Analysis of oil synthesis pathway in Cyperus esculentus tubers and identification of oleosin and caleosin genes.

The tubers of the widely distributed Cyperus esculentus are rich in oil, and therefore, the plant is considered to have a high utilization value in the vegetable oil industry. Oleosins and caleosins are lipid-associated proteins found in oil bodies of seeds; however oleosins and caleosins genes have not been identified in C. esculentus. In this study, we performed transcriptome sequencing and lipid metabolome analysis of C. esculentus tubers at four developmental stages to obtain the information on their genetic profile, expression trends, and metabolites in oil accumulation pathways. Overall, 120,881 non-redundant unigenes and 255 lipids were detected; 18 genes belonged to the acetyl-CoA carboxylase (ACC), malonyl-CoA:ACP transacylase (MCAT), ß-ketoacyl-ACP synthase (KAS), and fatty acyl-ACP thioesterase (FAT) gene families involved in fatty acid biosynthesis, and 16 genes belonged to the glycerol-3-phosphate acyltransferase (GPAT), diacylglycerol acyltransferase 3 (DGAT3), phospholipid:diacylglycerol acyltransferase (PDAT), FAD2, and lysophosphatidic acid acyltransferase (LPAAT) gene families playing important roles in triacylglycerol synthesis. We also identified 9 oleosin- and 21 caleosin-encoding genes in C. esculentus tubers. These results provide detailed information on the C. esculentus transcriptional and metabolic profiles, which can be used as reference for the development of strategies to increase oil content in C. esculentus tubers.

The Potential Neuroprotective Effect of Cyperus esculentus L. Extract in Scopolamine-Induced Cognitive Impairment in Rats: Extensive Biological and Metabolomics Approaches.

The aim of the present study is to investigate the phytochemical composition of tiger nut (TN) (Cyperus esculentus L.) and its neuroprotective potential in scopolamine (Scop)-induced cognitive impairment in rats. The UHPLC-ESI-QTOF-MS analysis enabled the putative annotation of 88 metabolites, such as saccharides, amino acids, organic acids, fatty acids, phenolic compounds and flavonoids. Treatment with TN extract restored Scop-induced learning and memory impairments. In parallel, TN extract succeeded in lowering amyloid beta, ß-secretase protein expression and acetylcholine esterase (AChE) activity in the hippocampus of rats. TN extract decreased malondialdehyde levels, restored antioxidant levels and reduced proinflammatory cytokines as well as the Bax/Bcl2 ratio. Histopathological analysis demonstrated marked neuroprotection in TN-treated groups. In conclusion, the present study reveals that TN extract attenuates Scop-induced memory impairments by diminishing amyloid beta aggregates, as well as its anti-inflammatory, antioxidant, anti-apoptotic and anti-AChE activities.

Chemical Constituents of Cyperus esculentus Leaves and the Protective Effect against Agricultural Fungicide-Induced Hepatotoxicity.

Cyperus esculentus is cultivated as a crop plant due to its edible and oily tubers (tiger nut). However, little is known about the phytochemicals and bioeffects of the leaves. This study was conducted to identify and quantify the chemical constituents of C. esculentus leaves and evaluate their bioactivities. By liquid chromatography-mass spectrometry, 30 compounds including flavan-3-ols, caffeic acid derivatives, and flavones, were identified from the leaves. The quantitative analysis revealed that gallocatechin (8), procyanidin B1 (15), catechin (16), chlorogenic acid (19), orientin (30), and luteolin 7-O-glucuronide (31) are the major chemical constituents of C. esculentus leaves. The contents of these six chemical constituents in the leaves collected in September in Hohhot, China, reached to 1460.85±7.66, 10178.77±302.65, 1048.35±17.37, 1722.15±26.13, 5318.62±277.16, and 1526.54±11.95 µg, respectively, in one gram of the dried leaves. The leaf extract (CELE) showed strong antioxidant activity in vitro, with compounds 8, 15, and 19 contributing the most. CELE showed significant protection against the agricultural fungicide tebuconazole-induced developmental toxicity and hepatotoxicity in zebrafish.

Quantification and purification of procyanidin B1 from food byproducts.

The flavan-3-ols of 10 primarily plant food byproducts, including Muscat Hamburg grape seed, hawthorn sarcocarp, litchi pericarp, cocoa bean, peanut skin, lotus seedpod, Xinyang Maojian green tea, Cinnamomi cortex, Sargentodoxa cuneata stem, and Cyperus esculentus, leaves were analyzed. Ultrahigh-performance liquid chromatography-triple quadrupole mass spectrometry was used for the analysis. Cyperus esculentus leaves contained a high amount of procyanidin B1 (198.9 mg/100 g), second only to Muscat Hamburg grape seed (292.9 mg/100 g). Unlike grape seed that contained several procyanidin B isomers with very similar retention times, C. esculentus leaves contained primarily procyanidin B1 with few isomers. Procyanidin B1 was enriched in the ethyl acetate fraction of a 70% methanol extract of C. esculentus leaves and purified at 95% purity by two runs of open column chromatography. Direct chromatography of the plant extract on octadecylsilane and Sephadex LH20 open columns improved the yield of the resultant leaf procyanidin B1 (95% purity) to 0.21‰. The present research demonstrated that the leaves of C. esculentus, byproducts of tigernut, are ideal plant sources for isolating and providing high-purity procyanidin B1. PRACTICAL APPLICATION: Procyanidin B1 has a broad range of health benefits. Cyperus esculentus is cultivated in many countries with nearly 6190 square hectares (hm2 ) in the Spanish Mediterranean region in 2020-2021 and over 16,700 hm2 in China in recent years, primarily for its tubers. The byproducts, the leaves of C. esculentus, contain high levels of procyanidin B1, with few isomers that interfere with its isolation and purification. Thus, the leaves of this plant provide a viable source for preparing high-purity procyanidin B1.

Cyperus esculentus L. protects testis and sperm morphology of hyperglycaemic rats / Cyperus esculentus L. protege la morfología de los testículos y los espermatozoides de ratas hiperglicémicas

Cyperus esculentus L. (tiger nut) is a tuberous plant that promotes and protects reproductive functions, which are usually hampered in diabetics. The present study investigated the effect of Cyperus esculentus tuber extract (CETE) on testicular histology and sperm viability of alloxan-induced hyperglycaemic Wistar rats. Twenty-five adult male Wistar rats weighing 150-200g and grouped into five (n=5): Group 1, the control, administered tap water (20mL/kg), while groups 2-5 were administered a single intraperitoneal dose (120mg/kg b.w.) of alloxan, and each further received orally tap water (20mL/kg), CETE (100mg/kg), CETE (500 mg/kg) and metformin (500 mg/kg), respectively for 21 days. The animals were sacrificed, their sperm collected for analysis, while the testes were harvested, and processed for histology. Results showed significantly increased (p<0.05) blood glucose and testosterone, and significantly decreased (p<0.05) sperm pH, motility, count, morphology and density, as well as disruptions and hypertrophy of the spermatogenic and Sertoli cells of the hyperglycaemic group. There were significant (p<0.05) blood glucose decline, while the sperm parameters and testicular weight improved with normal testicular histology in the 100 mg/kg CETE, 500 mg/kg CETE, and metformin-treated groups compared to the control and hyperglycaemic group. Treatment with CETE showed blood glucose amelioration and improved sperm quality, as well as testicular damage attenuation.

Cyperus esculentus L. es una planta tuberosa que promueve y protege las funciones reproductivas, que generalmente se ven afectadas en los diabéticos. El presente estudio investigó el efecto del extracto de tubérculo de Cyperus esculentus (CETE) sobre la histología testicular y la viabilidad de los espermatozoides de ratas wistar con hiperglicemia inducida por alloxan. Veinticinco ratas Wistar macho adultas que pesaban 150-200 g y se agruparon en cinco (n = 5): el grupo 1, el control, administró agua del grifo (20ml / kg), mientras que los grupos 2-5 se les administró una dosis intraperitoneal única (120 mg / kg p.v.) de alloxan, y agua del grifo por vía oral (20ml/kg), CETE (100 mg/kg), CETE (500 mg/kg) y metformina (500 mg/kg), respectivamente durante 21 días. Los animales fueron sacrificados, su esperma recolectada para su análisis, mientras que los testículos fueron retirados y procesados para histología. Los resultados mostraron un aumento significativo (p<0,05) de la glucosa en sangre y la testosterona, y una disminución significativa (p<0,05) del pH, la motilidad, el recuento, la morfología y la densidad de los espermatozoides, así como interrupciones e hipertrofia de las células espermatogénicas y sertoli del grupo hiperglucémico. Hubo una disminución significativa (p<0,05) de la glucosa en sangre, mientras que los parámetros espermáticos y el peso testicular mejoraron con la histología testicular normal en los grupos de 100 mg / kg de CETE, 500 mg / kg de CETE y tratados con metformina en comparación con el grupo de control e hiperglucémico. El tratamiento con CETE mostró una mejora de la glucosa en sangre y una mejora de la calidad de los espermatozoides, así como atenuación del daño testicular.

Tracing Key Molecular Regulators of Lipid Biosynthesis in Tuber Development of Cyperus esculentus Using Transcriptomics and Lipidomics Profiling.

Cyperus esculentus is widely representing one of the important oil crops around the world, which provides valuable resources of edible tubers called tiger nut. The chemical composition and high ability to produce fats emphasize the role of tiger nut in promoting oil crop productivity. However, the underlying molecular mechanism of the production and accumulation of lipids in tiger nut development still remains unclear. Here, we conducted comprehensive transcriptomics and lipidomics analyses at different developmental stages of tuber in Cyperus esculentus. Lipidomic analyses confirmed that the accumulation of lipids including glycolipids, phospholipids, and glycerides were significantly enriched during tuber development from early to mature stage. The proportion of phosphatidylcholines (PC) declined during all stages and phosphatidyl ethanolamine (PE) was significantly declined in early and middle stages. These findings implied that PC is actively involved in triacylglycerol (TAG) biosynthesis during the tubers development, whereas PE may participate in TAG metabolism during early and middle stages. Comparative transcriptomics analyses indicated several genomic and metabolic pathways associated with lipid metabolism during tuber development in tiger nut. The Pearson correlation analysis showed that TAG synthesis in different developmental stages was attributed to 37 candidate transcripts including CePAH1. The up-regulation of diacylglycerol (DAG) and oil content in yeast, resulted from the inducible expression of exogenous CePAH1 confirmed the central role of this candidate gene in lipid metabolism. Our results demonstrated the foundation of an integrative metabolic model for understanding the molecular mechanism of tuber development in tiger nut, in which lipid biosynthesis plays a central role.

Selection and Validation of Reference Genes for qRT-PCR Analysis in the Oil-Rich Tuber Crop Tiger Nut (Cyperus esculentus) Based on Transcriptome Data.

Tiger nut (Cyperus esculentus), a perennial C4 plant of the Cyperaceae family, is an unconventional crop that is distinguished by its oil-rich tubers, which also possesses the advantages of strong resistance, wide adaptability, short life periods, and large biomass. To facilitate studies on gene expression in this species, we identified and validated a series of reference genes (RGs) based on transcriptome data, which can be employed as internal controls for qRT-PCR analysis in tiger nut. Fourteen putative candidate RGs were identified and evaluated across nine different tissues of two cultivars, and the RGs were analyzed using three different algorithms (geNorm, NormFinder, and BestKeeper). The stability rankings of the candidate RGs were merged into consensus lists with RankAggreg. For the below-ground storage organ of tiger nut, the optimal RGs were TUB4 and UCE2 in different developmental stages of tubers. UCE2 and UBL5 were the most stably expressed RGs among all tissues, while Rubisco and PGK exhibited the lowest expression stability. UCE2, UBL5 and Rubisco were compared to normalize the expression levels of the caleosin (CLO) and diacylglycerol acyltransferase 2-2 (DGAT2-2) genes across the same tissues. Our results showed that the RGs identified in this study, which exhibit more uniform expression patterns, may be utilized for the normalization of qRT-PCR results, promoting further research on gene expression in various tissues of tiger nut.

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.

Fluoride-induced testicular degeneration and sperm quality deteriorations: Salutary role of Cyperus esculentus tubers (tiger nut) extract in animal model.

OBJECTIVE: Chronic exposure to fluoride causes tissue damage induced by oxidative imbalance, Cyperus esculentus (CE) possess anti-inflammatory and immunostimulatory properties. This study focused on Salutary role of Cyperus esculentus in sodium fluoride (NaF) induced testicular degeneration and sperm quality deteriorations. METHODS: Sexually mature male Sprague-Dawley rats were randomly divided into four groups (n=6). Animals in control group received 2 mls of normal saline per day; CE group received 500mg/kg bw of CE; NaF group received 5mg/kg bw of NaF; NaF+CE group received 500mg/kg bw of CE (for 14 days pre-treatment) and NaF co-treatment till 56 days via gastric gavage. Parameters tested include: testicular histology, sperm parameters, sex hormone, fertility test, malondialdehyde (MDA), superoxide dismutase (SOD), reduced glutathione, glutathione peroxidase (GPX), catalase (CAT), testicular fluoride and testicular cholesterol. RESULTS: Sodium fluoride significantly (p<.05) decrease testicular antioxidant (SOD, CAT, GSH and GPx), sperm quality, hormone profiles (TT, FSH, LH, estrogen levels), testicular cholesterol, morphometric parameters, Johnsen's Score and number of implantations in female rats with corresponding (p<.05) increase in oxidative stress makers and abnormal sperm morphology. Also depleted seminiferous epithelium and degenerate spermatogenic cells. Pretreatment with 500mg/kg bw of CE lowered NaF toxicity by significantly reducing the lipid peroxidation products, fluoride accumulation in the testis, histopathological changes of the testes and spermatozoa abnormalities and reverted observed NaF-induced inhibition in antioxidant parameters and weight of accessory sex organs. CONCLUSIONS: Cyperus esculentus attenuated NaF-induced testicular injuries and protected the seminiferous epithelium, reduced oxidative stress and promoted spermatogenesis.

Protective effect of Cyperus esculentus (tiger nut) extract against scopolamine-induced memory loss and oxidative stress in mouse brain.

Objectives The juice extract of Cyperus esculentus commonly known as tiger nuts (TINUT) is widely used for its numerous health promoting effects including alleviation of symptoms associated with neurological disorders. Herein, we investigated the influence of the aqueous extract of C. esculentus on cognitive disorder and the underlying changes in acetylcholinesterase (AChE) activity and oxidative stress biomarkers in mice exposed to scopolamine. Methods C. esculentus (50-200 mg/kg) or saline (10 mL/kg) was given alone or with scopolamine 30 min after, to male Swiss mice (6/group) daily for seven days. We evaluated the cognitive performance using Y-maze and object recognition on day seven post-treatment. Brains of the animals were afterwards processed for spectrophotometric determination of AChE activity and contents of oxidative stress biomarkers (malondialdehyde [MDA], glutathione [GSH], catalase, superoxide dismutase and nitrite). Results The extract improves cognitive function and also upturned scopolamine amnesia in mice. The extract markedly reduced brain AChE, MDA, and nitrite contents in mice injected with scopolamine (p<0.05). It also attenuated scopolamine-induced deregulated GSH contents and antioxidant enzymes in mouse brain. Conclusions The results of this study suggest that regular consumption of TINUT might offer beneficial effects in memory-related disorders.

Antioxidant, anti-inflammatory and anti-apoptotic effects of hydro-ethanolic extract of Cyperus esculentus L. (tigernut) on lead acetate-induced testicular dysfunction in Wistar rats.

AIM: Lead acetate impairs testicular function by enhancing testicular oxidative stress and apoptosis. Cyperus esculentus possesses antioxidants and has shown great improvement of testicular function. This study investigated the protective effect of hydro-ethanolic extract of Cyperus esculentus on lead acetate-induced testicular dysfunction in Wistar rats. MATERIALS AND METHODS: Twenty-five male Wistar rats (180-195 g) were randomly divided into 5 groups (n = 5) namely: Normal control (NC), Lead control (PbC) (20 mg/kg b.w. i.p.), C. esculentus-treated (CE) (500 mg/kg b.w p.o.), Pb + CE(500) (20 mg/kg of lead and 500 mg/kg of extract) and Pb + CE(1000) (20 mg/kg of lead and 1000 mg/kg of extract). Administration lasted for 21 days. RESULTS: Sperm count, motility, viability, serum testosterone and follicle stimulating hormone, Johnsen's score, Leydig cell count, Sertoli cell count, testicular testosterone, B-cell lymphoma protein-2 (Bcl-2), steroidogenic acute regulatory protein, cytochrome P450 A1, 3ß-hydroxysteroid dehydrogenase (HSD), 17ß-HSD, enzymatic antioxidant activities and total antioxidant capacity were significantly (p < 0.05) decreased in PbC compared with NC. These parameters however increased significantly (p < 0.05) in Pb + CE(500) and Pb + CE(1000) compared with PbC. Lead acetate upregulated (p < 0.05) testicular malondialdehyde, nitric oxide, glucose, lactate, lactate dehydrogenase, C-reactive protein, tumor necrosis factor-α, interleukin (IL)-6, IL-1ß, Bcl-2 associated X (Bax), Bax/Bcl-2 and cleaved caspase-3 levels. All these parameters were downregulated (p < 0.05) in Pb + CE(500) and Pb + CE(1000) in comparison with PbC. CONCLUSION: C. esculentus exhibited a dose-dependent mitigation of lead acetate-induced testicular dysfunction in Wistar rats via its antioxidant, anti-inflammatory and anti-apoptotic effects.

Functional Characterization of Three Novel Genes Encoding Diacylglycerol Acyltransferase (DGAT) from Oil-Rich Tubers of Cyperus esculentus.

Cyperus esculentus is probably the only plant that is known to accumulate large amounts of oil in its tubers. However, the underlying metabolic mechanism and regulatory factors involved in oil synthesis of tubers are still largely unclear. In this study, one gene encoding type I diacylglycerol acyltransferase (DGAT) (CeDGAT1) and two genes encoding type II DGAT (CeDGAT2a and CeDGAT2b) from C. esculentus were identified and functionally analyzed. All three DGAT genes were found to be expressed in tuber, root and leaf tissues. CeDGAT1 is highly expressed in roots and leaves, whereas CeDGAT2b is dominantly expressed in tubers. Furthermore, the temporal expression pattern of CeDGAT2b is well coordinated with the oil accumulation in developing tubers. When each CeDGAT was heterologously expressed in triacylglycerol (TAG)-deficient mutant of Saccharomyces cerevisiae, Arabidopsis thaliana wild type or its TAG1 mutant with AtDGAT1 disruption, only CeDGAT2b showed the ability to restore TAG biosynthesis with lipid body formation in yeast mutant, enhance seed oil production of Arabidopsis wild type and rescue multiple seed phenotypes of TAG1 mutant. In addition, CeDGAT2b was shown to have a substrate preference for unsaturated fatty acids toward TAG synthesis. Taken together, our results indicated that CeDGAT2b from C. esculentus is an actively functional protein and is most likely the major contributor to tuber oil biosynthesis containing common fatty acids, in contrast to oil-rich seeds and fruits where DGAT1 plays a more central role than DGAT2 in oil production accumulating normal fatty acids, whereas DGAT2 is a primary regulator for oil synthesis rich in unusual fatty acids.

Sucrose metabolism in developing oil-rich tubers of Cyperus esculentus: comparative transcriptome analysis.

BACKGROUND: Cyperus esculentus is unique in that it can accumulate significant amounts of oil, starch and sugar as major storage reserves in tubers with high tuber yield and therefore considered as a novel model to study carbon allocation into different storage reserves in underground sink tissues such as tubers and roots. Sucrose (Suc) plays a central role in control of carbon flux toward biosynthesis of different storage reserves; however, it remains unclear for the molecular mechanism underlying Suc metabolism in underground oil-rich storage tissues. In the present study, a comprehensive transcriptome analysis of C. esculentus oil tuber compared to other plant oil- or carbohydrate-rich storage tissues was made for the expression patterns of genes related to the Suc metabolism. RESULTS: The results revealed some species-specific features of gene transcripts in oil tuber of C. esculentus, indicating that: (i) the expressions of genes responsible for Suc metabolism are developmentally regulated and displayed a pattern dissimilar to other plant storage tissues; (ii) both of Suc breakdown and biosynthesis processes might be the major pathways associated with Suc metabolism; (iii) it was probably that Suc degradation could be primarily through the action of Suc synthase (SUS) other than invertase (INV) during tuber development. The orthologs of SUS1, SUS3 and SUS4 are the main SUS isoforms catalyzing Suc breakdown while the vacuolar INV (VIN) is the leading determinant controlling sugar composition; (iv) cytosolic hexose phosphorylation possibly relies more on fructose as substrate and uridine diphosphate glucose pyrophosphorylase (UGP) plays an important role in this pathway; (v) it is Suc-phosphate synthase (SPS) B- and C-family members rather than SPS A that are the principal contributors to SPS enzymes and play crucial roles in Suc biosynthesis pathway. CONCLUSIONS: We have successfully identified the Suc metabolic pathways in C. esculentus tubers, highlighting several conserved and distinct expressions that might contribute to sugar accumulation in this unique underground storage tissue. The specific and differential expression genes revealed in this study might indicate the special molecular mechanism and transcriptional regulation of Suc metabolism occurred in oil tubers of C. esculentus.

The Effect of Solvent Type and Roasting Processes on Physico-Chemical Properties of Tigernut (Cyperus esculentus L.) Tuber Oil.

In this study, physico-chemical properties of raw and roasted tigernut oils extracted by two different solvents were determined. Peroxide values of raw and roasted tigernut oils extracted by petroleum ether and n-hexane solvents changed between 0.83 and 0.91 meqO2/100g to 1.57 and 1.63 meqO2/100g, respectively. While oleic acid contents of raw tigernut oils extracted by petroleum ether and n-hexane are determined as 66.83 and 67.47%, oleic acid contents of roasted tigernut oils extracted by petroleum ether and n-hexane were determined as 67.08 and 68.16%, respectively. The highest δ-tocopherol content was found in raw tigernut oil extracted by petroleum ether (54.91 mg/100g), while the lowest level is determined in roasted tigernut oil by n-hexane (50.77 mg/100g). As a result, the fatty acid profiles of roasted tigernut oil extracted by n-hexane were higher compared to results of raw tigernut oils extracted by petroleum ether (p < 0.05).

Oil Biosynthesis in Underground Oil-Rich Storage Vegetative Tissue: Comparison of Cyperus esculentus Tuber with Oil Seeds and Fruits.

Cyperus esculentus is unique in that it can accumulate rich oil in its tubers. However, the underlying mechanism of tuber oil biosynthesis is still unclear. Our transcriptional analyses of the pathways from pyruvate production up to triacylglycerol (TAG) accumulation in tubers revealed many distinct species-specific lipid expression patterns from oil seeds and fruits, indicating that in C. esculentus tuber: (i) carbon flux from sucrose toward plastid pyruvate could be produced mostly through the cytosolic glycolytic pathway; (ii) acetyl-CoA synthetase might be an important contributor to acetyl-CoA formation for plastid fatty acid biosynthesis; (iii) the expression pattern for stearoyl-ACP desaturase was associated with high oleic acid composition; (iv) it was most likely that endoplasmic reticulum (ER)-associated acyl-CoA synthetase played a significant role in the export of fatty acids between the plastid and ER; (v) lipid phosphate phosphatase (LPP)-δ was most probably related to the formation of the diacylglycerol (DAG) pool in the Kennedy pathway; and (vi) diacylglyceroltransacylase 2 (DGAT2) and phospholipid:diacylglycerolacyltransferase 1 (PDAT1) might play crucial roles in tuber oil biosynthesis. In contrast to oil-rich fruits, there existed many oleosins, caleosins and steroleosins with very high transcripts in tubers. Surprisingly, only a single ortholog of WRINKLED1 (WRI1)-like transcription factor was identified and it was poorly expressed during tuber development. Our study not only provides insights into lipid metabolism in tuber tissues, but also broadens our understanding of TAG synthesis in oil plants. Such knowledge is of significance in exploiting this oil-rich species and manipulating other non-seed tissues to enhance storage oil production.

The in vitro and in vivo antioxidant properties of Cyperus esculentus oil from Xinjiang, China.

BACKGROUND: Cyperus esculentus oil is also known as the new health care oil. This study aimed to analyse the fatty acid profile and content of C. esculentus oil by gas chromatography-mass spectrometry and to assess the antioxidant activity of C. esculentus oil. These properties were evaluated based on the reducing power, hydroxyl radical and diphenyl picryl hydrazyl radical scavenging, and a combination of in vitro and in vivo antioxidant experiments. RESULTS: Composition analyses showed that C. esculentus oil contained more than 800 g kg(-1) unsaturated fatty acid, of which oleic acid accounted for 691.4 g kg(-1), linoleic acid accounted for 107.0 g kg(-1) and palmitic acid accounted for 158.0 g kg(-1). In vitro results showed that the total antioxidant activity and the scavenging capacity of hydroxyl radicals and diphenyl picryl hydrazyl radicals increased with increasing concentration. The in vitro antioxidant ability increased as the concentration of C. esculentus oil, with 15 mL kg(-1) BW day(-1) being established as the optimal dose. CONCLUSION: Taken together, the results of this study clearly indicate that C. esculentus oil has good antioxidant properties.