Volatile composition and antimicrobial activity of twenty commercial frankincense essential oil samples

Trees from the genus Boswellia (Burseraceae) are traditionally used as a medicine, a fumigant, in various cosmetic formulations and in aromatherapy in several countries around the world. This plant produces a commercial oil known as frankincense which has a woody, spicy and haunting smell. Frankincense oil has several pharmacological properties, of which many elude to the anti-infective potential. Variation in the chemical composition of this oil has been reported in literature. These factors prompted an investigation to study the commercial frankincense oils from various international suppliers. Twenty essential oils were analyzed by gas chromatography coupled to mass spectrometry. Considering the major constituents, the oils were found to be qualitatively similar. However, there was immense quantitative variation for certain oil constituents. The components identified and their range in the oils include α-pinene (2.0–64.7%); α-thujene (0.3–52.4%); β-pinene (0.3–13.1%); myrcene (1.1–22.4%); sabinene (0.5–7.0%); limonene (1.3–20.4%); p-cymene (2.7–16.9%) and β-caryophyllene (0.1–10.5%). The antimicrobial activity (minimum inhibition concentration assay) of the oils was investigated against five reference test organisms and the activity ranged from 4–16 mg/ml (Staphylococcus aureus); 1.5–8.3 mg/ml (Bacillus cereus); 4.0–12.0 mg/ml (Escherichia coli); 2.0–12.8 mg/ml (Proteus vulgaris) and 5.3–12.0 mg/ml (Candida albicans).     

Antimycobacterial,antibacterial and antifungal activities of Terminalia superba (Combretaceae)

The methanol extract from the stem bark of Terminalia superba (TSB), fractions (TSB1–7) and two compounds isolated following bio-assay guided fractionation namely 3,4′-di-O-methylellagic acid 3′-O-β-d-xylopyranoside (1) and 4′-O-galloy-3,3′-di-O-methylellagic acid 4-O-β-d-xylopyranoside (2) were evaluated for their antimycobacterial, antibacterial and antifungal activities. The broth microdilution, the microplate Alamar Blue assay (MABA) and the agar disc diffusion methods were used for the investigations. The results of the antimycobacterial assays showed that the crude extract, fractions TSB5–7 and compound 1 were able to prevent the growth of all the studied mycobacteria. The lowest minimal inhibitory concentration (MIC) value of 39.06 µg/ml for this extract was recorded on both M. smegmatis and M. tuberculosis MTCS2. The corresponding values were 19.53 µg/ml and 4.88 µg/ml for fractions and compounds respectively. The MIC determination results on other organisms indicated values ranging from 19.53 to 78.12 µg/ml for TSB and compound 2 on 90.9% of the tested organisms, meanwhile compound 1 as well as fractions TSB 6 and 7 exhibited detectable MIC values on all studied microorganisms. The overall results provide promising baseline information for the potential use of the crude extract from T. superba, fractions 6–7 and the tested compounds in the treatment of tuberculosis, bacterial and fungal infections.     

Yeast alpha glucosidase inhibitory and antioxidant activities of six medicinal plants collected in Phalaborwa,South Africa

Recent decades have experienced a sharp increase in the incidence and prevalence of diabetes mellitus. One antidiabetic therapeutic approach is to reduce gastrointestinal glucose production and absorption through the inhibition of carbohydrate-digesting enzymes such as α-amylase and α-glucosidase and α-amylase. The aim of the current study was to screen six medicinal plant species, with alleged antidiabetic properties for α-glucosidase inhibitory activities. Powdered plant materials were extracted with acetone, and tested for ability to inhibit baker's yeast α-glucosidase and α-amylase activities. The largest mass (440 mg from 10 g) of the extract was obtained from Cassia abbreviata, while both Senna italica and Mormordica balsamina yielded the lowest mass of the extracts. Extracts of stem bark of C. abbreviata inhibited baker's yeast α-glucosidase activity with an IC₅₀ of 0.6 mg/ml. This plant species had activity at low concentrations, with 1.0 mg/ml and above resulting in inhibition of over 70%. The other five plant extracts investigated had IC₅₀ values of between 1.8 and 3.0 mg/ml. Senna italica only managed to inhibit the activity of enzyme-glucosidase at high concentrations with an IC₅₀ value of 1.8 mg/ml, while Tinospora fragosa extracts resulted in about 55% inhibition of the activity of the enzyme at a concentration of 3.5 mg/ml, with an estimated IC₅₀ value of 2.8 mg/ml. The bark extract of C. abbreviata was the most active inhibitor of the enzyme, based on the IC₅₀ values (0.6 mg/ml). The bark extract of C. abbreviata contains non-competitive inhibitor(s) of α-glucosidase, reducing V_max value of this enzyme from 5 mM·s^–1 to 1.67 mM·s^–1, while K_m remained unchanged at 1.43 mM for para-nitrophenyl glucopyranoside. Antioxidant activity of the extracts was also investigated. The C. abbreviata extract was more active as an antioxidant than the positive control, trolox. The extracts did not inhibit alphaamylase activity more than about 20% at the highest concentration tested.     

Chemotaxonomy of Hypericum genus from Portugal: Geographical distribution and essential oils composition of Hypericum perfoliatum, Hypericum humifusum, Hypericum linarifolium and Hypericum pulchrum

The geographical distribution and analysis of the essential oils of species from three sections of Hypericum L. (Guttiferae/Clusiaceae/Hypericaceae) from Portugal are presented. Hypericum perfoliatum (section Drosocarpium) grows wild in the centre and south of Portugal; Hypericum humifusum and Hypericum linarifolium are both from section Oligostema, the former occurring throughout the country, while the second is distributed mainly in the north and centre; Hypericum pulchrum (section Taeniocarpium) is confined to the littoral north of Portugal. The essential oils were obtained by distillation–extraction, hydrodistillation and distillation in a modified Marcusson apparatus from the dried aerial parts of the different populations and were analysed by GC and GC–MS. Monoterpene hydrocarbons constituted the main fraction in all oils (43–69%, 53–85%, 28–45% and 48–65% for H. perfoliatum, H. humifusum, H. linarifolium and H. pulchrum, respectively). Sesquiterpene hydrocarbons (2–13%, 6–18%, 21–27% and 16–18%, respectively) and a third fraction of non-terpenic compounds (20–29%, 3–16%, 2–14% and 5–11%, respectively) from the four species attained relatively high amounts in all oils. Within each species, no major differences were detected in the essential oil composition, despite the fact that different locations, phenological phases and extraction methodologies were used. Notwithstanding the dominance of α-pinene in all four species' oils, cluster and principal components analysis on the identified components showed that the range of α-pinene, β-pinene and n-nonane supported a separation of the four species. The essential oil composition of the four species showed some qualitative resemblances, which correlate well with the taxonomical classification based on morphological characters.     

Bioactivities of black cumin essential oil and its main terpenes from Tunisia

Ex vivo antioxidant, anti-inflammatory, anticancer and antibacterial activities of the essential oil from Tunisian Nigella sativa seeds and its main terpenes (p-cymene, γ-terpinene, thymoquinone, β-pinene, carvacrol, terpinen-4-ol and longifolene) were determined. The essential oil exhibited strong ex vivo antioxidant activity, inhibiting DCFH oxidation with an IC₅₀ of 1.0 µg/ml, and high anti-inflammatory activity, inhibiting NO radical excretion with an IC₅₀ value of 6.3 µg/ml. Thymoquinone was found to be the most active to decrease DCFH oxidation and NO excretion. The oil was found to significantly inhibit the growth of A-549 and DLD-1 cancer cell lines (IC₅₀ values of 43.0 and 46.0 µg/ml, respectively) and to exert antibacterial activity against Staphylococcus aureus and Escherichia coli with IC₅₀ values of 12.0 and 62.0 µg/ml. The anticancer and antibacterial activities could be mainly due to the action of thymoquinone and longifolene.     

Composition and antimicrobial activity of the essential oil of six Hypericum species from Serbia

The volatile composition of six Hypericum species has been studied. The essential oils were obtained by steam distillation in 500 mL H₂O for 2 h in a modified Clevenger apparatus with a water-cooled oil receiver to reduce hydrodistillation over-heating artifacts, and their analyses were performed by GC and GC–MS. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. A total of 100 different compounds were identified. The main constituents of the investigated populations of each taxon have been revealed as follows: Hypericum alpinum: (−)-β-pinene, γ-terpinene, (−)-(E)-caryophyllene; Hypericum barbatum: (−)-α-pinene, (−)-β-pinene, (−)-limonene, (−)-(E)-caryophyllene, (−)-caryophyllene oxide; Hypericum rumeliacum: (−)-α-pinene, (−)-β-pinene, (−)-limonene, Hypericum hirsutum: nonane, undecane, (−)-(E)-caryophyllene, (−)-caryophyllene oxide; Hypericum maculatum: spathulenol, globulol; Hypericum perforatum: (−)-α-pinene, (Z)-β-farnesene, germacrene D; Monoterpene hydrocarbons were shown to be the main group of the taxa belonging to the section Drosocarpium, while the taxa of section Hypericum were more rich in sesquiterpene hydrocarbons.     

Chemical composition and larvicidal activity of essential oils from Piper species

The larvicidal activity of essential oils of four species of Piper from the Amazon Forest was tested using third-instar larvae of Aedes aegypti. The oils were extracted by steam distillation and analyzed by GC and GC–MS. The main components isolated from each Piper species were as follows: viridiflorol (27.50%), aromadendrene (15.55%) and β-selinene (10.50%) from Piper gaudichaudianum; β-selinene (15.77%) and caryophyllene oxide (16.63%) from Piper humaytanum; dillapiol (54.70%) and myristicin (25.61%) from Piper permucronatum; and asaricin (27.37%) and myristicin (20.26%) from Piper hostmanianum. Amongst all essential oils tested, the most active against larvae of A. aegypti was the oil extracted from P. permucronatum, with a LC₅₀ = 36 μg/ml (LC₉₀ = 47 μg/ml), followed by the essential oil of P. hostmanianum, with a LC₅₀ = 54 μg/ml (LC₉₀ = 72 μg/ml). The oils with higher content of arylpropanoids were more active against larvae of A. aegypti.     

Inhibitory effect of essential oils of Allium sativum and Piper longum on spontaneous muscular activity of liver fluke, Fasciola gigantica

Effects of essential oil of Allium sativum (garlic) and Piper longum (Indian long pepper) were evaluated on muscular activity of whole Fasciola gigantica and its strip preparation. The whole flukes and longitudinal strip preparations of the flukes were isometrically mounted to record the spontaneous muscular activity (SMA) and to evaluate effects of cumulative doses (0.1, 0.3, 1.0 and 3.0 mg/ml) of the plant essential oils. Whole flukes and the strip preparations exhibited continuous SMA without any significant difference in its baseline tension, frequency and amplitude for 2 h. Essential oil of A. sativum produced significant reduction in the frequency and the amplitude of the SMA of whole fluke at 1 and 3 mg/ml concentrations. It caused complete paralysis of the fluke after 15 min of administration of 3 mg/ml concentration. Similar to whole fluke, essential oil of A. sativum (3 mg/ml) also produced flaccid paralysis in the strip preparations of the flukes. Essential oil of P. longum firstly induced marked excitatory effect and then there was flaccid paralysis of the whole fluke following 15 min exposure at 3 mg/ml concentration. Complete flaccid paralysis of the strip preparation was also ensued after 15 min of administration of 3 mg/ml concentration of P. longum. In both the essential oils, the whole fluke and strip preparations did not recover from paralysis following 2-3 washes. In conclusion, the observations demonstrated irreversible paralytic effect of essential oils of A. sativum and P. longum on F. giganticain vitro which might possibly help to developing herbal-based anthelmintic.     

Isolation, structural characterization and antioxidant activity of a new water-soluble polysaccharide from Acanthophyllum bracteatum roots

ABPS-1, a new water-soluble polysaccharide with molecular weight of 26 kDa and a specific optical rotation of +170° (c 1.0, H₂O), was extracted from the roots of Acanthophyllum bracteatum by warm water and further successively purified through DEAE-cellulose A52 and Sephadex G-100 columns. Monosaccharide analysis revealed that the ABPS-1 was composed of Glc, Gal and Ara with a relative molar ratio of 1.4:5.2:1.0. Its structural features were elucidated by a combination of FT-IR, methylation and GC-MS analysis, periodate oxidation and Smith degradation, partial acid hydrolysis and ¹³C and ¹H NMR spectroscopy. The data obtained indicate that ABPS-1 possessed a backbone of α-(1 → 6)-linked Gal with branches attached to O-2 by α-1 → linked Glc and at O-3 by α-1 → linked Gal and by α-(1 → 3)-linked Ara. The in vitro antioxidant activity showed that ABPS-1 possesses DPPH radical-scavenging activity in a concentration-dependent manner with an EC₅₀ value of 2.6 mg/ml.     

Characterization and application of a detergent-stable alkaline α-amylase from Bacillus subtilis strain AS-S01a

A strain AS-S01a, capable of producing high-titer alkaline α-amylase, was isolated from a soil sample of Assam, India and was taxonomically identified as Bacillus subtilis strain AS-S01a. Optimized α-amylase yield by response surface method (RSM) was obtained as 799.0 U with a specific activity of 201.0 U/mg in a process control bioreactor. A 21.0 kDa alkaline α-amylase purified from this strain showed optimum activity at 55 °C and pH 9.0, and it produced high molecular weight oligosaccharides including small amount of glucose from starch as the end product. The K_m and V_max values for this enzyme towards starch were determined as 1.9 mg/ml and 198.21 μmol/min/mg, respectively. The purified α-amylase retained its activity in presence of oxidant, surfactants, EDTA and various commercial laundry detergents, thus advocating its suitability for various industrial applications.     

Bioactivity of essential oil of Litsea cubeba from China and its main compounds against two stored product insects

During our screening program for agrochemicals from Chinese medicinal herbs and wild plants, the essential oil of Litsea cubeba fruits was found to possess strong contact toxicity against the cigarette beetle Lasioderma serricorne adults and the booklouse Liposcelis bostrychophila, with LD₅₀ values of 27.33 μg/adult and 71.56 μg/cm², respectively, and also showed strong fumigant toxicity against the two stored product insects with LC₅₀ values of 22.97 and 0.73 mg/L, respectively. The essential oil obtained by hydrodistillation was investigated by GC MS. The main components of the essential oil were identified to be E-citral (geranial) (27.49%), Z-citral (neral) (23.57%) and d-limonene (18.82%) followed by β-thujene (3.34%), β-pinene (2.85%), α-pinene (2.57%), 6-methyl-5-hepten-2-one (2.40%) and linalool (2.36%). Citral (Z/E-citral), d-limonene, β-pinene, α-pinene and linalool were separated and purified by silica gel column chromatography and preparative thin layer chromatography, and further identified by means of physicochemical and spectrometric analysis. Citral and linalool showed strong contact toxicity against L. serricorne and L. bostrychophila (LD₅₀ = 11.76, 12.74 μg/adult and 20.15, 99.97 μg/cm², respectively) and fumigant toxicity against L. serricorne and L. bostrychophila (16.54, 18.04 mg/L air and 0.14, 0.71 mg/L air, respectively). Otherwise, citral, d-limonene and linalool were strongly repellent against the cigarette beetle L. serricorne as the essential oil whereas β-pinene and α-pinene exhibited weaker repellency against the cigarette beetle compared with the positive control, DEET. Moreover, except α-pinene and linalool, the other three compounds as well as the essential oil exhibited comparable repellency against the booklouse relative to DEET.     

Pteronia divaricata (Asteraceae): A newly recorded Cape herbal medicine

The first ethnobotanical data on Pteronia divaricata is presented, which shows that the plant is an important traditional Cape medicine, especially in the Cederberg region (Western Cape Province) and in the Middelpos and Nieuwoudtville districts of the Northern Cape Province. Surprisingly, not a single publication could be found that records any uses for the species. We accurately documented nine separate anecdotes, which include various medicinal uses (for the treatment of colds, fever, influenza, stomach pain, diarrhoea, back pain, chest ailments, high blood pressure and tuberculosis). The novel data also includes seven previously unrecorded vernacular names, namely flip-se-bos, inflammasiebos, pylbos, dassiebos, dassiepisbos, perdebos and boegabos. Since the species is poorly known, its general morphology, leaf anatomy and essential oil composition were studied. Oil is produced in secretory ducts along the midribs below the main vascular bundle; secretory trichomes are also present on the leaf surface. The oil is relatively complex and contains a combination of sabinene, myrcene, β-caryophyllene and bicyclogermacrene as main compounds with smaller amounts of limonene, p-cymene, tetradecane, pentadecane, terpinen-4-ol and δ-cadinene. Dichloromethane extracts exhibited antibacterial activity (especially against Bacillus cereus) at MIC values as low as 1.0 mg/ml. Other solvent extracts and the essential oils were less active.     

The SGNH-hydrolase of Streptomyces coelicolor has (aryl)esterase and a true lipase activity

The Streptomyces coelicolor A3(2) gene SCI11.14c was overexpressed and purified as a His-tagged protein from heterologous host, Streptomyces lividans. The purification procedure resulted in 34.1-fold increase in specific activity with an overall yield of 21.4%. Biochemical and physical properties of the purified enzyme were investigated and it was shown that it possesses (aryl)esterase and a true lipase activity. The enzyme was able to hydrolyze p-nitrophenyl-, α- and β-naphthyl esters and poly(oxyethylene) sorbitan monoesters (Tween 20–80). It showed pronounced activity towards p-nitrophenyl and α- and β-naphthyl esters of C₁₂–C₁₆. Higher activity was observed with α-naphthyl esters. The enzyme hydrolyzed triolein (specific activity: 91.9 U/mg) and a wide range of oils with a preference for those having higher content of linoleic or oleic acid (C18:2; C18:1, cis). The active-site serine specific inhibitor 3,4-dichloroisocoumarin (DCI) strongly inhibited the enzyme, while tetrahydrofurane and 1,4-dioxane significantly increased (2- and 4- fold, respectively) hydrolytic activity of lipase towards p-nitrophenyl caprylate. The enzyme exhibited relatively high temperature optimum (55 °C) and thermal stability. CD analysis revealed predominance of α-helical structure (54% α-helix, 21% β-sheet) and a T_m value at 66 °C.     

Volatile and molecular analysis of Juniperus brevifolia (Seub.) Antoine,an Azorean endemic species

Chemical and molecular analyses were performed for the characterization of Juniperus brevifolia (Seub.) Antoine (Cupressaceae), an Azorean endemic species. Forty-two individual twig samples were collected at seven Azorean islands (S. Miguel, Terceira, S. Jorge, Pico, Faial, Flores and Corvo). Volatile compounds were isolated by distillation–extraction and analyzed by GC and GC-MS. The volatile oils consisted mainly of monoterpene hydrocarbons (84–96%), limonene (33–87%), α-pinene (1–48%) and β-myrcene (1–5%) being the main components, and cluster analysis showed a high correlation among all samples (S_corr = 0.84). DNA fingerprinting was performed using thirty-seven RAPD and eleven ISSR primers, generating 881 polymorphic bands. Cluster analysis showed a moderate correlation among accessions (S_Dice = 0.43), which grouped according to their geographical origin. Chemical and molecular data did not show superimposable clustering profiles. Although the molecular approaches tested were useful in assessing genetic diversity, no straight correlation could be drawn between chemical and molecular data sets.     

Kinetics of an extracellular exo-inulinase production from a 5-flourocytosine resistant mutant of Geotrichum candidum using two-factorial design

In the present study, eight different strains of Geotrichum candidum were isolated and screened for an extracellular exo-inulinase production using chemically enriched sucrose–mineral media. The isolate (Zool-3i) with a better enzyme activity (1.38 IU/ml) was subjected to induced mutagenesis using methyl methane sulphonate (MMS) and a mutant with an enzyme activity of 32.06 IU/ml was obtained. Further exposure to ethyl methane sulphonate (EMS) and ultraviolet (UV) radiations yielded a mutant exhibiting an improved activity of 39.34 IU/ml. The potential mutant was cultured overnight and plated on 5fc–YPR agar medium and thus made resistant against 5-flourocytocine. Over 50-fold enhancement in enzyme production (71.85 IU/ml) was achieved when the process parameters including incubation period (48 h), sucrose concentration (5.0 g/L), pH (6.0), inoculum size (2.0%, 16 h old) and urea (0.2%) were identified using Plackett–Burman design. On the basis of kinetic variables, notably Q_p (0.723 U/g/h), Y_p/s (2.036 U/g) and q_p (0.091 U/g cells/h), the mutant MEU-5fc-6 was found to be a hyper producer of exo-inulinase (HS, LSD 0.045, p ? 0.05).     

Chemotypes of Achillea millefolium transferred from 14 different locations in Lithuania to the controlled environment

The composition of essential oils hydrodistilled from 19 samples of inflorescences and leaves of Achillea millefolium L. plants, which were transferred from 14 natural habitats in Lithuania to the field collection, is reported. Total content of oil was 0.15–0.55% in inflorescences and 0.06–0.19% (v/w) in leaves. In total 117 compounds were identified positively or tentatively. Data obtained clearly indicate the presence of a remarkable chemical polymorphism within the population of A. millefolium in Lithuania. The content of the major constituents in the oils from inflorescences varied in the following ranges: β-pinene, 0.33–62.29%; β-myrcene, 0.05–69.76%; α-phelandrene, 0.13–29.96%; 1,8-cineole, 2.30–21.57%; and chamazulene, 0.08–30.70%. According to the major components the essential oils' six chemotypes of A. millefolium were defined.     

Seasonal acclimation in resting metabolism of the skink, Mabuya brevicollis (Reptilia: Scincidae) from southwestern Saudi Arabia

The resting metabolic rate (RMR) of seasonally-acclimated Mabuya brevicollis of various body masses was determined at 20, 25, 30, 35 and 40 °C, using open-flow respirometry. RMR (ml g⁻¹ h⁻¹) decreased with increasing mass at each temperature. RMRs increaProd. Type: FTPsed as temperature increased. The highest and lowest Q₁₀ values were obtained for the temperature ranges 20–25 °C and 30–35 °C for the summer-acclimated lizards. The exponent of mass “b” in the metabolism-body mass relation ranged from 0.41 to 0.61. b values were lower in the autumn and winter-acclimated lizards than in spring and summer-acclimated lizards. Seasonal acclimation effects were evident at all temperatures (20–40 °C) for M. brevicollis. Winter-acclimated skinks had the lowest metabolic rates at different temperatures. The pattern of acclimation exhibited by M. brevicollis may represent a useful adaptation for lizards inhabiting subtropical deserts to promote activity during their active seasons.     

A novel screening method based on menadione mediated rapid reduction of tetrazolium salt for testing of anti-mycobacterial agents

A microplate-based rapid, inexpensive and robust technique is developed by using tetrazolium salt 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) and menadione to determine the viability of Mycobacterium tuberculosis, Mycobacterium bovis BCG and Mycobacterium smegmatis bacilli in microplate format. In general, XTT reduction is an extremely slow process which takes almost 24 h to produce a detectable signal. Menadione could drastically induce this reduction to an almost equal extent within a few minutes in a dose dependent manner. The reduction of XTT is directly proportional to the cell concentration in the presence of menadione. The standardized protocol used 200 μM of XTT and 60 μM of menadione in 250 μl of cell suspension grown either in aerobic or anaerobic conditions. The cell suspension of M. bovis BCG and M. tuberculosis were incubated for 40 min before reading the optical density at 470 nm whereas M. smegmatis was incubated for 20 min. Calculated Signal/Noise (S/N) ratios obtained by applying this protocol were 5.4, 6.4 and 9.4 using M. bovis BCG, M. tuberculosis and M. smegmatis respectively. The calculated Z′ factors were > 0.8 for all mycobacterium bacilli indicating the robustness of the XTT Reduction Menadione Assay (XRMA) for rapid screening of inhibitors. The assay protocol was validated by applying 10 standard anti-tubercular agents on M. tuberculosis, M. bovis BCG and M. smegmatis. The Minimum Inhibitory Concentration (MIC) values were found to be similar to reported values from Colony Forming Unit (CFU) and REMA (resazurin microplate assay) assays. Altogether, XRMA is providing a novel anti-tubercular screening protocol which could be useful in high throughput screening programs against different physiological stages of the bacilli.