微藻中的高附加值天然产物与挖掘策略

微藻是一类单细胞的光合自养真核生物,因为生长速度快,油脂含量高,对土地和水资源的要求宽松而被认为是下一代的液体燃料来源。此外,微藻还能够生产多种多样的天然化合物,包括微藻多糖、长链不饱和脂肪酸、色素和生物碱等。与植物中丰富的生物碱研究相比,对微藻中生物碱的研究仍处于起步阶段。微藻中的许多天然产物,通常具有多样性的生物活性,可以作为食品添加剂、营养保健品乃至医药,具有较高的经济价值。本文将简要介绍微藻产生的几类高附加值产品,并就微藻中高附加值天然产物的挖掘策略与规模化培养做简要的探讨。     

Balkans’ Asteraceae Species as a Source of Biologically Active Compounds for the Pharmaceutical and Food Industry

Herbal drugs are a useful source of different bioactive compounds. Asteraceae species, as the most widespread vascular plants, can be used both as food and as medicine due to the great diversity of recorded chemical components – different phenolic compounds, terpenes, carotenoids, vitamins, alkaloids, etc. The Balkan Peninsula is characterized by great diversity of plants from Asteraceae family, including presence of rare and endemic species. In this review, results of the survey of chemical composition and biological activity, mainly focusing on antioxidant, antimicrobial and anticancer effects of selected Balkans’ Asteraceae species were provided. In addition, information on edible plants from Asteraceae family is presented, due to growing interest for the so‐called ‘healthy diet’ and possible application of Balkans’ Asteraceae species as food of high nutritional value or as a source of functional food ingredients.     

Potential use of Tunisian Pituranthos chloranthus essential oils as a natural disinfectant

Aims:  To highlight the bactericidal and fungicidal activities of Tunisian Pituranthos chloranthus essential oils and to study their potential use as powerful and natural disinfectant.
Methods and Results:  The essential oils were obtained by hydro-distillation of the aerial part of P. chloranthus . The bactericidal and fungicidal properties of essential oils were investigated by using the NCCLS broth dilution method and the EN 1275 and EN 1276 European standard methods. High bactericidal and fungicidal effects of 1·87–3·75 and 7·5 mg l⁻¹ were obtained, respectively. Essential oils concentrations of 0·5% and 1% (w/v) allowed reductions in viability higher than 5 and 4 log units per ml for standard bacteria and fungi, respectively, within a contact time of 5 min under dirty conditions.
Conclusions:  Our results support the traditional uses of P. chloranthus as a natural disinfectant and insecticide. It could be used to manage life-threatening pathogens as well as food preservative.
Significance and Impact of the Study:  This natural disinfectant could play a vital role in alleviating the spread of pathogenic micro-organisms and environmental problems associated with the indiscriminate use of synthetic chemicals.     

A Review of the Chemistry and Biological Activities of Natural Colorants,Dyes, and Pigments: Challenges,and Opportunities for Food,Cosmetics, and Pharmaceutical Application

Natural pigments are important sources for the screening of bioactive lead compounds. This article reviewed the chemistry and therapeutic potentials of over 570 colored molecules from plants, fungi, bacteria, insects, algae, and marine sources. Moreover, related biological activities, advanced extraction, and identification approaches were reviewed. A variety of biological activities, including cytotoxicity against cancer cells, antioxidant, anti-inflammatory, wound healing, anti-microbial, antiviral, and anti-protozoal activities, have been reported for different pigments. Considering their structural backbone, they were classified as naphthoquinones, carotenoids, flavonoids, xanthones, anthocyanins, benzotropolones, alkaloids, terpenoids, isoprenoids, and non-isoprenoids. Alkaloid pigments were mostly isolated from bacteria and marine sources, while flavonoids were mostly found in plants and mushrooms. Colored quinones and xanthones were mostly extracted from plants and fungi, while colored polyketides and terpenoids are often found in marine sources and fungi. Carotenoids are mostly distributed among bacteria, followed by fungi and plants. The pigments isolated from insects have different structures, but among them, carotenoids and quinone/xanthone are the most important. Considering good manufacturing practices, the current permitted natural colorants are: Carotenoids (canthaxanthin, β-carotene, β-apo-8′-carotenal, annatto, astaxanthin) and their sources, lycopene, anthocyanins, betanin, chlorophyllins, spirulina extract, carmine and cochineal extract, henna, riboflavin, pyrogallol, logwood extract, guaiazulene, turmeric, and soy leghemoglobin.     

Induction of Enzymes and Phenolic Compounds Related to the Natural Defence Response of Netted Melon Fruit by a Bio-elicitor

Fungal disease in netted melon fruit is an important factor affecting their postharvest quality and therefore an important cause of large economic losses around the world. Among the alternatives to control fungal diseases, the induction of the natural defence response (NDR) in fruits is promising. The objective of this study was to induce the NDR in netted melon treated with a bio-elicitor formulated from Fusarium oxysporum growth in a potato dextrose agar enriched with netted melon skin. Netted melon fruits (cv 'Primo') were not treated (C), untreated and inoculated with F. oxysporum (IN), treated with a bio-elicitor (FES), or treated with the bio-elicitor and inoculated (FES + IN). After treatments, fruits were stored for 8 days at 20°C with 90–92% relative humidity. Melon was sampled every 2 days at 20°C to evaluate the development of Fusarium rot symptoms as disease index percentage (DI), changes in phenolic compounds, changes in phenylalanine ammonia-lyase (PAL) activity, chitinase activity (ChA) and β-1,3-glucanase activity (GA). It was found that DI in netted melon fruit was significantly reduced in the FES + IN as compared with the IN treatment. FES + IN and FES treatments showed the highest increase of phenolic acids. Higher levels of PAL activity were observed in the treatments IN, FES, and FES + IN with respect to C, after 4 days of storage. A large increase in ChA activity was observed in the treatments IN, FES and FES + IN after 6 days of storage. No differences in GA activity were found among FES, FES + IN and C treatments throughout storage. IN treatment showed the highest increase in GA activity after 4 days of storage. It is concluded that the bio-elicitor activates the NDR as measured by the increase in phenolic acids synthesis, PAL and ChA enzymes activity, in a similar way as the infection by the living pathogen.     

Synthesis and Spectral Characterization of Asymmetric Azines Containing a Coumarin Moiety: The Discovery of New Antimicrobial and Antioxidant Agents

Nine unsymmetrical azines containing a coumarin moiety were prepared by the reaction of the hydrazone of 4‐hydroxy‐3‐acetylcoumarin with differently substituted aromatic aldehydes. The azines were fully spectrally characterized, including a complete assignment of ¹H‐ and ¹³C‐NMR resonances, and were assessed for their acute toxicities in the Artemia salina model. Their free radical scavenging activities were tested in the DPPH assay, and in vitro antimicrobial activities were determined against seven bacterial and two fungal strains. The azines containing a p‐hydroxyphenyl group were shown to be the most effective antimicrobial agents, and in the case of resistant strains of Staphylococcus aureus and Acinetobacter baumannii, the activity was comparable to that of chloramphenicol. The derivative having a 3,5‐dimethoxy‐4‐hydroxyphenyl group exhibited pronounced antioxidant power reacting rapidly and in 1 : 1 mol ratio with the DPPH radical.     

The Mechanism of l-Canavanine Cytotoxicity: Arginyl tRNA Synthetase as a Novel Target for Anticancer Drug Discovery

There is a clear need for agents with novel mechanisms of action to provide new therapeutic approaches for the treatment of pancreatic cancer. Owing to its structural similarity to l-arginine, l-canavanine, the δ-oxa-analog of l-arginine, is a substrate for arginyl tRNA synthetase and is incorporated into nascent proteins in place of l-arginine. Although l-arginine and l-canavanine are structurally similar, the oxyguanidino group of l-canavanine is significantly less basic than the guanidino group of l-arginine. Consequently, l-canavanyl proteins lack the capacity to form crucial ionic interactions, resulting in altered protein structure and function, which leads to cellular death. Since l-canavanine is selectively sequestered by the pancreas, it may be especially useful as an adjuvant therapy in the treatment of pancreatic cancer. This novel mechanism of cytotoxicity forms the basis for the anticancer activity of l-canavanine and thus, arginyl tRNA synthetase may represent a novel target for the development of such therapeutic agents.     

Food Quality Constraints in Daphnia: Interspecific Differences in the Response to the Absence of a Long Chain Polyunsaturated Fatty Acid in the Food Source

The effect of the long chain polyunsaturated fatty acid (PUFA) eicosapentaenoic acid (EPA, 20:53) on food quality for Daphnia galeata, Daphnia hyalina and a D. galeata×hyalina hybrid was examined. Somatic growth rates of all three species were determined when growing on EPA-free Scenedesmus obliquus and on S. obliquus which had been supplemented with free EPA prior to the growth experiments. Growth rates on S. obliquus were substantially higher in D. galeata(0.45day^–1) than in D. hyalina(0.27day^–1) and D. galeata×hyalina(0.31day^–1). Supplementary EPA increased growth of D. galeata and D. hyalina, but not of the hybrid. Hence within the D. galeata/hyalina complex species differ in their ability to cope with an EPA-free diet. Analysis of fatty acids revealed that tissue concentrations of 18:33, 18:43, 20:33 and 20:43 were higher in D. galeata than in D. hyalina which indicated higher rates of assimilation and biosynthesis of PUFAs in D. galeata. This was contrasted by lower tissue concentrations of 20:53 D. galeata than in D. hyalina which suggests that 20:53 is metabolised with growth. In the D. galeata×hyalina hybrid high PUFA assimilation and biosynthesis were associated with low growth rates which explains the finding that tissue concentrations of 20:53 were highest and that growth was not constrained by the availability of 20:53.     

The livestock reservoir for antimicrobial resistance: a personal view on changing patterns of risks,effects of interventions and the way forward

The purpose of this review was to provide an updated overview on the use of antimicrobial agents in livestock, the associated problems for humans and current knowledge on the effects of reducing resistance in the livestock reservoir on both human health and animal production. There is still limiting data on both use of antimicrobial agents, occurrence and spread of resistance as well as impact on human health. However, in recent years, emerging issues related to methicillin-resistant Staphylococcus aureus, Clostridium difficile, Escherichia coli and horizontally transferred genes indicates that the livestock reservoir has a more significant impact on human health than was estimated 10 years ago, where the focus was mainly on resistance in Campylobacter and Salmonella. Studies have indicated that there might only be a marginal if any benefit from the regular use of antibiotics and have shown that it is possible to substantially reduce the use of antimicrobial agents in livestock production without compromising animal welfare or health or production. In some cases, this should be done in combination with other measures such as biosecurity and use of vaccines. To enable better studies on both the global burden and the effect of interventions, there is a need for global harmonized integrated and continuous surveillance of antimicrobial usage and antimicrobial resistance, preferably associated with data on production and animal diseases to determine the positive and negative impact of reducing antimicrobial use in livestock.     

A Remarkable Case of Ornithophily in Calceolaria: Food Bodies as Rewards for a Non-nectarivorous Bird*

In southernmost South America, the pollination biology of Calceolaria uniflora Lam. (Scrophulariaceae) was studied in the field. One of the most striking features of the flower of this species is a corolla appendage folded against the outside of the lower lip. This massive and fleshy structure is pecked off by Thinocorus rumicivorus (Thinocoridae, Charadriiformes) as a food body. The percentage of damaged flowers averaged 64% and was as high as 81% in one study site. Pollen is placed on the front of the bird's head by the exserted stamens with large versatile anthers. This pollination syndrome is unique for the bird involved and exceptional in the kind of reward offered. This Calceolaria species, and probably a second one endemic to the Falkland Islands (Islas Malvinas), are the only ornithophilous species in a mostly oil-bee pollinated genus. Their reproduction strategy appears to be adapted to an environment lacking in oil-collecting bees.     

Fungal endophytes from leaves of Avicennia marina growing in semi-arid environment as a promising source for bioactive compounds

Endophytic fungi are broadly dispersed residing inside plant tissues and have been demonstrated as a treasure for bioactive natural products. Unexplored harsh and heavy metal contaminant habitat of Avicennia marina may have diverse and potential fungal association. Therefore, this work aimed to isolate the culturable fungal endophytes associated with leaves of A. marina and to evaluate their medical potentialities. Seventeen isolates of endophyte fungi were isolated from healthy leaves and their antimicrobial activities were evaluated. Results showed that isolates had activity against micro-organisms in addition to their antioxidant activity produced a variety of phenolic compounds, besides exhibited a lowest cytotoxicity against ATCC-CCL-81 cell line. Consequently, selected endophytic fungal isolates were identified genetically as Chaetomium sp., Chaetomium madrasense, Chaetomium sp., Chaetomium globosum, Aspergillus hiratsukae, Aspergillus ochraceus, Alternaria tenuissima and Curvularia lunata with gene bank accession numbers MT089951, MT089952, MT089953, MT089954, MT089955, MT089956, MT089957 and MT089958 respectively. The most potent fungus extract was analysed using Gas chromatography–mass spectrometry which verified the presence of numerous bioactive compounds. These findings confirmed that new endophytic fungal strains derived from A. marina thrive in harsh ecosystem produce bioactive metabolites which can be recommended as a novel source for drug discovery.     

Chronic Food Deprivation Decreases Extracellular Dopamine in the Nucleus Accumbens: Implications for a Possible Neurochemical Link Between Weight Loss and Drug Abuse

In rats reduced to 80% of normal body weight (n=9), the basal levels of extracellular dopamine (DA) in the nucleus accumbens (NAC), as determined by microdialysis, decreased significantly to 33 % (mean ± SEM) of their normal baseline (p<.01). Basal extracellullar DA did not change significantly over a matching 3-week period in controls (n=7). No changes were observed in NAC serotonin after weight reduction. These results indicate that parts of the mesolimbic DA system are depressed in underweight rats. The observed decrease in basal DA may be responsible for a variety of behavioral changes observed in undernourished humans and animals including the tendency to eat and gain weight when food becomes available. Given that DA can be released in the NAC when rats self-inject drugs of abuse, the present findings may help explain why animals increase drug intake when they are underweight.     

Shortcomings in USEPA's Approach for Predicting Risk Due to Consumption of Animal Food Products Impacted by Air Emissions from Hazardous Waste Combustion Facilities: A Case Study Involving Phthalates

As a part of the permitting process for hazardous waste combustion facilities, regulatory agencies are now conducting site-specific, multipathway risk assessments. In accordance with the approach established by the USEPA, the Texas Natural Resource Conservation Commission uses a prospective risk assessment paradigm whereby site-specific activity pattern and land use information is used to determine plausible exposure scenarios and pathways. A set of exposure scenarios defined as receptors (i.e., resident adult, resident child, farmer adult, farmer child, fisher adult and fisher child) is then assumed to be exposed via multiple applicable exposure pathways. In conducting such risk assessments, modeled air emissions of di-n-octyl phthalate (DNOP), at concentrations near or below detectable levels, have been observed to produce an unacceptable hazard in the farmer exposure scenario. Sensitivity analyses indicated that two key parameters affected hazard estimates for DNOP in the farmer scenario: the octanol-water partition coefficient (K_ow), which is used to predict bioaccumulation in animal tissue, and the metabolism factor, which is used to account for metabolism and elimination. Evidence indicates that K_ow values for highly lipophillie compounds are accurately determined using a slow-stir method. In addition, evidence indicates that the phthalates of interest are extensively metabolized and eliminated. However, current USEPA guidance includes geometric mean K_ow values for highly lipophillie compounds derived in part on methods that are outdated and no longer considered accurate. In addition, USEPA guidance only considers metabolism for bis-% ethylhexyl phthalate (BEHP). Collectively, these two shortcomings in the USEPA approach result in a 38-fold underestimation of hazard for BEHP and a 172,000-fold overestimation of hazard for DNOP.     

Natural sulforaphane as a functional chemopreventive agent: including a review of isolation,purification and analysis methods

Epidemiological data show that a diet rich in fruits and vegetables can reduce the risk from a number of cancers and chronic diseases. Sulforaphane (SF), a phytochemical constituent of cruciferous vegetables, has been widely researched in recent decades as a potential chemopreventive compound. Nonexistent in intact vegetables, natural SF, is formed from glucoraphanin hydrolyzed by myrosinase. This review summarizes and compares different analysis, isolation and purification methods engaged in SF research. Major important chemopreventive properties of SF investigated in existing research are reviewed and discussed, including antioxidant, anticarcinogenic and anti-inflammatory functions. Considering the potential applications of SF in the future, metabolism, stability and formulation developments of SF are also discussed. Research opportunities are identified based on the review of existing studies to facilitate future explorations on SF, a promising natural compound in chemopreventive therapy.     

The fruit fly parasitoid Fopius arisanus: reproductive attributes of pre-released females and the use of added sugar as a potential food supplement in the field

Fopius (= Biosteres) arisanus (Sonan) (= Opius oophilus Fullaway) (Hymenoptera: Braconidae) is an egg-pupal parasitoid of tephritid fruit flies. Small scale releases of F. arisanus were undertaken in coffee, Coffea arabica L., on the island of Kauai, to evaluate its potential for suppression of fruit fly populations. In conjunction with field releases, assays were conducted to determine the quality of pre-released parasitoids. In addition, the suitability of various sugars as potential food supplements in the field was evaluated. Spermathecal dissection showed that >70% of a total 1.7 million females released in 1998 and 1999 were successfully mated. Moreover, a sperm rating of 2.5–2.6 indicated that the spermathecae of inseminated females were 50% full. There were 85-137 matured eggs (mean =101.7±11.5) in the ovaries of mated or virgin females. When honey was replaced with ripe coffee and water, ripe coffee, or water alone, 10 days after emergence, females remained alive for another 5.5, 5.4, and 4.9 days, respectively. There was corresponding deterioration in the ovaries of gravid females. Mean eggs of honey-deprived females declined from >100 to <70 shortly before their death. Suitability test of various sugars showed that females lived longer when fed with honey (26 days), maple syrup (25 days) or molasses (20 days). Moreover, females provided with these sugars produced mean cumulative progeny per female of 77.2±19, 67±7, and 81±14, respectively, during a 2-week egging period. Our findings provided a basis for development of field release strategy for F. arisanus.