Lipid and fatty acid composition of mesocarp and seed of avocado fruits harvested at northern range in Japan

Comparative analysis of antioxidant and fatty acid composition in avocado (Persea americana Mill.) fruits: Exploring regional and commercial varieties

On Madeira Island, Portugal, the avocado crop benefits from a Mediterranean climate, exhibiting exceptional phytochemical and biochemical properties. Aiming to evaluate the antioxidant quality and fatty acid composition with a commercial avocado, flours were obtained from five varieties (four regional and one commercial Hass) across different tissues (pulp and by-products) and cycles (years and on-tree maturation stages). Results showed that a regional variety with thin purple skin had the highest antioxidant qualities and lipid content, surpassing the other regional and commercial Hass varieties. Oleic acid prevailed in all samples, with regional avocados containing arachidonic acid which is an uncommon occurrence among higher plants. Variations in fatty acid content were influenced by the timing of harvest. These outcomes highlight the promising potential of avocados from Madeira Island.

Looking into the lipid profile of avocado and byproducts: Using lipidomics to explore value-added compounds

Consumer priorities in healthy diets and lifestyle boosted the demand for nutritious and functional foods as well as plant-based ingredients. Avocado has become a food trend due to its nutritional and functional values, which in turn is increasing its consumption and production worldwide. Avocado edible portion has a high content of lipids, with the pulp and its oil being rich in monounsaturated fatty acids and essential omega - 3 and omega - 6 polyunsaturated fatty acids (PUFA). These fatty acids are mainly esterified in triacylglycerides, the major lipids in pulp, but also in minor components such as polar lipids (phospholipids and glycolipids). Polar lipids of avocado have been overlooked despite being recently highlighted with functional properties as well. The growth in the industry of avocado products is generating an increased amount of their byproducts, such as seed and peels (nonedible portions), still undervalued. The few studies on avocado byproducts pointed out that they also contain interesting lipids, with seeds particularly rich in polar lipids bearing PUFA, and thus can be reused as a source of add-value phytochemical. Mass spectrometry-based lipidomics approaches appear as an essential tool to unveil the complex lipid signature of avocado and its byproducts, contributing to the recognition of value-added lipids and opening new avenues for their use in novel biotechnological applications. The present review provides an up-to-date overview of the lipid signature from avocado pulp, peel, seed, and its oils.

Effect of Predry-treatment on the bioactive constituents and quality of avocado (Persea americana Mill.) oil from three cultivars growing in China

Avocado oil has gained a lot of favor in foods and cosmetics because of its high-quality fatty acid composition and bioactive components. This study aimed to compare the effect of various predry-treatments on the yield and quality of avocado oil from three Chinese avocado (Persea americana Mill.) varieties (Hass, Reed, and Pinkerton). The results showed that drying methods had significant effect on the avocado oil yield and its composition. Among the three drying methods the highest yield was obtained by freeze drying, and Hass showed the highest yield in the three avocado varieties with its oil owning the lowest peroxide and anisidine value. Reed oil owned the highest levels of functional micronutrients (e.g., tocopherols, phenolics, squalene). Vacuum drying resulted in higher concentrations of tocopherols, phytosterols, phenolics, squalene, and thus rendered greater DPPH and ABTS scavenging activity. These results are important to improve the quality of Chinese avocado oil.

An overview on lipids in nuts and oily fruits: oil content, lipid composition, health effects, lipidomic fingerprinting and new biotechnological applications of their by-products

Tree nuts and oily fruits are used as a diet complement and are highly consumed worldwide. The production and consumption of these foods have been increasing, and an enormous global market value is forecasted for 2023. Besides their high nutritional value and lipid content, they provide health benefits to fat metabolism, heart, skin, and brain. The industrial by-products of these oily foods represent promising raw materials for many industries. However, the lipidomic analysis of nuts and oily fruits is still in its early stages. State-of-the-art analytical approaches for the lipid profiling and fingerprinting of nuts and oily fruits have been developed using high-performance liquid chromatography and high-resolution mass spectrometry for the accurate identification and structural characterization at the molecular species level. It is expected to bring a new understanding of these everyday foods' nutritional and functional value. This review comprises the oil content and lipid composition of various nuts and oily fruits, particularly those mostly consumed worldwide and having recognized beneficial health effects, biological activities associated with the lipids from different oily foodstuffs, analytical methodologies to analyze lipids in nuts and oily fruits, and the potential biotechnological applications of their industrial by-products for a lipid-based commercial valorization.

Acyl-CoA-dependent and acyl-CoA-independent avocado acyltransferases positively influence oleic acid content in nonseed triacylglycerols

In higher plants, acyl-CoA:diacylglycerol acyltransferase (DGAT) and phospholipid:diacylglycerol acyltransferase (PDAT) catalyze the terminal step of triacylglycerol (TAG) synthesis in acyl-CoA-dependent and -independent pathways, respectively. Avocado (Persea americana) mesocarp, a nonseed tissue, accumulates significant amounts of TAG (~70% by dry weight) that is rich in heart-healthy oleic acid (18:1). The oil accumulation stages of avocado mesocarp development coincide with high expression levels for type-1 DGAT (DGAT1) and PDAT1, although type-2 DGAT (DGAT2) expression remains low. The strong preference for oleic acid demonstrated by the avocado mesocarp TAG biosynthetic machinery represents lucrative biotechnological opportunities, yet functional characterization of these three acyltransferases has not been explored to date. We expressed avocado PaDGAT1, PaDGAT2, and PaPDAT1 in bakers' yeast and leaves of Nicotiana benthamiana. PaDGAT1 complemented the TAG biosynthesis deficiency in the quadruple mutant yeast strain H1246, and substantially elevated total cellular lipid content. In vitro enzyme assays showed that PaDGAT1 prefers oleic acid compared to palmitic acid (16:0). Both PaDGAT1 and PaPDAT1 increased the lipid content and elevated oleic acid levels when expressed independently or together, transiently in N. benthamiana leaves. These results indicate that PaDGAT1 and PaPDAT1 prefer oleate-containing substrates, and their coordinated expression likely contributes to sustained TAG synthesis that is enriched in oleic acid. This study establishes a knowledge base for future metabolic engineering studies focused on exploitation of the biochemical properties of PaDGAT1 and PaPDAT1.

Avocado seed discoveries: Chemical composition, biological properties, and industrial food applications

The processing industry discards avocado seeds, which increases production and ultimately pollutes the environment. It would be advantageous to handle these waste by-products both economically and environmentally. Avocado seeds are rich in polysaccharides, proteins, lipids, vitamins, minerals, and other bioactive substances. The nutritional and phytochemical composition of avocado seeds has been well studied and discussed. Avocado-seed extracts also have many health-related bioactive properties, such as anti-hyperglycaemic, anticancer, anti-hypercholesterolemia, antioxidant, anti-inflammatory, and anti-neurogenerative effects are clearly demonstrated how these properties can be used to formulate or fortify food. The health-promoting properties of avocado seeds have been studied. These properties are attributed to various phytochemicals, such as acetogenin, catechin, epicatechin, procyanidin B1, estragole, etc. Additionally, items made from valorized avocado seeds that people can consume have been explored. The best applications of valorized by-products have been created for the pharmaceutical, functional food, and nutraceutical sectors while considering quality and safety. More clinical testing and product development research are required to prove the effectiveness of avocado seeds.

Assessment of the Nutritional Quality of Plant Lipids Using Atherogenicity and Thrombogenicity Indices

Dietary lipids derived from plants have different compositions of individual fatty acids (FA), providing different physical and chemical properties with positive or adverse health effects on humans. To evaluate the nutritional value and assess the FA composition of various plants, the atherogenicity (AI) and thrombogenicity (TI) indices were calculated and reviewed for nine different categories of fats and oils. This included common oils, unconventional oils, nut oils originating from temperate regions, Amazonian and tropical fats and oils, chia seed oil, traditional nuts originating from temperate regions, unconventional nuts, seeds, and fruits, and their products. The main factors influencing fatty acid composition in plants are growth location, genotype, and environmental variation, particularly temperature after flowering, humidity, and frequency of rainfall (exceeding cultivar variation). The lowest AI was calculated for rapeseed oil (0.05), whereas the highest value was obtained for tucuman seeds (16.29). Chia seed oil had the lowest TI (0.04), and murumuru butter had the highest (6.69). The differences in FA composition and subsequent changes in the lipid health indices of the investigated fats and oils indicate their importance in the human diet.

The Enigmatic Aliphatic Acetogenins and Their Correlations With Lipids During Seed Germination and Leaf Development of Avocado (Persea americana Mill.)

Lipids in avocados have been widely studied due to their nutritional value and several reported bioactivities. Aliphatic acetogenins are a relevant component of the avocado lipidome and have been tested for several potential food and pharma industries applications. This work followed the evolution of avocado fatty acids (FAs) and aliphatic acetogenins during seed germination and leaf growth. Oil extracts of embryonic axes, cotyledons, and leaves from seedlings and trees were divided to analyze free acetylated acetogenins (AcO-acetogenins), and free FAs. Embryonic axes from germinating seeds contained the highest amount of AcO-acetogenins and FAs; this tissue also accumulated the most diverse FA profile with up to 22 detected moieties. Leaves presented the highest variations in AcO-acetogenin profiles during development, although leaves from seedlings accumulated the simplest FA profile with only 10 different FAs. Remarkably, AcO-acetogenins represented half of the carbons allocated to lipids in grown leaves, while embryonic axes and cotyledons always contained more carbons within FAs during germination. Thus, we hypothesized the use of the AcO-acetogenin acyl chain for energy production toward β-oxidation. Also, α-linolenic and docosahexaenoic acids (DHAs) were proposed as close AcO-acetogenin intermediaries based on a correlation network generated using all these data. Another part of the oil extract was fractionated into different lipid classes before transesterification to profile FAs and acetogenins bound to lipids. Acetogenin backbones were identified for the first time in triglycerides from cotyledons and mainly in polar lipids (which include phospholipids) in all developing avocado tissues analyzed. Seed tissues accumulated preferentially polar lipids during germination, while triglycerides were consumed in cotyledons. Seedling leaves contained minute amounts of triglycerides, and polar lipids increased as they developed. Results from this work suggest acetogenins might be part of the energy and signaling metabolisms, and possibly of membrane structures, underlining the yet to establish role(s) of these unusual lipids in the avocado plant physiology.

Ectopic overexpression of a type-II DGAT (CeDGAT2-2) derived from oil-rich tuber of Cyperus esculentus enhances accumulation of oil and oleic acid in tobacco leaves

BACKGROUND

Engineering triacylglycerol (TAG) accumulation in vegetative tissues of non-food crops has become a promising way to meet our increasing demand for plant oils, especially the renewable production of biofuels. The most important target modified in this regard is diacylglycerol acyltransferase (DGAT) enzyme responsible for the final rate-limiting step in TAG biosynthesis. Cyperus esculentus is a unique plant largely accumulating oleic acid-enriched oil in its underground tubers. We speculated that DGAT derived from such oil-rich tubers could function more efficiently than that from oleaginous seeds in enhancing oil storage in vegetative tissues of tobacco, a high-yielding biomass crops.

RESULTS

Three CeDGAT genes namely CeDGAT1, CeDGAT2-1 and CeDGAT2-2 were identified in C. esculentus by mining transcriptome of developing tubers. These CeDGATs were expressed in tissues tested, with CeDGAT1 highly in roots, CeDGAT2-1 abundantly in leaves, and CeDGAT2-2 predominantly in tubers. Notably, CeDGAT2-2 expression pattern was in accordance with oil dynamic accumulation during tuber development. Overexpression of CeDGAT2-2 functionally restored TAG biosynthesis in TAG-deficient yeast mutant H1246. Oleic acid level was significantly increased in CeDGAT2-2 transgenic yeast compared to the wild-type yeast and ScDGA1-expressed control under culture with and without feeding of exogenous fatty acids. Overexpressing CeDGAT2-2 in tobacco led to dramatic enhancements of leafy oil by 7.15- and 1.7-fold more compared to the wild-type control and plants expressing Arabidopsis seed-derived AtDGAT1. A substantial change in fatty acid composition was detected in leaves, with increase of oleic acid from 5.1% in the wild type to 31.33% in CeDGAT2-2-expressed tobacco and accompanied reduction of saturated fatty acids. Moreover, the elevated accumulation of oleic acid-enriched TAG in transgenic tobacco exhibited no significantly negative impact on other agronomic traits such as photosynthesis, growth rates and seed germination except for small decline of starch content.

CONCLUSIONS

The present data indicate that CeDGAT2-2 has a high enzyme activity to catalyze formation of TAG and a strong specificity for oleic acid-containing substrates, providing new insights into understanding oil biosynthesis mechanism in plant vegetative tissues. Overexpression of CeDGAT2-2 alone can significantly increase oleic acid-enriched oil accumulation in tobacco leaves without negative impact on other agronomy traits, showing CeDGAT2-2 as the desirable target gene in metabolic engineering to enrich oil and value-added lipids in high-biomass plants for commercial production of biofuel oils.

Fruit seeds and their oils as promising sources of value-added lipids from agro-industrial byproducts: oil content, lipid composition, lipid analysis, biological activity and potential biotechnological applications

Thousands of tons of fruit seeds are discarded every year worldwide as agro-industrial byproducts. Fruit seeds have a high oil content, are rich in monounsaturated fatty acids (FA) and in n-6 and n-3 polyunsaturated essential FA. Sterols, phospholipids, glycolipids, carotenoids, tocopherols and polyphenols are other seed phytochemicals that make them interesting from a commercial viewpoint. Fruit seeds have high potential as raw material for several industries, but their lipid profile remains poorly studied. Current analytical approaches for the analysis of lipids that are based on high-performance liquid chromatography and high-resolution mass spectrometry allow the separation and analysis of compounds with the accurate identification and structural characterization of molecular species in very small quantities. Even though lipidomic analysis of fruit seeds' lipids is still in its infancy, it will bring a new look over these value-added byproducts. This review covers the following topics: (a) the lipid content of various fruit seed oils; (b) their lipid composition (FA, triacylglycerol, sterol, phospholipid and glycolipid profiles), (c) current and future analytical methodologies for the analysis of lipids in fruit seeds; (d) biological activities of fruit seeds' extracts; and (e) potential biotechnological applications of fruit seed oils for their commercial valorization based on lipids.

Fatty Acid Content in Biomasses: State-of-the-Art and Novel Physical Property Estimation Methods

In line with the growing environmental awareness developed along the last decades, modern societies are urged to evolve into sustainable economics where the reuse of organic wastes represents the key feedstock for a green transaction. The oil phase obtained from different biomasses has the potential to be a source of food supplements, medicines, cosmetics, or feedstock for biofuel production. In the present work, the composition of 104 different biomasses including seeds, peels, flowers, plants, and leaves has been reviewed for the lipid content. Based on the most frequent fatty acids screened, experimental data for normal boiling point temperature, normal melting point, critical properties, and acentric factor were collected and compared with the most common estimation methods, which are functions of the molecular structure and interaction between different functional groups. New predictive equations have been proposed to reduce the estimation deviation and to provide simple correlations to be used in simulation software when dealing with biomass processes. For all the properties, the estimations proposed have an absolute average deviation equal to or lower than 4.6%.

Preliminary Studies of Chemical and Physical Properties of Two Varieties of Avocado Seeds Grown in Chile

In Chile, the most cultivated avocado varieties are Hass and Negra de la Cruz. The increase in the production of fast food preparations, salads, and avocado oil has generated large amounts of seeds and husks as waste, which may constitute a possible new source of bioactive compounds, of great interest to the food and pharmaceutical industry. Therefore, the objective of this study was to determine different nutritional, biochemical, antimicrobial, and physical properties of the SH and SNC seeds grown in Chile. In SH and SNC, their nutritional composition, lipophilic components, and total phenols (PTs) were determined. The antioxidant and antibacterial activity of extracts were measured in different solvent combinations. In addition, the color change of seeds (ΔE) during the browning, the mechanical resistance to the cut, and their thermal transitions by differential calorimetry (DSC) were determined. The results indicated that SH has a higher protein content and lipophilic components. In the ethanol extract, SNC showed greater antiradical activity and is an inhibitor of Gram (+) bacteria. The SNC browning given by ΔEwas greater and adjusted well to kinetic and enzymatic models. The physical analyses of the seeds indicated that SNC presented higher cut resistance and lower transition temperature (Tg) with a lower thermal fusion of its lipids, which would be due to its higher unsaturated composition. These properties of SH and SNC can be useful for the agrifood, pharmaceutical, and chemical industries.

Differentiation of avocados according to their botanical variety using liquid chromatographic fingerprinting and multivariate classification tree

BACKGROUND

The oil content, composition and marketing threshold value of an avocado depends on the cultivar hence, identifying the cultivar of the avocado fruit is desirable. However, analytical methods have not been reported with this aim.

RESULTS

A multivariate classification tree method was proposed to discriminate three commercial botanical varieties of avocado: Hass, Fuerte and Bacon, using high-performance liquid chromatography coupled to a charged aerosol detector (HPLC-CAD). Prior to the chromatographic analysis the avocados were lyophilized and then the oil fraction was extracted using a pressurized liquid extraction system. Normal and reverse phase liquid chromatography were applied in order to obtain the chromatographic fingerprint for each sample. Soft independent modelling of class analogies (SIMCA) and partial least-squares discriminant analysis (PLS-DA) were applied. Classification quality metrics were determined to evaluate the performance of the classification. Several strategies to develop the classification models were employed. Finally, the useful application of 'classification trees' methodology, which has been scarcely applied in the field of analytical food control, was evaluated to perform a multiclass classification.

CONCLUSION

Discrimination of the three botanical varieties was achieved. The best classification was obtained when the PLS-DA is applied on the normal-phase chromatographic fingerprints. Classification trees are showed to be useful tools that provide complementary information to single concatenated models showing different results from the same prediction sample set. © 2019 Society of Chemical Industry.

Lipidomic Profiling of the Olive (Olea europaea L.) Fruit towards Its Valorisation as a Functional Food: In-Depth Identification of Triacylglycerols and Polar Lipids in Portuguese Olives

Olives (Olea europaea L.) are classic ingredients in the Mediterranean diet with well-known health benefits, but their lipid composition has not been fully addressed. In this work, we characterised triacylglycerol (TAG) and polar lipid profiles of the olive pulp while using a complementary methodological approach that was based on solid-phase extraction to recover the neutral lipid (NL) and the polar lipid-rich fractions. The TAG profile was analysed in the NL-fraction by C₃₀ reversed-phase liquid chromatography (LC) and the polar lipid profile by normal-phase hydrophilic interaction liquid chromatography (HILIC), with both being coupled to electrospray ionization-mass spectrometry (ESI-MS) and ESI-MS/MS. This approach identified 71 TAG ions that were attributed to more than 350 molecular species, with fatty acyl chain lengths from C11:0 to C26:0, including different polyunsaturated acyl chains. The polar lipids included 107 molecular species that belonged to 11 lipid classes that comprised phospholipids, glyceroglycolipids, glycosphingolipids, and betaine lipids. In addition to polyunsaturated fatty acids, some of the phospholipids, glycolipids, and glycosphingolipids that were identified in the olive pulp have been described as biologically active molecules. Lipidomic phenotyping of the olive pulp has led to the discovery of compounds that will allow for a better assessment of its nutritional value and new applications of bioactive lipid components in this functional food.

Maternal Supplementation With Avocado (Persea americana Mill.) Pulp and Oil Alters Reflex Maturation, Physical Development, and Offspring Memory in Rats

Avocado (Persea americana Mill.) is an oleaginous fruit source of fatty acids with high levels of neuroprotective phytocomplexes. The objective of this study was to evaluate the development of reflex and somatic maturation, fatty acid profiles in the brain, and memory in different stages of life in the offspring of dams supplemented with avocado pulp and oil during gestation and lactation. The dams were randomly divided into three groups (n = 15 pups/group), and recieved by gavage supplementation: control group (CG)-distilled water; Avocado Oil (AO)-3,000 mg avocado oil/kg animal weight, and Avocado Pulp (AP)-3,000 mg avocado pulp/kg animal weight. We performed the following tests: Analysis of Somatic Development and Ontogeny of Postnatal Reflex (T0 to T21), the Open Field Habituation Test and the Object Recognition Test (ORT) in the adolescent (T45) and adult (T90) phases. The cerebral fatty acids content was evaluated at times T0, T21, T45, and T90. The results were analyzed using the statistical program GraphPad Prism and significant statistics were considered when p < 0.05. Acceleration of reflex maturation and reflex ontogeny was observed in the offspring of AO and AP fed dams, with the results being more pronounced in the pulp fed group (p < 0.05). All groups presented a decrease in the ambulation parameter in the second exposure to the Open Field Habituation Test, at T45 and T90 (p < 0.05). In the ORT, the AO and AP offspring presented memory improvements in the short and long term in the adult and adolescent phases (p < 0.05). The results of the brain fatty acid profiles presented higher polyunsaturated fatty acids (PUFA) content in the AO and AP groups at T21, T45, and T90. The docosahexaenoic fatty acid (DHA) content was higher at T21 (AO and AP), at T45 (AO and AP), and at T90 (AP) (p < 0.05). The arachidonic acid (ARA) content was higher at T45 (AO and AP), and at T90 (AO) (p < 0.05). Maternal supplementation with avocado oil and pulp anticipates reflex maturation and somatic postnatal development, and improves memory during the adolescent and adult phases.

Oleosome Oil Storage in the Mesocarp of Two Avocado Varieties

Studies on avocado oil have focused on the most common commercial cultivars, Hass, Fuerte, and Bacon, rather than the less common varieties, P. americana var. drymifolia and P. americana var. americana, even though the drymifolia variety has a higher oil content and the americana variety is the most common avocado grown in the tropics. The most abundant storage structures for plant oils are the oleosomes, and the aim of this study was to determine the oleosome size, oil yield, and fatty acid composition of the americana and drymifolia varieties, using the Hass cultivar as a reference. Differences were found between the three avocado types for 1) oil yield, with drymifolia having higher and americana lower oil content (p < 0.05%), 2) oleosome size, with Hass having a larger (41.53 µm) and americana a smaller (11.96 µm) size, and 3) fatty acid composition, with the americana and drymifolia varieties showing less monounsaturated fatty acids (oleic) and more polyunsaturated fatty acids (linoleic) and saturated fatty acids (palmitic); while Hass had a high level (60%) of monounsaturated fatty acids. Small but significant differences were also found between oleosome and mesocarp oils isolated from the drymifolia and Hass types.

Analytical Method To Detect and Quantify Avocatin B in Hass Avocado Seed and Pulp Matter

Avocatin B, an avocado-derived compound mixture, was demonstrated recently to possess potent anticancer activity by selectively targeting and eliminating leukemia stem cells. Avocatin B is a mixture of avocadene and avocadyne, two 17-carbon polyhydroxylated fatty alcohols (PFAs), first discovered in avocado seeds; their quantities in avocado pulp are unknown. Analytical methods to detect avocado seed PFAs have utilized NMR spectroscopy and GC-MS; both of these lack quantitative capacity and accuracy. Herein, we report a sensitive LC-MS method for the quantitation of avocadene and avocadyne in avocado seed and pulp. The method has a reliable and linear response range of 0.1-50 μM (0.03-17.2 ng/μL) for both avocadene and avocadyne ( r² > 0.990) with a lower limit of quantitation (LLOQ) of 0.1 μM. The intra- and interassay accuracy and precision of the quality control (QC) samples at LLOQ showed ≤18.2% percentage error and ≤14.4% coefficient of variation (CV). The intra- and interassay accuracy and precision for QC samples at low and high concentrations were well below 10% error and CV. This method was successfully applied to quantify avocadene and avocadyne in total lipid extracts of Hass avocado pulp and seed matter.

Avocado fruit maturation and ripening: dynamics of aliphatic acetogenins and lipidomic profiles from mesocarp, idioblasts and seed

BACKGROUND

Avocado fruit contains aliphatic acetogenins (oft-acetylated, odd-chain fatty alcohols) with promising bioactivities for both medical and food industries. However, we have scarce knowledge about their metabolism. The present work aimed to study changes in acetogenin profiles from mesocarp, lipid-containing idioblasts, and seeds from 'Hass' cultivar during fruit development, germination, and three harvesting years. An untargeted LC-MS based lipidomic analysis was also conducted to profile the lipidome of avocado fruit in each tissue.

RESULTS

The targeted analysis showed that acetogenin profiles and contents remained unchanged in avocado mesocarp during maturation and postharvest ripening, germination, and different harvesting years. However, a shift in the acetogenin profile distribution, accompanied with a sharp increase in concentration, was observed in seed during early maturation. Untargeted lipidomics showed that this shift was accompanied with remodeling of glycerolipids: TAGs and DAGs decreased during fruit growing in seed. Remarkably, the majority of the lipidome in mature seed was composed by acetogenins; we suggest that this tissue is able to synthesize them independently from mesocarp. On the other hand, lipid-containing idioblasts accumulated almost the entire acetogenin pool measured in the whole mesocarp, while only having 4% of the total fatty acids. The lipidome of this cell type changed the most when the fruit was ripening after harvesting, TAGs decreased while odd-chain DAGs increased. Notably, idioblast lipidome was more diverse than that from mesocarp.

CONCLUSIONS

Evidence shown here suggests that idioblasts are the main site of acetogenin biosynthesis in avocado mesocarp. This work unveiled the prevalence of aliphatic acetogenins in the avocado fruit lipidome and evidenced TAGs as initial donors of the acetogenin backbones in its biosynthesis. It also sets evidence for acetogenins being included in future works aimed at characterizing the avocado seed, as they are a main component of their lipidome.

Oil biosynthesis in a basal angiosperm: transcriptome analysis of Persea Americana mesocarp

BACKGROUND

The mechanism by which plants synthesize and store high amounts of triacylglycerols (TAG) in tissues other than seeds is not well understood. The comprehension of controls for carbon partitioning and oil accumulation in nonseed tissues is essential to generate oil-rich biomass in perennial bioenergy crops. Persea americana (avocado), a basal angiosperm with unique features that are ancestral to most flowering plants, stores ~ 70 % TAG per dry weight in its mesocarp, a nonseed tissue. Transcriptome analyses of select pathways, from generation of pyruvate and leading up to TAG accumulation, in mesocarp tissues of avocado was conducted and compared with that of oil-rich monocot (oil palm) and dicot (rapeseed and castor) tissues to identify tissue- and species-specific regulation and biosynthesis of TAG in plants.

RESULTS

RNA-Seq analyses of select lipid metabolic pathways of avocado mesocarp revealed patterns similar to that of other oil-rich species. However, only some predominant orthologs of the fatty acid biosynthetic pathway genes in this basal angiosperm were similar to those of monocots and dicots. The accumulation of TAG, rich in oleic acid, was associated with higher transcript levels for a putative stearoyl-ACP desaturase and endoplasmic reticulum (ER)-associated acyl-CoA synthetases, during fruit development. Gene expression levels for enzymes involved in terminal steps to TAG biosynthesis in the ER further indicated that both acyl-CoA-dependent and -independent mechanisms might play a role in TAG assembly, depending on the developmental stage of the fruit. Furthermore, in addition to the expression of an ortholog of WRINKLED1 (WRI1), a regulator of fatty acid biosynthesis, high transcript levels for WRI2-like and WRI3-like suggest a role for additional transcription factors in nonseed oil accumulation. Plastid pyruvate necessary for fatty acid synthesis is likely driven by the upregulation of genes involved in glycolysis and transport of its intermediates. Together, a comparative transcriptome analyses for storage oil biosynthesis in diverse plants and tissues suggested that several distinct and conserved features in this basal angiosperm species might contribute towards its rich TAG content.

CONCLUSIONS

Our work represents a comprehensive transcriptome resource for a basal angiosperm species and provides insight into their lipid metabolism in mesocarp tissues. Furthermore, comparison of the transcriptome of oil-rich mesocarp of avocado, with oil-rich seed and nonseed tissues of monocot and dicot species, revealed lipid gene orthologs that are highly conserved during evolution. The orthologs that are distinctively expressed in oil-rich mesocarp tissues of this basal angiosperm, such as WRI2, ER-associated acyl-CoA synthetases, and lipid-droplet associated proteins were also identified. This study provides a foundation for future investigations to increase oil-content and has implications for metabolic engineering to enhance storage oil content in nonseed tissues of diverse species.

Oil biosynthesis in a basal angiosperm: transcriptome analysis of Persea Americana mesocarp

BACKGROUND

The mechanism by which plants synthesize and store high amounts of triacylglycerols (TAG) in tissues other than seeds is not well understood. The comprehension of controls for carbon partitioning and oil accumulation in nonseed tissues is essential to generate oil-rich biomass in perennial bioenergy crops. Persea americana (avocado), a basal angiosperm with unique features that are ancestral to most flowering plants, stores ~ 70 % TAG per dry weight in its mesocarp, a nonseed tissue. Transcriptome analyses of select pathways, from generation of pyruvate and leading up to TAG accumulation, in mesocarp tissues of avocado was conducted and compared with that of oil-rich monocot (oil palm) and dicot (rapeseed and castor) tissues to identify tissue- and species-specific regulation and biosynthesis of TAG in plants.

RESULTS

RNA-Seq analyses of select lipid metabolic pathways of avocado mesocarp revealed patterns similar to that of other oil-rich species. However, only some predominant orthologs of the fatty acid biosynthetic pathway genes in this basal angiosperm were similar to those of monocots and dicots. The accumulation of TAG, rich in oleic acid, was associated with higher transcript levels for a putative stearoyl-ACP desaturase and endoplasmic reticulum (ER)-associated acyl-CoA synthetases, during fruit development. Gene expression levels for enzymes involved in terminal steps to TAG biosynthesis in the ER further indicated that both acyl-CoA-dependent and -independent mechanisms might play a role in TAG assembly, depending on the developmental stage of the fruit. Furthermore, in addition to the expression of an ortholog of WRINKLED1 (WRI1), a regulator of fatty acid biosynthesis, high transcript levels for WRI2-like and WRI3-like suggest a role for additional transcription factors in nonseed oil accumulation. Plastid pyruvate necessary for fatty acid synthesis is likely driven by the upregulation of genes involved in glycolysis and transport of its intermediates. Together, a comparative transcriptome analyses for storage oil biosynthesis in diverse plants and tissues suggested that several distinct and conserved features in this basal angiosperm species might contribute towards its rich TAG content.

CONCLUSIONS

Our work represents a comprehensive transcriptome resource for a basal angiosperm species and provides insight into their lipid metabolism in mesocarp tissues. Furthermore, comparison of the transcriptome of oil-rich mesocarp of avocado, with oil-rich seed and nonseed tissues of monocot and dicot species, revealed lipid gene orthologs that are highly conserved during evolution. The orthologs that are distinctively expressed in oil-rich mesocarp tissues of this basal angiosperm, such as WRI2, ER-associated acyl-CoA synthetases, and lipid-droplet associated proteins were also identified. This study provides a foundation for future investigations to increase oil-content and has implications for metabolic engineering to enhance storage oil content in nonseed tissues of diverse species.

Merging a sensitive capillary electrophoresis-ultraviolet detection method with chemometric exploratory data analysis for the determination of phenolic acids and subsequent characterization of avocado fruit

Herein we present the development of a powerful CE-UV method able to detect and quantify an important number of phenolic acids in 13 varieties of avocado fruits at 2 ripening stages. All the variables involved in CE separation were exhaustively optimized and the best results were obtained with a capillary of 50 μm i.d. × 50 cm effective length, sodium tetraborate 40 mM at a pH of 9.4, 30 kV, 25 °C, 10s of hydrodynamic injection (0.5 psi) and UV detection at 254 nm. This optimal methodology was fully validated and then applied to different avocado samples. The number of phenolic acids determined varied from 8 to 14 compounds; in general, they were in concentrations ranging from 0.13 ppm to 3.82 ppm, except p-coumaric, benzoic and protocatechuic acids, which were found at higher concentrations. Principal component analysis (PCA) was applied to highlight the differences between varieties and ripening degrees, looking for the most influential analytes.

Antiprotozoal and antimycobacterial activities of Persea americana seeds

Background

Persea americana seeds are widely used in traditional Mexican medicine to treat rheumatism, asthma, infectious processes as well as diarrhea and dysentery caused by intestinal parasites.

Methods

The chloroformic and ethanolic extracts of P. americana seeds were prepared by maceration and their amoebicidal, giardicidal and trichomonicidal activity was evaluated. These extracts were also tested against Mycobacterium tuberculosis H37Rv, four mono-resistant and two multidrug resistant strains of M. tuberculosis as well as five non tuberculosis mycobacterium strains by MABA assay.

Results

The chloroformic and ethanolic extracts of P. americana seeds showed significant activity against E. histolytica, G. lamblia and T. vaginalis (IC₅₀ <0.634 μg/ml). The chloroformic extract inhibited the growth of M. tuberculosis H37Rv, M. tuberculosis MDR SIN 4 isolate, three M. tuberculosis H37Rv mono-resistant reference strains and four non tuberculosis mycobacteria (M. fortuitum, M. avium, M. smegmatis and M. absessus) showing MIC values ≤50 μg/ml. Contrariwise, the ethanolic extract affected only the growth of two mono-resistant strains of M. tuberculosis H37Rv and M. smegmatis (MIC ≤50 μg/ml).

Conclusions

The CHCl₃ and EtOH seed extracts from P. americana showed amoebicidal and giardicidal activity. Importantly, the CHCl₃ extract inhibited the growth of a MDR M. tuberculosis isolate and three out of four mono-resistant reference strains of M. tuberculosis H37Rv, showing a MIC = 50 μg/ml. This extract was also active against the NTM strains, M. fortuitum, M. avium, M. smegmatis and M. abscessus, with MIC values <50 μg/ml.

Avocado consumption is associated with better diet quality and nutrient intake, and lower metabolic syndrome risk in US adults: results from the National Health and Nutrition Examination Survey (NHANES) 2001-2008

BACKGROUND

Avocados contain monounsaturated fatty acids (MUFA) dietary fiber, essential nutrients and phytochemicals. However, no epidemiologic data exist on their effects on diet quality, weight management and other metabolic disease risk factors. The objective of this research was to investigate the relationships between avocado consumption and overall diet quality, energy and nutrient intakes, physiological indicators of health, and risk of metabolic syndrome.

METHODS

Avocado consumption and nutrition data were based on 24-hour dietary recalls collected by trained NHANES interviewers using the USDA Automated Multiple Pass Method (AMPM). Physiological data were collected from physical examinations conducted in NHANES Mobile Examination Centers. Diet quality was calculated using the USDA's Healthy Eating Index-2005. Subjects included 17,567 US adults ≥ 19 years of age (49% female), including 347 avocado consumers (50% female), examined in NHANES 2001-2008. Least square means, standard errors, and ANOVA were determined using appropriate sample weights, with adjustments for age, gender, ethnicity, and other covariates depending on dependent variable of interest.

RESULTS

Avocado consumers had significantly higher intakes of vegetables (p<0.05); fruit, diet quality, total fat, monounsaturated and polyunsaturated fats, dietary fiber, vitamins E, K, magnesium, and potassium (p<0.0001); vitamin K (p=0.0013); and lower intakes of added sugars (p<0.0001). No significant differences were seen in calorie or sodium intakes. Body weight, BMI, and waist circumference were significantly lower (p<0.01), and HDL-C was higher (p<0.01) in avocado consumers. The odds ratio for metabolic syndrome was 50% (95th CI: 0.32-0.72) lower in avocado consumers vs. non-consumers.

CONCLUSIONS

Avocado consumption is associated with improved overall diet quality, nutrient intake, and reduced risk of metabolic syndrome. Dietitians should be aware of the beneficial associations between avocado intake, diet and health when making dietary recommendations.

Protective effect of pulp oil extracted from Canarium odontophyllum Miq. Fruit on blood lipids, lipid peroxidation, and antioxidant status in healthy rabbits

The aim of this paper was to compare the effects of pulp and kernel oils of Canarium odontophyllum Miq. (CO) on lipid profile, lipid peroxidation, and oxidative stress of healthy rabbits. The oils are rich in SFAs and MUFAs (mainly palmitic and oleic acids). The pulp oil is rich in polyphenols. Male New Zealand white (NZW) rabbits were fed for 4 weeks on a normal diet containing pulp (NP) or kernel oil (NK) of CO while corn oil was used as control (NC). Total cholesterol (TC), HDL-C, LDL-c and triglycerides (TG) levels were measured in this paper. Antioxidant enzymes (superoxide dismutase and glutathione peroxidise), thiobarbiturate reactive substances (TBARSs), and plasma total antioxidant status (TAS) were also evaluated. Supplementation of CO pulp oil resulted in favorable changes in blood lipid and lipid peroxidation (increased HDL-C, reduced LDL-C, TG, TBARS levels) with enhancement of SOD, GPx, and plasma TAS levels. Meanwhile, supplementation of kernel oil caused lowering of plasma TC and LDL-C as well as enhancement of SOD and TAS levels. These changes showed that oils of CO could be beneficial in improving lipid profile and antioxidant status as when using part of normal diet. The oils can be used as alternative to present vegetable oil.

Associations of whole-blood fatty acids and dietary intakes with prostate cancer in Jamaica

OBJECTIVE

To investigate the association of whole-blood fatty acids and reported intakes of fats with risk of prostate cancer (PCa).

DESIGN

Case-control study of 209 men 40-80 years old with newly diagnosed, histologically confirmed prostate cancer and 226 cancer-free men attending the same urology clinics. Whole-blood fatty acid composition (mol%) was measured by gas chromatography and diet assessed by food frequency questionnaire.

RESULTS

High whole-blood oleic acid composition (tertile 3 vs. tertile 1: OR, 0.37; CI, 0.14-0.0.98) and moderate palmitic acid proportions (tertile 2: OR, 0.29; CI, 0.12-0.70) (tertile 3: OR, 0.53; CI, 0.19-1.54) were inversely related to risk of PCa, whereas men with high linolenic acid proportions were at increased likelihood of PCa (tertile 3 vs. tertile 1: OR, 2.06; 1.29-3.27). Blood myristic, stearic and palmitoleic acids were not associated with PCa. Higher intakes of dietary MUFA were inversely related to prostate cancer (tertile 3 vs. tertile 1: OR, 0.39; CI 0.16-0.92). The principal source of dietary MUFA was avocado intake. Dietary intakes of other fats were not associated with PCa.

CONCLUSIONS

Whole-blood and dietary MUFA reduced the risk of prostate cancer. The association may be related to avocado intakes. High blood linolenic acid was directly related to prostate cancer. These associations warrant further investigation.

Increasing the energy density of vegetative tissues by diverting carbon from starch to oil biosynthesis in transgenic Arabidopsis

Increasing the energy density of biomass by engineering the accumulation of triacylglycerols (TAGs) in vegetative tissues is synergistic with efforts to produce biofuels by conversion of lignocellulosic biomass. Typically, TAG accumulates in developing seeds, and little is known about the regulatory mechanisms and control factors preventing oil biosynthesis in vegetative tissues in most plants. Here, we engineered Arabidopsis thaliana to ectopically overproduce the transcription factor WRINKLED1 (WRI1) involved in the regulation of seed oil biosynthesis. Furthermore, we reduced the expression of APS1 encoding a major catalytic isoform of the small subunit of ADP-glucose pyrophosphorylase involved in starch biosynthesis using an RNAi approach. The resulting AGPRNAi-WRI1 lines accumulated less starch and more hexoses. In addition, these lines produced 5.8-fold more oil in vegetative tissues than plants with WRI1 or AGPRNAi alone. Abundant oil droplets were visible in vegetative tissues. TAG molecular species contained long-chain fatty acids, similar to those found in seed oils. In AGPRNAi-WRI1 lines, the relative expression level of sucrose synthase 2 was considerably elevated and correlated with the level of sugars. The relative expression of the genes encoding plastidic proteins involved in de novo fatty acid synthesis, biotin carboxyl carrier protein isoform 2 and acyl carrier protein 1, was also elevated. The relative contribution of TAG compared to starch to the overall energy density increased 9.5-fold in one AGPRNAi-WRI1 transgenic line consistent with altered carbon partitioning from starch to oil.

Some analytical assays for the determination of bioactivity of exotic fruits

INTRODUCTION

The consumption of new exotic fruits, with their high nutritional and sensory value, has significantly increased in the past few years. Among the tropical fruits durian (Durio zibethinus Murr.) is less known than mango (Mangifera indica L.) and avocado (Persea americana). It has been shown that durian, mango and avocado possessed high nutritional and bioactive properties, but these data were determined using different methods. In order to obtain reliable results we investigated samples of durian, mango and avocado of the same stage of ripeness and unified methods were used for determination of the antioxidant potential. As far as we know, no results of such comparative investigation of three tropical fruits (durian, mango and avocado) and the use of such tests for phytochemical control have been published.

OBJECTIVE

Lyophilised durian, mango and avocado samples harvested in 2008 in Thailand and Israel were investigated.

METHODOLOGY

The contents of crude protein, fat, carbohydrate, dietary fibre, total polyphenols, flavonoids, tannins and flavanols were determined by elemental analysis and UV spectroscopy. The presence of polyphenols (flavonoids and phenolic acids) in the investigated samples was studied by Fourier transform infrared (FT-IR) spectroscopy and three-dimensional fluorometry. Four complementary radical scavenging assays were used for antioxidant determination: ferric reducing antioxidant power (FRAP), 2, 2-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) diamonium salt (ABTS(*+)), 1-diphenyl-2-picrylhydrazyl method (DPPH) and cupric reducing antioxidant capacity (CUPRAC). Chemometrical processing was used for statistical comparison of the fruits.

RESULTS

All spectrometric measurements were highly correlated. The contents of total fibre, proteins and fats were significantly higher (p < 0.05) in avocado, and carbohydrates were significantly lower in avocado (p > 0.05) than in the two other fruits. The wavelength numbers of FTIR spectra for three investigated fruits were in the same range (1700-600 cm(-1)) as for catechin and gallic acid, used as standards. One main peak could be easily observed at the approximate location of ex/em 275/305 nm and the other one at ex/em 350/430 nm in the methanol polyphenol extracts of investigated fruits in three-dimensional fluorescence, in contour and cross fluorescence maps. Similarity was found between durian, mango and avocado in polyphenols (9.88 +/- 1.0, 12.06 +/- 1.3 and 10.69 +/- 1.1, mg gallic acid equivalents/g dry weight, d.w.), and in antioxidant assays such as CUPRAC (27.46 +/- 2.7, 40.45 +/- 4.1 and 36.29 +/- 3.7, microM Trolox equivalent (TE)/g d.w.) and FRAP (23.22 +/- 2.0, 34.62 +/- 3.4 and 18.47 +/- 1.9, microM TE/g d.w.), respectively. The multisample median test between all possible pairs of groups is a Tukey-HSD type comparison and denotes the different groups in a case when a pair-wise test is significant and its q statistical value is greater than the table q parameter. The multisample median test of FRAP values were chosen from the compared fruits triplets as similar or homogenous subsets durian and avocado.

CONCLUSION

Nutritional and bioactive values of durian are comparable with these indices in mango and avocado. These fruits contain high, comparable quantities of basic nutritional and antioxidant compounds, and possess high antioxidant potentials. All fruits show a high level of correlation between the contents of phenolic compounds and the antioxidant potential. The methods used (three-dimensional fluorescence, FTIR spectroscopy, radical scavenging assays) are suitable for bioactivity determination of these fruits. In order to receive best results, a combination of these fruits has to be included in the diet. The methods used are applicable for bioactivity determination in phytochemical analysis in general.