Essential oils of Alpinia conchigera Griff. and their antimicrobial activities

The essential oils from the dried leaves, pseudostems and rhizomes of Alpinia conchigera Griff. (KL 5049), collected from Jeli province of Kelantan, east coast of Peninsular Malaysia, were isolated by hydrodistillation. The collected oils were analyzed by capillary GC and GC–MS. Forty one compounds were identified, among which 13 have not been detected previously. The leaf, pseudostem and rhizome oils afforded 40, 33 and 39 constituents, respectively. The most abundant components in the leaf oil included β-bisabolene (15.3%), β-pinene (8.2%), β-sesquiphellandrene (7.6%), chavicol (7.5%) and β-elemene (6.0%), while β-bisabolene (19.9%), β-sesquiphellandrene (11.3%), β-caryophyllene (8.8%) and β-elemene (4.7%) were the main components in the pseudostem. In the rhizome, 1,8-cineole (17.9%), β-bisabolene (13.9%), β-sesquiphellandrene (6.8%) and β-elemene (4.0%) were the major components. The essential oils were also subjected to antifungal and antibacterial tests, using the minimum inhibitory concentration (MIC) method. Results revealed weak inhibitions against the microorganisms tested.     

Thermodynamic activation and structural analysis of trypsin I from Monterey sardine (Sardinops sagax caerulea)

In this work, we report the molecular characterisation of trypsin I (Try I) from Monterey sardine (Sardinops sagax caerulea). Aspects such as thermodynamic activation parameters, molecular model and cDNA-deduced amino acid sequence allow a more in depth understanding of its activity at low temperatures. The analysis of the thermodynamic activation parameters suggests that this molecule is a cold-adapted protease. From the molecular cloning, we deduced the amino acid sequence and predicted a theoretical structural model of sardine Try I with a classical trypsin fold. Cold-adaptation of this enzyme probably comes from amino acid replacement of key residues to improve flexibility at low temperature, thus increasing k_cat. The cold-adaptation of sardine Try I opens a wide range of biotechnological applications for this protease and also it is interesting from the structure function relationship point of view of serine protease proteins.     

Advanced glycation end products inhibitors from Alpinia zerumbet rhizomes

Advanced glycation end products (AGEs) are major factors responsible for the complication of diabetes. The present study was carried out to investigate the inhibitory activities on fructosamine adduct and α-dicarbonyl formations by hexane extracts of various parts of Alpinia zerumbet. Furthermore, we isolated two previously known compounds, namely 5,6-dehydrokawain (DK) and dihydro-5,6-dehydrokawain (DDK). 8(17),12-Labdadiene-15,16-dial (labdadiene) was isolated for the first time from the rhizome of A. zerumbet. The results showed that labdadiene (IC₅₀ = 51.06 μg/mL) had similar activity to rutin and quercetin against fructosamine adduct. The inhibition of α-dicarbonyl compounds formation by labdadiene was significantly higher than that of DK and DDK. Our results indicate that labdadiene is a potent antiglycation agent which was found to inhibit AGEs formation in three different steps in the pathway. These data indicate that labdadiene could be used to prevent glycation-associated complications in diabetes.     

New diarylheptanoids from the rhizome of Alpinia officinarum Hance

Three diarylheptanoids, officinaruminane A (1), officinaruminane B (2), 5(S)-acetoxy-7-(4-dihydroxyphenyl)-1-phenyl-3-heptanone (3), together with six known ones , (5R)-5-hydroxy-1-(4-hydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-3-heptanone (4),(5R)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(4,5-dihydroxy-3-methoxyphenyl)-3-heptanone (5), 1-phenyl-7-(4-hydroxy-3-methoxyphenyl)-4E-en-3-heptanone (6), 1-(4-hydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-4E-en-3-heptanone (7), 1-phenyl-7-(4-hydroxyphenyl)- 4E- en-3-heptanone (8), and 3,6-furan-7-(4′′-hydroxy-3′′-methoxyphenyl)-1-phenylheptane (9), were isolated from the rhizomes of Alpinia officinarum Hance by column chromatography on silica gel, MPLC and preparative thin-layer chromatography (TLC). The structures of these compounds were elucidated on the basis of mass spectrometry, ¹H NMR, ¹³C NMR, HMQC and HMBC data. Among them, 1 is a diarylheptanoid with a pyridine ring, and 2 is a diarylheptane monoterpene.     

Anti-inflammatory effects of compounds from Kaempferia parviflora and Boesenbergia pandurata

Kaempferia parviflora and Boesenbergia pandurata are perennial herbs in the Zingiberaceae family. The rhizomes of these two plants have been used as food ingredients and in Thai traditional medicine for treatment of several inflammatory-related diseases, such as gout, allergy, apthous ulcer and peptic ulcer. The compounds isolated from the rhizomes of K. parviflora and B. pandurata were, therefore, examined for their inhibitory activities against nitric oxide (NO) production. For K. parviflora, compound 5 (5-hydroxy-3,7,3′,4′-tetramethoxyflavone) exhibited the highest activity against the NO inhibitory effect, with an IC₅₀ value of 16.1 μM, followed by 4 (IC₅₀ = 24.5 μM) and 3 (IC₅₀ = 30.6 μM). Regarding the NO inhibitory activity of B. pandurata, compound 2 (panduratin A) displayed the most potent effect with an IC₅₀ value of 5.3 μM, followed by 3 (hydroxypanduratin A, IC₅₀ = 13.3 μM) and 7 (cardamonin, IC₅₀ = 24.7 μM), respectively. The 5-hydroxy-3,7,3′,4′-tetramethoxyflavone (5), panduratin A (2) and hydroxypanduratin A (3), were also tested on prostaglandin E₂ (PGE₂) and tumour necrosis factor-alpha (TNF-α) production. 5-Hydroxy-3,7,3′,4′-tetramethoxyflavone (5) exhibited a potent inhibitory effect on PGE₂ production (IC₅₀ = 16.3 μM), but a mild effect on TNF-α (IC₅₀ > 100 μM). Panduratin A and hydroxypanduratin A showed strong activity against PGE₂ with IC₅₀ values of 10.5 and 12.3 μM, respectively, and a moderate effect on TNF-α (IC₅₀ = 60.3 and 57.3 μM, respectively). This study indicated that compound 5 (5-hydroxy-3,7,3′,4′-tetramethoxyflavone) is responsible for anti-inflammatory activity of K. parviflora, while 2 (panduratin A) and 3 (hydroxypanduratin A), the prenylated chalcones, are responsible for that of B. pandurata.     

Fumigant toxicity of essential oils from three Thai plants (Zingiberaceae) and their major compounds against Sitophilus zeamais, Tribolium castaneum and two parasitoids

Fumigant toxicity of essential oils from rhizomes of Alpinia conchigera, Zingiber zerumbet, Curcuma zedoaria and their major compounds; camphene, camphor, 1,8-cineole, α-humulene, isoborneol, α-pinene, β-pinene and terpinen-4-ol was investigated with adults of Sitophilus zeamais, Tribolium castaneum, Anisopteromalus calandrae and Trichogramma deion larvae. The last two insects are parasitoids commonly used to control stored-product weevils and moths. The trial was evaluated at 0, 37, 74, 148, 296, 444, 593 μL/L in air after 12, 24 and 48 h for S. zeamais, T. castaneum and A. calandrae, and 24 h for T. deion. Alpinia conchigera oils were toxic to S. zeamais, T. castaneum and T. deion, while the other two plant oils had low toxicity. Adults of S. zeamais and T. castaneum were more susceptible to A. conchigera oils than their eggs, larvae or pupae. Sitophilus zeamais adults (LC₅₀ 85 μL/L in air) were slightly more tolerant of A. conchigera oils than T. castaneum (LC₅₀ 73 μL/L in air) after 48 h exposure. Synthetic essential oils, a mixture of pure compounds in the same ratios of the extracted essential oils, were tested with S. zeamais and T. castaneum adults. Synthetic essential oils were more toxic than the extracted essential oils to both insects. Zingiber zerumbet oils (LC₅₀ 26 μL/L in air) and C. zedoaria oils (LC₅₀ 25 μL/L in air) were significantly more toxic to adults of A. calandrae than A. conchigera oils (LC₅₀ 37 μL/L in air) whereas T. deion larvae were more sensitive to A. conchigera oils (LC₅₀ 62 μL/L in air) than Z. zerumbet and C. zedoaria oils (LC₅₀ > 593 μL/L in air). Tribolium castaneum was more susceptible than S. zeamais to the eight pure compounds. Terpinen-4-ol was highly toxic to both insects.     

Anti-influenza A virus effects of fructan from Welsh onion (Allium fistulosum L.)

A fructan that acts as an anti-influenza A virus substance was isolated from hot water extract of the green leafy part of a Welsh onion (Allium fistulosum L.). The structure of the fructan was characterised and elucidated by chemical and spectroscopic analyses. The fructan was composed of terminal (21.0%) and 2,1-linked β-d-Fruf residues (65.3%) with 1,6-linked β-d-Glcp residues (13.7%). The molecular weight of the polysaccharide and polydispersity was estimated to be 1.5 × 10³ and 1.18, respectively. Although the fructan did not show anti-influenza A virus activity in vitro, it demonstrated an inhibitory effect on virus replication in vivo when it was orally administered to mice. In addition, the polysaccharide enhanced the production of neutralising antibodies against influenza A virus. Therefore, the antiviral mechanism of the polysaccharide seemed to be dependent on the host immune system, i.e., enhancement of the host immune function was achieved by the administration of the polysaccharide. From our observations, the fructan from Welsh onions is suggested to be one of the active principles which exert an anti-influenza virus effect.     

Diversity of culturable microorganisms and occurrence of Listeria monocytogenes and Salmonella spp. in Tuber aestivum and Tuber melanosporum ascocarps

The aim of this study was to investigate the total mesophilic microorganisms, Pseudomonas genus, Enterobacteriaceae family, mold and yeast counts and the presence of Listeria monocytogenes and Salmonella spp on Tuber aestivum and Tuber melanosporum ascocarps. The results confirmed that the major percentage of the microorganisms, approximately 9.0 log ufc/g, were present in the peridium, the glebas of healthy truffles being practically free of microorganisms. The predominant microbial group was the Pseudomonas averaging 8.3 and 8.4 log cfu/g on T. aestivum and T. melanosporum whole ascocarps, respectively. The Enterobacteriaceae also achieved high populations, especially in T. aestivum truffles, with 6.3 log cfu/g. Molds and yeasts never exceeded 5.0 log cfu/g. The characterization of the isolates revealed that the fluorescens pseudomonads were the most prevalent. Raoultella terrigena and Enterobacter intermedius were the dominant Enterobacteriaceae. The identification of the yeast isolates revealed five species: Debaryomyces hansenii, Issatchenkia scutulata, Rhodotorula aurantiaca, Saccharomyces dairensis and Trichosporon beigelii subspecies A and B. The mold genera detected in both species of truffles were Aspergillus, Cladosporium, Penicillium and Fusarium, Trichoderma being present only in T. aestivum. L. monocytogenes was found in 10% of the samples of T. aestivum analysed but Salmonella spp. was not detected. Knowledge of the microbial population in terms of possible food borne and pathogen microorganisms is very useful for establishing successful disinfection and storage methods to prolong the shelf-life of ascocarps of T. aestivum and T. melanosporum.     

Short communication: Biofilm production characterization of mecA and mecC methicillin-resistant Staphylococcus aureus isolated from bovine milk in Great Britain

Staphylococcus aureus is an important cause of contagious intramammary infection in dairy cattle, and the ability to produce biofilm is considered to be an important virulence property in the pathogenesis of mastitis. The aim of this study was to characterize the biofilm formation capacity of methicillin-resistant Staph. aureus (MRSA), encoding mecA or mecC, isolated from bulk tank milk in Great Britain. For this purpose, 20 MRSA isolates were grown on microtiter plates to determine the biofilm production. Moreover, the spa-typing and the presence of the intercellular adhesion genes icaA and icaD were analyzed by PCR. All MRSA isolates tested belonged to 9 spa-types and were PCR-positive for the ica genes; 10 of them (50%) produced biofilm in the microtiter plate assay. This is also the first demonstration of biofilm production by mecC MRSA.     

Antimicrobial properties and action of galangal (Alpinia galanga Linn.) on Staphylococcus aureus

The ethanol extracts of the Zingiberaceae family (galangal, ginger, turmeric and krachai) were evaluated for antimicrobial action on Staphylococcus aureus 209P and Escherichia coli NIHJ JC-2 by using an agar disc diffusion assay. The galangal extract had the strongest inhibitory effect against S. aureus. The minimum inhibitory concentration (MIC) of the galangal extract was 0.325 mg/ml and the minimum bactericidal concentration (MBC) at 1.3 mg/ml using the broth dilution method. Transmission electron microscopy clearly demonstrated that the galangal extract caused both outer and inner membrane damage, and cytoplasm coagulation. The disruption of the cytoplasmic membrane properties was determined by the releasing of cell materials including nucleic acid which absorbed UV/VIS spectrophotometer at 260 nm. The major compound of the extract was d,l-1′-acetoxychavicol acetate which was identified by GC-MS and NMR.     

Antioxidant activity and contents of essential oil and phenolic compounds in flowers and seeds of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm

Alpinia zerumbet leaves and rhizomes have been extensively studied for their chemical compositions and biological activities. However, less attention has been given to its flowers and seeds. In our study, essential oil, total phenolics and antioxidant capacities assayed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and β-carotene bleaching methods were evaluated in flowers and seeds of A. zerumbet. In addition, their phenolic composition was determined by GC–MS and HPLC. 1,8-Cineol, camphor, methyl cinnamate and borneol were the major constituents in flower oils, whereas the main components in seeds oil were α-cadinol, T-muurolol, α-terpineol, δ-cadinene and terpinene-4-ol. The results showed that the hexane extract of flowers contained a significantly higher quantity of dihydro-5,6-dehydrokawain (DDK) than that of seeds. Total phenolic contents of flower and seed extracts were measured as 56.7 and 13.7 mg gallic acid equivalent per gram extract, respectively. The ethyl acetate extract of flowers and seeds possessed a high antiradical activity and prevented the bleaching of β-carotene. The HPLC analysis indicated that p-hydroxybenzoic acid, ferulic acid and syringic acid were the predominant phenolics in the ethyl acetate extract of flowers, whilst p-hydroxybenzoic acid, syringic acid and vanillin were the major phenolics in seeds.     

Effect of Capsicum carotenoids on growth and ochratoxin A production by chilli and paprika Aspergillus spp. isolates

The aim of this study was to determine the effect of a natural carotenoid mixture (Capsantal FS-30-NT), containing capsanthin and capsorubin, on growth and mycotoxin production of ochratoxin A-producing A. ochraceus, A. westerdijkiae, and A. tubingensis isolates.One isolate of each species, previously isolated from paprika or chilli, was inoculated on Czapek Yeast extract Agar (CYA) medium supplemented with different amounts of capsantal (0 to 1%) and incubated at 10, 15 and 25 °C for 21 days. Growth rates and lag phases were obtained, and OTA production was determined at 7, 14 and 21 days.The taxonomically related A. ochraceus and A. westerdijkiae showed the same behavior at 15 °C, but A. ochraceus was able to grow at 10 °C and had higher growth rates at 25 °C. A. tubingensis had the highest growth rates and lowest OTA production capacity of the assayed isolates, and it was not able to grow at 10 °C.Capsantal addition resulted in increased lag phases at 15 °C for all the strains, while growth rates remained rather constant. At 25 °C capsantal reduced growth rates, with rather constant lag phases. However, the effect of capsantal on OTA production was inconclusive, because it depended on temperature or time, and mostly was not significant.Low temperature has been a crucial factor in OTA production, regardless of the capsantal concentration tested, especially for A. tubingensis and A. westerdijkiae. Industrial storage temperature for paprika and chilli is approximately 10 °C. If this temperature is maintained, mould growth and OTA production should be reduced.     

Essential oils of the aerial parts of three Salvia species from Jordan: Salvia lanigera, S. spinosa and S. syriaca

The compositions of the essential oils of three Jordanian Salvia species, S. lanigera and S. spinosa from a desert climate, and S. syriaca from a Mediterranean habitat, were studied. All three oils are rich in monoterpene derivatives (68–73%).     

Characterisation of esterolytic activity from two wild mushroom species, Amanita vaginata var. vaginata and Tricholoma terreum

Characterisation of esterase activities from the edible mushroom species, Amanita vaginata var. vaginata and Tricholoma terreum, were investigated. Native electrophoresis of the crude extracts prepared from both mushroom samples showed the presence of esterolytic activities. The extracts had the greatest activity in the presence of p-nitrophenyl butyrate (pNPB) as a substrate. pH and temperature optima were found to be 8.0 and 30 °C for both enzymes, respectively. V_max and K_m values were determined as 14.2 U/l and 71 μM for A. vaginata var. vaginata and 34.6 U/l and 9.6 μM for T. terreum, respectively. The pH-stability profile showed a stationary line between 3.0 and 10.0 for both enzymes. The esterolytic activities from the extracts were maintained between 10 and 40 °C for 4 h and started to decrease at 50 °C. The effects of EDTA, NaN₃, DTT and PMSF on the enzyme activity were also investigated.     

A bacteriocin-like substance produced from Lactobacillus pentosus 39 is a natural antagonist for the control of Aeromonas hydrophila and Listeria monocytogenes in fresh salmon fillets

We studied the ability of Lactobacillus pentosus 39, a BLS (Bacteriocin-like substance)-producing strain, to control the growth of Aeromonas hydrophila ATCC 14715 and Listeria monocytogenes ATCC 19117 artificially added to fresh salmon fillets at refrigeration temperatures and under simulated cold-chain break conditions.At refrigeration temperatures, Lb. pentosus 39 protective culture and its putative bacteriocin significantly reduced A. hydrophila counts compared with the control (2.1 and 1.4 log CFU/g reductions, respectively). Similar behaviour was observed for L. monocytogenes (3.6 and 1.3 log CFU/g reductions, respectively).Under simulated cold-chain break conditions, an increase in temperature (30°C for 12h) produced an evident increase in the development of A. hydrophila, L. monocytogenes, but also of Lb. pentosus 39, with a consequent increase in BLS production. This condition resulted in a greater reduction of both pathogens compared with samples stored at 4°C throughout the experiment (2.8 log CFU/g reduction for A. hydrophila, 5.8 log CFU/g reduction for L. monocytogenes). In samples treated with the putative bacteriocin alone, a less marked decrease was observed.Our study demonstrates the capability of Lb. pentosus 39 to control the growth of psychrotrophic bacteria in an experimental seafood model system. A similar biopreservation technology could provide more prolonged shelf-life during storage of ready-to-eat seafood, ensuring safety, even under extreme conditions.     

Tenderness enhancement of beef from Bos indicus and Bos taurus cattle following electrical stimulation

High voltage electrical stimulation (1130 V peak, 14.28 bidirectional half sinusoidal pulses/s) or low voltage stimulation (45 V peak, 36 alternating square wave pulses/s) was used on cattle: (1) low voltage stimulation applied for 10 or 40 s with fast and slow chilling or high voltage stimulation for 60 s with normal chilling, applied to 100% Bos taurus cattle, (2) low voltage stimulation (40 s) and high voltage stimulation (60 s) with normal chilling applied to mixed Bos indicus and B.taurus cattle, (3) high voltage stimulation (54 s) with normal chilling applied to B. taurus and B. indicus cattle of 0–100% B. indicus composition, and (4) high voltage stimulation (60 s) applied to 100% B. taurus and 100% B. indicus cattle. All stimulation parameters enhanced the tenderness of steaks from M. longissimus thoracis et lumborum (LTL) aged at 1 °C up to 28 days compared with non stimulated LTL. Short low voltage stimulation of 10 s was marginally more effective than no stimulation and longer durations of 40 s were very effective and high voltage stimulation was most effective.     

In vitro antimicrobial and anti-inflammatory effects of herbs against Propionibacterium acnes

Propionibacterium acnes play an important role in the pathogenesis of acne by inducing certain inflammatory mediators and comedogenesis. The objective of this study was to evaluate the antimicrobial and anti-inflammatory effects of herbal extracts against P. acnes. Among the ten tested herbs, methanolic extracts of rose (Rosa damascene), duzhong (Eucommia ulmoides Oliv.), and yerba mate (Ilex paraguariensis) were found to inhibit the growth of P. acnes with respective minimum inhibitory concentrations of 2, 0.5, and 1 mg/ml. In addition, duzhong and yerba mate extracts reduced the secretion of pro-inflammatory cytokines such as tumour necrosis factor-α, interleukin (IL)-8, and IL-1β by human monocytic THP-1 cells pretreated with heat-killed P. acnes at a concentration of 0.1 mg/ml. Our results suggested that duzhong and yerba mate extracts possess both antimicrobial and anti-inflammatory effects against P. acnes and can possibly be used as therapeutic agents for acne.     

Resistance of Tripsacorn to Sitophilus zeamais and Oryzaephilus surinamensis

One strategy that has been used to find germplasm for developing improved plant varieties is to test ancestral germplasm for the desired traits. Although the progenitors of commercial maize are not known, a hybrid (called Tripsacorn) developed from a perennial teosinte, Zea diploperennis, and eastern gamagrass, Tripsacum dactyloides, resembles the earliest known samples of primitive domesticated maize. We tested resistance of whole Tripsacorn to the primary storage pest (primary storage pests can infest intact kernels) the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and resistance of ground Tripsacorn to the secondary storage pest (secondary pests usually cannot infest intact kernels) the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Tripsacorn was immune to attack by S. zeamais. The weevils were unable to lay eggs in the Tripsacorn, and we hypothesized that the hardness of the fruitcase was responsible for lack of weevil oviposition. Oryzaephilus surinamensis were able to complete immature development on ground Tripsacorn, but duration of development was longer and weight of emerged adults was less than for beetles developing on wheat. Hardness of the fruitcase may have been a primitive mechanism of defense against insects and other pests, but probably would not be an acceptable trait in commercial varieties. It remains to be determined whether the possible antibiotic effect demonstrated in ground Tripsacorn would be a useful trait in commercial maize hybrids.     

The effects of X-ray radiation on Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri inoculated on whole Roma tomatoes

In the last two decades several foodborne disease outbreaks associated with produce were reported. Tomatoes, in particular, have been associated with several multi-state Salmonella outbreaks. Inactivation of inoculated Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri on whole Roma tomato surfaces by X-ray at 0.1, 0.5, 0.75, 1.0, and 1.5 kGy was studied. The main purpose of this study was to achieve a 5 log reduction in consistent with the recommendations of the National Advisory Committee on Microbiological Criteria for Foods. Moreover, the effect of X-ray on inherent microflora (mesophilic counts, psychrotrophic counts and yeast and mold counts) of untreated and treated Roma tomatoes, during storage at ambient temperature (22 °C) for 20 days was also determined. Mixtures of three or two strains of each tested organism was spot inoculated (100 μl) onto the surface of Roma tomatoes (approximately 7–9 log per tomato), separately, and air-dried, followed by treatment with X-ray doses at 22 °C and 55–60% relative humidity. Surviving bacterial populations on tomato surfaces were evaluated using a nonselective medium (tryptic soy agar) with a selective medium overlay for each bacteria; E. coli O157:H7 (CT-SMAC agar), L. monocytogenes (MOA), and S. enterica and S. flexneri (XLD). Treatment with X-ray significantly reduced the population of the tested pathogens on whole Roma tomato surfaces, compared with the control. Approximately 4.2, 2.3, 3.7 and 3.6 log CFU reduction of E. coli O157:H7, L. monocytogenes, S. enterica and S. flexneri per tomato were achieved by treatment with 0.75 kGy X-ray, respectively. More than a 5 log CFU reduction per tomato was achieved at 1.0 or 1.5 kGy X-ray for all tested pathogens. Furthermore, treatment with X-ray significantly reduced the inherent microflora on Roma tomatoes. Inherent levels were significantly (p < 0.05) lower than the control sample throughout storage for 20 days.