Antioxidant Activity of the Essential Oil and Oleoresin ofZingiber OfficinaleRoscoe as Affected by Chemical Environment

Anti-Hyperglycemic Effects of Thai Herbal Medicines

This study aims to investigate selected medicinal plants' anti-oxidative and antihyperglycemic activities to develop an effective remedy for lowering blood glucose levels and/or reducing diabetes complications. Thai medicinal plants, reported to have blood sugar-lowering effects, were selected for the study: Coccinia grandis, Gymnema inodorum, Gynostemma pentaphyllum, Hibiscus sabdariffa, Momordica charantia, Morus alba, and Zingiber officinale. Each species was extracted by Soxhlet's extraction using ethanol as solvent. The ethanolic crude extract of each species was then evaluated for its phytochemicals, anti-oxidant, and antihyperglycemic activities. The results showed that the extract of Z. officinale gave the highest values of total phenolic and total flavonoid content (167.95 mg gallic acid equivalents (GAE)/g and 81.70 mg CE/g, respectively). Anti-oxidant activity was determined using DPPH and ABTS radical scavenging activity. Among the ethanolic extracts, Z. officinale exhibited the highest anti-oxidant activity with IC50 values of 19.16 and 8.53 µg/mL, respectively. The antihyperglycemic activity was assessed using α-glucosidase inhibitory and glucose consumption activities. M. alba and G. pentaphyllum demonstrated the highest α-glucosidase inhibitory activity among the ethanolic extracts, with IC50 values of 134.40 and 329.97 µg/mL, respectively. Z. officinale and H. sabdariffa showed the highest percentage of glucose consumption activity in induced insulin-resistant HepG2 cells at a concentration of 50 µg/mL with 145.16 and 107.03%, respectively. The results from α-glucosidase inhibitory and glucose consumption activities were developed as an effective antihyperglycemic remedy. Among the remedies tested, the R1 remedy exhibited the highest potential for reducing blood glucose levels, with an IC50 value of 122.10 µg/mL. Therefore, the R1 remedy should be further studied for its effects on animals.

Insecticidal activity of Thymus pallescens de Noë and Cymbogon citratus essential oils against Sitophilus zeamais and Tribolium castaneum

The thrust of the study was to determine the chemical composition of the essential oils extracted from Thymus pallescens de Noé and Cymbogon citratus Stapf. as well as to evaluate their efficacy in controlling Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) in either single or combined populations. Carvacrol (56.04%) and geraniol (20.86%) were identified as the major constituents of T. pallescens and C. citratus respectively. The tested essential oils showed pronounced insecticidal activity against the pest species in relation with the applied doses. T. pallescens EO had the highest efficacy and S. zeamais was found to be more susceptible to both individual and combined treatments. With reference to the contact and fumigation assessments, T. pallescens EO effectuated corrected mortality rates ranging from 42.5-100% to 25-100% in S. zeamais with corresponding lethal concentration (LC50) values of 17.7 µl/ml and 15µL/L air respectively. Whereas, the T. pallescens EO exhibited corrected mortality rates of 42.5-100% and 20-100% with corresponding LC50 values of 18.1 µl/ml and 15.5 µL/L air against T. castaneum in contact and fumigation assessments, respectively. The corrected mortality rates increased for both insect species when using combination treatments, with significant increases in the LC50 values, ranging from 8.59 to 49.9% for both pest species. Analysis of energy biomarkers in the treated insects indicate significantly increased protein and carbohydrate contents and decreased lipids levels. The study therefore demonstrated the bio-insecticidal toxicity of the EOs from T. pallescens and C. citratus against two important maize post-harvest pests, concurrently revealing significant positive and negative insecticidal activity gradients in relation to single or combined populations.

Antioxidant Properties of Dried Ginger (Zingiber officinale Roscoe) var. Bentong

Ginger (Zingiber officinale Roscoe) is a popular culinary herb used in the Eastern culture. The essential cultivar of the Zingiber genus is rich in antioxidants and is crucial in the fight against oxidative stress-related diseases. The antioxidant properties of dried ginger were evaluated and compared for their efficacy from different drying processes (sun-, oven-, vacuum- and freeze-drying) and using three extraction solvents: hot water, aqueous ethanol (80%, v/v) and ethanol. The drying process demonstrated a positive effect on the antioxidant activities of ginger. A significant difference (p < 0.05) was observed in the extracting ability of each solvent. Sun-dried ginger extracted with ethanol performed better than the fresh ginger extract in the form of increased yield (3.04-fold), TFC values (12.25-fold), reducing power (FRAP) (15.35-fold), total antioxidant activity (TAA) (6.82-fold) and inhibition of ABTS•+ radical cation (3.51-fold) and DPPH• radical (95%). Meanwhile, freeze-dried aqueous ginger extracts demonstrated significantly higher TPC (1.66-fold), TFC (3.71-fold), FRAP (3.26-fold), TAA (2.97-fold), ABTS•+ scavenging activity (1.48-fold) and DPPH• radical inhibition (77%), compared to fresh ginger extracts. In addition, it was found that ethanol was significantly superior to aqueous ethanol in phenolic content recovery, despite the lower yield. Furthermore, ethanol ginger extracts exhibited higher antioxidant activity than aqueous ethanol extracts. On the other hand, hot water was the least potent solvent for extraction. In summary, there was an excellent correlation between TPC, TFC and antioxidant activity. Sun-drying is the most desirable method for preserving and enhancing ginger quality due to its cost effectiveness and bioactive compound efficacy.

Supercritical CO2 extraction, chemical composition, and antioxidant effects of Coreopsis tinctoria Nutt. oleoresin

Coreopsis tinctoria Nutt. was used to extract oleoresin through supercritical CO₂ extraction technology. The extraction conditions were optimized using response surface methodology, and the chemical composition of C. tinctoria Nutt. oleoresin (CTO) was analyzed. Under the optimal conditions, the antioxidant activity of oleoresin was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH˙) and 2,2′-azino-bis-(3-ethylbenzo-thiazoline-6-sulphonic acid)diammonium salt (ABTS˙⁺) free radical scavenging assays. The optimal extraction conditions were a 27.5 MPa extraction pressure, a 45°C extraction temperature, and a 3 h extraction time. Under these extraction conditions, oleoresin yield was up to 3.163%. Compared to steam distillation extraction, the CTO extracted using supercritical CO₂ had more abundant components. The EC₅₀ of CTO for DPPH˙ and ABTS˙⁺ free radical scavengers was 1.54 and 1.07 mg/mL, respectively.

Dose-dependent Action of Zingiber officinale on Colonic Dysmotility and Ex Vivo Spontaneous Intestinal Contraction Modulation

Ginger (Zingiber officinale) rhizomes are commonly used in foods and employed for many ailments including gastrointestinal disorders. Our main objective was to evaluate the effect of Zingiber officinale aqueous extract (ZOAE) on gastrointestinal (GI) physiological motility and colonic dysmotility. Thereby, Wistar rats were given loperamide (LP, 3 mg/kg, b.w.) and ZOAE (75, 150, and 300 mg/kg, b.w.) or yohimbine (YOH, 2 mg/kg, b.w.). ZOAE-action on intestinal secretion was assessed using Ussing chamber technique and intestinal motility with isometric transducer. GI-transit (GIT) and gastric emptying (GE) were evaluated with the charcoal meal test and the red phenol methods. ZOAE-bioactive components were analyzed by liquid chromatography-high resolution electrospray ionization mass spectrometry (LC-HRESIMS). Constipation was induced with LP and the different indicators such as stool composition, GIT, oxidative stress biological parameters, and colonic mucosa histological alteration were performed. Anti-constipation effect of ZOAE was confirmed on stool composition, GIT (53.42% to 85.57%), GE (55.47% to 98.88%), and re-established oxidative balance. ZOAE induces an amplitude increase of spontaneous intestinal contraction with EC50 of 10.52 μg/mL. No effect of ZOAE was observed on electrogenic transport of intestinal fluid. These findings suggest that ZOAE-bioactive candidates might exert an anti-constipation action and spontaneous intestinal contraction modulation.

Simultaneous Hydrodistillation-Steam Distillation of Rosmarinus officinalis, Lavandula angustifolia and Citrus aurantium from Morocco, Major Terpenes: Impact on Biological Activities

Interest in the use of essential oils (EOs) in the biomedical and food industries have seen growing over the last decades due to their richness in bioactive compounds. The challenges in developing an EO extraction process that assure an efficient levels of monoterpenes with impact on biological activities have driven the present study, in which the EO extraction process of rosemary, lavender and citrus was performed by simultaneous hydrodistillation-steam distillation, and the influence of EO composition on biological activities, namely antioxidant, anti-inflammatory, antidiabetic, anti-acetylcholinesterase, anti-tyrosinase, antibacterial, and antibiofilm activity, were evaluated. The EO yields of combinations were generally higher than the individual plants (R. officinalis (Ro), L. angustifolia (La), and C. aurantium (Ca)) extracted by the conventional hydrodistillation. The EOs obtained by this process generally had a better capacity for scavenging the free radicals, inhibiting α-glucosidase, and acetylcholinesterase activities than the individual EOs. The combination of EOs did not improve the ability for scavenging peroxide hydrogen or the capacity for inhibiting lipoxygenase activity. The antioxidant activity or the enzyme inhibition activity could not only be attributed to their major compounds because they presented lower activities than the EOs. The chemical composition of the combination Ro:La:Ca, at the ratio 1/6:1/6:2/3, was enriched in 1,8-cineole, linalool, and linalyl acetate and resulted in lower MIC values for all tested strains in comparison with the ratio 1/6:2/3:1/6 that was deprived on those components. The biofilm formation of Gram positive and Gram negative bacteria was impaired by the combination Ro:La:Ca at a sub-inhibitory concentration.

Synthesis and Characterization of Green Carbon Dots for Scavenging Radical Oxygen Species in Aqueous and Oil Samples

Carbon dots (CDs) due to their unique optical features, chemical stability and low environmental hazard are applied in different fields such as metal ion sensing, photo-catalysis, bio-imaging and tribology, among others. The aims of the present research were to obtain CDs from vegetable wastes (tea and grapes) as carbon sources and to explore their potential properties as radical scavengers. CDs from glutathione/citric acid (GCDs) were synthetized for comparison purposes. The CDs were investigated for their chemical structure, morphology, optical and electronical properties. The antioxidant activity has been explored by DPPH and Folin-Ciocelteau assays in aqueous media. Due to their solubility in oil, the CDs prepared from tea wastes and GCDs were assayed as antioxidants in a mineral oil lubricant by potentiometric determination of the peroxide value. CDs from tea wastes and GCDs exhibited good antioxidant properties both in aqueous and oil media. Possible mechanisms, such as C-addition to double bonds, H-abstraction and SOMO-CDs conduction band interaction, were proposed for the CDs radical scavenging activity. CDs from natural sources open new application pathways as antioxidant green additives.

The influence of the storage temperature on the stability of lipid microparticles containing ginger oleoresin

Ginger oleoresin (GO) can be encapsulated within a protective lipid matrix in order to facilitate handling, provide protection against the external environment or promote the stability of GO compounds. The aim of this study was to verify the ability of solid lipid microparticles (SLMs) containing GO (10-20% w/w) to maintain or improve the stability of ginger compounds, by monitoring SLMs' characteristics during storage at different temperatures (25 and 40 °C). The lipids matrix of SLMs were composed by stearic acid (90, 80, 75, 65% w/w) and oleic acid (15% w/w), The crystalline structure of the particles after 84 days of storage did not present any polymorphic alterations, while presenting spherical form upon scanning by electron microscopy. SLMs containing oleic acid showed degradation of 6-gingerol when stored at 40 °C. Major volatile compounds had better stability in particles containing oleic acid. Kinetics of volatiles release resulted in a diffusion mechanism. SLMs showed better stability of GO compounds during storage at 25 °C than un-encapsulated GO and could, therefore, improve its distribution in foods due to its conversion to powder.

Laurus nobilis, Zingiber officinale and Anethum graveolens Essential Oils: Composition, Antioxidant and Antibacterial Activities against Bacteria Isolated from Fish and Shellfish

Several bacterial strains were isolated from wild and reared fish and shellfish. The identification of these strains showed the dominance of the Aeromonas hydrophila species in all seafood samples, followed by Staphylococcus spp., Vibrio alginolyticus, Enterobacter cloacae, Klebsiella ornithinolytica, Klebsiella oxytoca and Serratia odorifera. The isolates were studied for their ability to produce exoenzymes and biofilms. The chemical composition of the essential oils from Laurus nobilis leaves, Zingiber officinale rhizomes and Anethum graveolens aerial parts was studied by GC and GC/MS. The essential oils' antioxidant and antibacterial activities against the isolated microorganisms were studied. Low concentrations of the three essential oils were needed to inhibit the growth of the selected bacteria and the lowest MBCs values were obtained for the laurel essential oil. The selected essential oils can be used as a good natural preservative in fish food due to their antioxidant and antibacterial activities.

Composition and Comprehensive Antioxidant Activity of Ginger (Zingiber officinale) Essential Oil from Ecuador

In the present study, the chemical composition and antioxidant potential of an essential oil of ginger rhizomes from Ecuador was elucidated. The analysis of the essential oil by GC/FID/MS resulted in identification of 71 compounds, of which the main are citral (geranial 10.5% and neral 9.1%), α-zingiberene (17.4%), camphene (7.8%), α-farnesene (6.8%) and β-sesquiphellandrene (6.7%). The in vitro antioxidant activity of the essential oil expressed by IC50 in descending order is: hydroxyl radical (OH•) scavenging (0.0065 μg/mL) > chelating capacity (0.822 μg/mL) > 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS•+) scavenging (3.94 μg/mL) > xanthine oxidase inhibition (138.0 μg/mL) > oxygen radical (CV) scavenging (404.0 μg/mL) > 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) scavenging (675 μg/mL). Lipid peroxidation inhibition of the essential oil was less efficient than butylhydroxy-toluol (BHT) in both stages, i.e. hydroperoxide and malondialdehyde formation. In vivo studies in Saccharomyces cerevisiae demonstrated a significant dose-dependent increase in antioxidant marker enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), blocking the oxidation processes in yeast cells. Moreover, ginger essential oil in concentrations of 1.6 mg/mL increases the viability of cells to oxidative stress induced by H2O2.