 cells in culture, although the SFE extract presented superior cytotoxic activity. The SFE presented IC₅₀ = 437 (428-446) μg/mL in 24 h of incubation, decreasing to IC₅₀ = 291 (282-299) μg/mL at 48 h. The HCE started causing DNA cleavage at 160 μg/mL while the SFE extract started at 40 μg/mL, a concentration enough to initiate the in vitro cleavage. The presence of polyacetylenes as the major compounds in SFE was confirmed by TL chromatography combined with UV-vis analyses. Ehrlich ascites carcinoma-bearing mice were used for the antitumor study. Animals were divided in five groups: normal, negative control, positive control (Doxorubicin 0.06 mg/kg), test group HCE and test group SFE (100 mg/kg b.w. per day). After 9 days of treatment, 50% of randomly chosen animals from each group were sacrificed for the study. The parameters evaluated were: body weight, abdominal circumference, volume of ascitic fluid and tumor cells, viable and nonviable tumor cell count, determination of mean survival time and increased life-span. Both extracts presented antitumor activity, but SFE reduced more the volumes of ascites fluid and the tumor cells (4 ± 1 and 1 ± 0.4 mL, respectively), while caused higher mean survival time (17 days) and increased life span (∼31%). The results suggest the importance of the polyacetylenes from B. pilosa as leader molecules to contribute to a new anticancer drug by using the supercritical technology.     

Biologically Active Digests from Pumpkin Oil Cake Protein: Effect of Cross-linking by Transglutaminase

The objective of this study was to show that biologically active hydrolysates can be obtained by simulated human gastrointestinal digestion (HGD) of transglutaminase cross-linked pumpkin oil cake protein (Tg-C) which was previously reported as a potential functional food additive. A two-stage in vitro digestion model system (by pepsin and α chymotrypsin and trypsin, simultaneously) was used to simulate the process of HGD on native and Tg-C major storage pumpkin oil seed/cake protein, cucurbitin (C). The biologically active potential of the digests was evaluated, measuring the angiotensin-converting-I enzyme (ACE) inhibitory and anti-oxidant capacity. The ACE inhibitory activity was determined in both final digests, with IC₅₀ = 0.30 ± 0.04 mg/ml for C and IC₅₀ = 0.28 ± 0.01 for Tg-C. The anti-oxidant potency of the examined proteins was enhanced by the digestion process. The 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation activities and reducing power testing showed that all the hydrolysates act as a radical quencher and reducing agents. Overall, the results showed that the cross-linking by Tg did not influence the digestion process, as well as having no effect on the biological activity of the hydrolysates. These also indicate that Tg-C, if used as functional food additive, after food consumption can be digested and become a source of peptides exerting positive effects on human health.     

Radiochemical ageing of an amine cured epoxy network. Part I: change of physical properties

An aromatic rich, amine cured epoxy network (initial glass transition temperature 250 °C), was irradiated in air (pressure 0.22 MPa), at 30 and 120 °C, by gamma rays with two dose rates 2 and 20 kGy/h, for doses upto 70 MGy. The following characteristics were recorded, thickness of oxidised layer (TOL) from IR microspectrophotometry, flexural strength σ_R, toughness K_IC and glass transition temperature T_g. σ_R decreases from 120 MPa to about 40 MPa in the most degraded samples. This decrease is sharply linked to TOL showing the key role of the oxidised layer in crack initiation. K_IC decreases from 0.7 to 0.55 MPa m^1/2. Data are too much scattered to allow a kinetic study but it appears that, in the early period of exposure, K_IC decreases more rapidly at 120 °C than at 30 °C. T_g decreases from 250 to 140 °C in the most degraded samples, and the decrease is faster at 30 °C than at 120 °C. The decrease of T_g is attributed to a predominant chain scission process. The decrease of K_IC can be attributed to a combination of chain scission and physical ageing or chain scission and crosslinking. A relationship between T_g and the number of chain scissions, derived from the Di Marzio's theory, is proposed.     

Optimization of process variables for essential oil components from Satureja hortensis by supercritical fluid extraction using Box-Behnken experimental design

The oil and extracts of Satureja hortensis cultivated in Iran were extracted using supercritical carbon dioxide and hydrodistillation method. The oil and extracts were analyzed by GC-FID and GC/MS. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of various parameters such as pressure, temperature, percent of modifier (methanol) and extraction time, were investigated by a fractional factorial design (2^4-1) to determine the significant parameters and their interactions. The results showed that the pressure, temperature and percent of modifier are significant (p < 0.05), but the extraction time was found to be insignificant. The response surface methodology (RSM), based on Box-Behnken design was employed to obtain the optimum conditions of the significant parameters (pressure, temperature and percent of modifier). The optimal conditions could be obtained at a pressure of 35.0 MPa, temperature of 72.6 °C, and 8.6% (v/v) for methanol. The main extracted components using SFE were γ-Terpinene (35.5%), Thymol (18.2%) and Carvacrol (29.7%).     

Sustainable Production of Biosurfactant from Agro-Industrial Oil Wastes by Bacillus subtilis and Its Potential Application as Antioxidant and ACE Inhibitor

The microbial conversion of agro-industrial oil wastes into biosurfactants shows promise as a biomass refinery approach. In this study, Bacillus subtilis #309 was applied to produce surfactin using rapeseed and sunflower cakes, the most common oil processing side products in Europe. Studies of the chemical composition of the substrates were performed, to determine the feasibility of oil cakes for surfactin production. Initially, screening of proteolytic and lipolytic activity was performed to establish the capability of B. subtilis #309 for substrate utilization and hence effective surfactin production. B. subtilis #309 showed both proteolytic and lipolytic activity. The process of surfactin production was carefully analyzed by measurement of the surfactin concentration, pH, surface tension (ST) and emulsification index (E₂₄). The maximal surfactin concentration in the sunflower and rapeseed cake medium reached 1.19 ± 0.03 and 1.45 ± 0.09 g/L, respectively. At the same time, a progressive decrease in the surface tension and increase in emulsification activity were observed. The results confirmed the occurrence of various surfactin homologues, while the surfactin C₁₅ was the dominant one. Finally, the analysis of surfactin biological function exhibited antioxidant activity and significant angiotensin-converting enzyme (ACE)-inhibitory activity. The half-maximal inhibitory concentration (IC₅₀) value for ACE inhibition was found to be 0.62 mg/mL for surfactin. Molecular docking of the surfactin molecule to the ACE domains confirmed its inhibitory activity against ACE. Several interactions, such as hydrophobic terms, hydrogen bonds and van der Waals interactions, were involved in the complex stabilization. To the best of our knowledge, this is the first report describing the effect of a lipopeptide biosurfactant, surfactin, produced by B. subtilis for multifunctional properties in vitro, namely the ACE-inhibitory activity and the antioxidant properties, using different assays, such as 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). Thus, the ACE-inhibitory lipopeptide biosurfactant shows promise to be used as a natural antihypertensive agent.     

Preparation of liposomes entrapping essential oil from Atractylodes macrocephala Koidz by modified RESS technique

A modified technique of rapid expansion of supercritical solutions (RESS) was applied to incorporate essential oil extracted from Atractylodes macrocephala Koidz into liposomes. In the modified RESS process, both the liposomal materials and the essential oil were dissolved in the mixture of supercritical carbon dioxide (SC-CO₂)/ethanol and then the solution was sprayed into an aqueous medium through a coaxial nozzle to form liposomes suspension. The encapsulation performance of liposomes could be controlled by changing expansion processing conditions such as pressure, temperature of SC-CO₂ and the amount of ethanol. The entrapment efficiency, drug loading and average particle size of liposomes were found to be 82.18%, 5.18% and 173 nm, respectively, under the optimum conditions of at a pressure of 30 MPa, a temperature of 338 K and a ethanol mole fraction in SC-CO₂ [(x(CH₃CH₂OH)] of 15%. The formed liposomes appeared as double-layered colloidal spheres with a uniform and narrow particle size distribution. The physicochemical properties of liposomes including entrapment efficiency, dissolution rate and stability were complied with the provisions of Chinese pharmacopoeia. All these results indicate that the modified RESS technique is an innovative way for self-assembly of liposomes incorporation of multi-components extracted from Chinese traditional medicines in the SC-CO₂.