Nutritional value, chemical composition and antioxidant activity of three Tuber species from China

Phytotoxic Strains of Fusarium commune Isolated from Truffles

Most Fusarium species are known as endophytes and/or phytopathogens of higher plants and have a worldwide distribution. Recently, information discovered with molecular tools has been also published about the presence of these fungi in the microbiome of truffle fruiting bodies. In the present work, we isolated and identified three Fusarium strains from truffle fruiting bodies. All isolates were assigned to the same species, F. commune, and the strains were deposited in the All-Russian Collection of Microorganisms under accession numbers VKM F-5020, VKM F-5021, and VKM F-5022. To check the possible effects of the isolated strains on the plants, the isolates were used to infect sterile seedlings of Sarepta mustard (Brassica juncea L.). This model infection led to a moderate suppression of the photosynthetic apparatus activity and plant growth. Here, we present characteristics of the F. commune isolates: description of the conidial morphology, pigmentation, and composition of the mycelium fatty acids. Overall, this is the first description of the Fusarium cultures isolated from truffle fruiting bodies. Possible symbiosis of the F. commune strains with truffles and their involvement in the cooperative fatty acid production are proposed.

Transcriptome and metabolome analysis reveals stage-specific metabolite accumulation during maturity of Chinese black truffle Tuber indicum

Tuber indicum is the most economically important member of Tuber, with the highest production and widest distribution in China. However, the overexploitation of immature ascocarps not only has driven wild resources of the species toward extinction, but also has caused enconomic losses and a decline in the reputation of T.indicum quality. In this study, stage-specific metabolites of T. indicum in relation to nutritional quality and the mechanism of their accumulations were explored by transcriptome and metabolome analysis at five harvest times, representing four maturation stages. A total of 663 compounds were identified in T. indicum ascocarps by a widely targeted metabolomic approach. Lipid compounds are the most prominent metabolites (18%) in our samples and also are higher accumulation at the immature stage than at mature stage, representing 30.16% differential accumulated metabolites in this stage. Levels of some of the amino acids, such as S-(methyl) glutathione, S-adenosylmethionine, which are known truffle aroma precursors, were increased at the mature stage. The gene expression level related to the biosynthesis of volatile organic compounds were verified by qPCR. This study contributes to the preliminary understanding of metabolites variations in T. indicum ascocarps during maturity for quality evaluation and truffle biology.

Pressurized Liquid (PLE) Truffle Extracts Have Inhibitory Activity on Key Enzymes Related to Type 2 Diabetes (α-Glucosidase and α-Amylase)

An optimized PLE method was applied to several truffle species using three different solvent mixtures to obtain bioactive enriched fractions. The pressurized water extracts contained mainly (1 → 3),(1 → 6)-β-D-glucans, chitins, and heteropolymers with galactose and mannose in their structures. The ethanol extracts included fatty acids and fungal sterols and others such as brassicasterol and stigmasterol, depending on the species. They also showed a different fatty acid lipid profile depending on the solvent utilized and species considered. Ethanol:water extracts showed interesting lipids and many phenolic compounds; however, no synergic extraction of compounds was noticed. Some of the truffle extracts were able to inhibit enzymes related to type 2 diabetes; pressurized water extracts mainly inhibited the α-amylase enzyme, while ethanolic extracts were more able to inhibit α-glucosidase. Tuber brumale var. moschatum and T. aestivum var. uncinatum extracts showed an IC₅₀ of 29.22 mg/mL towards α-amylase and 7.93 mg/mL towards α-glucosidase. Thus, use of the PLE method allows o bioactive enriched fractions to be obtained from truffles with antidiabetic properties.

Black Truffle Extract Exerts Antidiabetic Effects through Inhibition of Inflammation and Lipid Metabolism Regulation

Black truffle, a culinary and medical fungus, is highly valued worldwide for its nutritional and therapeutic importance. To enhance the existing knowledge about the beneficial properties, this study investigates the antioxidant, antihyperlipidemic, and anti-inflammatory effects of black truffle extract in in vitro biochemical assays and animal study. Briefly, black truffle extract was administered orally to treat streptozotocin- (STZ-) induced diabetic Wistar rats for 45 days. At the end of the experimental duration, rats were sacrificed to perform biochemical and gene expression analyses related to lipid regulatory and inflammatory pathways. Our results indicated that total cholesterol, triglycerides, free fatty acids, phospholipids, and low-density lipoprotein in different tissues and circulation were significantly increased in diabetic rats. Furthermore, the β-hydroxy β-methylglutaryl-CoA enzyme was also significantly increased; lipoprotein lipase and lecithin-cholesterol acyltransferase enzymes were significantly decreased in diabetic rats. However, the above conditions were reversed upon black truffle extract feeding. Furthermore, black truffle extract was also found to downregulate the expression of proinflammatory cytokines (tumor necrosis factor-α and interleukin-6) and lipid regulatory genes (serum regulatory element-binding protein-1 and fatty acid synthase). The truffle extract-treated effects were comparable to glibenclamide and medication commonly used to treat diabetes mellitus. Overall, our results suggested that black truffle possesses strong antihyperlipidemic and anti-inflammatory effects on diabetic rats. These findings will enhance the current knowledge about the therapeutic importance of black truffles. They might be exploited as a possible food supplement or even as a natural source of pharmaceutical agents for diabetes prevention and treatment.

Phenolics, flavonoids content and antioxidant activities of Tuber indicum at different maturity stages

The Chinese black truffle   Tuber indicum   (Ascomycota, Pezizales) is a ectomycorrhizal fungus forming hypogeous edible ascocarps. As a famous wild edible mushroom in the world, this species also attracted an increasing interest in their chemical composition and pharmacological activity. In this study, the total phenolic content, total flavonoid content and antioxidant activities of Tuber indicum collected from July to November at different maturity stages in China were analyzed. Our results showed that T. indicum collected in July (immature stage) possessed the highest amount of flavonoids (3.89 mg/g dw) and the highest ABTS⦁+  scavenging activity (EC50 =3.73 mg/ml). In addition, those samples collected in August (moderate mature stage) contained the highest phenolics content (4.78 mg/g dw), the highest DPPH⦁  radical scavenging activity(EC50 =3.73 mg/ml) and ferric reducing activity power(243.63 μmol FeSO4 /g). The study reveals T. indicum in the early maturity stage yield significantly higher content of phenolics and flavonoids and possessed stronger antioxidant activity than those collected in other months. This study provided important data for understanding the relationship between maturity stages and truffle formation and evaluating the quality of Chinese black truffle at different maturity.

Chemical Screening of Metabolites Profile from Romanian Tuber spp

Truffles are the rarest species and appreciated species of edible fungi and are well-known for their distinctive aroma and high nutrient content. However, their chemical composition largely depends on the particularities of their grown environment. Recently, various studies investigate the phytoconstituents content of different species of truffles. However, this research is still very limited for Romanian truffles. This study reports the first complete metabolites profiles identification based on gas chromatography-mass spectrometry (GC-MS) and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF-MS) of two different types of Romania truffles: Tuber magnatum pico and Tuber brumale. In mass spectra (MS) in positive mode, over 100 metabolites were identified from 14 secondary metabolites categories: amino acids, terpenes, alkaloids, flavonoids, organic acids, fatty acids, phenolic acids, sulfur compounds, sterols, hydrocarbons, etc. Additionally, the biological activity of these secondary metabolite classes was discussed.

Mycochemical composition and insecticidal bioactivity of Algerian desert truffles extract against two stored-product insects: Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae)

The present study aimed to highlight the insecticidal activity of the Algerian desert truffle Terfezia claveryi Chatin against two post-harvest pests of rice and other cereal products, the rice weevil Sitophilus oryzae (L.), and the lesser grain borer Rhyzopertha dominica (F.), using direct contact application method with the filter paper impregnation technique. Soxhlet apparatus was used for extraction with chloroform as solvent. The major compounds in chloroform extract of T. claveryi were identified using gas chromatography-mass spectrometry (GC-MS). The two-way ANOVA was used for statistical analysis to determine the exposure time and doses with the greatest insecticidal activity. Findings of this study revealed that the major compounds were fatty acids: linoleic acid, methyl ester (14.84%), 11,14-eicosadienoic acid, methyl ester (11.55%), oleic acid, methyl ester (7.1%), and palmitic acid (6.96%). However, chamazulene (0.88%) was found to be minor compound. Our results describe for the first time the presence of chamazulene in desert truffle. The result showed also that the most potent insecticidal activity of chloroform extract of T. claveryi was found towards S. oryzea with LD₅₀ value of 162.11 µg/mL. For concentrations of 250 and 300 µg/mL, this extract was able to eradicate 96.65 ± 1.15% and 100.0 ± 0.0% of S. oryzea after 24 h of exposure. However, it caused only 47.24 ± 1.15% and 50.66 ± 1.15% of mortality of R. dominica, respectively, after 6 days. This work offers promising prospects for the use of desert truffles extracts as a potential insecticidal agent for improving quality and safety of stored foods against damage caused by stored-product pests.

Anti-angiogenic and anti-inflammatory activity of the summer truffle (Tuber aestivum Vittad.) extracts and a correlation with the chemical constituents identified therein

Fungi are a huge source of unexplored bioactive compounds. Owing to their biological activities, several fungi have shown commercial application in the health industry. Tuber aestivum Vittad. is one such edible fungi with an immense scope for practical biological applications. In the present study, the anti-angiogenic activity of petroleum ether and ethanol extracts of T. aestivum was investigated using the chick chorioallantoic membrane assay and compared to the positive controls silibinin and lenalidomide. Both the extracts showed a dose-dependent anti-angiogenic response. The extracts were also assessed for their anti-inflammatory potential by lipoxygenase-inhibition assay. The IC₅₀ values for LOX inhibition assay, computed by the Boltzmann plot, were 368.5, 147.3 and 40.2 µg/mL, for the petroleum ether extract, ethanol extract, and the positive control ascorbic acid, respectively. The ethanol extract of T. aestivum showed superior anti-angiogenic and anti-inflammatory activity than the petroleum ether extract. Compositional investigation of the extracts by GC-MS revealed the presence of various bioactive compounds. The compounds were correlated to their anti-angiogenic and anti-inflammatory activity based on a meticulous literature search.

Potentials of truffles in nutritional and medicinal applications: a review

Truffles, the symbiotic hypogeous edible fungi, have been worldwide regarded as a great delicacy because of their unique flavor and high nutritional value. By identifying their bioactive components such as phenolics, terpenoids, polysaccharides, anandamide, fatty acids, and ergosterols, researchers have paid attention to their biological activities including antitumor, antioxidant, antibacterial, anti-inflammatory, and hepatoprotective activities. In addition, numerous factors have been investigating that can affect the quality and productivity of truffles to overcome their difficulty in culturing and preserving. To provide the information for their potential applications in medicine as well as in functional food, this review summarizes the relevant literature about the biochemical composition, aromatic and nutritional benefits, and biological properties of truffles. Besides, various factors affecting their productivity and quality as well as the preservation methods are also highlighted.

Component features, odor-active volatiles, and acute oral toxicity of novel white-colored truffle Tuber japonicum native to Japan

Component analysis of a novel white-colored truffle native to Japan, Tuber japonicum, was performed to determine its characteristic features. The analysis of odor-active volatile compound showed a high contribution of 1-octen-3-ol and 3-methyl-2,4-dithiapentane to the odor of T. japonicum. Although 2,4-dithiapentane is a key odorant of well-known white truffle T. magnatum, 3-methyl-2,4-dithiapentane was detected from the ripe T. japonicum. The chemical components of T. japonicum showed no clear difference with those of edible truffles T. magnatum and T. melanosporum. It was rich in crude protein, crude fiber, and minerals (especially potassium), and low in crude fat. Glutamine and glutamic acid were detected in T. japonicum as free amino acids, while T. magnatum contained a large amount of alanine. Acute oral toxicity tests showed no abnormality, with an LD50 value of over 2000 mg/kg under the test conditions. The present study may support future market distribution of T. japonicum as a high-class foodstuff.

Chemical Composition and Antioxidant Activity of Tuber indicum from Different Geographical Regions of China

Tuber indicum, an endemic truffle species in eastern Asian, is an edible mushroom that is both an important export and widely distributed across China. Many existing studies on truffles focus on analyzing their taxonomy, population genetics, volatile organic compounds and artificial cultivation of the truffles, while little information is available about their nutrient composition and pharmacological activity, especially the relationship between chemical composition in ascocarps and their geographic distributions. This study presents a comprehensive investigation of the chemical composition of T. indicum, including free sugars, fatty acids, organic acids, phenolic acids, flavonoids, and polysaccharides, and tracks the antioxidant activity of T. indicum ascocarps collected from five geographical regions of four provinces in P. R. China: Hebei, Tibet, Yunnan, and Liaoning province. Our results showed that T. indicum collected from Qujing, Yunnan province, possessed the highest amount of free sugars (23.67 mg/g dw), total flavonoids (2.31 mg/g dw), total phenolics (4.46 mg/g dw) and the highest DPPH and ABTS radical-scavenging activities. The amount of water-soluble polysaccharides was the highest (115.24 mg/g dw) in ascocarps from Tibet, the total organic acids was the highest (22.073 mg/g dw) in ascocarps from Gongshan, and polyunsaturated fatty acids were most abundant in those from Hebei province. This study reveals that the quantity of chemical compounds in T. indicum varies by geographical origin. Detecting differences in chemical composition may provide important data for understanding the relationship between environmental factors and truffle formation, as well as quality evaluation of the commercial species T. indicum throughout China.

Black Truffle Aqueous Extract Attenuates Oxidative Stress and Inflammation in STZ-Induced Hyperglycemic Rats via Nrf2 and NF-κB Pathways

Background and Purpose: Tuber melanosporum (black truffle) has been considered as a medicinal mushroom for a long time. T. melanosporum has the ability to attenuate oxidative stress and in turn diabetes mellitus (DM). DM has become an awfully common chronic unwellness, threatening people's well-being. There are nearly 1 in 10 people in the world affected by diabetes. Oxidative stress plays a crucial role in vascular complications related to DM. Our study aimed to attain an effective treatment method to alleviate oxidative stress by scavenging free radicals and reducing inflammation, to display how truffle aqueous extract (TE) attenuates hyperglycemia. Methods: Streptozotocin (STZ)-induced hyperglycemic rat model was accustomed to check the hypoglycemic effect of black truffle by relating it with Nrf2 and NF-κB pathways. Varied biomarkers and inflammatory markers were analyzed. Results: Rats treated with TE showed reduced glucose levels, attenuated oxidative stress through regulation of SOD, CAT, VIT-E, and VIT-C. The gene expression of Nrf2 and NF-κB in rats treated with TE was increased to normal group level. The mRNA expression of inflammatory pathway genes and oxidative stress pathway genes in rats treated with TE was brought back normal. Similar results were achieved in the rats treated with standard drug, glibenclamide (GB). TE conjointly inhibits the state of inflammation within the tissues generally littered with the symptoms of hyperglycemia. Conclusion: The results of our study show the hypoglycemic impact of black truffle on STZ-induced hyperglycemia in rats via Nrf2 and NF-κB pathways, and both pathways have significant improvement that may support the hypoglycemic impact of truffle.