Comparing ultrasonic- and microwave-assisted methods for extraction of phenolic compounds from Kabkab date seed (Phoenix dactylifera L.) and stepwise regression analysis of extracts antioxidant activity

This study aimed to extract bioactive compounds (phenolics and flavonoids and condensed tannins) from roasted date seed (Phoenix dactylifera L. cv Kabkab) using various solvent systems (W: water, AE: aqueous-ethanol, AA: aqueous-acetone) and extraction method (ultrasonic-assisted (UAE), microwave-assisted (MAE) and the combination of these two methods (UMAE) maceration (ME) and Decoction-Infusion (DIE) Extraction). Moreover, the feasibility of antioxidant activity prediction was investigated based on stepwise regression analysis and phytochemical properties. Extraction yield, Total phenolic content (TPC), total flavonoid content (TFD) and antioxidant activity (DPPH*, ABTS*⁺, FRAP and averaged antioxidant activity: AAA) of the extracts were evaluated. The main effect of solvent systems and extraction methods on phytochemical compounds and antioxidant activity were significant (P < 0.01). Water and aqueous-ethanol solvents extracted higher phytochemical compounds than aqueous-acetone (P < 0.05). Although the highest extraction performance was observed for the ME method, the novel methods show an acceptable result in a much shorter time. Among novel methods, the highest and lowest performances were recorded for UAE and MAE. There was no significant difference between novel-green methods (e.g., UAE and UMAE). Although the lowest phytochemical yield was obtained for MAE, this performance was obtained in less than 5 min. The highest and lowest correlation between the phytochemical compositions and antioxidant activity parameters were for DPPH* and AAA, respectively. Stepwise-regression analysis showed the weakest and strongest prediction models for AAA (10-fold S = 0.098 and 10-fold R² = 87.07) and ABTS*⁺ (10-fold S = 0.129 and 10-fold R² = 78.25), respectively.     

Flavonoid compositions and antioxidant activity of calamondin extracts prepared using different solvents

Calamondin has been demonstrated to exhibit antioxidant function and tyrosinase inhibitory activity, which might be attributed to its flavonoid compounds. To improve their application, the flavonoid compositions and antioxidant activity of calamondin extracts, prepared by different solvents, were investigated. The results showed that total phenolic and flavonoid contents of extracts from peel of calamondin were higher than that from pulp, except the flavonoid content in hot water extract. The flavonoids found in extracts of calamondin were 3′,5′-di-C-β-glucopyranosylphloretin (DGPP), naringin, hesperidin, nobiletin, tangeretin, and diosmin. DGPP exhibited the highest quantity, while naringin and hesperidin were the other two major flavonoids. The content of DGPP in hot water extract of peel was higher than in extracts of organic solvents, however, the contents of nobiletin and tangeretin were found only in extracts of organic solvents. The highest levels of total flavonoids and DGPP were obtained in hot water extract from peel at 90°C. The extracts of hot water and ethyl acetate showed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging potency than that of ethanol and methanol. A positive relationship existed between total phenolic contents and DPPH scavenging potency (p < 0.01), while total flavonoid compositions also showed correlation (p < 0.05). Thus, DGPP, naringin, and hesperidin might contribute to antioxidant activity. Collectively, the hot water extract of calamondin peel might have potential for health food and cosmetic applications due to its good antioxidant activity and high level of DGPP.     

Chemical composition, and antioxidant and antimicrobial activities of three hazelnut (Corylus avellana L.) cultivars.

Hazelnut (Corylus avellana L.) is a very popular dry fruit in the world being consumed in different form and presentations. In the present work, three hazelnut cultivars (cv. Daviana, Fertille de Coutard and M. Bollwiller) produced in Portugal, were characterized in respect to their chemical composition, antioxidant potential and antimicrobial activity. The samples were analysed for proximate constituents (moisture, fat, crude protein, ash), nutritional value and fatty acids profile by GC/FID. Antioxidant potential was accessed by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and beta-carotene linoleate model system. Their antimicrobial capacity was also checked against Gram positive (Bacillus cereus, B. subtilis, Staphylococcus aureus) and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi (Candida albicans, Cryptococcus neoformans). Results showed that the main constituent of fruits was fat ranging from 56% to 61%, being the nutritional value around 650 kcal per 100 g of fruits. Oleic was the major fatty acid varying between 80.67% in cv. F. Coutard and 82.63% in cv. Daviana, followed by linoleic, palmitic, and stearic acids. Aqueous hazelnut extract presented antioxidant activity in a concentration-dependent way, in general with similar behaviour for all cultivars. Hazelnut extracts revealed a high antimicrobial activity against Gram positive bacteria (MIC 0.1 mg/mL) showing a good bioactivity of these fruits.     

Biological activities of commercial bee pollens: Antimicrobial,antimutagenic, antioxidant and anti-inflammatory

Bee pollen is considered, since memorable times, a good source of nourishing substances and energy. The present study aimed to evaluate the biological activities of eight commercial bee pollens purchased from the market. The origin of sample A was not specified in the labeling; samples B, C, D and G were from Portugal and the remaining were from Spain. The sample E presented the highest value of phenolics (32.15 ± 2.12 mg/g) and the H the lowest (18.55 ± 095 mg/g). Sample C had the highest value of flavonoids (10.14 ± 1.57 mg/g) and sample H the lowest (3.92 ± 0.68 mg/g). All the samples exhibited antimicrobial activity, being Staphylococcus aureus the most sensitive and Candida glabrata the most resistant of the microorganisms studied. All the samples exhibited antimutagenic activity, even though some samples were more effective in decreasing the number of gene conversion colonies and mutant colonies. Regarding the antioxidant activity, assessed using two methods, the more effective was sample B. The anti-inflammatory activity, assessed using the hyaluronidase enzyme, was highest in samples B and D. Pearson’s correlation coefficients between polyphenols, flavonoids, antioxidant activity and antimicrobial activity were computed. It was also performed a discriminant analysis.     

The evaluation of five bioactive compounds content and in vitro antioxidant of Caryophylli Flos extracts obtained by natural deep eutectic solvents

In this study, a simple, green and efficient method based on ultrasound-assisted NADESs was used to extract ellagic acid, isoquercitrin, myricetin, luteolin and eugenol from Caryophylli Flos. Nine different NADESs were synthesized and screened, and 1,3-butanediol-levulinic acid (molar ratio 1: 3) was selected as the topgallant solvent for maximizing target compounds extraction yields. Single factor experiments combined with response surface methodology and genetic algorithm were applied for efficient optimization of the main variables in the extraction procedure. The optimum experimental conditions were as follows: water content in NADES 29%, liquid-solid ratio 21 mL/g and extraction time 30 min. After the optimization of several main variables, an extract obtained showed higher extraction yields and DPPH and ABTS radical scavenging rate than conventional organic solvents extracts which were used for comparison. Consequently, this study provides a suitable strategy for efficiently extracting bioactive compounds from Caryophylli Flos, and NADESs can be employed as green extraction media for obtaining other natural products.     

Vasoactive and antioxidant activities of plants used in Mexican traditional medicine for the treatment of cardiovascular diseases

This study demonstrated that the aqueous extracts of plants employed in Mexican traditional medicine for the treatment of cardiovascular diseases are able to modify the tone of arterial smooth muscle. Agastache mexicana (Kunth) Lint & Epling (Labiatae), Chenopodium murale L. (Chenopodiaceae), Chirantodendron pentadactylon Larreat (Sterculiaceae), Dracocephalum moldavica L. (Labiatae), Psittacanthus calyculatus G. Don (Loranthaceae), Prunus serotina ssp. capuli (Cav. ex Spreng) McVaugh (Rosaceae), and Sechium edule Sw. (Cucurbitaceae) contain secondary metabolites that promote vascular relaxation and display antioxidant activities. As expected, their antioxidant effects showed a significant correlation with the polyphenolics content. However, a lower correlation was found between the antioxidant activity and the maximum vasodilatory effect, suggesting that the vasodilatation elicited by the plant extracts could be only partly attributed to their antioxidant properties. The extract of P. calyculatus, which displayed a maximum vasorelaxant effect that was higher than that of acetylcholine, induced endothelium-dependent vasodilatation. Futhermore, the vasorelaxant response to the P. calyculatus extract was reduced after adding an inhibitor of soluble guanylate cyclase activity, providing evidence that the NO/cGMP pathway is involved. On the other hand, the extracts of Bocconia frutescens L. (Papaveraceae), Magnolia grandiflora L. (Magnoliaceae), and Solanum rostratum Dunal (Solanaceae) induced concentration-dependent contraction of rat aortic rings, suggesting that these plants have potential health benefits for the treatment of ailments such as venous insufficiency. The pharmacological activities of the extracts studied provide scientific support for their ethnomedical use.     

Chemical composition,antibacterial and antioxidant activities of leaf essential oil and extracts of Metasequioa glyptostroboides Miki ex Hu

The aims of this study were to analyze the chemical composition of leaf essential oil of Metasequioa glyptostroboides Miki, and to test the efficacy of oil and extracts (hexane, chloroform, ethyl acetate and methanol) against food spoilage and food-borne pathogenic bacteria and their antioxidant activity. The GC–MS analysis revealed 49 compounds representing 94.62% of the total oil containing 2-butaneone (30.6%), cyclopentane (15.1%), β-myrcene (13.29%), cyclobutane (7.67%), furan (3%), valeramide (2.81%), borneol (1.2%), β-farnesene (1.67%), thymol (1.44%) and α-pinene (1.46%) as major components. The oil (1000 μg/disc), and extracts (1500 μg/disc) exhibited promising antibacterial effect as a diameter of zones of inhibition (10–18 and 7–13 mm), respectively. MIC values of oil and the extracts were ranged 125–2000 and 250 to <2000 μg/ml, respectively. Also the oil had strong antibacterial effect on the viable counts. Scanning electron microscopic study demonstrated potential detrimental effect of the oil on the morphology of S. aureus KCTC1916. The free radical scavenging activities of the oil and ethyl acetate extract were found to be 11.32 and 19.12 μg/ml, respectively. Also the ethyl acetate extract revealed the highest phenolic contents (85.17 mg/g of dry wt) as compared to the other extracts.     

Chemical composition and antioxidant activity of essential oils and solvent extracts of Ptychotis verticillata from Morocco

The objective of this study was to characterize the chemical composition of the essential oil and extracts of Ptychotis verticillata. The antioxidative activities of this species were also evaluated to suggest it as a new potential source of natural antioxidants. Analysis of the chemical composition of P. verticillata essential oil from Morocco was carried out using GC and GC-MS. The oil was dominated by phenolic compounds (48.0%) with carvacrol (44.6%) and thymol (3.4%) as the main compounds. Plant phenolics constitute one of the major groups of components that act as primary antioxidant free radical terminators. The amounts of total phenolics and flavonoids in the solvent extracts (diethyl ether and ethyl acetate) were determined spectrometrically. Furthermore, the antioxidant activities of the essential oil and extracts were determined using a DPPH test system. The DPPH scavenging activity of extracts increased in the order ethyl acetate > ascorbic acid > diethyl ether > essential oil. Finally, a relationship was observed between the antioxidant activity potential and total phenolic and flavonoid levels of the extract.     

金银花-山银花水提液不同配比体外抗氧化作用研究

目的观察金银花、山银花水提液不同配比(1∶0、2∶1、1∶1、1∶2、0∶1)对3种自由基的清除作用,以及对H2O2诱导的内皮细胞氧化损伤的保护作用。方法采用1,1-二苯基-2-苦肼基自由基(DPPH·)、羟基自由基(·OH)、超氧阴离子自由基(O2-·[O])清除法测定金银花—山银花水提液5个不同配比组的抗氧化活性;采用体外培养HUVECs细胞并复制细胞损伤模型,测定金银花—山银花水提液5个不同配比组受损细胞的活力、受损细胞上清中乳酸脱氢酶(LDH)和一氧化氮(NO)的含量。结果金银花—山银花水提液不同配比均有一定的抗氧化作用,其中金银花—山银花2∶1组最佳。金银花—山银花水提液不同配比能够使受损细胞NO的含量增加、LDH释放减少,其中金银花—山银花1∶0组作用最强,2∶1组次之。结论金银花—山银花不同配比在体外有较强的抗自由基和抗氧化作用,并且能够保护损伤的HUVECs细胞,金银花-山银花2∶1综合效果最佳。     

In vitro antioxidant activity and total phenolic content of ethanolic leaf extract of Stevia rebaudiana Bert.

The aim of this study was to assess the in vitro potential of ethanolic leaf extract of Stevia rebaudiana as a natural antioxidant. The DPPH activity of the extract (20, 40, 50, 100 and 200 μg/ml) was increased in a dose dependent manner, which was found in the range of 36.93–68.76% as compared to ascorbic acid 64.26–82.58%. The IC₅₀ values of ethanolic extract and ascorbic acid in DPPH radical scavenging assay were obtained to be 93.46 and 26.75 μg/ml, respectively. The ethanolic extract was also found to scavenge the superoxide generated by EDTA/NBT system. Measurement of total phenolic content of the ethanolic extract of S. rebaudiana was achieved using Folin–Ciocalteau reagent containing 61.50 mg/g of phenolic content, which was found significantly higher when compared to reference standard gallic acid. The ethanolic extract also inhibited the hydroxyl radical, nitric oxide, superoxide anions with IC₅₀ values of 93.46, 132.05 and 81.08 μg/ml, respectively. However, the IC₅₀ values for the standard ascorbic acid were noted to be 26.75, 66.01 and 71.41 μg/ml respectively. The results obtained in this study clearly indicate that S. rebaudiana has a significant potential to use as a natural antioxidant agent.     

Development of HPLC fingerprints for Mallotus species extracts and evaluation of the peaks responsible for their antioxidant activity

Some Mallotus species are used in traditional medicine in Vietnam. To use certain species in Western medicines or as food supplements, they should be identified and quality control should be more strict, for instance, to avoid the erroneous switching of species. In species with interesting activities, the compounds responsible for them should be identified. For these identifications, HPLC fingerprint methodology can be used.In this paper, HPLC fingerprints of different lengths were developed for a number of Mallotus species. Secondly, a multivariate regression model was constructed to model the antioxidant activity of the Mallotus samples from the HPLC fingerprints with the aim to indicate peaks possibly responsible for this activity. For this purpose, after data pretreatment, the calibration technique partial least squares (PLS) was applied.     

Stability and antioxidant activity of polyphenols in extracts of Myrtus communis L. berries used for the preparation of myrtle liqueur

Flavonoids and anthocyanins in berry extracts from Myrtus communis, prepared by following a typical Sardinia myrtle liqueur recipe, were identified by HPLC coupled with Electrospray Mass Spectrometry and quantified by HPLC coupled with Ultraviolet/Visible Detection in order to evaluate the stability of the extracts during 1 year of storage. Antioxidant activity was measured by using TEAC assay, and the free-radical scavenging activity was monitored during time of the stability evaluation.

Anthocyanins have found to be the most instable compounds, but a considerable instability was observed also for flavonoids, suggesting the use of extracts not over 3 months from their preparation. The myrtle extract showed interesting free-adical scavenging activity. Antioxidant activity was preserved in 3 months.     

Stability and antioxidant activity of polyphenols in extracts of Myrtus communis L. berries used for the preparation of myrtle liqueur

Flavonoids and anthocyanins in berry extracts from Myrtus communis, prepared by following a typical Sardinia myrtle liqueur recipe, were identified by HPLC coupled with Electrospray Mass Spectrometry and quantified by HPLC coupled with Ultraviolet/Visible Detection in order to evaluate the stability of the extracts during 1 year of storage. Antioxidant activity was measured by using TEAC assay, and the free-radical scavenging activity was monitored during time of the stability evaluation.Anthocyanins have found to be the most instable compounds, but a considerable instability was observed also for flavonoids, suggesting the use of extracts not over 3 months from their preparation. The myrtle extract showed interesting free-adical scavenging activity. Antioxidant activity was preserved in 3 months.     

气相色谱-质谱联用分析莳萝子中挥发油和油脂的化学成分及其抗氧化活性研究

目的 提取莳萝子的挥发油和油脂,并对其组成进行分析,筛选出活性成分,为莳萝子挥发油、油脂的临床应用研究提供依据。方法 2021年6月至2022年2月采用水蒸气蒸馏法提取挥发油,经石油醚索氏提取油脂,用气相色谱-质谱联用（GCMS）联用仪分析鉴定其组分,并通过检测清除自由基能力评价抗氧化活性。结果 莳萝子挥发油提取率为（5.850±0.141）%,共鉴定出19种化合物,主要含有黄酮类化合物（61.418%）及萜类化合物（29.471%）;莳萝子油脂提取率为（13.168±0.117）%,共鉴定出16种化合物,主要包括亚油酸甲酯（5.58%）、顺式亚油酸（5.58%）、十八碳六烯酸甲酯（56.73%）等。1,1-二苯基-2-三硝基苯肼（DPPH）自由基清除率结果是挥发油的IC50值（半抑制浓度）为42.963 mg/L,油脂的IC50值为28.430 mg/L;2’-联氨-双（3-乙基苯并噻唑啉-6-磺酸）二胺盐（ABTS）自由基清除率结果是莳挥发油的IC50值为21.129 mg/L,油脂的IC50值为9.722 mg/L。结论 莳萝子挥发油、油脂均具有较强的抗氧化能力。     

Essential oil variation in the populations of Artemisia spicigera from northwest of Iran: Chemical composition and antibacterial activity

Context: Artemisia spicigera C. Koch (Asteraceae) is a perennial shrubby herb and is generally distributed in Armenia, Iran, and Middle Anatolia. This species traditionally has been used in medicines.

Objective: The aim of this research is to study the chemical composition and antibacterial activity of essential oils from Artemisia spicigera populations in northwest of Iran.

Materials and methods: The essential oil of A. spicigera was obtained by hydrodistillation from eight populations collected from different regions of East Azerbaijan and West Azerbaijan provinces (Iran) and analyzed by gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of the oils was investigated against four Gram-positive and four Gram-negative bacteria using MIC determinations and the agar-gel diffusion method.

Results: Fourteen compounds were identified as the main components of the essential oils and the most abundant constituents are 1,8-cineole, camphor, α-thujone, camphene, β-thujone and p-cymene. Essential oil of population No. 1 showed the highest activity against Escherichia coli, Enterobacter aerogenes, Serratia marcescens and Staphylococcus aureus but the highest activity against St. saprophyticus, Bacillus megaterium, and B. cereus was found with population No. 6 and for Citrobacter amalonaficus with population No. 5. MIC values of essential oils ranged from 6 µg/mL against Bacillus megaterium to 12 µg/mL against Citrobacter amalonaficus.

Discussion: This study demonstrates the occurrence of 1,8-cineole/camphor/camphene chemotype of A. spicigera but there is also significant chemical variation between the studied populations. The findings showed the studied oils have good antibacterial activity, and thus potential to be used as natural health products.     

Determination of phenolic compounds and their antioxidant activity in Erigeron acris L. extracts and pharmaceutical formulation by flow injection analysis with inhibited chemiluminescent detection

It was found that the chemiluminescence (CL) produced from the reaction of luminol with iodine in the alkaline medium was strongly inhibited by plant phenolic compounds. Based on this finding, a new flow injection CL method was developed for the determination of caffeic acid and 6'-caffeoylerigeroside. The latter compound was isolated for the first time from Erigeron acris L. herb. The method was simple, rapid and sensitive with a detection limit of 4 x 10(-3) ng mL(-1) (caffeic acid) and 0.18 ng mL(-1) (6'-caffeoylerigeroside), linear range of 0.1-1.5 ng mL(-1) (caffeic acid) and 1-200 ng mL(-1) (6'-caffeoylerigeroside), relative standard deviation of 3.3% for 10 measurements of 0.45 ng mL(-1) caffeic acid and 2.9% for 40 ng mL(-1) 6'-caffeoylerigeroside. This method was successfully applied to determine the content of phenolic compounds/antioxidant activity of E. acris L. extracts and phenolic acids content in pharmaceutical formulation. A possible mechanism of the inhibition of the proposed CL system was discussed.     

An analytical and theoretical approach for the profiling of the antioxidant activity of essential oils: the case of Rosmarinus officinalis L

The antioxidant constituents of essential oils (EOs) of Rosmarinus officinalis L. (α-pinene chemotype) were isolated at the flowering (A), post-flowering (B), and vegetative stages (C). GC-MS was used to analyze total chemical composition, Folin-Ciocalteau and Prussian blue methods for reducing substances. Radical scavenging capacity (DPPH test, IC(50) 36.78±0.38, 79.69±1.54, 111.94±2.56μL) and anti-lipoperoxidant activity (TBARS, IC(50) 0.42±0.04, 1.20±0.06μL, 4.07±0.05μL) differed widely in the three stages. Antioxidant activity, identified after silica gel fractionation chromatography, was closely related (R(2)=0.9959) to each EO's content of hydroxilated derivatives, (containing alcohols, phenols and 1,8 cineole): 15.26±0.12%, 7.22±0.06%, and 5.09±0.10% in EOs from A, B, and C. Modeling the C, H, O terpenes in a simulated phospholipid bilayer indicated that anti-lipoperoxidant activity depended on the stability and rapidity of their interactions with the membrane bilayer components, and their positioning over its surface.