Potential health benefits of natural products derived from truffles: A review

Melanin Inhibitory Effect of Tuber himalayense Isolated in Incheon, Korea

There has been a growing interest in skin beauty and antimelanogenic products. Melanogenesis is the process of melanin synthesis whereby melanocytes are activated by UV light or hormone stimulation to produce melanin. Melanogenesis is mediated by several enzymes, such as tyrosinase (TYR), microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TRP-1), and TRP-2. In this study, we investigated the effect of Tuber himalayense extract on melanin synthesis in α-melanocyte-stimulating hormone (α-MSH)-treated B16F10 melanoma cells. We confirmed that T. himalayense extract was not toxic to α-MSH-treated B16F10 melanoma cells and exhibited a significant inhibitory effect on melanin synthesis at concentrations of 25, 50, and 100 μg/ml. Additionally, the T. himalayense extract inhibited melanin, TRP-1, TRP-2, tyrosinase, and MITF, which are enzymes involved in melanin synthesis, in a concentration-dependent manner. Furthermore, T. himalayense extract inhibited the mitogen-activated protein kinase (MAPK) pathways, such as extracellular signal-regulated kinase-1/2 (ERK), c-Jun N-terminal kinase (JNK), and p38. Therefore, we hypothesized that various components of T. himalayense extract affect multiple factors involved in melanogenesis in B16F10 cells. Our results indicate that T. himalayense extract could potentially be used as a new material for preparing whitening cosmetics.

Impact of ultrasonication on the contents, profiles and biofunctional properties of free and bound phenolics from white desert truffle (Tirmania nivea) and its protein fractions

The molecular and biofunctional properties of protein and phenolic fractions in edible truffles remain largely unknown. This study examined the effect of ultrasonication on the contents, profiles, and bioactive properties of free and bound phenolics (FP and BP) from desert truffle (Tirmania nivea) and its protein fractions. Protein fractions from the Osborne extraction scheme were biochemically and structurally characterized. The albumin fraction showed the highest abundance (16.8%) and yield (35.8%). Total phenolic contents were the highest in non-sonicated samples (3.5-34.1 mg/g), particularly in the albumin fraction and in whole truffle. FP extracted at 30 °C (FP-30 °C) accounted for the largest proportion of total phenolics in all protein fractions, whereas BP-30 °C and FP-60 °C were predominant in non-sonicated and sonicated truffle, respectively. The highest antioxidant activity was obtained with FP-30 °C extracts from non-sonicated albumins, globulins and truffle (91.9, 72.7 and 30.0%), followed by BP-30 °C from non-sonicated albumins (25.4%) and FP-60 °C from sonicated glutelins-1 (24.2%). High inhibition of α-amylase was evidenced in several extracts, including FP-30 °C from non-sonicated glutelins-1 (99.2%) and FP-30 °C from sonicated globulins (72.4%). Several extracts also displayed high inhibition of angiotensin I-converting enzyme (ACE), including FP-60 °C from non-sonicated glutelins-1 (65.1%) and sonicated glutelins-1 (71.1%) and globulins (64.7%). Most extracts were rich in epicatechin, gallic acid, chlorogenic acid and catechin. Correlations between phenolic content, antioxidant activity, anti-α-amylase and anti-ACE activities were influenced by sonication. Sonication reduced the particle size of the proteins and modified their structural characteristics. These findings demonstrate that white desert truffle proteins co-occur with bioactive phenolics whose functionalities can be tailored by protein fractionation and sonication.

Aromatic profile of black truffle grown in Argentina: Characterization of commercial categories and alterations associated to maturation, harvesting date and orchard management practices

Black truffle (Tuber melanosporum) is one of the most appreciated fungi in the world mainly due to its aromatic properties. In the emerging markets such as Argentina, the aroma of locally produced truffles has not been described yet. The volatile organic compounds (VOCs) from 102 black truffles from Argentina were analyzed using solid phase microextraction gas chromatography coupled with mass spectrometer detector (SPME-GC-MS). Several factors such as commercial category, maturity stage, host tree, geographical origin, and aromatic defects detected during classification were also registered and considered. As a result, 79 VOCs were detected, among which 2-methyl-propanal, 2-butanone, 2-methyl-1-propanol, butanal-3-methyl, 3-methyl-1-butanol, 2-methyl-1-butanol were present in high percentage in fresh mature truffles, whereas immature truffles were associated with 3,5-dimethoxytoluene, 2-phenyl-2-butenal, 2,3-dimethoxytoluene. The Argentine black truffles showed significant similarities in their aromatic profile when compared with their Australian and European counterparts, but with some distinctive notes.

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.

Characterization and discrimination of volatile organic compounds and lipid profiles of truffles under different treatments by UHPLC-QE Orbitrap/MS/MS and P&T-GC-MS

The lipid profiles of the truffles with different treatments were determined by ultra-high-performance liquid chromatography-Quadrupole-Exactive Orbitrap mass spectrometry (UHPLC-QE Orbitrap/MS/MS) and the volatile organic compounds (VOCs) were identified by purge-and-trap-gas chromatography-mass spectrometry (P&T-GC-MS). A total of 37 lipid molecular species and 28 VOCs were tentatively identified. Lysophophatidylcholine (LPC), triacylglycerol (TG) and sphingomyelin (SM) in heat-drying truffles, phosphatidic acid (PA) in freeze-drying and fresh truffles might be the key lipids that bound VOCs. Furthermore, the correlation between lipids and VOCs were analyzed by 19 differential lipids and 7 VOCs. The findings indicated that TG 18:2/18:2/18:2 and Cardiolipin (CL) 16:0/16:0/18:2/18:2 might be the key lipid molecule species for the formation of 2-methoxyphenol. The study helps to understand the effect of different treatments on the lipid profiles and provides the mechanistic insights to the relationship between the lipids and VOCs of truffles.

Effects of Mild Thermal Processing and Storage Conditions on the Quality Attributes and Shelf Life of Truffles (Terfezia claveryi)

This study investigated the effects of two mild thermal processing (MTP) (63 °C, 40 °C, 3 min) methods, in a brine storage medium (7-16% (w/v) NaCl) and a vinegar solution (5% vinegar, 1% salt, and 0.5% sugar), on some physicochemical properties of truffles (Terfezia claveryi). Weight loss, phenolic compounds, firmness, ascorbic acid and microbial loads were evaluated during 160 days of storage. It was demonstrated that a 5% vinegar treatment with 63 °C MTP was effective to reduce the weight loss, microbial spoilage and increased firmness and of truffles during storage. However, phenolic compounds and ascorbic acid content were decreased by heating. Both MTPs inhibited the microbial load, but the 63 °C, 3 min MTP was most effective and resulted in an immediate (3.05-3.2 log CFU/g) reduction in the total aerobic bacteria (TAB) and remained at an acceptable level during storage, while the 40 °C, 3 min MTP reduced (1.12-2 log CFU/g) of the TAB. The results of this study suggest that the 63 °C MTP and immersion in 5% vinegar increased the shelf life of the truffles without perceptible losses in quality attributes.

HPLC analysis, mycochemical contents and biological activities of two edible hypogeous ascomycetes: Tirmania nivea and Terfezia boudieri

Truffle, the hypogeous, ascomycetous macrofungus, has been recognized as a delicacy for centuries, and it is gaining elevated status in the culinary domain. The chemical composition and biological activities of aqueous extract and ground material of two desert Tunisian Tirmania nivea and Terfezia boudieri were studied for the first time. Using three assays antioxidant activity of the aqueous extract and ground material of the two truffles were investigated. Indeed, the aqueous extract and ground material of Terfezia boudieri showed the highest capacity for the DPPH scavenging test (IC₅₀ = 0.18 mg/mL) and with regard to the chelating power of iron (IC₅₀ = 0.22 mg/mL). At the same time, the highest capacity for iron reduction was recorded in the crude material of Tirmania nivea. Besides, the total phenolic, flavonoid, flavanol, tannin, and proanthocyanidin contents of both truffles extracts were determined. The ground material showed the best antibacterial activity for two ascomycetes against seven strains of bacteria. HPLC analysis of aqueous extracts showed that the predominant phenolic compounds in T. boudieri and T. nivea were gallic acid (33.25%) and myricetin (52.91%). Therefore, these truffles are a source of natural antioxidant and antimicrobial agents and could be used as a potential health food.

Extraction and trapping of truffle flavoring compounds into food matrices using supercritical CO2

A supercritical fluid extraction methodology was used to extract flavoring and bioactive compounds from truffles. Some parameters such as CO₂ flow rate (1-3 mg/mL), extraction time (15-90 min) and different trapping food matrices (grape seed oil, gelatin, agar agar and water) were optimized using response surface methodology to enhance extraction and trapping yields. The optimal conditions (2.27 mg/mL CO₂ flow rate, 82.5 min when using 40 °C and 30 MPa, with 1 mL grape seed oil as trapping matrix) obtained with Tuber melanosporum were applied to three different truffle species: Terfezia claveryi, Tuber aestivum and Tuber indicum. A total of 32 metabolites were profiled in the extracts using ultra-high-performance supercritical fluid chromatography coupled to quadrupole time-of-flight mass spectrometry. Compounds such as brassicasterol ergosta-7,22-dienol, oleic and linoleic acid were found at similar amounts in all the extracts but other molecules (e.g. fungal sterols) showed a particular distribution depending on the specie studied and whether a trapping matrix was used at the SFE outlet.

The Microbiome Structure of the Symbiosis between the Desert Truffle Terfezia boudieri and Its Host Plant Helianthemum sessiliflorum

The desert truffle Terfezia boudieri is an ascomycete fungus that forms ect-endomycorrhiza in the roots of plants belonging to Cistaceae. The fungus forms hypogeous edible fruit bodies, appreciated as gourmet food. Truffles and host plants are colonized by various microbes, which may contribute to their development. However, the diversity and composition of the bacterial community under field conditions in the Negev desert are still unknown. The overall goal of this research was to identify the rhizosphere microbial community supporting the establishment of a symbiotic association between T. boudieri and Helianthemum sessiliflorum. The bacterial community was characterized by fruiting bodies, mycorrhized roots, and rhizosphere soil. Based on next-generation sequencing meta-analyses of the 16S rRNA gene, we discovered diverse bacterial communities of fruit bodies that differed from those found in the roots and rhizosphere. Families of Proteobacteria, Planctomycetes, and Actinobacteria were present in all four samples. Alpha diversity analysis revealed that the rhizosphere and roots contain significantly higher bacterial species numbers compared to the fruit. Additionally, ANOSIM and PCoA provided a comparative analysis of the bacterial taxa associated with fruiting bodies, roots, and rhizosphere. The core microbiome described consists of groups whose biological role triggers important traits supporting plant growth and fruit body development.

Role and potentialities of bacteria associated with Tuber magnatum: A mini-review

Among the hypogeous ectomycorrhizal fungi, the white truffle Tuber magnatum Picco is the species of greatest interest, both from an ecological and economic point of view. The increasing market demand of the precious white truffle along with the fall in its natural production led to a growing interest in cultivation techniques and encouraged truffle growers and researchers to deeper investigate factors that could affect and improve T. magnatum productivity. In this context, microbial communities play a central role. Indeed, in the last few years, the hypothesis of a potential link between microbial community composition and truffle orchard productivity is arousing a greater attention. Moreover, since the value of the prized T. magnatum can vary in relation to its provenience, the need to define a reliable tracking system is also emerging and bacteria appear to be a promising tool. Accordingly, the present mini-review summarises the knowledge currently available on T. magnatum microbial communities, focusing on the role of truffle-associated bacteria and highlighting similarities and differences between samples of different origin, to address the following issues: (i) Is there a correlation between microbial taxa and truffle ground productivity? (ii) Can bacteria actually be used as markers of T. magnatum geographic origin? The identification of microorganisms able to promote T. magnatum formation may represent an important advance in the field of truffle farming. Similarly, the detection of bacterial taxa that can be used as markers of T. magnatum origin could have a considerable impact on truffle industry and trade, even at local scale.

Role of Sulfur Compounds in Vegetable and Mushroom Aroma

At the base of the food pyramid is vegetables, which should be consumed most often of all food products, especially in raw and unprocessed form. Vegetables and mushrooms are rich sources of bioactive compounds that can fulfill various functions in plants, starting from protection against herbivores and being natural insecticides to pro-health functions in human nutrition. Many of these compounds contain sulfur in their structure. From the point of view of food producers, it is extremely important to know that some of them have flavor properties. Volatile sulfur compounds are often potent odorants, and in many vegetables, belonging mainly to Brassicaeae and Allium (Amaryllidaceae), sulfur compounds determine their specific flavor. Interestingly, some of the pathways that form volatile sulfur compounds in vegetables are also found in selected edible mushrooms. The most important odor-active organosulfur compounds can be divided into isothiocyanates, nitriles, epithionitriles, thiols, sulfides, and polysulfides, as well as others, such as sulfur containing carbonyl compounds and esters, R-L-cysteine sulfoxides, and finally heterocyclic sulfur compounds found in shiitake mushrooms or truffles. This review paper summarizes their precursors and biosynthesis, as well as their sensory properties and changes in selected technological processes.

Mushrooms on the plate: Trends towards NAFLD treatment, health improvement and sustainable diets

Non-alcoholic fatty liver disease (NAFLD) is a most important cause of liver disease. Similar to other non-communicable diseases (NCD), such as obesity and type II diabetes mellitus, NAFLD can strongly affected by diet. Diet-related NCD and malnutrition are rising in all regions being a major cause of the global health, economic and environmental burdens. Mushrooms, important dietary components since the hunter-gathering communities, have increasingly gained momentum in biomedical research and therapeutics due to their interplay in metabolism traits. We emphasize here the beneficial effects of mushroom-enriched diets on the homeostasis of lipid and sugar metabolism, including their modulation, but also interfering with insulin metabolism, gut microbiota, inflammation, oxidative stress and autophagy. In this review, we describe the cellular and molecular mechanisms at the gut-liver axis and the liver-white adipose tissue (WAT) axis, that plausibly cause such positive modulation, and discuss the potential of mushroom-enriched diets to prevent or ameliorate NAFLD and related NCD, also within the shift needed towards healthy sustainable diets.

Barley: a potential cereal for producing healthy and functional foods

Barley is the fourth largest cereal crop in the world. It is mainly used for feeding, beer production and food. Barley is receiving more attention from both agricultural and food scientists because of its special chemical composition and health benefits. In comparison with other cereal crops, including wheat, rice and maize, barley grains are rich in dietary fiber (such as β-glucan) and tocols, which are beneficial to human health. It is well proved that diets rich in those chemicals can provide protection against hypertension, cardiovascular disease, and diabetes. Barley has been widely recognized to be great potential as a healthy or functional food. In this review, we present the information about the studies on physical structure of barley grain and the distribution of main chemical components, nutrient and functional composition of barley grain and their health benefits, and the approaches of improving and utilizing the nutrient and functional chemicals in barley grain. With the development of processing technologies, functional components in barley grains, especially β-glucan, can be efficiently extracted and concentrated. Moreover, nutrient and functional components in barley grains can be efficiently improved by precise breeding and agronomic approaches. The review highlights the great potential of barley used as healthy and functional foods, and may be instructive for better utilization of barley in food processing.

A review of the therapeutic and biological effects of edible and wild mushrooms

Throughout history, mushrooms have occupied an inseparable part of the diet in many countries. Mushrooms are considered a rich source of phytonutrients such as polysaccharides, dietary fibers, and other micronutrients, in addition to various essential amino acids, which are building blocks of vital proteins. In general, mushrooms offer a wide range of health benefits with a large spectrum of pharmacological properties, including antidiabetic, antioxidative, antiviral, antibacterial, osteoprotective, nephroprotective, hepatoprotective, etc. Both wild edible and medicinal mushrooms possess strong therapeutic and biological activities, which are evident from their in vivo and in vitro assays. The multifunctional activities of the mushroom extracts and the targeted potential of each of the compounds in the extracts have a broad range of applications, especially in the healing and repair of various organs and cells in humans. Owing to the presence of the aforementioned properties and rich phytocomposition, mushrooms are being used in the production of nutraceuticals and pharmaceuticals. This review aims to provide a clear insight on the commercially cultivated, wild edible, and medicinal mushrooms with comprehensive information on their phytochemical constituents and properties as part of food and medicine for futuristic exploitation. Future outlook and prospective challenges associated with the cultivation and processing of these medicinal mushrooms as functional foods are also discussed.

Tour of Truffles: Aromas, Aphrodisiacs, Adaptogens, and More

Truffles are the fruiting bodies of ascomycete fungi that form underground. Truffles are globally valued, culturally celebrated as aphrodisiacs, and highly sought-after delicacies in the culinary world. For centuries, naturalists have speculated about their mode of formation, and in cultures surrounding the Mediterranean Sea, many species have been prized as a delectable food source. Truffle fruiting bodies form underground and emit a variety of volatile organic compounds (VOCs). Truffle volatiles are believed to have evolved to attract animals that disperse their spores. The main VOCs identified from truffles include sulfur compounds, such as dimethyl sulfide (DMS) and dimethyl disulfide (DMDS); in addition, 1-octen-3-ol and 2-methyl-1-propanol have been found in most truffle species. Humans use pigs and dogs trained to detect truffle VOCs in order to find these prized subterranean macrofungi. Truffles have pharmacological potential, but until more reliable cultivation methods become available their high price means they are unlikely to see widespread use as medicinals.

Increased Extracellular Saponin Production after the Addition of Rutin in Truffle Liquid Fermentation and Its Antioxidant Activities

Saponins possess a variety of pharmacological effects and exhibit great potential in the food industry as bioactive substances. In this study, extracellular saponin production via the liquid fermentation of Tuber melanosporum occurred with the addition of rutin. For this purpose, medium composition and culture conditions were optimized using single-factor experiments and an orthogonal experiment design. The optimal medium consisted of glucose (43.5 g/L), peptone (6 g/L), KH2PO4 (1.15 g/L), NaCl (0.2 g/L), vitamin B2 (0.082 g/L), vitamin B6 (0.1 g/L), vitamin C (0.02 g/L), and rutin (4.8 g/L). The culture conditions were as follows: 12.5% (v/v) inoculation, medium volume of 50 mL/250 mL flask, culture temperature of 24 °C, shaker speed of 190 rpm, initial pH of 5.7, and culture time of 96 h. Finally, a maximal extracellular saponin content of 0.413 g/L was obtained, which was 134.7% higher than that in the base medium. Rutin proved to be an excellent promoter, because the saponin production was increased by 50.2% compared to that in the optimized medium without rutin. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, hydroxyl radical scavenging activity, and ferric reducing antioxidant power of truffle saponins reached 94.13%, 79.26%, and 42.22 mM, respectively. This study provides a useful strategy for fungal bioactive saponin production by liquid fermentation with the addition of flavonoid compounds.

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.

Chemical composition and evaluation of antioxidant, antimicrobial and antiproliferative activities of Tuber and Terfezia truffles

Ten truffle species of Tuber and Terfezia genera were chemical characterized, assessing their proximate composition, individual nutrient compounds and some bioactive molecules. The bioactive properties of these species were also evaluated, namely their antioxidant, antimicrobial and cytotoxic potential. Carbohydrates were the main macronutrients present in truffles, followed by proteins. Furthermore, the levels of polyunsaturated fatty acids (PUFA), subsequently presented as a percentage, were higher in truffles (38.2-79.3%) except in Tuber magnatum and Terfezia arenaria, which have a more saturated fatty acids (SFA) profile (70.7% and 53.7%, respectively). Comparing the species, T. magnatum revealed the highest levels of total phenolic compounds (TPC) (290 mg GAE/100 g truffle), as also the best results in the four methods used to evaluate the antioxidant activity. On the other hand, only five extracts obtained from some studied truffle species (Terfezia magnusii, Tuber aestivum, Tuber gennadii, and Tuber melanosporum) showed a slight inhibition of microbial growth, tested against different bacteria. Terfezia and T. gennadii extracts, showed potential to inhibit the cellular growth of NCI-H460, HeLa, HepG2, and MCF-7 cell lines (GI₅₀ concentrations range: 19-78, 33-301, 83-321 and 102-321 µg/mL, respectively), indicating anti-proliferative activity. Nevertheless, T. arenaria revealed some potential hepatotoxicity, inhibiting the growth of PLP2 cells (GI₅₀ concentration of 220 µg/mL), a primary cell culture obtained from porcine liver.

An Overview on Truffle Aroma and Main Volatile Compounds

Truffles are underground edible fungi that grow symbiotically with plant roots. They have been globally considered as one of the most expensive foods because of their rarity, unique aroma, and high nutritional value as antioxidant, anti-inflammatory, antiviral, hepatoprotective, anti-mutagenic, antituberculoid immunomodulatory, antitumor, antimicrobial, and aphrodisiac. The unique flavor and fragrance of truffles is one of the main reasons to get worldwide attraction as a food product. So, the aim of this review was to summarize the relevant literature with particular attention to the active aroma components as well as the various sample preparation and analytical techniques used to identify them. The major analytical methods used for the determination of volatile organic compounds (VOC) in truffles are gas chromatography (GC), proton-transfer-reaction mass spectrometry (PTR-MS), and electronic nose sensing (EN). In addition, factors influencing truffle aroma are also highlighted. For this reason, this review can be considered a good reference for research concerning aroma profiles of different species of truffles to deepen the knowledge about a complex odor of various truffles.

Agrobacterium tumefaciens-Mediated Genetic Transformation of the Ect-endomycorrhizal Fungus Terfezia boudieri

Mycorrhizal desert truffles such as Terfezia boudieri, Tirmania nivea, and Terfezia claveryi, form mycorrhizal associations with plants of the Cistaceae family. These valued truffles are still collected from the wild and not cultivated under intensive farming due to the lack of basic knowledge about their biology at all levels. Recently, several genomes of desert truffles have been decoded, enabling researchers to attempt genetic manipulations to enable cultivation. To execute such manipulations, the development of molecular tools for genes transformation into truffles is needed. We developed an Agrobacterium tumefaciens-mediated genetic transformation system in T. boudieri. This system was optimized for the developmental stage of the mycelia explants, bacterial optical density, infection and co-cultivation durations, and concentrations of the selection antibiotics. The pFPL-Rh plasmid harboring hph gene conferring hygromycin resistance as a selection marker and the red fluorescent protein gene were used as visual reporters. The optimal conditions were incubation with 200 μM of acetosyringone, attaining a bacterial optical density of 0.3 OD₆₀₀; transfer time of 45 min; and co-cultivation for 3 days. This is the first report on a transformation system for T. boudieri, and the proposed protocol can be adapted for the transformation of other important desert truffles as well as ectomycorrhizal species.

Different maturities drive proteomic and metabolomic changes in Chinese black truffle

Chinese black truffle (Tuber indicum) is rich in nutrition. However, commercial interests lead to the aroma components and nutrients of T. indicum being greatly affected by overexploitation without consideration of their maturity. This study investigated the proteomic and metabolomic profiles of truffle fruiting bodies at different maturities using a meta-proteomic approach. Among the 3007 identified proteins, the most up-expressed protein in the mature ascocarps was involved in the peptidyl-diphthamide biosynthetic process, while thiamine metabolism was the most differentially expressed pathway. Furthermore, a total of 54 metabolites identified upon LC-MS differed significantly, with 30 being up-expressed in the mature ascocarps, including organic acids, carnitine substances and polysaccharides. Additionally, the ash, protein, fat, crude fiber and total sugar contents were all higher in the mature ascocarps. Overall, our findings reveal that mature truffles have a higher nutritional value, providing a basis for further exploring protein functionality of T. indicum at different maturities.

Comparison of the Partial Structure and Antioxidant Activity of Polysaccharides from Two Species of Chinese Truffles

Truffles are world-renowned premium commodities. Due to their unique aroma and rarity, the price of truffles has always been very high. In this study, Diethylaminoethyl anion exchange chromatography and gel filtration were employed for polysaccharide purification from two different species of Chinese truffles. Three polysaccharide fractions were obtained from Tuber panzhihuanense and referred to as TPZ-NP, TPZ-I, and TPZ-II. Additionally, two polysaccharide fractions were purified from T. pseudoexcavatum (TPD-NP and TPD-I). The results of structural elucidation indicated that the polysaccharide from different species showed different monosaccharide composition and linkage units, as well as molecular weight. Two of the polysaccharide fractions with the highest yield, TPZ-I and TPD-I, were chosen for biological testing. The results indicated that both fractions displayed antioxidant properties through mediation of the intestinal cellular antioxidant defense system, which could protect cultured intestinal cells from oxidative stress-induced damage and cell viability suppression. The TPD-I fraction showed stronger antioxidant effects, which may be due to the difference in structure. Further study on the structure-activity relationship is needed to be done.

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.

Effects of gamma irradiation on the shelf-life and bioactive compounds of Tuber aestivum truffles packaged in passive modified atmosphere

The effects of gamma irradiation (0.5, 1.0, 1.5 and 2.5 kGy doses) on Tuber aestivum packaged under modified atmosphere was evaluated. The respiration rate, microbial populations, sensory characteristics and content of bioactive compounds (total carbohydrates, chitins, β-glucans, proteins, total phenols and sterols) were monitored from immediately after treatment up to day 42 of storage at 4 °C. All the irradiation treatments tested reduced the microbial groups studied by more than 3 log cfu/g. Increasing irradiation doses slowed down the subsequent microbial development throughout the conservation period for all the groups studied. The irradiation treatments did not negatively affect truffle sensory characteristics. Only a slight visible superficial yeast growth was detected at the end of the shelf-life in all doses applied. Total carbohydrate content, chitins, β-glucans and proteins levels were not affected after irradiation. However, sterols, particularly stigmasterol, slightly decreased after irradiation, while levels of phenolic compounds doubled during storage. Gamma irradiation (2.5 kGy) could be used to extend the shelf-life of summer truffles packaged under modified atmosphere, since no remarkable reduction of bioactive compounds were noticed after 42 days of storage, and their sensory and microbial parameters were of higher quality than those of non-irradiated controls.

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.

Colonization by Tuber melanosporum and Tuber indicum affects the growth of Pinus armandii and phoD alkaline phosphatase encoding bacterial community in the rhizosphere

The synthesis of truffle ectomycorrhizae and the ecology of truffle-colonized seedlings in the early symbiotic stage are important for the successful truffle cultivation. In this study, two black truffle species, Tuber melanosporum and Tuber indicum, were selected to colonize Pinus armandii seedlings. 2, 4, 6 and 8 months after inoculation, the growth performance of the host and the rhizosphere soil properties were detected. The dynamic changes of two mating type genes in substrate were also monitored to assess the sexual distribution of truffles. Additionally, the variation of soil bacterial communities encoded by phoD alkaline phosphatase genes was investigated through next-generation sequencing. The results indicated that both T. melanosporum and T. indicum colonization promoted the growth of P. armandii seedlings to some extent, including improving their biomass, total root surface area, root superoxide dismutases and peroxidase activity. The organic matter and available phosphorus in rhizosphere soil were also significantly enhanced by two truffles' colonization. The phoD-harboring bacterial community structure was altered by both truffles, and T. melanosporum decreased their diversity or richness on the 6th and 8th month after inoculation. Pseudomonas, Xanthomonas, and Sinorhizobium, a N₂-fixer with phoD genes, were found more abundant in truffle-colonized treatments. The mating type distribution of the two truffles was uneven, with MAT1-1-1 gene occupying the majority. Overall, T. melanosporum and T. indicum colonization affected the micro-ecology of truffle symbionts during the early symbiotic stage. These results could give us a better understanding on the truffle-plant-soil-microbe interactions, which would be beneficial to the subsequent truffle cultivation.

Multi-platform metabolomic approach to discriminate ripening markers of black truffles (Tuber melanosporum)

Black truffle is characterized by a black ascocarp and white veins. This hypogeous fruit body is known for its aroma. Understanding metabolic variation during ripening can shed light on truffle biology. In this work, the comprehensive polar metabolome and the volatile organic compounds of T. melanosporum were studied at different ripening stages by means of a metabolomic approach using GC-MS. Multivariate statistical data analysis indicated that the metabolic profile changed during ripening and that the metabolites that mostly discriminated truffles in the early ripening stages belonged to the classes of carbohydrates, while free fatty acids and amino acids, among which precursors of VOCs, characterized the late stages of ripening. Principal component analysis of the volatilome indicated that dimethylsulfide and dimethyldisulfide characterized most of the samples collected in December-January, while 1-octen-3-ol samples collected in February-March.

LC-MS-Based Metabolomic Approach Revealed the Significantly Different Metabolic Profiles of Five Commercial Truffle Species

Truffles are ascomycetous ectomycorrhizal fungi that have elevated status in the culinary field due to their unique aroma and taste as well as their nutritional value and potential biological activities. Tuber melanosporum, T. indicum, T. panzhihuanense, T. sinoaestivum, and T. pseudoexcavatum are five commercial truffle species mainly distributed in Europe or China. In this study, an untargeted metabolomics technology based on an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was applied to analyze the metabolic profiles and variations among these five truffle species. In our results, a total of 2376 metabolites were identified under positive ion mode, of which 1282 had significantly differential amounts and covered 110 pathways or metabolisms. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) revealed a clear separation from each of these five truffles, indicating a significantly different metabolic profile among them, with the biggest difference between T. melanosporum and the other four truffles. The differential metabolites covered various chemical categories, and a detailed analysis was performed for nine metabolic categories, including amino acids, saccharides and nucleosides, organic acids, alkaloids, flavonoids, carnitines, phenols and alcohols, esters, and sulfur compounds. For each of the nine categories, most of metabolites predominantly accumulated in T. melanosporum compared with the other four truffles. Meanwhile, there were significant differences of the average ion intensity in each category among the five truffles, e.g., higher amounts of amino acids was detected in T. panzhihuanense and T. pseudoexcavatum; T. indicum contained significantly more carnitines, while there were more alkaloids in T. melanosporum. Additionally, some metabolites with biological activities were discussed for each category, such as acetyl-L-carnitine, adenine, neobavaisoflavone, and anandamide. Generally, this study may provide the valuable information regarding the variation of the metabolic composition of these five commercial truffle species, and the biological significance of these metabolites was uncovered to explore the metabolic mechanisms of truffles, which would be helpful for further research on the compounds and potential biological functions in truffles that have not yet been investigated.

Essential Elements as a Distinguishing Factor between Mycorrhizal Potentials of Two Cohabiting Truffle Species in Riparian Forest Habitat in Serbia

True truffles (Tuber sp.) that establish ectomycorrhizal symbiosis (ECM) with trees in the Mediterranean and temporal regions have species specific abilities to assimilate soil born elements. Suitable habitats are usually inhabited by few truffle species, while distinguishing their symbiotic potentials appeared very difficult. Two species that commonly inhabit riparian forests in Serbia are the most prized one, Tuber magnatum Pico (Piedmont white truffle) and not so highly valued Tuber brumale Vitt. In order to assess potential differences between their assimilation and accumulation abilities, the differences between contents of elements that may be the subjects of the symbiotic trade between the host plant and fungi were evaluated in accumulation target (ascocarps) and their source (the soil). Essential (K, Na, Ca, Mg, Fe, P, S, and Zn) and essential trace elements (Co, Cr, Cu, Mn, and Se) in truffles and soil samples were determined by means of inductively coupled plasma with optical emission spectrometry (ICP-OES). Their concentrations (mg/kg) in ascocarps were in the range from 1.364±0.591 (Cr) to 10760.862±16.058 (K), while in soil ranged from 23.035±0.010 (Cr) to 20809.300±122.934 (Fe). Element accumulation potential (bioaccumulation factor) was calculated in the system truffle/soil. The statistical approaches were used for establishing the differences, while the possible differentiation between symbiotic potentials of two mycelia in the defined soil conditions was discussed.

Potent in Vitro α-Glucosidase Inhibition of Secondary Metabolites Derived from Dryopteris cycadina

α-glucosidase is responsible for the hydrolysis of complex carbohydrates into simple absorbable glucose and causes postprandial hyperglycemia. α-glucosidase inhibition is thus the ideal target to prevent postprandial hyperglycemia. The present study was therefore designed to analyze the effects of various compounds isolated from Dryopteris cycadina against α-glucosidase including β-Sitosterol 1, β-Sitosterol3-O-β-d-glucopyranoside 2, 3, 5, 7-trihydroxy-2-(p-tolyl) chorman-4-one 3, Quercetin-3-0-β-d-glucopyranoside (3^/→0-3^///)- β-d- Quercetin -3-0- β –d-galactopyranoside 4 and 5, 7, 4^/-Trihydroxyflavon-3-glucopyranoid 5. The in vitro spectrophotometric method was used for the analysis of test compounds against possible inhibition. Similarly, molecular docking studies were performed using the MOE software. These compounds showed concentration-dependent inhibition on α-glucosidase, and compounds 1 (IC₅₀: 143 ± 0.47 µM), 3 (IC₅₀:133 ± 6.90 µM) and 5 (IC₅₀: 146 ± 1.93 µM) were more potent than the standard drug, acarbose (IC₅₀: 290 ± 0.54 µM). Computational studies of these compounds strongly supported the in vitro studies and showed strong binding receptor sensitivity. In short, the secondary metabolites isolated from D. cycadina demonstrated potent α-glucosidase inhibition that were supported by molecular docking with a high docking score.

Anti-Parkinson Potential of Silymarin: Mechanistic Insight and Therapeutic Standing

Parkinson’s disease (PD) involves aggregation of α-synuclein and progressive loss of dopaminergic neurons. Pathogenesis of PD may also be related to one’s genetic background. PD is most common among geriatric population and approximately 1–2% of population suffers over age 65 years. Currently no successful therapies are in practice for the management of PD and available therapies tend to decrease the symptoms of PD only. Furthermore, these are associated with diverse range of adverse effects profile. The neuroprotective effects of polyphenols are widely studied and documented. Among phytochemicals, silymarin is one of the most widely used flavonoids because of its extensive therapeutic properties and has been indicated in pathological conditions of prostate, CNS, lungs, skin, liver, and pancreas. Silymarin is a mixture of flavonolignans (silybin, isosilybin, and silychristin), small amount of flavonoids (taxifolin), fatty acids, and other polyphenolic compounds extracted from the dried fruit of Silybum marianum and is clinically used for hepatoprotective effects since ancient times. Neuroprotective effects of silymarin have been studied in various models of neurological disorders such as Alzheimer’s disease, PD, and cerebral ischemia. The aim of the present study is to provide a comprehensive review of the recent literature exploring the effects of silymarin administration on the progression of PD. Reducing oxidative stress, inflammatory cytokines, altering cellular apoptosis machinery, and estrogen receptor machinery are mechanisms that are responsible for neuroprotection by silymarin, as discussed in this review. Additionally, because of poor aqueous solubility, the bioavailability of silymarin is low and only 23–47% of silymarin reaches systemic circulation after oral administration. Our primary focus is on the chemical basis of the pharmacology of silymarin in the treatment of PD and its mechanisms and possible therapeutic/clinical status while addressing the bioavailability limitation.

Antimicrobial activity of gallic acid against food-related Pseudomonas strains and its use as biocontrol tool to improve the shelf life of fresh black truffles

Refrigeration alone or in combination with other technologies represents the main tool used in the last decades to preserve the freshness of black truffles. This is principally due to the delicateness and vulnerability of this edible hypogeous fungus, so that other invasive preservation practices cannot be adopted. However, the proliferation of some microbial species during the cold storage still represents an unsolved problem. Pseudomonads are among the main spoiler bacteria responsible for the deterioration of refrigerated black truffles. Their growth ability at low temperatures requires the use of additional hurdles to prolong the shelf-life of truffles without altering their major features. The use of natural compounds may represent an alternative system for the biocontrol of this kind of product. Specifically, gallic acid (GA) is a phenolic acid naturally present in different foods, whose effectiveness was in vitro demonstrated against Pseudomonas spp. In our study, we reported the antimicrobial activity expressed by GA not only in vitro, using as target bacteria Pseudomonas putida DSMZ 291^T, P. fluorescens DSMZ 50090^T, P. fragi DSMZ 3456^T and Pseudomonas spp. P30-4, previously isolated from black truffles, but also in situ on fresh black truffles stored at 4°C for 28days. Our results showed Minimum Inhibitory Concentrations (MIC) of 2.5mg/mL GA for all tested strains, except for P. fluorescens DSMZ 50090^T, having a MIC corresponding to 5mg/mL GA. The Minimum Bactericidal Concentration (MBC) was 10mg/mL for all strains. The analysis of kinetic parameters showed that the survival declined passing from 2.5 to 10mg/mL GA concentrations, with P. fluorescens confirmed to be the most resistant strain. Moreover, images obtained from Scanning Electron Microscopy revealed that Pseudomonas cells were strongly injured by the treatment with GA at 2.5mg/mL concentration, displaying visible pores on the cellular surfaces, absence of flagella and lysis with loss of cytoplasmic material. The storage test performed on fresh black truffles confirmed in situ the GA antimicrobial activity observed in vitro, with a drastic reduction not only of Pseudomonas spp., but also of the other assessed microbial groups, including Enterobacteriaceae and Eumycetes. Finally, sensory analysis established the absence of off-flavours and the preservation of positive features in black truffles treated with 2.5mg/mL GA and stored for 28 d at 4°C. The results obtained in this study suggest that GA is a potential biocontrol tool to decontaminate and preserve fresh black truffles during refrigerated storage.