Antioxidant and antimicrobial activities of rosemary extracts linked to their polyphenol composition

Rosmarinus officinalis extracts were investigated by a combination of bioassays and biochemical analysis to identify bioactive compounds. The 2,2-diphenyl-2-picrylhydracyl hydrate (DPPH) radical scavenging method, Folin–Ciocaulteau method and HPLC chromatography were used to study the distribution and levels of antioxidants (AOXs). Antimicrobial activity analysis was carried out using the disk diffusion and broth dilution techniques. A good correlation between the AOX activities and total phenol content in the extracts was found. Although all rosemary extracts showed a high radical scavenging activity, a different efficacy as antimicrobial agent was observed. Methanol extract containing 30% of carnosic acid, 16% of carnosol and 5% of rosmarinic acid was the most effective antimicrobial against Gram positive bacteria (minimal inhibition concentration, MIC, between 2 and 15 μg/ml), Gram negative bacteria (MIC between 2 and 60 μg/ml) and yeast (MIC of 4 μg/ml). By contrast, water extract containing only 15% of rosmarinic acid showed a narrow activity. MIC value of the methanol and water extracts is in a good correlation with the values obtained with pure carnosic acid and rosmarinic acid, respectively. Therefore, our results suggested that the antimicrobial rosemary extracts efficacy was associated with their specific phenolic composition. Carnosic acid and rosmarinic acid may be the main bioactive antimicrobial compounds present in rosemary extracts. From a practical point of view, rosemary extract may be a good candidate for functional foods as well as for pharmaceutical plant-based products.     

Antioxidant and antimicrobial activities of rosemary extracts linked to their polyphenol composition

Rosmarinus officinalis extracts were investigated by a combination of bioassays and biochemical analysis to identify bioactive compounds. The 2,2-diphenyl-2-picrylhydracyl hydrate (DPPH) radical scavenging method, Folin-Ciocaulteau method and HPLC chromatography were used to study the distribution and levels of antioxidants (AOXs). Antimicrobial activity analysis was carried out using the disk diffusion and broth dilution techniques. A good correlation between the AOX activities and total phenol content in the extracts was found. Although all rosemary extracts showed a high radical scavenging activity, a different efficacy as antimicrobial agent was observed. Methanol extract containing 30% of carnosic acid, 16% of carnosol and 5% of rosmarinic acid was the most effective antimicrobial against Gram positive bacteria (minimal inhibition concentration, MIC, between 2 and 15 μg/ml), Gram negative bacteria (MIC between 2 and 60 μg/ml) and yeast (MIC of 4 μg/ml). By contrast, water extract containing only 15% of rosmarinic acid showed a narrow activity. MIC value of the methanol and water extracts is in a good correlation with the values obtained with pure carnosic acid and rosmarinic acid, respectively. Therefore, our results suggested that the antimicrobial rosemary extracts efficacy was associated with their specific phenolic composition. Carnosic acid and rosmarinic acid may be the main bioactive antimicrobial compounds present in rosemary extracts. From a practical point of view, rosemary extract may be a good candidate for functional foods as well as for pharmaceutical plant-based products.     

Phytotoxic and antimicrobial activities and chemical analysis of leaf essential oil fromAgastache rugosa

Seasonal variations in the chemical composition of leaves fromAgastache rugosa were analyzed by gas chromatography-mass spectrometry (GC-MS). Phytotoxic and antimicrobial activities of its essential oil were investigated by characterizing 31 components, primarily methylchavicol (80.24%),dl-limonene (3.50%), linalool (4.23%), 5-methyl-2-(1-methylethylidene)-cyclohexanone (3.84%), and β-caryophyllene (2.39%). The contents of most of these chemical constituents varied significantly (P<0.05) over time, with the highest oil yield being early in the growing season (May). Their phytotoxic effects on the seed germination ofMajorana hortensis, Trifolium repens, Rudbeckia hirta, Chrysanthemum zawadskii var.latilobum, Melissa officinalis,Taraxacum platycarpum, andTagetes patula also were determined. These oils partially or completely inhibited germination, and prevented the growth of radicles and hypocotyls. Results of antimicrobial testing showed that the oils also entirely blocked the growth of four microorganisms (Staphylococcus aureus sub.aures, Escherichia coli, Salmonella enteritidis, andPseudomonas aeruginosa). These inhibitory effects might depend on the activity of methylchavicol, a main compound inA. rugosa.     

Nutritionally rich biochemical profile in essential oil of various Mentha species and their antimicrobial activities

Protoplasma - The Mentha species of family Lamiaceae are famous for their flavor and are commercially used in many food products worldwide. They are widely used to cure digestive problems as well...     

Antioxidant and antimicrobial activities of Spirulina platensis extracts and biogenic selenium nanoparticles against selected pathogenic bacteria and fungi

This study investigated the antimicrobial and antioxidant activity of three Spirulina extracts (methanol, acetone, and hexane) and the biological selenium nanoparticles (SeNPs) fabricated by Bacillus subtilis AL43. The results showed that Spirulina extracts exhibited antimicrobial activity against tested pathogens. Besides, Spirulina extracts significantly scavenged ABTS and DPPH radicals in a dose-dependent manner. The methanolic extract had higher total phenolic content, antimicrobial activity, and antioxidant activity than other extracts. The selenium nanoparticles were synthesized by Bacillus subtilis AL43 under aerobic conditions and were characterized as spherical, crystalline with a size of 65.23 nm and a net negative charge of ?22.7. We evidenced that SeNPs possess considerable antimicrobial activity against three gram-positive, three gram-negative bacteria, and three strains from both Candida sp. and Aspergillus sp. Moreover, SeNPs were able to scavenge ABTS and DPPH radicals in a dose-dependent manner. An association was found between the total phenolic content of Spirulina and SeNPs and their biological activities. Our results indicate that Spirulina and SeNPs with significant antimicrobial and antioxidant activities seem to be successful candidates for safe and reliable medical applications.     

Norsesquiterpene hydrocarbon, chemical composition and antimicrobial activity of Rhaponticum carthamoides root essential oil

A detailed analysis of Rhaponticum carthamoides (Willd.) Iljin root essential oil was carried out by GC, GC-MS and GC-FTIR techniques. In total, 30 components were identified, accounting for 98.0% of total volatiles. A norsesquiterpene 13-norcypera-1(5),11(12)-diene (22.6%), followed by aplotaxene (21.2%) and cyperene (17.9%), were isolated and their structures confirmed by 1D and 2D-NMR spectra (COSY, ROESY, HSQC, HMBC and INADEQUATE). Selinene type sesquiterpenes and aliphatic hydrocarbons were among minor constituents of the essential oil. The oil exhibited antimicrobial activity against 5 of 9 strains of bacteria and yeast, when tested using broth micro-dilution method. Minimum inhibitory concentrations ranged between 32 and 256 μg/ml.     

Chemical composition, antioxidant and antimicrobial activities of essential oil of Thymus algeriensis wild-growing in Libya

The composition of essential oil isolated from Thymus algeriensis growing wild in Libya was analyzed by GC and GC-MS. The essential oil was characterized with thymol (38.50%) as the major component. The oil was screened for antioxidant activity using DPPH assay, and compared to thymol and carvacrol. Antioxidant activity was high, with the IC₅₀ of 0.299 mg/ml, compared to 0.403 and 0.105 mg/ml for thymol and carvacrol, and 0.0717 mg/ml for BHA. In addition, antimicrobial activity was tested against eight bacteria and eight fungi. T. algeriensis oil showed inhibitory activity against tested bacteria at 0.001–0.05 mg/ml, while bactericidal activity (MBC) was achieved at 0.0025–0.05 mg/ml. For antifungal activity MICs ranged 0.0005–0.025 mg/ml and MFC 0.001–0.05 mg/ml. High antimicrobial activity against the fungi in particular suggests that the essential oil of Thymus algeriensis could have a useful practical application.     

印度块菌提取物抗氧化活性的研究

对印度块菌Tuber indicum子实体的提取物,包括55%乙醇粗提物(ECE)、石油醚提取物(PEF)和乙酸乙酯提取物(EAF)的清除DPPH自由基和羟基自由基能力、铁离子鳌合能力以及各提取物的总酚含量等进行了研究和测定,结果显示,3种提取物的清除自由基能力和铁离子鳌合能力具有显著差异(P0.05);ECE对DPPH自由基的清除活性最高,其EC50值为1.61g/L;EAF对羟基自由基及铁离子表现出较强的清除或螯合的能力,其EC50值分别为3.31g/L和0.70g/L;EAF的总酚含量(2.964mg GAE/g提取物)最高,其次是ECE,总酚含量为(2.618mg GAE/g提取物);PEF的清除自由基和铁离子鳌合能力较差,其总酚含量也最低(1.124mg GAE/g提取物);总酚含量与印度块菌提取物清除自由基以及鳌合铁离子的能力密切相关。     

Antioxidant activities of enzymatic extracts from brown seaweeds

Potential antioxidative activities of enzymatic extracts from seven species of brown seaweeds were evaluated using four different reactive oxygen species (ROS) scavenging assays containing DPPH (1,1-diphenyl-2-pricrylhydrazyl) free radical, superoxide anion, hydroxyl radical and hydrogen peroxide scavenging assay. The brown seaweeds were enzymatically hydrolyzed to prepare water-soluble extracts by using five carbohydrate degrading enzymes (Viscozyme, Celluclast, AMG, Termamyl and Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavourzyme and Alcalase) of commercial and inexpensive enzymes obtained from Novozyme Co. (Novozyme Nordisk, Bagsvaerd, Denmark). The enzymatic extracts exhibited more prominent effects in hydrogen peroxide scavenging activity (approximately 90%) compared to the other scavenging activities and the activity of enzymatic extracts was even higher than that of the commercial antioxidants. In particular, Ultraflo and Alcalase extracts of S. horneri were dose-dependent and thermally stable. Moreover the two enzymatic extracts strongly inhibited DNA damage (approximately 50%). Those extracts showed significantly (p<0.05) remarkable scavenging effects in DPPH free radical scavenging assay and the activity indicated a marked correlation with phenolic contents. From the results, enzymatic extracts of the brown seaweeds might be valuable antioxidative sources.     

李氏块菌提取物抗氧化活性的研究

对李氏块菌Tuber liyuanum子实体的不同提取物,包括甲醇提取物(ME)、乙醇提取物(EE)、丙酮提取物(AE)、正丁醇提取物(BAE)和乙酸乙酯提取物(EAE),进行清除DPPH自由基、羟基自由基、超氧阴离子自由基、铁离子螯合能力、还原力以及总酚含量的测定和研究,发现ME对DPPH自由基、超氧阴离子自由基清除及还原力活性最高,EC50值分别为23.37mg/m L、11.65mg/m L和24.47mg/m L;EE对羟基自由基清除和铁离子螯合能力活性最高,EC50值分别为7.24mg/m L和小于0.5mg/m L;ME的总酚含量最高(3.08mg GAE/g提取物),其次是EE(1.34mg GAE/g提取物),提取物总酚含量与抗氧化活性呈现出一定的正相关性。     

Antioxidant activities of extracts and fractions from Lysimachia foenum-graecum Hance

The antioxidant activities of water extract, methanol extract, ethyl acetate, and n-BuOH fractions of methanol extract from Lysimachia foenum-graecum Hance were investigated in this study. Various methods, such as the total antioxidant capacity measured by phosphomolybdenum method, scavenging activities towards 1,1-diphenyl-2-picryhydrazyl (DPPH) radical, superoxide anion radical, and hydroxyl radical, were established in in vitro systems. The amounts of total phenolics and total flavonoids in the extracts and fractions were also determined by spectrophotometric methods. The results showed that all the extracts and fractions exhibited antioxidant and radical-scavenging activities at different magnitudes of potency. The decreasing order of antioxidant and radical-scavenging activities among the extracts assayed through all the four methods were found to be ethyl acetate fraction>n-BuOH fraction>methanol extract>water extract. This similar order of the amounts of total phenolics and total flavonoids shows that the extent of antioxidant and radical-scavenging activities is in accordance with the amounts of phenolics and flavonoids present in extracts and fractions. The extracts of L. foenum-graecum Hance might be valuable antioxidant natural sources and seemed to be applicable in both healthy medicine and food industry.     

Optimal methods for evaluating antimicrobial activities from plant extracts

The search for antimicrobial agents from plants has been a growing interest in the last few decades. However, results generated from many of these studies cannot be directly compared due to the absence of standardization in particular antimicrobial methods employed. The need for established methods with consistent results for the evaluation of antimicrobial activities from plant extracts has been proposed by many researchers. Nevertheless, there are still many studies reported in the literature describing different methodologies. The aim of this study was to find optimal methods to give consistent quantitative antimicrobial results for studying plant extracts. Three different agar-based assays (pour plate disc diffusion (PPDD), streak plate disc diffusion (SPDD) and well-in agar (WA)) and one broth-based (turbidometric (TB)) assay were used in this study. Extracts from two plant species (Duabanga grandiflora and Acalypha wilkesiana) were tested on two bacterial species, namely Escherichia coli and Staphylococcus aureus. Amongst the agar-based assays, PPDD produced the most reproducible results. TB was able to show the inhibitory effects of the test samples on the growth kinetic of the bacteria including plant extracts with low polarity. We propose that both agar- (i.e PPDD) and broth-based assays should be employed when assessing the antimicrobial activity of plant crude extracts.     

Antioxidant activities and phytochemical characteristics of extracts from Acacia confusa bark

The present study was carried out to evaluate the antioxidant activities of bark extract of Acacia confusa and some of the isolated constituents from its ethyl acetate (EtOAc) fraction in various in vitro systems to gain mechanistic insights. Results from antioxidant assays together with authentic antioxidant standards revealed that EtOAc fraction showed strong superoxide radical scavenging activity, reducing power, and ferrous ion-chelating ability. Following an in vitro antioxidant activity-guided fractionation procedure, 16 constituents including 12 benzoic acids, three cinnamic acids and one lignans were isolated and identified from the EtOAc fraction. We also evaluated the structure-activity relationships of benzoic and cinnamic acid derivatives. Results obtained indicated that the bark extracts and the derived phytochemicals from A. confusa have a great potential to prevent disease caused by the overproduction of radicals and also it might be used as a potential source of natural antioxidant agent.     

Thyme essential oil for antimicrobial protection of natural textiles

The study was aimed at increasing the resistance of lignocellulosic textiles to bacteria and mould action using a biocide of plant origin. The biocide used in the study was thyme essential oil. This kind of oil is characterized by low toxicity for humans and the environment. The antimicrobial efficiency of thyme essential oil applied to linen–cotton blended fabric and linen fabric was evaluated by determining bacterial growth, degree of mould growth, and their impact on fabric strength. Thyme essential oil applied as 8% concentration in methanol to linen–cotton blended fabric showed very high antibacterial and antifungal activity – no mould growth and no significant loss of breaking force were observed. Microscopic evaluation of the tested fabrics was also performed by Scanning Electron Microscopy. Applying the eco-friendly biocide to fabrics containing natural fibres in the finishing process produces antimicrobial barrier properties.     

江西迷迭香精油的成分分析及抗氧化、抑菌活性研究

为了研究江西迷迭香精油的化学成分及抗氧化、抑菌活性,采用水蒸气蒸馏法提取迷迭香精油,利用气相色谱-质谱联用法(GC-MS)对迷迭香精油成分进行分析,通过对DPPH自由基、羟基自由基的清除活性和还原力来研究迷迭香精油的体外抗氧化活性;通过以枯草芽孢杆菌、金黄色葡萄球菌和大肠杆菌为供试菌,测定抑菌圈大小和最低抑菌浓度(MIC)来研究迷迭香精油的抑菌活性。实验结果表明,从迷迭香精油中鉴定出40种化学成分,占精油总量的99.46%,其主要化学成分有α-蒎烯(39.05%)和1,8-桉叶素(16.86%),其次是莰烯(4.22%)、D-柠檬烯(3.87%)、龙脑(3.74%)、β-石竹烯(3.11%)等,α-蒎烯的含量高于国内其他产地;迷迭香精油对DPPH、羟基自由基和还原力的半数清除率IC₅₀值分别为76.42、51.40和49.15μL/mL;精油对枯草芽孢杆菌、金黄色葡萄球菌和大肠杆菌的抑菌圈大小分别为14.40±0.66、11.41±0.19、11.70±0.27 mm,最低抑菌浓度(MIC)分别为2.50、10.00、10.00μL/mL,对枯草芽孢杆菌的抑制作用明显强于金黄色葡萄球菌和大肠杆菌。结果表明迷迭香精油具有较好的抗氧化、抑菌活性。     

Antioxidant activities of the volatile oils and methanol extracts from olive stems

This study was designed to examine the chemical composition and antioxidant activities of the volatile oils and methanol extracts of Olea europaea L. (cvs) chemlali and neb jmel stems. GC and GC–MS analyses of the volatile oils resulted in the identification of 38 and 35 compounds, representing 91.1 and 87.4 % of the volatile oils. Phenylethyl alcohol was found in the volatile oil of each cultivar, which was also the major volatile component of cv. chemlali and cv. neb jmel stems. Besides benzyl alcohol, methyl salicylate and 3-ethenylpyridine were the main volatile compounds of cv. chemlali, while nonanal, 3-ethenylpyridine and benzyl alcohol of cv. neb jmel stems were also the main constituents. Significant differences were also found in total tannin contents among two cultivars, representing 8.10 mg CEQ/g DW in cv. chemlali and 20.47 mg CEQ/g DW in cv. neb jmel. The highest contents of total phenols and o-diphenols were observed in stems extracts of cv. neb jmel (78.26, and 9.56 mg/100 g, respectively). The HPLC profiles for methanol extracts from stems of cv. chemlali and cv. neb jmel showed that oleuropein, vanillic acid and gallic acid were the predominant free phenolic compounds. Antioxidant activities of the volatile oils and the methanolic extract from stems parts were evaluated by DPPH and ABTS⁺ radical-scavenging activity assays. In all tests, methanolic extracts obtained from stems parts showed better antioxidant activity than volatile oils. Principal components analysis of the phenolics content and antioxidant activities showed discrimination between methanol extracts of the two cultivars.     

Antioxidant activities of ethanolic extracts from the twigs of Cinnamomum osmophloeum

Cinnamomum osmophloeum Kaneh. is an indigenous tree species in Taiwan. In this study, phytochemical characteristics and antioxidant activities of ethanolic extracts from the twigs of C. osmophloeum were investigated for the first time. The extracts were obtained successively using liquid-liquid partition to yield n-hexane (Hex), ethyl acetate (EtOAc), n-butanol (BuOH) and water fractions. The antioxidant activities of C. osmophloeum twig extracts were examined using various antioxidant assays, such as DPPH, NBT, reducing power, lipid peroxidation using mouse brain homogenates, metal chelating ability, and photochemiluminescence (PCL). In addition, total phenolic contents were also determined. Results revealed that the BuOH fraction exhibited the best performance in DPPH assay, NBT assay, reducing power assay and lipid peroxidation using mouse brain homogenates assay. Furthermore, the BuOH fraction has the highest total phenolic contents (496.7 mg of GAE/g). Consequently, kaempferol-7-O-rhamnoside was also isolated from the antioxidative BuOH fraction and its activity was also confirmed. These results demonstrated that ethanolic extracts of C. osmophloeum twigs have excellent antioxidant activities and thus it has great potential as a source for natural health products.     

四种子囊菌甲醇提取物的抗氧化活性研究

比较了冬虫夏草Cordyceps sinensis、古尼虫草Cordyceps gunnii、蛹虫草Cordyceps militaris、黑柄炭角菌Xylaria nigripes等四种子囊菌提取物的抗氧化活性,对它们的子实体(F)和菌丝体(M)甲醇提取物清除DPPH自由基能力、还原力、金属离子鳌合能力和总酚含量进行了测定,结果显示四种子囊菌子实体的自由基清除能力、还原力和总酚含量均高于其菌丝体(P0.05),但四种子囊菌子实体的DPPH清除能力不存在显著差异(P0.05);古尼虫草和蛹虫草子实体的还原力和总酚含量显著高于冬虫夏草和黑柄炭角菌子实体(P0.05),但前两者之间不存在显著差异(P0.05)。总酚含量和DPPH自由基清除能力、还原力呈正相关。     

Antioxidant and insect growth regulatory activities of stilbenes and extracts from Yucca periculosa

The methanol extract from the bark of Yucca periculosa F. Baker afforded 4,4'-dihydroxstilbene, resveratrol and 3,3',5,5'-tetrahydroxy-4-methoxystilbene and had growth regulatory activity against the Fall Army worm (Spodoptera frugiperda J.E. Smith, Lepidoptera:Noctuidae) an insect pest of corn. The most active compound was 3,3',5,5'-tetrahydroxy-4-methoxystilbene which had significant effects at 3 microg/g in diets. In addition to the inhibitory activity on bleaching of crocin induced by alkoxyl radicals, these compounds also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl in TLC autographic and spectrophotometric assays. Our results indicate that these compounds could be involved in interference of sclerotization and moulting. These compounds appear to have selective effects on the pre-emergence metabolism of the insect. The results were fully comparable to known natural insect growth inhibitors such as gedunin and Cedrela extracts and have had a possible role as natural insecticidal agents.     

Antifungal properties of essential oil and crude extracts of Hypericum linarioides Bosse

The chemical composition of the essential oil isolated from the aerial parts of Hypericum linarioides Bosse by hydrodistillation was analysed by GC–MS. It was determined that 74 compounds, which represent 84.1% of total oil, were present in the oil. The oil contains mainly δ-cadinene (6.9%), (Z)-β-farnesene (5.2%), γ-muurolene (5.5%), spathulenol (4.8%), hexahydrofarnesyl acetone (4.5%) and α-selinene (4.0%). The oil was also characterized by high content of sesquiterpenes (64.2% of total oil). The oil was tested for antifungal activity using mycelial growth inhibition assays (in vitro) against 11 agricultural pathogenic fungi, which consisted of six Fusarium species (Fusarium acuminatum, Fusarium culmorum, Fusarium equiseti, Fusarium oxysporum, Fusarium sambucinum and Fusarium solani) and three anastomosis groups of Rhizoctonia solani (AG-5, AG-9 and AG-11), Alternaria solani and Verticillium albo-atrum. The oil of H. linarioides showed antifungal activity against AG-9 and V. albo-atrum. In addition, petroleum ether, chloroform, acetone and methanol extracts of H. linarioides were tested against species of 11 fungi. The extracts showed moderate inhibition effects on the growth of A. solani, F. culmorum, F. equiseti and all anastomosis groups of R. solani.