Triacylglycerols composition, oxidation and oxidation compounds in camellia oil using liquid chromatography-mass spectrometry

Camellia seed oil is one of most important edible oil, rich in oleic acid and contains many natural antioxidants with various biological activities. During preparation of foods or storage camellia oil oxidizes by the auto-oxidation and produce oxidized compounds. Traditional analytical techniques like FFA, POV are used for the determination of oxidation and adulteration of oils and fats. These methods were rarely able to detect the oxidized compounds produced and extent of oxidation. This paper presents the uses of liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS) for the analysis of triacylglycerols (TAGs) composition and evaluation of auto-oxidation and oxidation products of camellia seed oil. The camellia oil was auto-oxidized for 12 months at room temperature. The TAGs were identified from their characteristics fragmentations such as protonated molecular ion, ammonium and sodium adducts, diacylglycerols, epoxy-diacylglycerols fragments and mono-acylglycerol fragments in ESI-MS mass spectra. HPLC-ESI-MS data revealed the separation and identification of 15 TAGs. The major TAGs separated and identified in camellia seed oil were POO, OOO, OLO, PLO/POL, OLL, SOO, ALO and OLLn. The auto-oxidation studies revealed a total loss of LnLLn, LnOLn, LLLn and OLLn amounting about 13.5% total oxidation. The auto-oxidation products were epoxy hydroperoxides, epoxy epidioxides, and mono-epoxides. It was observed that these were characteristic compounds produced in high oleic oils.     

Secreting glandular trichomes: more than just hairs

Secreting glandular plant trichome types which accumulate large quantities of metabolic products in the space between their gland cell walls and cuticle permit the plant to amass secretions in a compartment that is virtually outside the plant body. These structures not only accumulate and store what are often phytotoxic oils but they position these compounds as an apparent first line of defense at the surface of the plant. Recent advances in methods for isolation and study of trichome glands have allowed more precise analysis of gland cell metabolism and enzymology. Isolation of mutants with altered trichome phenotypes provides new systems for probing the genetic basis of trichome development. These advances and their continuation can pave the way for future attempts at modification of trichome secretion. The biochemical capability of glandular secreting trichomes and the potential for its future manipulation to exploit this external storage compartment is the focus of this review.     

Metabolic engineering of fatty acid biosynthesis in plants.

Fatty acids are the most abundant form of reduced carbon chains available from nature and have diverse uses ranging from food to industrial feedstocks. Plants represent a significant renewable source of fatty acids because many species accumulate them in the form of triacylglycerol as major storage components in seeds. With the advent of plant transformation technology, metabolic engineering of oilseed fatty acids has become possible and transgenic plant oils represent some of the first successes in design of modified plant products. Directed gene down-regulation strategies have enabled the specific tailoring of common fatty acids in several oilseed crops. In addition, transfer of novel fatty acid biosynthetic genes from noncommercial plants has allowed the production of novel oil compositions in oilseed crops. These and future endeavors aim to produce seeds higher in oil content as well as new oils that are more stable, are healthier for humans, and can serve as a renewable source of industrial commodities. Large-scale new industrial uses of engineered plant oils are on the horizon but will require a better understanding of factors that limit the accumulation of unusual fatty acid structures in seeds.     

Lipids from heterotrophic microbes: advances in metabolism research

Heterotrophic oleaginous microorganisms are capable of producing over 20% of their weight in single cell oils (SCOs) composed of triacylglycerols (TAGs). These TAGs contain fatty acids, such as palmitic, stearic and oleic acids, that are well-suited for biodiesel applications. Although some of these microbes are able to accumulate SCOs while growing on inexpensive agro-industrial biomass, the competition with plant oil resources means that a significant increase in productivity is desired. The present review aims to summarize recent details in lipid metabolism research and engineering (e.g. direct fatty acid ethyl ester production), as well as culture condition optimization and innovations, such as solid-state or semi-solid-state fermentation, that can all contribute to higher productivity and further advancement of the field.     

Simplifying Hansen Solubility Parameters for Complex Edible Fats and Oils

Hansen solubility parameters (HSPs), often used to predict the miscibility between two compounds, are an alternative tool in evaluating the ability of the solvent to interact via dispersion, dipole-dipole, and hydrogen bonding interactions. The aim of this paper is to find a simple way to calculate HSPs for complex mixtures of triglycerides (TAGs). HSPs were calculated using two approaches: the first assumes that the contributions to the dispersion, dipole-dipole, and hydrogen bonding interactions may be subdivided into larger functional moieties (i.e., fatty acids and fatty acid methyl esters) that are additive, while the second approach assumes that vegetable oils are comprised of mixtures of simple TAGs in the same mass fractions as the fatty acids. The HSPs obtained using the two approaches are compared to reference values determined using the “Hansen Solubility Parameters in Practice” software (HSPiP) considering the complex TAG profile for each vegetable oil.HSPs for vegetable oils, obtained with the HSPiP software, did not correspond well to the HSPs obtained from the group contribution approach, when using fatty acids, fatty acids + glycerol or fatty acid methyl esters. In contrast, the HSPs calculated for vegetable oils, assuming that all TAGs are simple and in the same mass fractions as the fatty acids, provide similar values to the HSPs obtained from the HSPiP software. Therefore, it is possible to calculate the HSPs for complex oils by simply knowing the fatty acid composition. Knowledge of HSPs may be used to rationalize the ability of certain low molecular weight molecules to develop organogels in vegetable oils as well as the crystallization of triglycerides.     

Plant essential oils: a substitute for conventional insecticides against Tribolium species (Coleoptera: Tenebrionidae)-achievements and challenges

Abstract

The literature on efficacy of plant essential oils and their constituents for the management of Tribolium spp. (T. castaneum and T. confusum), instigating infestation of a variety of stored grains and their products is reviewed here. Both species caused significant losses in the diverse food grains and their products through infestation. Essential oils of higher plants showed potential activity in the management of these infestation driven losses. Researchers have found that essential oils and their chemical constituents have significant toxicity against both the species of Tribolium via different modes of action like repellent, insecticidal, ovicidal, larvicidal, pupicidal, ovipositional and feeding deterrent actions. Concerning repellency and in vivo bioassays, few studies have been done with the essential oils against T. confusum, thus, more investigations are required to find the repellent agents against this insect. There are some essential oil-based botanical insecticides which have been proved effective for the protection of food grains from both beetles during storage. These botanical insecticides also exhibited behaviour altering properties against both beetles, thus, reducing the problem of pest resistance which is a problem with conventional insecticides. Therefore, essential oils-based botanical insecticides may be preferred option than conventional insecticides for protecting stored grains and their products against Tribolium infestation.     

Long chain polyunsaturated fatty acid production and partitioning to triacylglycerols in four microalgae

Gas chromatographic profiling of fatty acids was performed during the growth cycle of four marine microalgae in order to establish which, if any, of these could act as a reliable source of genes for the metabolic engineering of long chain polyunsaturated fatty acid (LC-PUFA) synthesis in alternative production systems. A high-throughput column based method for extraction of triacylglycerols (TAGs) was used to establish how much and at what stage in the growth phase LC-PUFAs partition to storage lipid in the different species. Differences in the time course of production and incorporation of docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) into TAGs were found in the marine microalgae Nannochloropsis oculata (Eustigmatophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae), and the Haptophyte Pavlova lutheri. Differences were not only observed between species but also during the different phases of growth within a species. A much higher percentage of the total cellular EPA was partitioned to TAGs in stationary phase cells of N. oculata compared to P. tricornutum. Although P. tricornutum produces DHA it does not partition it to TAGs. Both T. pseudonana and P. lutheri produce EPA and DHA and partition these to TAGs during the stationary phase of growth. These two species are therefore good candidates for further biochemical and molecular analysis, in order to understand and manipulate the processes that are responsible for the incorporation of LC-PUFAs into storage oils.     

微藻三酰甘油合成途径及其最新研究进展

三酰甘油(triacylglycerols,TAGs)是动物、植物、微生物和微藻细胞主要的储藏性脂类,它可应用于食品、轻工业和生物燃料等方面,是一种新型可再生能源——生物柴油生产的重要原料。与高等油料作物相比,微藻具有光合作用效率高、生长速度快、油脂产量高、不占用农业耕地和适应多种生长环境等优势,是一种潜在的新型生物柴油生产原料。然而,目前人们对有机体,尤其是微藻细胞内TAG合成与积累的分子机制及细胞的代谢调控机制还知之甚少。对TAG合成的一系列重要过程,包括脂肪酸的合成,TAG生物合成的主要途径和旁路途径,以及与TAG合成相关的关键酶和重要基因等进行了综述,特别对微藻细胞中与TAG合成相关的关键基因的最新研究进展进行了总结,旨在更好地了解油脂代谢的调控途径,为最大限度地供应生物柴油的生产原料提供理论基础。     

Biosynthesis and metabolic engineering of palmitoleate production, an important contributor to human health and sustainable industry

Palmitoleate (cis-Δ9-16:1) shows numerous health benefits such as increased cell membrane fluidity, reduced inflammation, protection of the cardiovascular system, and inhibition of oncogenesis. Plant oils containing this unusual fatty acid can also be sustainable feedstocks for producing industrially important and high-demand 1-octene. Vegetable oils rich in palmitoleate are the ideal candidates for biodiesel production. Several wild plants are known that can synthesize high levels of palmitoleate in seeds. However, low yields and poor agronomic characteristics of these plants limit their commercialization. Metabolic engineering has been developed to create oilseed crops that accumulate high levels of palmitoleate or other unusual fatty acids, and significant advances have been made recently in this field, particularly using the model plant Arabidopsis as the host. The engineered targets for enhancing palmitoleate synthesis include overexpression of Δ9 desaturase from mammals, yeast, fungi, and plants, down-regulating KASII, coexpression of an ACP-Δ9 desaturase in plastids and CoA-Δ9 desaturase in endoplasmic reticulum (ER), and optimizing the metabolic flux into triacylglycerols (TAGs). This review will mainly describe the recent progress towards producing palmitoleate in transgenic plants by metabolic engineering along with our current understanding of palmitoleate biosynthesis and its regulation, as well as highlighting the bottlenecks that require additional investigation by combining lipidomics, transgenics and other "-omics" tools. A brief review of reported health benefits and non-food uses of palmitoleate will also be covered.     

BIOCHEMICAL AUTONOMY OF HIGHER PLANT CHLOROPLASTS AND THEIR SYNTHESIS OF SMALL MOLECULES

1. Mature chloroplasts are able to synthesize a wide variety of compounds of low molecular weight in addition to carbohydrates. 2. Mature chloroplasts from higher plants can synthesize fatty acids from acetate, and galactolipids from UDP-galactose; but, thus far, there is no direct evidence that chloroplasts can produce their principal fatty acid, α-linolenate, independently of the rest of the cell. 3. Chloroplasts possess the enzymic machinery necessary to generate most of the common amino acids from inorganic nitrogen plus appropriate a-keto analogs of amino acids. However, the plastids do not appear able to synthesize many α-keto carbon compounds from the initial products of photosynthetic carbon dioxide fixation. 4. Whether chloroplasts can generate their own supply of acetate remains in doubt. 5. There is little evidence for or against the existence of chloroplastic enzymes catalysing synthesis of purines and pyrimidines. 6. Recent evidence confirms that immature plastids possess the complement of enzymes required for synthesis of protochlorophyllide from 8-aminolaevulinic acid but leaves open the possibility that extrachloroplastic cofactors may be involved in protochlorophyllide biosynthesis. 7. The weight of the available evidence suggests that, despite its great metabolic versatility and possible reproductive autonomy, the chloroplast of the higher plant is not metabolically autonomous or nutritionally independent of the remainder of the plant cell. Therefore, if there is any validity to the oft-repeated speculation that chloroplasts have evolved from ancient free-living procaryotes, it appears that the evolution of the chloroplast has led to a considerable loss of nutritional autonomy concomitant with the development or preservation of photosynthetic competence.     

Commercial opportunities for pesticides based on plant essential oils in agriculture, industry and consumer products

In spite of intensive research on plant natural products and insect-plant chemical interactions over the past three decades, only two new types of botanical insecticides have been commercialized with any success in the past 15 years, those based on neem seed extracts (azadirachtin), and those based on plant essential oils. Certain plant essential oils, obtained through steam distillation and rich in mono- and sesquiterpenes and related phenols, are widely used in the flavouring and fragrance industries and in aromatherapy. Some aromatic plants have traditionally been used for stored product protection, but the potential for development of pesticides from plant essential oils for use in a wide range of pest management applications has only recently been realized. Many plant essential oils and their major terpenoid constituents are neurotoxic to insects and mites and behaviourally active at sublethal concentrations. Most plant essential oils are complex mixtures. In our laboratory we have demonstrated that individual constituents of oils rarely account for a major share of the respective oil’s toxicity. Further, our results suggest synergy among constituents, including among those that appear non-toxic in isolation. Repellent effects may be particularly useful in applications against public health and domestic pests, but may be useful in specific agricultural applications as well. In all of these applications, there is a premium on human and animal safety that takes priority over absolute efficacy. In agriculture, the main market niche for essential oil-based pesticides is in organic food production, at least in developed countries, where there are fewer competing pest management products. There is also scope for mixing these oils with conventional insecticides and for enhancing their efficacy with natural synergists. Some examples of field efficacy against agricultural pests are discussed.     

Plant species from Brazilian Caatinga: a control alternative for Aedes aegypti

The mosquito Aedes aegypti is the main vector for the virus dengue, chikungunya and Zika. For its control, it is essential to search for natural products with insecticidal effects. The climatic singularity of Caatinga, an exclusive Brazilian biome, aids the survival of plants that produce secondary metabolites, which could be toxic to insects. Therefore, this review discusses the insecticidal potential of Caatinga plants on Aedes aegypti mosquitoes. The meta-analysis was performed using Review Manager Software 5.4.1®. Several studies have demonstrated the insecticidal efficacy of Caatinga plants on the egg, larvae, pupae and adult phases of Ae. aegypti, with a predominance of the plant activity in the larval stage. The leaves were the most utilized part of the plant. The essential oils from Caatinga plants were significantly active against Ae. aegypti (RR = 0.21, 95 % CI = 0.07 – 0.68, p = 0.009). The most promising botanical genera as an insecticide are: Abarema, Myracrodruon, Croton, Lippia and Syagrus. Among chemical compounds from these insecticidal plants has been identified and isolated flavonoids and fatty acids. Therefore, the Caatinga plant is a promising plant that contain bioactive compounds that are useful in the control of vector insects. This could contribute to the characterisation and valorisation of flora of this biome, as well as the production of environmentally friendly insecticides with specific action on target insects.     

Does triacylglycerol (TAG) serve a photoprotective function in plant leaves? An examination of leaf lipids under shading and drought

Plant survival in many ecosystems requires tolerance of large radiation loads, unreliable water supply and suboptimal soil fertility. We hypothesized that increased production of neutral lipids (triacylglycerols, TAGs) in plant leaves is a mechanism for dissipating excess radiation energy. In a greenhouse experiment, we combined drought and shade treatments and examined responses among four species differing in life form, habitat, and drought‐ and shade‐tolerance. We also present a lipid extraction protocol suitable for sclerophyllous leaves of native Australian trees (e.g. Acacia, Eucalyptus). Fluorescence measurements indicated that plants exposed to full sunlight experienced mild photoinhibition during our experiment. Accumulation of TAGs did not follow photosynthetic capacity, but instead, TAG concentration increased with non‐photochemical quenching. This suggests that plants under oxidative stress may increase biosynthesis of TAGs. Moderate drought stress resulted in a 60% reduction in TAG concentration in wheat (Triticum aestivum). Shading had no effect on TAGs, but increased concentrations of polar lipids in leaves; for example, acclimation to shade in Austrodanthonia spp., a native Australian grass, resulted in a 60% increase in associated polar lipids and higher foliar chlorophyll concentrations. Shading also reduced the digalactosyldiacylglycerol:monogalactosyldiacylglycerol (DGDG:MGDG) ratio in leaves, with a corresponding increase in the degree of unsaturation and thus fluidity of thylakoid membranes of chloroplasts. Our results suggest that prevention of photodamage may be coordinated with accumulation of TAGs, although further research is required to determine if TAGs serve a photoprotective function in plant leaves.     

Analysis of Brassinosteroids in Plants

Brassinosteroids (BRs) are the polyhydroxylated plant hormones sharing a common resemblance with animal steroids. They are active even at very low concentrations and are implicated for their pleiotropic involvement in diverse physiological processes and defense strategies during stress in plants. These compounds are well apparent in the plant kingdom with higher amounts in juvenile tissues. A total of 62 steroidal compounds have been identified so far. Keeping their significance in mind, researchers not only have worked extensively on their isolation, but also they were synthesizing their synthetic isomers. Different analytical techniques like HPLC, GC-MS, LC-MS/MS, UPLC-MS/MS, and bioassay-based methods have been used for their isolation, detection, and characterization from composite plant materials. Therefore, this review provides comprehensive information to the readers intending to isolate and characterize BRs, using either laborious techniques or modern-day more efficient methods.     

Efficacy of some medicinal plant extracts and essential oils against Colorado potato beetle,Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae)

The Colorado potato beetle (CPB), Leptinotarsa decemlineata Say is one of the most important defoliator pests of potato in the world and it often causes extremely large potato yield losses. Potatoes are the preferred hosts for the pest, but it may feed and reproduce on a number of other plants in the Solanaceae family. Public concern related to pesticides and their residues in and on the foods had prompted a rise of consumer interest in organically produced foods. There have been growing efforts to detect and introduce suitable plant compounds that they have insecticidal properties. However, discovering of plant extracts for possible use in control of this pest requires more studying about plant extracts and compounds. Since resistance of CPB to common chemical insecticides is well documented and potato is one of the most prominent nutritious food products for many people in many countries, we examined the effect of essential oils (EOs) of European pennyroyal, lavander, mint, oregano and savory and methanolic extracts of fumitory, licorice and oregano on the pest. These plants were selected because they have medicinal properties and they are safe to human and environment. Adult CPBs were exposed to mentioned plant extracts and essential oils. LC₅₀ values for EOs of lavander and European pennyroyal were 4154 and 3561 ppm, respectively. The results demonstrated that essential oil of European pennyroyal (Mentha longifolia) would be suitable compound to control the pest, but essential oil of mint (Mentha spicata) was not effective against the pest. Also it is notable that at all treatments, the amount of adult feeding was very low.     

植物营养贮存蛋白及其生物学功能研究进展

植物营养贮存蛋白(vegetative storage proteins )是广泛存在于植物营养组织且含量丰富的蛋白, 最初是作为植物氮源的临时贮存形式而被人们认识。然而, 不同植物中的营养贮存蛋白的生化来源和生物学特性并不相同, 并且除了营养贮存功能外, 更重要的是这类蛋白在植物防御中也承担着多种多样的重要角色, 或具有抗虫活性, 或能够抑制病原细菌和病原真菌的生长, 或参与植物防御过程中的信号转导等。对植物营养贮存蛋白在植物防御中作用机制的深入研究将使这类蛋白在新型生物农药的开发和植物抗病基因工程中具有广阔的应用前景。     

Tung tree DGAT1 and DGAT2 have nonredundant functions in triacylglycerol biosynthesis and are localized to different subdomains of the endoplasmic reticulum

Seeds of the tung tree (Vernicia fordii) produce large quantities of triacylglycerols (TAGs) containing approximately 80% eleostearic acid, an unusual conjugated fatty acid. We present a comparative analysis of the genetic, functional, and cellular properties of tung type 1 and type 2 diacylglycerol acyltransferases (DGAT1 and DGAT2), two unrelated enzymes that catalyze the committed step in TAG biosynthesis. We show that both enzymes are encoded by single genes and that DGAT1 is expressed at similar levels in various organs, whereas DGAT2 is strongly induced in developing seeds at the onset of oil biosynthesis. Expression of DGAT1 and DGAT2 in yeast produced different types and proportions of TAGs containing eleostearic acid, with DGAT2 possessing an enhanced propensity for the synthesis of trieleostearin, the main component of tung oil. Both DGAT1 and DGAT2 are located in distinct, dynamic regions of the endoplasmic reticulum (ER), and surprisingly, these regions do not overlap. Furthermore, although both DGAT1 and DGAT2 contain a similar C-terminal pentapeptide ER retrieval motif, this motif alone is not sufficient for their localization to specific regions of the ER. These data suggest that DGAT1 and DGAT2 have nonredundant functions in plants and that the production of storage oils, including those containing unusual fatty acids, occurs in distinct ER subdomains.     

植物营养贮存蛋白及其生物学功能研究进展

植物营养贮存蛋白（vegetative storage proteins）是广泛存在于植物营养组织且含量丰富的蛋白,最初是作为植物氮源的临时贮存形式而被人们认识。然而,不同植物中的营养贮存蛋白的生化来源和生物学特性并不相同,并且除了营养贮存功能外,更重要的是这类蛋白在植物防御中也承担着多种多样的重要角色,或具有抗虫活性,或能够抑制病原细菌和病原真菌的生长,或参与植物防御过程中的信号转导等。对植物营养贮存蛋白在植物防御中作用机制的深入研究将使这类蛋白在新型生物农药的开发和植物抗病基因工程中具有广阔的应用前景。