Chemical composition and antimicrobial activity of volatile components from capitula and aerial parts of Rhaponticum acaule DC growing wild in Tunisia

Phytochemical Profiles and Biological Activities of Frankenia Species: A Review

The relatively small Frankeniaceae family is represented by halophyte plants, growing in arid and semi-arid climates in saline, alkaline or calcareous soils. Due to their living conditions, they usually produce a large diversity of compounds, which often exhibit bioactivities. Some species of this genus have long been used as traditional herbal medicines to treat dysentery, diarrhea, gonorrhea, vaginal leucorrhea, respiratory diseases and wounds. To date, several studies on either phytochemical or pharmacological aspects, or both, have revealed that this genus is a rich source of diverse and novel bioactive chemicals, including phenolics, flavonoids, alkaloids and fatty acids. This review describes all the reported chemical profiles of Frankenia species, as well as the corresponding biological properties, when available. The aim of this review is to show the potential of these plants for various applications, especially therapeutic ones.

Bioactive Analysis of Antibacterial Efficacy and Antioxidant Potential of Aloe barbadensis Miller Leaf Extracts and Exploration of Secondary Metabolites Using GC-MS Profiling

Aloe barbadensis Miller (ABM) is a traditional medicinal plant all over the world. Numerous studies were conducted to exhibit its medicinal properties and most of them were concentrated on its metabolites against human pathogens. The current research work evaluates the attributes of different polar-based extracts (ethanol, methanol, ethyl acetate, acetone, hexane, and petroleum ether) of dried Aloe barbadensis leaf (ABL) to investigate its phytochemical constituents, antioxidant potential (DPPH, ABTS), phenolic, tannin, flavonoid contents, identification of bioactive compounds, and functional groups by gas chromatography-mass spectrometry (GC-MS) and fourier transform infrared spectroscopy (FT-IR) respectively, and comparing antibacterial efficacy against human pathogens, aquatic bacterial pathogens, and zoonotic bacteria associated with fish and human. The present results showed that the methanolic extract of ABL showed higher antioxidant activity (DPPH-59.73 ± 2.01%; ABTS-74.1 ± 1.29%), total phenolic (10.660 ± 1.242 mg GAE/g), tannin (7.158 ± 0.668 mg TAE/g), and flavonoid content (49.545 ± 1.928 µg QE/g) than that of other solvent extracts. Non-polar solvents hexane and petroleum ether exhibited lesser activity among the extracts. In the case of antibacterial activity, higher inhibition zone was recorded in methanol extract of ABL (25.00 ± 0.70 mm) against Aeromonas salmonicida. Variations in antibacterial activity were observed depending on solvents and extracts. In the current study, polar solvents revealed higher antibacterial activity when compared to the non-polar and the mid-polar solvents. Diverse crucial bioactive compounds were detected in GC-MS analysis. The vital compounds were hexadecanoic acid (30.69%) and 2-pentanone, 4-hydroxy-4-methyl (23.77%) which are responsible for higher antioxidant and antibacterial activity. Similar functional groups were identified in all the solvent extracts of ABL with slight variations in the FT-IR analysis. Polar-based solvent extraction influenced the elution of phytocompounds more than that of the other solvents used in this study. The obtained results suggested that the ABM could be an excellent source for antioxidant and antibacterial activities and can also serve as a potential source of effective bioactive compounds to combat human as well as aquatic pathogens.

Endophytic fungal species Nigrospora oryzae and Alternaria alternata exhibit antimicrobial activity against gram-positive and gram-negative multi-drug resistant clinical bacterial isolates

BACKGROUND

The emergence of multidrug-resistant pathogens and the lack of new antimicrobial drugs is a major public health concern that needs urgent and innovative solutions. Endophytic fungi living in unique niches such as in endosymbiosis with plants are increasingly drawing attention as alternative sources of novel and chemically diverse compounds with unique mechanisms of action.

METHODS

In the present study, ten endophytic fungi isolated from the medicinal plant, Sclerocarya birrea were screened for bioactivity against a panel of indicator bacteria. Three bioactive endophytic fungi (strains P02PL2, P02MS1, and P02MS2A) were selected and identified through ITS-rDNA sequencing. The whole broth extracts of the three selected isolates were further screened against contemporary drug-resistant bacterial pathogens. This was followed by partial purification by solid phase extraction and GC-MS analysis of bioactive fractions.

RESULTS

The bioactive endophytic fungi were identified as Alternaria alternata species (strains P02PL2 and P02MS1) and Nigrospora oryzae (strain P02MS2A). The whole broth extracts from N. oryzae P02MS2A exhibited a MIC of one μg/mL and 16 μg/mL against gram-negative, MDR Pseudomonas 5625574 and gram-positive MRSA 25775 clinical isolates, respectively. After partial purification and GC-MS analysis of whole broth extract from A. alternaria PO2MS1, 2-fluorobenzoic acid heptadecyl was putatively identified as the active compound in fraction C of this extract. This compound was also putatively identified in fraction E of A. alternata P02PL2, fraction B of A. alternata P02MS1 and fraction B of N. oryzae P02MS2A, and interestingly, all these fractions retained activity against the two MDR clinical isolates.

CONCLUSION

The putative identification of 2-fluorobenzoic acid heptadecyl compound showing a broad-spectrum of activity, more especially against gram-negative MDR contemporary pathogens is highly encouraging in the initiative at developing novel drugs to combat multi-drug resistance.

Comparative Study on the Essential Oils Extracted from Tunisian Rosemary and Myrtle: Chemical Profiles, Quality, and Antimicrobial Activities

Rosemary (Rosmarinus officinalis L.) and myrtle (Myrtus communis L.) are perennial herbs, typical of the Tunisian flora, with an intense aromatic flavor. Their essential oils, obtained by hydro-distillation, were analyzed by gas chromatography coupled to mass spectrometry and by infrared Fourier transform spectrometry. In addition, these oils were assessed for their physicochemical properties as well as their antioxidant and antibacterial activities. The physicochemical characterization proved to be of good quality by analyzing pH, water content (%), density at 15 °C (g/cm³), and iodine values according to standard test methods. The study of the chemical composition allowed for the identification of 1,8-cineole (30%) and α-pinene (40.4%) as the main constituents of myrtle essential oil, while 1,8-cineole (37%), camphor (12.5%), and α-pinene (11.6%) were identified as principal components in rosemary essential oil. The evaluation of their antioxidant activities permitted to obtain the IC₅₀ values, which ranged between 22.3 and 44.7 μg/mL for DPPH and between 15.52 and 28.59 μg/mL for ferrous chelating assay, for rosemary and myrtle essential oils, respectively, thus indicating that rosemary essential oil is the most effective antioxidant. Furthermore, the antibacterial activity of the essential oils was tested in vitro against eight bacterial strains by the disc diffusion method. The essential oils showed antibacterial effects on both Gram-positive and Gram-negative bacteria.

Essential Oil and Non-Volatile Metabolites from Kaunia longipetiolata (Sch.Bip. ex Rusby) R. M. King and H. Rob., an Andean Plant Native to Southern Ecuador

Kaunia longipetiolata (Sch.Bip. ex Rusby) R. M. King and H. Rob. (Asteraceae) is a plant native to southern Ecuador. The dry leaves afforded, by steam distillation, an essential oil that was qualitatively and quantitatively analyzed by GC-MS and GC-FID, respectively, on two orthogonal columns of different polarity. Sesquiterpenes predominated in the volatile fraction, among which α-zingiberene (19.7-19.1%), ar-curcumene (17.3-18.1%), caryophyllene oxide (5.1-5.3%), (Z)-β-caryophyllene (3.0-3.1%), (2Z,6Z)-farnesal (2.6-3.6%), and spathulenol (2.0-2.1%) were the major components. In addition to the identified compounds, two main unidentified constituents (possibly oxygenated sesquiterpenes) with probable molecular masses of 292 and 230, respectively, were detected. They constituted about 5% and 8% (w/w), respectively, of the whole essential oil. The oil chemical composition was complemented with the enantioselective analysis of ten chiral components. Four scalemic mixtures and six enantiomerically pure terpenes were identified. An enantiomeric excess (ee) was determined for (1R,5R)-(+)-β-pinene (65.0%), (R)-(-)-α-phellandrene (94.6%), (S)-(+)-linalool (15.0%), and (R)-(-)-terpinen-4-ol (33.8%). On the other hand, (1R,5R)-(+)-α-pinene, (1R,5R)-(+)-sabinene, (S)-(-)-limonene, (S)-(+)-β-phellandrene, (1R,2S,6S,7S,8S)-(-)-α-copaene, and (R)-(+)-germacrene D were enantiomerically pure. Finally, the non-volatile fraction obtained by extraction of the leaves with MeOH was investigated. Eight known compounds were isolated by liquid column chromatographic separations. Their structures were determined by NMR spectroscopy as dehydroleucodine, kauniolide, (3S,3aR,4aR,6aS,9aS,9bR)-3-hydroxy-1,4a-dimethyl-7-methylene-5,6,6a,7,9a,9b-hexahydro-3H-oxireno[2',3':8,8a]azuleno[4,5-b]furan-8(4aH)-one, novanin, bisabola-1,10-diene-3,4-trans-diol, (R)-2-(2-(acetoxymethyl)oxiran-2-yl)-5-methylphenyl isobutyrate, eupalitin-3-O-glucoside, and 3,5-di-O-caffeoylquinic acid. Literature data about the identified metabolites indicate that K. longipetiolata is a rich source of biologically active natural products.

Health Benefits, Pharmacological Effects, Molecular Mechanisms, and Therapeutic Potential of α-Bisabolol

α-Bisabolol is one of the important monocyclic sesquiterpenes, derived naturally from essential oils of many edible and ornamental plants. It was first obtained from Matricaria chamomilla, commonly known as chamomile or German chamomile. The available literature indicates that this plant along with other α-Bisabolol containing plants is popularly used in traditional medicine for potential health benefits and general wellbeing. Nutritional studies are indicative of the health benefits of α-Bisabolol. Numerous experimental studies demonstrated pharmacological properties of α-Bisabolol including anticancer, antinociceptive, neuroprotective, cardioprotective, and antimicrobial. This review aims to collectively present different pharmacological activities based on both in vitro and in vivo studies. In the present review using synoptic tables and figures, we comprehensively present that α-Bisabolol possesses therapeutic and protective activities, therefore, it can be used for potential health benefits based on pharmacological effects, underlying molecular mechanism, and favorable pharmaceutical properties. Based on the studies mostly performed on cell lines or animal models, it is evident that α-Bisabolol may be a promising nutraceutical and phytomedicine to target aberrant biological mechanisms which result in altered physiological processes and various ailments. Given the polypharmacological effects and pleiotropic properties, along with favorable pharmacokinetics, and dietary availability and safety, α-Bisabolol can be used as a dietary agent, nutraceutical or phytopharmaceutical agent or as an adjuvant with currently available modern medicines. The regulatory approval of this molecule for use as food additives, and in cosmetics and fragrance industry is also supportive of its human usage. Moreover, further studies are necessary to address pharmaceutical, pharmacological, and toxicological aspects before clinical or nutritional usage in humans. The biological actions and health benefits open opportunities for pharmaceutical development with pharmacological basis of its use in future therapeutics.

Labdane Diterpenoids from Salvia tingitana Etl. Synergize with Clindamycin against Methicillin-Resistant Staphylococcus aureus

Quorum-sensing (QS) is a regulatory mechanism in bacterial communication, important for pathogenesis control. The search for small molecules active as quorum-sensing inhibitors (QSI) that can synergize with antibiotics is considered a good strategy to counteract the problem of antibiotic resistance. Here the antimicrobial labdane diterpenoids sclareol (1) and manool (2) extracted from Salvia tingitana were considered as potential QSI against methicillin-resistant Staphylococcus aureus. Only sclareol showed synergistic activity with clindamycin. The quantification of these compounds by LC-MS analysis in the organs and in the calli of S. tingitana showed that sclareol is most abundant in the flower spikes and is produced by calli, while manool is the major labdane of the roots, and is abundant also in the leaves. Other metabolites of the roots were abietane diterpenoids, common in Salvia species, and pentacyclic triterpenoids, bearing a γ-lactone moiety, previously undescribed in Salvia. Docking simulations suggested that 1 and 2 bind to key residues, involved in direct interactions with DNA. They may prevent accessory gene regulator A (AgrA) binding to DNA or AgrA activation upon phosphorylation, to suppress virulence factor expression. The antimicrobial activity of these two compounds probably achieves preventing upregulation of the accessory gene regulator (agr)-regulated genes.

Detection of microorganisms with antibacterial activities from different industrial wastes and GC-MS analysis of crude microbial extract

Many soil microorganisms' i.e., bacteria and fungi produce secondary metabolites called antibiotics. These are used for the treatment of some of the bacterial, fungal and protozoal diseases of humans. There is a need for isolation of a broad spectrum of antibiotics from microorganisms due to the emergence of antibiotic resistance. In the present study two antibiotic producing bacteria Klebsiella pneumoniae and Bacillus cereus were isolated from pharmaceutical and poultry feed industry of Hattar, Haripur Pakistan. Total 10 waste samples were collected from different industries (Marble, Ghee, Soap, Mineral, Steel, Poultry Feed, Pharmaceutical, Qarshi, Cosmetic and Glass). Thirty-three bacterial strains were isolated from industrial wastes of these ten different industries. Fourteen out of thirty-three bacterial strains exhibited antimicrobial activities against at least one of the test microbes considered in this study including Escherchia coli, Staphylococcus aureus and Salmonella typhi. The bacteria were isolated by standard serial dilution spread plate technique. Morphological characterization of the isolates was done by Gram staining. Nine bacterial isolates out of fourteen were initially identified as B. cereus and five as K. pneumoniae through biochemical characterization. The antibacterial activities were tested by well diffusion method. Maximum number of antibiotic producing bacteria were isolated from pharmaceutical and poultry feed industry based on the results of primary screening, the most potential isolates S9, S19, S20, S22 and S23 were selected for secondary screening. The maximum activity against E. coli and S. aureus was recorded by bacterial isolate S19 i.e zones of inhibition of 6.5mm and 9mm while S20 showed 7.5mm and 6mm zones respectively. Molecular identification was carried out on the basis of 16S rRNA sequence analysis. Finally, the isolates were identified as B. cereus accession number LC538271and K. pneumoniae accession number MT078679. Analysis of bacterial extract S20 through GC-MS indicated the presence of 8 compounds of diverse nature and structure. Present study suggests that wastes of pharmaceutical and poultry feed industry may have antibiotic producing bacteria. These bacteria could be utilized for the production of antibiotics. B. cereus and K. pneumoniae isolated from wastes of poultry feed and pharmaceutical industries have the potential to produce antibiotics and could be used to control the microbial growth.

Photorhabdus sp. ETL Antimicrobial Properties and Characterization of Its Secondary Metabolites by Gas Chromatography-Mass Spectrometry

Entomopathogenic nematodes (EPNs) are known to be highly pathogenic to insect pests, due to their associated symbiotic bacteria, which produce virulence factors, exo-enzymes and other harmful secondary metabolites to conquer, kill, and degrade their insect hosts. However, these properties are not fully characterized. This study reports on the antimicrobial activities of Photorhabdus sp. strain ETL, symbiotically associated to an insect pathogenic nematode, Heterorhabditis zealandica, against human pathogenic bacteria and toxigenic fungi, as well as the non-targeted profiling of its secondary metabolites (SMs) using gas chromatography coupled to high-resolution time-of-flight mass spectrometry. Fatty acids including 3-eicosene, (E)-; 5-eicosene, (E)-; eicosene; 9-octadecenamide; undecanoic acid with shown antimicrobial activities were detected. This provided more insight on the composition and bioactivities of SMs produced by the Photorhabdus sp.

In Vitro Antifungal Activity of Plant Extracts on Pathogenic Fungi of Blueberry (Vaccinium sp.)

Three pathogenic fungi of blueberry (Vaccinium spp.) responsible for dieback disease, identified as Pestalotiopsis clavispora, Colletotrichum gloeosporioides and Lasiodiplodia pseudotheobromae, were isolated in the northwestern region of the state of Michoacán, Mexico. The mycelial growth in vitro of these fungi was inhibited by extracts from Lantana hirta, Argemone ochroleuca and Adenophyllum porophyllum, medicinal plants collected in Sahuayo, Michoacán, Mexico. The extracts showed different degrees of inhibition; the most effective were: M5L extract from L. hirta and M6LFr extract from A. ochroleuca, both of which inhibited 100% of the mycelial growth of P. clavispora and C. gloeosporioides; and M4LS extract from A. porophyllum, which inhibited 100% of the mycelial growth of the three pathogens. The extracts were fractionated by thin layer and column chromatography, and the most active fractions were analyzed by gas chromatography-mass spectrometry. The major compounds identified in L. hirta extract were Phytol and α-Sitosterol. The compounds identified in A. ochroleuca were Toluene and Benzene, 1,3-bis(3-phenoxyphenoxy)-. In A. porophyllum, the compound identified was Hexanedioic acid, bis(2-ethylhexyl) ester. These results show the potential of L. hirta, A. ochroleuca and A. porophyllum as a source of antifungal compounds.

Antibacterial activity of noscapine analogs

The antibacterial properties of close noscapine analogs have not been previously reported. We used our pDualrep2 double-reporter High Throughput Screening (HTS) platform to identify a series of noscapine derivatives with promising antibacterial activity. The platform is based on RPF (SOS-response/DNA damage) and Katushka2S (inhibition of translation) proteins and simultaneously provides information on antibacterial activity and the mechanism of action of small-molecule compounds against E. coli. The most potent compound exhibited an MIC of 13.5 µM(6.25 µg/ml) and a relatively low cytotoxicity against HEK293 cells (CC₅₀ = 71 µM, selectivity index: ~5.5). Some compounds from this series induced average Katushka2S reporter signals, indicating inhibition of translation machinery in the bacteria; however, these compounds did not attenuate translation in vitro in a luciferase-based translation assay. The most effective compounds did not significantly arrest the mitotic cycle in HEK293 cells, in contrast to the parent compound in a flow cytometry assay. Several molecules showed activity against clinically relevant gram-negative and gram-positive bacterial strains. Compounds from the discovered series can be reasonably regarded as good templates for further development and evaluation.

Ecdysteroids from the underground parts of Rhaponticum acaule (L.) DC

In addition to two known ecdysteroids, 20-hydroxyecdysone and turkesterone, three previously undescribed stigmastane-type ecdysteroids were isolated from the underground parts of Rhaponticum acaule (L.) DC. by chromatographic techniques (CC, VLC, MPLC). The structures of the compounds were established by chemical (acetylation) and spectroscopic methods including UV, IR, HRMS, 1D-NMR: ¹H-NMR, ¹³C-NMR, DEPT-135. and 2D-NMR: COSY, NOESY, HSQC, HMBC. Two compounds were isolated as an isomeric mixture and each of them was purified and converted to the corresponding acetylated derivative. Based on all of the evidence, the structures of three undescribed stigmastane-type ecdysteroids were established as 2β,3β,11α,20β,22α,24,28-heptahydroxy-6-oxo-stigmast-7-en-25,29-lactone and the cyclic 22,29-hemiacetals 22R and 22S stigmast-7-en-29-al,2β,3β,11α,20α,22,28-hexahydroxy-6-oxo, and the trivial names acaulesterone and rhapocasterones A and B are suggested, respectively. The structures and absolute configurations of 20-hydroxyecdysone and cyclic-22,29-hemiacetal-22R-stigmast-7-en-29-al,2β,3β,11α,20α,22,28-hexahydroxy-6-oxo were confirmed by X-ray crystal-structure analyses of their acetyl derivatives.

In-depth in vitro Evaluation of the Activity and Mechanisms of Action of Organic Acids and Essential Oils Against Swine Enteropathogenic Bacteria

Alternative antimicrobials require a deep understanding of their action mechanisms by in vitro assays which support science-based field use. This study focuses on the characterization of bactericidal mechanisms of potential antimicrobial compounds, two organic acids and three single essential oil (EO) compounds against swine enteropathogenic bacteria Escherichia coli, Salmonella enterica subsp. enterica serovar Typhimurium, and Clostridium perfringens. Target concentrations of the compounds were evaluated using the inhibitory potential of the vapor phase and bacterial viability after short-term exposure, while cell targets were disclosed using flow cytometry (FC), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). All tested compounds exhibited vapor phase activity against the three bacterial species, except sodium salt of coconut fatty acid distillates against C. perfringens. Survival test results evidenced that effects on bacterial viability were concentration dependent and higher in single EO compounds than in organic acids. In detail, thymol and its isomer carvacrol were the most effective compounds. Further characterization of thymol and cinnamaldehyde activity revealed that thymol main target was the cell membrane, since it caused striking damages in the membrane permeability, integrity and composition evidenced by FC and FTIR in the three enteric pathogens. In contrast, cinnamaldehyde was more effective against enterobacteria than against C. perfringens and only caused slightly damages at the highest concentration tested. Its target at the molecular level differed between enterobacteria and C. perfringens isolates. The SEM micrographs allowed us to confirm the results previously obtained for both EO compounds by other techniques. Altogether, the study showed the straight effect of these antimicrobials, which could constitute relevant information to optimize their feed inclusion rates in field studies or field use.

Zingerone in the Flower of Passiflora Maliformis Attracts an Australian Fruit Fly, Bactrocera Jarvisi (Tryon)

Passiflora maliformis is an introduced plant in Australia but its flowers are known to attract the native Jarvis’s fruit fly, Bactrocera jarvisi (Tryon). The present study identifies and quantifies likely attractant(s) of male B. jarvisi in P. maliformis flowers. The chemical compositions of the inner and outer coronal filaments, anther, stigma, ovary, sepal, and petal of P. maliformis were separately extracted with ethanol and analyzed using gas chromatography-mass spectrometry (GC-MS). Polyisoprenoid lipid precursors, fatty acids and their derivatives, and phenylpropanoids were detected in P. maliformis flowers. Phenylpropanoids included raspberry ketone, cuelure, zingerone, and zingerol, although compositions varied markedly amongst the flower parts. P. maliformis flowers were open for less than one day, and the amounts of some of the compounds decreased throughout the day. The attraction of male B. jarvisi to P. maliformis flowers is most readily explained by the presence of zingerone in these flowers.

Antibacterial activity of Centaurea pumilio L. root and aerial part extracts against some multidrug resistant bacteria

Background

In the context of searching for potent, safe, natural antimicrobial agents to combate the global antimicrobial resistance (AMR) phenomenon, the current study evaluates for the first time ever, the broad-spectrum antimicrobial activity of essential oil (EO) and extracts from the rare wild plant Centaurea pumilio L.. It has tremendous ethnomedicinal values; its dried root is used as a fattening agent, a treatment for bad breath and diabetes, and screened for schistosomicidal activity.

Methods

C. pumilio EO was extracted by hydrodistillation using a Clevenger apparatus. Chemical constituents of aerial part were extracted using a sequential solvent/solvent procedure employing four solvents with increasing polarities in the following order: petroleum ether, chloroform, ethyl acetate, and n-butanol. The chemical constituents were identified by GC-MS. Fifty-two microbial strains were used; twenty-six multidrug resistant (MDR), sixteen clinical, and ten reference strains. The identification of the microbial strains was performed by MALDI-TOF-MS. The antimicrobial activity of the EO and the aerial part and the root extracts was assessed through disc diffusion assay. A minimum inhibitory concentration (MIC) of the EO and extracts was determined using the broth micro-dilution method.

Results

The growth of reference and clinical strains was inhibited by EO, methanol, chloroform, and ethyl acetate aerial part extracts and chloroform root extract. The MDR strains growth, however, was inhibited only by EO and chloroform aerial part extract. GC-MS identified for the first time eighteen constituents from aerial part EO and chloroform extract each. EO showed antimicrobial activity against the reference, clinical, and MDR strains with MIC values of 31.25–125, 31.25–125, and 62.50–250 μg/mL, respectively. Methanol aerial part extract exhibited high antimicrobial activities with MIC values of 62.50–250 μg/mL against reference and clinical strains. Chloroform root extract displayed strong antimicrobial activity against reference and clinical strains recording MIC values of 62.50–250 μg/mL and 62.50–125 μg/mL, respectively. The chloroform aerial part extract demonstrated potent antimicrobial activity against the reference, clinical, and MDR strains with 31.25, 31.25, and 15.62 μg/mL MIC values, respectively.

Conclusions

Present data unravel the C. pumilio pharmacological magnitude to discover eco-friendly potent antimicrobial agents to fight AMR phenomenon.

Chemical Composition, Algicidal, Antimicrobial, and Antioxidant Activities of the Essential Oils of Taiwania flousiana Gaussen

Taiwania flousiana (T. flousiana) Gaussen is a precious wood in the family Taxodiaceae. This study investigated the chemical components of the essential oil from the stem bark of T. flousiana and its algicidal, antifungal, and antioxidant properties. Sixty-nine compounds representing 89.70% of the stem bark essential oil were identified by GC-MS. The essential oil showed strong anti-algae, anti-bacteria, and anti-fungus activities against the tested species, and antioxidant activities. The IC₅₀ values of the essential oil against chlorophyll a, chlorophyll b, and the total chlorophyll of Spirogyra communis (a species of algae), 24-96 h after the treatment, ranged from 31.77 to 84.92 μg/mL, while the IC₅₀ values of butachlor ranged from 40.24 to 58.09 μg/mL. Ultrastructure changes revealed by the transmission electron microscopy indicated that the main algicidal action sites were the chloroplast and cell wall. The essential oil showed antifungal activities on Rhizoctonia solani (EC₅₀ = 287.94 μg/mL) and Colletotrichum gloeosporioiles (EC₅₀ = 378.90 μg/mL). It also showed bactericidal activities on Ralstonia solanacearum and Staphylococcus aureus, with zones of inhibition (ZOIs) being 18.66 and 16.75 mm, respectively at 40 μg/disk. Additionally, the essential oil possessed antioxidant activity estimated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method (IC₅₀ = 33.51 μg/mL; IC₅₀ value of the positive control ascorbic acid was 7.98 μg/mL). Thus, the essential oil of this plant might be used as a possible source of natural bioactive molecules in agrochemical industry as well as in food and cosmetic industries.

Synergistic and Antagonistic Effects of Metal Nanoparticles in Combination with Antibiotics Against Some Reference Strains of Pathogenic Microorganisms

Background and Aim

Nanosized inorganic antibacterial materials have received increasing attention in recent years. The present study aimed to determine the antimicrobial activity of silver (Ag) and zinc oxide (ZnO) nanoparticles alone and in combination with antibiotics against reference strains of pathogenic microorganisms as Staphylococcus aureus (Staph. aureus), Salmonella enterica subsp. Bukuru, Escherichia coli (E.coli) and Candida albicans ( C. albicans).

Methods

The antimicrobial effect of metal-nanoparticles (AgNPs and ZnONPS) and in combination with antibiotics was studied using the normal disc-diffusion method.

Results

Both AgNPs and ZnONPs had increased antibacterial activity with an increase in their concentration against Gram-positive bacterium (Staph. aureus), Gram-negative bacteria (E. coli and Salmonella spp) and no effect on C. albicans. The synergistic effect of antibiotics (azithromycin, cefotaxime, cefuroxime, fosfomycin and chloramphenicol) against E. coli was significantly increased in the presence of AgNPs compared to antibiotic only. However, all antibiotics had a synergistic effect in the presence of AgNps against Salmonella spp. On the other hand, the antibacterial action of AgNPs with oxacillin and neomycin antibiotics against Staph. aureus was significantly decreased in comparison with antibiotics only. The synergistic effect of antibiotics (azithromycin, oxacillin, cefotaxime, cefuroxime, fosfomycin and oxytetracycline) against E. coli was significantly increased in presence of ZnONPs compared to antibiotic only and also the synergistic effect of antibiotics (azithromycin, cefotaxime, cefuroxime, fosfomycin, chloramphenicol and oxytetracycline) against Staph. aureus was significantly increased in the presence of ZnONPs compared to antibiotics only. On the other hand, most antibiotics had an antagonistic effect in presence of ZnONps against Salmonella spp.

Conclusion

AgNPs and ZnONPs demonstrate a good synergistic effect with antibiotics and this may open the door for a future combination therapy against pathogenic bacteria.

Spasmolytic activity of Aquilariae Lignum Resinatum extract on gastrointestinal motility involves muscarinic receptors, calcium channels and NO release

CONTEXT

Aquilariae Lignum Resinatum (ALR), the dry rhizome of Aquilaria agallocha R. (Thymelaeaeeae), has been widely used to treat emesis, stomachache and gastrointestinal dysfunction.

OBJECTIVE

This study evaluates the effects of ALR methanol extract on gastrointestinal motility (GIM) and possible mechanisms of the action involved.

MATERIALS AND METHODS

In vivo, the study evaluated the effects of ALR (200-800 mg/kg) on gastric emptying and small intestinal motility in normal and neostigmine-induced adult KM mice. The in vitro effects of ALR (0.2-1.6 mg/mL) on GIM were performed on isolated jejunum of Wistar rats, pretreated with acetylcholine (ACh), KCl, CaCl₂, and pre-incubation with l-NAME (a selective inhibitor of the nitric oxide synthase).

RESULTS

In vivo, ALR (800 mg/kg) decreased gastric emptying (70.82 ± 9.81%, p < 0.01, compared with neostigmine group 91.40 ± 7.81%), small intestinal transit (42.82 ± 3.82%, p < 0.01, compared with neostigmine group 85.53 ± 5.57%). In vitro, ALR concentration dependently decreased the contractions induced by ACh (10^-5 M) and KCl (60 mM) with respective EC₅₀ values of 0.35 and 0.32 mg/mL. The Ca²⁺ concentration-response curves were shifted by ALR to the right, similar to that caused by verapamil (the positive). The spasmolytic activity of ALR was inhibited by pre-incubation with l-NAME.

DISCUSSION AND CONCLUSIONS

ALR played a spasmolytic role in GIM, which is probably mediated through inhibition of muscarinic receptors, blockade of Ca²⁺ influx and NO release. This is the first study presenting a comprehensive description of the effects of ALR on GIM.

Stable isotope labeling-assisted GC/MS/MS method for determination of methyleugenol in food samples

BACKGROUND

Methyleugenol is a common phenylpropanoid compound found in many plants and has been widely used as a flavoring agent in people's daily life. In this study, a stable isotope dilution assay-coupled gas chromatography/triple quadrupole mass spectrometry (SIDA-GC/MS/MS) method was developed for the quantitative determination of methyleugenol in food samples. Methyleugenol-D₃ was synthesized and used as an isotope internal standard for the determination of methyleugenol. The QuEChERS (quick, easy, cheap, effective, rugged and safe) method was applied to the clean-up of food sample extracts. Confirmation and quantification were carried out by GC/MS/MS.

RESULTS

The analytical performance of the method was validated. The determination range of methyleugenol was linear from 4 to 500 µg L^-1 . Method detection limits for solid food samples, semi-solid food samples and liquid beverages were 50, 50 and 1 µg kg^-1 respectively. Satisfactory recoveries in the range 94.29-100.27% were obtained. Intra- and inter-day precision was also validated and the values were all lower than 9%. The method was successfully applied to quantify methyleugenol in different kinds of food samples.

CONCLUSION

This article describes a new method for the accurate quantification of methyleugenol in food samples based on a stable isotope labeling-assisted GC/MS/MS method. Methyleugenol-D₃ was synthesized and used as an isotope internal standard for the determination of methyleugenol. Excellent results were generated with the method, and the detection sensitivity and accuracy of the method were good. © 2018 Society of Chemical Industry.

Rhaponticum acaule (L) DC essential oil: chemical composition, in vitro antioxidant and enzyme inhibition properties

BACKGROUND

α-glucosidase is a therapeutic target for diabetes mellitus (DM) and α-glucosidase inhibitors play a vital role in the treatments for the disease. Furthermore, xanthine oxidase (XO) is a key enzyme that catalyzes hypoxanthine and xanthine to uric acid which at high levels can lead to hyperuricemia which is an important cause of gout. Pancreatic lipase (PL) secreted into the duodenum plays a key role in the digestion and absorption of fats. For its importance in lipid digestion, PL represents an attractive target for obesity prevention.

METHODS

The flowers essential oil of Rhaponticum acaule (L) DC (R. acaule) was characterized using gas chromatography-mass spectrometry (GC-MS). The antioxidant activities of R. acaule essential oil (RaEO) were also determined using 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), reducing power, phosphomolybdenum, and DNA nicking assays. The inhibitory power of RaEO against α-glucosidase, xanthine oxidase and pancreatic lipase was evaluated. Enzyme kinetic studies using Michaelis-Menten and the derived Lineweaver-Burk (LB) plots were performed to understand the possible mechanism of inhibition exercised by the components of this essential oil.

RESULTS

The result revealed the presence of 26 compounds (97.4%). The main constituents include germacrene D (49.2%), methyl eugenol (8.3%), (E)-β-ionone (6.2%), β-caryophyllene (5.7%), (E,E)-α-farnesene (4.2%), bicyclogermacrene (4.1%) and (Z)-α-bisabolene (3.7%). The kinetic inhibition study showed that the essential oil demonstrated a strong α-glucosidase inhibiton and it was a mixed inhibitor. On the other hand, our results evidenced that this oil exhibited important xanthine oxidase inhibitory effect, behaving as a non-competitive inhibitor. The essential oil inhibited the turkey pancreatic lipase, with maximum inhibition of 80% achieved at 2 mg/mL. Furthermore, the inhibition of turkey pancreatic lipase by RaEO was an irreversible one.

CONCLUSION

The results revealed that the RaEO is a new promising potential source of antioxidant compounds, endowed with good practical applications for human health.

Chemical composition, immunostimulatory, cytotoxic and antiparasitic activities of the essential oil from Brazilian red propolis

Most studies of Brazilian red propolis have explored the composition and biological properties of its ethanolic extracts. In this work, we chemically extracted and characterized the essential oil of Brazilian red propolis (EOP) and assessed its adjuvant, antiparasitic and cytotoxic activities. The chemical composition of EOP was analyzed using gas chromatography with mass spectrometry (GC-MS). EOP was tested for in vitro activity against Trichomonas vaginalis (ATCC 30236 isolate); trophozoites were treated with different concentrations of EOP (ranging from 25 to 500 μg/mL) in order to establish the MIC and IC₅₀ values. A cytotoxicity assay was performed in CHO-K1 cells submitted to different EOP concentrations. BALB/c mice were used to test the adjuvant effect of EOP. The animals were divided in 3 groups and inoculated as follows: 0.4 ng/kg BW EOP (G1); 50 μg of rCP40 protein (G2); or a combination of 0.4 ng/kg BW EOP and 50 μg of rCP40 (G3). Total IgG, IgG1 and IgG2a levels were assessed by ELISA. The major constituent compounds of EOP were methyl eugenol (13.1%), (E)-β-farnesene (2.50%), and δ-amorphene (2.3%). Exposure to EOP inhibited the growth of T. vaginalis, with an IC₅₀ value of 100 μg/mL of EOP. An EOP concentration of 500 μg/mL was able to kill 100% of the T. vaginalis trophozoites. The EOP kinetic growth curve showed a 36% decrease in trophozoite growth after a 12 h exposure to 500 μg/mL of EOP, while complete parasite death was induced at 24 h. With regard to CHO-K1 cells, the CC₅₀ was 266 μg/mL, and 92% cytotoxicity was observed after exposure to 500 μg/mL of EOP. Otherwise, a concentration of 200 μg/mL of EOP was able to reduce parasite proliferation by 70% and was not cytotoxic to CHO-K1 cells. As an adjuvant, a synergistic effect was observed when EOP was combined with the rCP40 protein (G3) in comparison to the administration of each component alone (G1 and G2), resulting in higher concentrations of IgG, IgG1 and IgG2a. EOP is constituted by biologically active components with promising antiparasitic and immunostimulatory activities and can be investigated for the formulation of new vaccines or trichomonacidal drugs.

Anti-cryptococcal activity of ethanol crude extract and hexane fraction from Ocimum basilicum var. Maria bonita: mechanisms of action and synergism with amphotericin B and Ocimum basilicum essential oil

CONTEXT

Ocimum basilicum L. (Lamiaceae) has been used in folk medicine to treat headaches, kidney disorders, and intestinal worms.

OBJECTIVE

This study evaluates the anti-cryptococcal activity of ethanol crude extract and hexane fraction obtained from O. basilicum var. Maria Bonita leaves.

MATERIALS AND METHODS

The MIC values for Cryptococcus sp. were obtained according to Clinical and Laboratory Standards Institute in a range of 0.3-2500 μg/mL. The checkerboard assay evaluated the association of the substances tested (in a range of 0.099-2500 μg/mL) with amphotericin B and O. basilicum essential oil for 48 h. The ethanol extract, hexane fraction and associations in a range of 0.3-2500 μg/mL were tested for pigmentation inhibition after 7 days of treatment. The inhibition of ergosterol synthesis and reduction of capsule size were evaluated after the treatment with ethanol extract (312 μg/mL), hexane fraction (78 μg/mL) and the combinations of essential oil + ethanol extract (78 μg/mL + 19.5 μg/mL, respectively) and essential oil + hexane fraction (39.36 μg/mL + 10 μg/mL, respectively) for 24 and 48 h, respectively.

RESULTS

The hexane fraction presented better results than the ethanol extract, with a low MIC (156 μg/mL against C. neoformans T₄₄₄ and 312 μg/mL against C. neoformans H99 serotype A and C. gattii WM779 serotype C). The combination of the ethanol extract and hexane fraction with amphotericin B and essential oil enhanced their antifungal activity, reducing the concentration of each substance needed to kill 100% of the inoculum. The substances tested were able to reduce the pigmentation, capsule size and ergosterol synthesis, which suggest they have important mechanisms of action.

CONCLUSIONS

These results provide further support for the use of ethanol extracts of O. basilicum as a potential source of antifungal agents.

Biological Significance of Marine Actinobacteria of East Coast of Andhra Pradesh, India

An attempt was made to identify actinobacterial strains present in the marine soil of East Coast regions viz., Chirala, Bapatla, and Peddaganjam, Andhra Pradesh; Kanyakumari, Tamil Nadu and Goa, Goa along with the study of their antimicrobial potential. Eight out of 73 actinobacterial strains isolated from these regions showed strong antimicrobial activity against Gram positive bacteria, Gram negative bacteria, and Candida albicans. Molecular identification (16S rRNA analysis) of the eight strains revealed that they belong to Dietzia sp., Kocuria sp., Nocardiopsis sp., and Streptomyces spp. ISP (International Streptomyces project) -1, ISP-2 and starch casein media supported high antimicrobial potential after 5-6 days of growth. Production of antimicrobials by the strains varied significantly with different carbon and nitrogen sources. Gas chromatography mass spectrometry (GCMS) analysis of volatile compounds produced by the strains illustrated an array of antimicrobial compounds such as 1, 2-benzene dicarboxylic acid, 2-piperidinone, pyrrolo[1,2-a]pyrazine-1,4-dion, phenyl ethyl alcohol, 3-phenyl propionic acid etc. Ours is the first report on the study and detection of above mentioned antimicrobial metabolites from Dietzia sp. (A3), Kocuria sp. (A5), and Nocardiopsis sp. (A7). By sequence based analysis for secondary metabolites, non-ribosomal peptide synthetase (NRPS) gene cluster was noticed in six strains (A2, A3, A4, A6, A7, and A8) and none of them had polyketide synthase (PKS) system. The present study intimates the biological potentiality of the actinobacterial strains isolated from East Coast of Andhra Pradesh, India which reveals further scope to investigate new bioactive compounds from them by employing both natural product chemistry and modern biotechnological aspects.

Isolation, identification, optimization, and metabolite profiling of Streptomyces sparsus VSM-30

Deep sea sediment samples of Bay of Bengal (Visakhapatnam) have been analyzed for actinomycetes as an elite source to screen for the production of bioactive metabolites. The actinomycetes strain VSM-30 has an exciting bioactivity profile and was isolated during our systemic screening of marine actinomycetes. It was identified as Streptomyces sparsus based on morphological, physiological, biochemical, and molecular approaches. Response surface methodology regression analysis was carried out to fit the experimental data of each response by the second-order polynomial. The results have proven right interaction among process variables at optimized values of incubation time at 12 days, pH at 8, temperature at 30 °C, concentrations of starch at 1%, and tryptone at 1% and the data have been adequately fitted into the second-order polynomial models. Under these conditions, the responses (zones of inhibition) of plant pathogenic fungi Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, Fusarium solani, and Penicillium citrinum were also matched with experimental and predicted results. Chemotypic analysis of ethyl acetate extract of the strain was done using LC-Q-TOF-MS revealed the presence of bioactive compounds including tryptophan dehydrobutyrine diketopiperazine, maculosin, 7-o-demethyl albocycline, albocycline M-2, and 7-o-demethoxy-7-oxo albocycline in a negative ion mode. The ethyl acetate extract of actinobacterium has been subjected to gas chromatography and mass spectroscopy (GC-MS) revealed the presence of diverse compounds such as dotriacontane, tetracosane 11-decyl-, diheptyl phthalate, 1-hexadecanesulfonyl chloride, L-alanyl-L-tryptophan, phthalic acid ethyl pentyl ester, 4-trifluoroacetoxyhexadecane, and 1H-imidazole 4,5-dihydro-2,4-dimethyl. Hence, the ethyl acetate extract of Streptomyces sparsus VSM-30 may have antibacterial, antifungal, and antioxidant activities due to the presence of secondary metabolites in ethyl acetate extract. The study also supports marine sediment samples of Bay of Bengal, a promising marine ecosystem remained to be explored for new bioactive compounds.

GC-MS Analysis of Bio-active Molecules Derived from Paracoccus pantotrophus FMR19 and the Antimicrobial Activity Against Bacterial Pathogens and MDROs

The present investigation is focused on the study of chemical composition of a bioactive compound derived from a rumen isolate Paracoccus pantotrophus FMR19 using GC-MS and to find out the antibacterial activity of the extracted crude bioactive compounds against multidrug resistant organisms (MDROs) and other clinical pathogens. GC-MS analysis revealed that P. pantotrophus FMR19 produced eight major compounds that have been reported to exhibit antimicrobial property. The main components identified from hexane fraction are long chain alkanes, fatty alcohols, fatty acid methyl ester and aromatic hydrocarbons. These molecules are not only active against clinical pathogens such as Salmonella sp. and Proteus sp. and also effective against MDROs such as Metallo β lactamase and Pan drug resistant bacterial strains and Methicillin resistant Staphylococcus aureus.

Evaluation of the cytotoxic effects of Cyperus longus extract, fractions and its essential oil on the PC3 and MCF7 cancer cell lines

Cyperus longus is one of the Iranian endemic species. However, to date, and to the best of our knowledge, there are no availale academic reports on the cytotoxicity of this plant. Thus, this study was carried out to examine the in vitro anti-proliferative and anti-apoptotic effects of Cyperus longus extract, fractions and essential oil (EO) on MCF7 and PC3 cell lines. The chemical constituents of EO were identified using gas chromatography (GC)-mass spectrometry (MS) analysis. The cells were cultured in RPMI-1640 medium and incubated with various concentrations of the plant extract and fractions. Cell viability was quantified by MTT assay following 24, 48 and 72 h of exposure to (12.5–200 µg/ml) of the methanol extract, the dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc) and water fractions, as well as the EO of the plant. The percentage of apoptotic cells was determined using propidium iodide staining of DNA fragments by flow cytometry (sub-G1 peak). The most effective fraction in the MCF7 cell line was the CH₂Cl₂ fraction (IC₅₀ after 48 h, 25.34±2.01). The EtOAc fraction (IC₅₀ after 48 h, 35.2±2.69) and the methanol extract (IC₅₀ after 48 h, 64.64±1.64) were also found to be effective. The IC₅₀ values obtained for the PC3 cell line were 37.97±3.87, 51.57±3.87 and 70.33±2.36 for the CH₂Cl₂ fraction, the EtOAc fraction and the methanol extract, respectively. Based on these data and due to the partial polarity of the most effective fraction (the CH₂Cl₂ fraction), we also examined the cytotoxicity of the plant EO. The IC₅₀ values after 48 h were 22.25±4.25 and 12.55±3.65 in the PC3 and MCF7 cell lines, respectively. DNA fragmentation assay also confirmed these data. Performing GC-MS analysis for the plant EO revealed that β-himachalene (10.81%), α-caryophyllene oxide (7.6%), irisone (4.78%), β-caryophyllene oxide (4.36%), humulene oxide (12%), viridiflorol (4.73%), aristolone (6.39%) and longiverbenone (6.04%) were the main constituents. Our results demonstrated that two of the constituents of Cyperus longus, viridiflorol and longiverbenone, should be investigated further as possible promising chemotherapeutic agents in cancer treatment.

Antimicrobial activity and composition profile of grape (Vitis vinifera) pomace extracts obtained by supercritical fluids

The possibility of increasing the aggregated value of the huge amount of residues generated by wineries around the world foment studies using the grape pomace - the residue from the wine production, composed by seed, skin and stems - to obtain functional ingredients. Nowadays, consumers in general prefer natural and safe products mainly for food and cosmetic fields, where the supercritical fluid extraction is of great importance due to the purity of the extracts provided. Therefore, the objective of this work is to evaluate the global extraction yield, the antimicrobial activity and the composition profile of Merlot and Syrah grape pomace extracts obtained by supercritical CO2 (SC-CO2) and CO2 added with co-solvent at pressures up to 300 bar and temperatures of 50 and 60 °C. The results were compared with the ones obtained by Soxhlet and by ultrasound-assisted leaching extraction methods. The main components from the extracts, identified by HPLC, were gallic acid, p-OH-benzoic acid, vanillic acid and epicatechin. The antibacterial and antifungal activities of the extracts were evaluated using four strains of bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa) and three fungi strains (Candida albicans, Candida parapsilosis, Candida krusei). Despite lower extraction yield results, the supercritical fluid extracts presented the highest antimicrobial effectiveness compared to the other grape pomace extracts due to the presence of antimicrobial active compounds. Syrah extracts were less efficient against the microorganisms tested and Merlot extracts were more active against Gram-positive bacteria.

Essential oil of the leaves of Ricinus communis L.: in vitro cytotoxicity and antimicrobial properties

Background

The aim of the present study was to appraise the antimicrobial activity of Ricinus communis L. essential oil against different pathogenic microorganisms and the cytotoxic activity against HeLa cell lines.

Methods

The agar disk diffusion method was used to study the antibacterial activity of Ricinus communis L. essential oil against 12 bacterial and 4 fungi strains. The disc diameters of zone of inhibition (DD), the minimum inhibitory concentrations (MIC) and the concentration inhibiting 50% (IC₅₀) were investigated to characterize the antimicrobial activities of this essential oil. The in vitro cytotoxicity of Ricinus communis L. essential oil was examined using a modified MTT assay; the viability and the IC₅₀ were used to evaluate this test.

Results

The essential oil from the leaves of Ricinus communis L. was analyzed by GC–MS and bioassays were carried out. Five constituents of the oil were identified by GC–MS. The antimicrobial activity of the oil was investigated in order to evaluate its efficacy against twelve bacteria and four fungi species, using disc diffusion and minimum inhibitory concentration methods. The essential oil showed strong antimicrobial activity against all microorganisms tested with higher sensitivity for Bacillus subtilis, Staphylococcus aureus and Enterobacter cloacae. The cytotoxic and apoptotic effects of the essential oil on HeLa cell lines were examined by MTT assay. The cytotoxicity of the oil was quite strong with IC50 values less than 2.63 mg/ml for both cell lines.

Conclusion

The present study showed the potential antimicrobial and anticarcinogenic properties of the essential oil of Ricinus communis L., indicating the possibilities of its potential use in the formula of natural remedies for the topical treatment of infections.

Methyl eugenol: its occurrence, distribution, and role in nature, especially in relation to insect behavior and pollination

This review discusses the occurrence and distribution (within a plant) of methyl eugenol in different plant species (> 450) from 80 families spanning many plant orders, as well as various roles this chemical plays in nature, especially in the interactions between tephritid fruit flies and plants.

The in-vitro evaluation of antibacterial, antifungal and cytotoxic properties of Marrubium vulgare L. essential oil grown in Tunisia

Background

In order to validate its antiseptic and anticancer properties with respect to traditional uses, we have screened for the first time the antimicrobial activity of aerial parts of M. vulgare L. essential oil against different pathogenic microorganisms and the cytotoxic activity against HeLa cell lines.

Methods

The agar disk diffusion method was used to study the antibacterial activity of M. vulgare essential oil against 12 bacterial and 4 fungi strains. The disc diameters of zone of inhibition (DD), the minimum inhibitory concentrations (MIC) and the concentration inhibiting 50% (IC₅₀) were investigated to characterize the antimicrobial activities of this essential oil. The in vitro cytotoxicity of M. vulgare essential oil was examined using a modified MTT assay; the viability and the IC₅₀ were used to evaluate this test.

Results

The antimicrobial activity of the essential oil was investigated in order to evaluate its efficacy against the different tested microorganisms. The present results results showed a significant activity against microorganisms especially Gram (+) bacteria with inhibition zones and minimal inhibitory concentration values in the range of 6.6-25.2 mm and 1120-2600 μg/ml, respectively, whereas Gram (-) bacteria exhibited a higher resistance. As far as the antifungal activity, among four strains tested, Botrytis cinerea exhibited the strongest activity with inhibition zones of 12.6 mm. However, Fusarium solani, Penicillium digitatum and Aspergillus niger were less sensitive to M. vulgare essential oil. About the citotoxicity assay, this finding indicate the capability of this essential oil to inhibited the proliferation of HeLa cell lines under some conditions with IC₅₀ value of 0.258 μg/ml.

Conclusion

This investigation showed that the M. vulgare essential oil has a potent antimicrobial activity against some Gram (+) pathogenic bacteria and Botrytis cinerea fungi. The present studies confirm the use of this essential oil as anticancer agent. Further research is required to evaluate the practical values of therapeutic applications.

Eucalyptus oleosa essential oils: chemical composition and antimicrobial and antioxidant activities of the oils from different plant parts (stems, leaves, flowers and fruits)

Essential oils obtained by hydrodistillation from the different parts (stems, adult leaves, immature flowers and fruits) of Eucalyptus oleosa were screened for their antioxidant and antimicrobial properties and their chemical composition. According to GC-FID and GC-MS, the principal compound of the stem, immature flowers and the fruit oils was 1,8-cineole, representing 31.5%, 47.0% and 29.1%, respectively. Spathulenol (16.1%) and γ-eudesmol (15.0%) were the two principal compounds of adult leaves oil. In the DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, the oils of the four parts showed moderate antioxidant activity. In the ABTS (2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate) assay, the most active part was the adult leaves, with a IC(50) value 13.0 ± 0.6 mg/L, followed by stems (IC(50) = 43.5 ± 1.4 mg/L). The essential oils showed a better antibacterial activity against Gram-positive and Gram-negative bacteria, and a significant antifungal activity also was observed against yeast-like fungi. A strong correlations between oxygenated monoterpenes and antimicrobial activity (especially 1,8-cineole) were noted (R2 = 0.99, 0.97 and 0.79 for B. subtilis, P. aeruginosa and C. albicans, respectively).

Chemical composition and antibacterial activity of Cordia verbenacea extracts obtained by different methods

The present study describes the chemical composition and the antibacterial activity of extracts from Cordia verbenacea DC (Borraginaceae), a traditional medicinal plant that grows widely along the southeastern coast of Brazil. The extracts were obtained using different extraction techniques: high-pressure operations and low-pressure methods. The high-pressure technique was applied to obtain C. verbenacea extracts using pure CO(2) and CO(2) with co-solvent at pressures up to 30MPa and temperatures of 30, 40 and 50 degrees C. Organic solvents such as n-hexane, ethyl acetate, ethanol, acetone and dichloromethane were used to obtain extracts by low-pressure processes. The antibacterial activity of the extracts was also subjected to screening against four strains of bacteria using the agar dilution method. The extraction yields were up to 5.0% w/w and up to 8.6% w/w for supercritical fluid extraction with pure CO(2) and with ethyl acetate as co-solvent, respectively, while the low-pressure extraction indicates yields up to 24.0% w/w in the soxhlet extraction using water and aqueous mixture with 50% ethanol as solvents. The inhibitory activity of the extracts in gram-positive bacteria was significantly higher than in gram-negative. The quantification and the identification of the extracts recovered were accomplished using GC/MS analysis. The most important components identified in the extract were artemetin, beta-sitosterol, alpha-humulene and beta-caryophyllene, among others.

Production of bioactive metabolites by Nocardia levis MK-VL_113

AIMS

To isolate and identify the bioactive compounds produced by Nocardia levis MK-VL_113.

METHODS AND RESULTS

Cultural characteristics of Noc. levis isolated from laterite soils of Guntur region were recorded on International Streptomyces Project media. Morphological studies of the strain through scanning electron microscopy revealed the clear pattern of its hyphal fragmentation into rod-shaped bacilli. Chemical examination of the secondary metabolites of the strain grown on sucrose-tryptone broth led to the isolation of three fractions active against Bacillus cereus. Further analysis of second fraction resulted in the isolation of two active subfractions. Two different phthalate esters, namely, bis-(2-ethylhexyl) phthalate and bis-(5-ethylheptyl) phthalate, were purified from the first active subfraction, and the structural elucidation of these compounds was confirmed on the basis of FT-IR, mass and NMR spectroscopy. The partially purified second subfraction subjected to Gas Chromatography-Mass spectroscopy contained nine components: decanedioic acid; 2,6-piperdione monooxime; 1-eicosanol; beta-1-arabinopyranoside, methyl; cyclopentaneundecanoic acid; hexadecanoic acid; silane, trichloro eicosyl; 1-hexacosanol; and 1,2-dodecanediol. The antimicrobial activity of the bioactive compounds produced by Noc. levis was expressed in terms of minimum inhibitory concentration.

CONCLUSIONS

The present study clearly revealed that the metabolites of Noc. levis act as bioactive compounds against gram-positive and gram-negative bacteria, yeast and filamentous fungi. It also supports the idea that there are a number of rare actinomycetes remained to be explored for new bioactive compounds.

SIGNIFICANCE AND IMPACT OF THE STUDY

Metabolites of Noc. levis exhibited antibacterial and antifungal activities. This is the first report of bis-(5-ethylheptyl) phthalate as well as the nine partially purified compounds from actinomycetes. In addition, this is also the first report of bis-(2-ethylhexyl) phthalate from the genus Nocardia.

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 microg/ml.