Enhanced production of sulforaphane by exogenous glucoraphanin hydrolysis catalyzed by myrosinase extracted from Chinese flowering cabbage (Brassica rapa var. parachinensis)

Computer-driven Evolution of Myrosinase from the Cabbage Aphid for Efficient Production of (R)-Sulforaphane

Myrosinase (Myr) catalyzes the hydrolysis of glucosinolates, yielding biologically active metabolites. In this study, glucoraphanin (GRA) extracted from broccoli seeds was effectively hydrolyzed using a Myr-obtained cabbage aphid (Brevicoryne brassicae) (BbMyr) to produce (R)-sulforaphane (SFN). The gene encoding BbMyr was successfully heterologously expressed in Escherichia coli, resulting in the production of 1.6 g/L (R)-SFN, with a remarkable yield of 20.8 mg/gbroccoli seeds, achieved using recombination E. coli whole-cell catalysis under optimal conditions (pH 4.5, 45 °C). Subsequently, BbMyr underwent combinatorial simulation-driven mutagenesis, yielding a mutant, DE9 (N321D/Y426S), showing a remarkable 2.91-fold increase in the catalytic efficiency (kcat/KM) compared with the original enzyme. Molecular dynamics simulations demonstrated that the N321D mutation in loopA of mutant DE9 enhanced loopA stability by inducing favorable alterations in hydrogen bonds, while the Y426S mutation in loopB decreased spatial resistance. This research lays a foundation for the environmentally sustainable enzymatic (R)-SFN synthesis.

Dietary isothiocyanates and anticancer agents: exploring synergism for improved cancer management

Human studies have shown the anticancer effects of dietary isothiocyanates (ITCs), but there are some inconsistencies, and more evidence supports that such anticancer effect is from higher doses of ITCs. The inconsistencies found in epidemiological studies may be due to many factors, including the biphasic dose-response (so called hormetic effect) of ITCs, which was found to be more profound under hypoxia conditions. In this comprehensive review, we aim to shed light on the intriguing synergistic interactions between dietary ITCs, focusing on sulforaphane (SFN) and various anticancer drugs. Our exploration is motivated by the potential of these combinations to enhance cancer management strategies. While the anticancer properties of ITCs have been recognized, our review delves deeper into understanding the mechanisms and emphasizing the significance of the hormetic effect of ITCs, characterized by lower doses stimulating both normal cells and cancer cells, whereas higher doses are toxic to cancer cells and inhibit their growth. We have examined a spectrum of studies unraveling the multifaceted interaction and combinational effects of ITCs with anticancer agents. Our analysis reveals the potential of these synergies to augment therapeutic efficacy, mitigate chemoresistance, and minimize toxic effects, thereby opening avenues for therapeutic innovation. The review will provide insights into the underlying mechanisms of action, for example, by spotlighting the pivotal role of Nrf2 and antioxidant enzymes in prevention. Finally, we glimpse ongoing research endeavors and contemplate future directions in this dynamic field. We believe that our work contributes valuable perspectives on nutrition and cancer and holds promise for developing novel and optimized therapeutic strategies.

Effect of Ultrasound and High Hydrostatic Pressure Processing on Quality and Bioactive Compounds during the Shelf Life of a Broccoli and Carrot By-Products Beverage

Vegetable beverages are a convenient strategy to enhance the consumption of horticultural commodities, with the possibility of being fortified with plant by-products to increase functional quality. The main objective was to develop a new veggie beverage from broccoli stalks and carrot by-products seasoned with natural antioxidants and antimicrobial ingredients. Pasteurization, Ultrasound (US), and High Hydrostatic Pressure (HHP) and their combinations were used as processing treatments, while no treatment was used as a control (CTRL). A shelf-life study of 28 days at 4 °C was assayed. Microbial load, antioxidant capacity, and bioactive compounds were periodically measured. Non-thermal treatments have successfully preserved antioxidants (~6 mg/L ΣCarotenoids) and sulfur compounds (~1.25 g/L ΣGlucosinolates and ~5.5 mg/L sulforaphane) throughout the refrigerated storage, with a longer shelf life compared to a pasteurized beverage. Total vial count was reduced by 1.5-2 log CFU/mL at day 0 and by 6 log CFU/mL at the end of the storage in HHP treatments. Thus, the product developed in this study could help increase the daily intake of glucosinolates and carotenoids. These beverages can be a good strategy to revitalize broccoli and carrot by-products with high nutritional potential while maintaining a pleasant sensory perception for the final consumer.

Interplay of broccoli/broccoli sprout bioactives with gut microbiota in reducing inflammation in inflammatory bowel diseases

Inflammatory Bowel Diseases (IBD) are chronic, reoccurring, and debilitating conditions characterized by inflammation in the gastrointestinal tract, some of which can lead to more systemic complications and can include autoimmune dysfunction, a change in the taxonomic and functional structure of microbial communities in the gut, and complicated burdens in a person's daily life. Like many diseases based in chronic inflammation, research on IBD has pointed towards a multifactorial origin involving factors of the person's lifestyle, immune system, associated microbial communities, and environmental conditions. Treatment currently exists only as palliative care, and seeks to disrupt the feedback loop of symptoms by reducing inflammation and allowing as much of a return to homeostasis as possible. Various anti-inflammatory options have been explored, and this review focuses on the use of diet as an alternative means of improving gut health. Specifically, we highlight the connection between the role of sulforaphane from cruciferous vegetables in regulating inflammation and in modifying microbial communities, and to break down the role they play in IBD.

Supplementation of cooked broccoli with exogenous moringa myrosinase enhanced isothiocyanate formation

Brassica vegetables, especially broccoli, have health benefits such as anticancer activity, which are attributed to isothiocyanate (ITC), products of glucosinolate hydrolysis. This study aimed to explore the effect of cooking time and addition of exogenous myrosinase (MYR) from moringa seeds on the yield of ITCs. The results showed that raw broccoli produced a significantly high amount of ITCs, which decreased by almost 40% after microwaving the broccoli for 1 min. Introducing exogenous MYR by adding ground moringa seeds to cooked broccoli caused a notable increase in ITC of 38%. At pH 4.0-6.0, MYR showed optimal activity, and the thermal stability of MYR from moringa seeds was better than that from broccoli. The kinetic parameters indicated that MYR from moringa seeds had a higher affinity to sinigrin than that from broccoli seeds. This study was novel in reporting that adding ground moringa seeds to cooked broccoli enhanced ITC formation.

Microorganisms-An Effective Tool to Intensify the Utilization of Sulforaphane

Sulforaphane (SFN) was generated by the hydrolysis of glucoraphanin under the action of myrosinase. However, due to the instability of SFN, the bioavailability of SFN was limited. Meanwhile, the gut flora obtained the ability to synthesize myrosinase and glucoraphanin, which could be converted into SFN in the intestine. However, the ability of microorganisms to synthesize myrosinase in the gut was limited. Therefore, microorganisms with myrosinase synthesis ability need to be supplemented. With the development of research, microorganisms with high levels of myrosinase synthesis could be obtained by artificial selection and gene modification. Researchers found the SFN production rate of the transformed microorganisms could be significantly improved. However, despite applying transformation technology and regulating nutrients to microorganisms, it still could not provide the best efficiency during generating SFN and could not accomplish colonization in the intestine. Due to the great effect of microencapsulation on improving the colonization ability of microorganisms, microencapsulation is currently an important way to deliver microorganisms into the gut. This article mainly analyzed the possibility of obtaining SFN-producing microorganisms through gene modification and delivering them to the gut via microencapsulation to improve the utilization rate of SFN. It could provide a theoretical basis for expanding the application scope of SFN.

Characterization of a Novel Myrosinase with High Activity from Marine Bacterium Shewanella baltica Myr-37

Myrosinase can hydrolyze glucosinolates to generate isothiocyanates, which have cancer prevention and anti-cancer properties. The main sources of myrosinase are cruciferous plants. To further improve the efficiency of isothiocyanates preparation, it is necessary to explore novel sources of myrosinases. In this study, we described a bacterium, Shewanella baltica Myr-37, isolated from marine mud, capable of producing a novel myrosinase (Smyr37) with a molecular weight of 100 kDa. The crude enzyme of Smyr37 showed the highest activity at 50 °C and pH 8.0. The sinigrin- and glucoraphanin-hydrolyzing activities of Smyr37 were 6.95 and 5.87 U/mg, respectively. Moreover, when the reaction temperature was 40 °C and pH was 7.0, the crude enzyme of Smyr37 could efficiently degrade glucoraphanin into sulforaphane within 25 min with a yield of 0.57 mg/mL. The corresponding conversion efficiency of sulforaphane from glucoraphanin was 89%. In summary, S. baltica Myr-37 myrosinase Smyr37, a novel myrosinase, can be used in the preparation of isothiocyanates.

Exogenous Selenium Treatment Promotes Glucosinolate and Glucoraphanin Accumulation in Broccoli by Activating Their Biosynthesis and Transport Pathways

Supplementation using selenium (Se) on plants is an effective and widely used approach. It can not only be converted to more Se rich compounds but promote the accumulation of glucosinolates (GSLs) with anti-carcinogenic properties. However, the molecular mechanism of Se in regulating GSLs synthesis remains unclear. In the present study, we analyzed the effects of Se treatment (50 μM sodium selenite) on GSLs, glucoraphanin (4MSOB), and sulforaphane compounds in broccoli tissues. The transcript levels of genes involved in sulfur absorption and transport, GSLs biosynthesis, translocation, and degradation pathways were also evaluated. The study showed that Se treatment remarkably promoted the accumulation of total sulfur and total Se contents and increased Trp-derived GSLs levels in roots by 2 times. The 4MSOB concentration and sulforaphane content in fresh leaves was increased by 67% and 30% after Se treatment, respectively. For genes expressions, some genes involved in sulfate uptake and transporters, GSLs biosynthesis, and transporters were induced strongly upon Se exposure. Results revealed that exogenous Se treatment promotes the overaccumulation of GSLs and 4MSOB content in broccoli by activating the transcript levels of genes involved in sulfur absorption, GSLs biosynthesis, and translocation pathways.

Assessment of Methodological Pipelines for the Determination of Isothiocyanates Derived from Natural Sources

Isothiocyanates are biologically active secondary metabolites liberated via enzymatic hydrolysis of their sulfur enriched precursors, glucosinolates, upon tissue plant disruption. The importance of this class of compounds lies in their capacity to induce anti-cancer, anti-microbial, anti-inflammatory, neuroprotective, and other bioactive properties. As such, their isolation from natural sources is of utmost importance. In this review article, an extensive examination of the various parameters (hydrolysis, extraction, and quantification) affecting the isolation of isothiocyanates from naturally-derived sources is presented. Overall, the effective isolation/extraction and quantification of isothiocyanate is strongly associated with their chemical and physicochemical properties, such as polarity-solubility as well as thermal and acidic stability. Furthermore, the successful activation of myrosinase appears to be a major factor affecting the conversion of glucosinolates into active isothiocyanates.

Sulphoraphane Affinity-Based Chromatography for the Purification of Myrosinase from Lepidium sativum Seeds

Sulforaphane and other natural isothiocyanates released from the respective plant glucosinolates by the plant enzyme myrosinase (β-thioglucoside glucohydrolase) show extensive anticancer and antimicrobial effects. In this study, myrosinase from garden cress (Lepidium sativum) seeds was purified to electrophoretic homogeneity by a fast and easy strategy consisting of fractionation by isoelectric precipitation with ammonium sulphate (AS) and affinity chromatography using sulforaphane (SFN) attached to cellulose resin. The overall purification of enzyme with respect to crude extract was 169-fold and recovery of 37%. Under non-reducing conditions, two protein bands exhibiting myrosinase activity with masses of about 114 and 122 kDa, respectively, and a 58 kDa protein band with no activity were detected by SDS-PAGE and zymography on polyacrylamide gel. MALDI-Tof/Tof of tryptic fragments obtained from the respective protein bands detected sequence motifs homologous to the regions responsible for glycoside-substrate binding and similarities to members of the enzyme subfamilies β-glucosidases and myrosinases GH. The enzyme hydrolyzed both the natural (sinigrin, sinalbin, glucoraphanin) and the synthetic (p-nitrophenol-β-D-glucopyranoside (pNPG)) substrates. The highest catalytic activity of purified enzyme was achieved against sinigrin. The K_M and V_max values of the enzyme for sinigrin were found to be 0.57 mM, and 1.3 mM/s, respectively. The enzyme was strongly activated by 30 μM ascorbic acid. The optimum temperature and pH for enzyme was 50 °C and pH 6.0, respectively. The purified enzyme could be stored at 4 °C and slightly acidic pH for at least 45 days without a significant decrease in specific activity.

Biochemical Characterization of a Novel Myrosinase Rmyr from Rahnella inusitata for High-Level Preparation of Sulforaphene and Sulforaphane

Myrosinase is a biotechnological tool for the preparation of sulforaphane and sulforaphene with a variety of excellent biological activities. In this study, a gene encoding the novel glycoside hydrolase family 3 (GH3) myrosinase Rmyr from Rahnella inusitata was heterologously expressed in Escherichia coli BL21 (DE3). The purified Rmyr shows the highest activity at 40 °C and pH 7.0; meanwhile, its half-life at 30 °C reaches 12 days, indicating its excellent stability. Its sinigrin-, glucoraphenin-, and glucoraphanin-hydrolyzing activities were 12.73, 4.81, and 6.99 U/mg, respectively. Rmyr could efficiently degrade the radish seed-derived glucoraphenin and the broccoli seed-derived glucoraphanin into sulforaphene and sulforaphane within 10 min with the highest yields of 5.07 mg/g radish seeds and 9.56 mg/g broccoli seeds, respectively. The highest conversion efficiencies of sulforaphane from glucoraphanin and sulforaphene from glucoraphenin reached up to 92.48 and 97.84%, respectively. Therefore, Rmyr is a promising and potent biocatalyst for efficient and large-scale preparation of sulforaphane and sulforaphene.

Preparation of Sulforaphene from Radish Seed Extracts with Recombinant Food-Grade Yarrowia lipolytica Harboring High Myrosinase Activity

Sulforaphene prepared from glucoraphenin by myrosinase is one of the main active ingredients of radish, which has various biological activities and brilliant potential for food and pharmaceutical applications. In this paper, a recombinant food-grade yeast transformant 20-8 with high-level myrosinase activity was constructed by over-expressing a myrosinase gene from Arabidopsis thaliana in Yarrowia lipolytica. The highest myrosinase activity produced by the transformant 20-8 reached 44.84 U/g dry cell weight when it was cultivated in a 10 L fermentor within 108 h. Under the optimal reaction conditions, 6.1 mg of sulforaphene was yielded from 1 g of radish seeds under the catalysis of the crude myrosinase preparation (4.95 U) at room temperature within 1.5 h. What is more is that when the whole yeast cells harboring myrosinase activity were reused 10 times, the sulforaphene yield still reached 92.53% of the initial level. Therefore, this efficient approach has broad application prospects in recyclable and large-scale preparation of sulforaphene.

The effect of processing and cooking on glucoraphanin and sulforaphane in brassica vegetables

Brassica vegetables are widely consumed mostly after processing and cooking. These processing and cooking methods not only can affect the taste, texture, flavor and nutrients of these vegetables, but also influence the levels of some important bioactive compounds, such as glucosinolates (GLSs). Glucoraphanin (GLR) is the most abundant GLSs and its hydrolyzed component, sulforaphane (SLR), is the most powerful anti-cancer compound in brassica vegetables. In this review, we find out that varied treatments impact the retention of GLR and the formation of SLR differently. Be specific, 1) freezing can avoid the losses of GLR while short-time microwaving, short-time steaming and fermentation promote the biotransformation from GLR to SLR; 2) Boiling and blanching cause the largest losses of GLR and SLR, while freezing significantly protect their losses.; 3) Stir-frying varies the levels of GLR and SLR in different cooking conditions.

Fine mapping of the major QTLs for biochemical variation of sulforaphane in broccoli florets using a DH population

Glucoraphanin is a major secondary metabolite found in Brassicaceae vegetables, especially broccoli, and its degradation product sulforaphane plays an essential role in anticancer. The fine mapping of sulforaphane metabolism quantitative trait loci (QTLs) in broccoli florets is necessary for future marker-assisted selection strategies. In this study, we utilized a doubled haploid population consisting of 176 lines derived from two inbred lines (86,101 and 90,196) with significant differences in sulforaphane content, coupled with extensive genotypic and phenotypic data from two independent environments. A linkage map consisting of 438 simple sequence repeats markers was constructed, covering a length of 1168.26 cM. A total of 18 QTLs for sulforaphane metabolism in broccoli florets were detected, 10 were detected in 2017, and the other 8 were detected in 2018. The LOD values of all QTLs ranged from 3.06 to 14.47, explaining 1.74-7.03% of the biochemical variation between two years. Finally, 6 QTLs (qSF-C3-1, qSF-C3-2, qSF-C3-3, qSF-C3-5, qSF-C3-6 and qSF-C7) were stably detected in more than one environment, each accounting for 4.54-7.03% of the phenotypic variation explained (PVE) and a total of 30.88-34.86% of PVE. Our study provides new insights into sulforaphane metabolism in broccoli florets and marker-assisted selection breeding in Brassica oleracea crops.

Identification of sulforaphane regulatory network in hepatocytes by microarray data analysis based on GEO database

For the past several years, more and more attention has been paid to the exploration of traditional medicinal plants. Further studies have shown that more dietary consumption of cruciferous vegetables can prevent the occurrence of tumor, indicating the potential applications in the chemoprevention of cancer. Sulforaphane (SFN) has been identified by the National Cancer Institute as a candidate for chemopreventive research; it is one of several compounds selected by the National Cancer Institute’s Rapid Access to Preventive Intervention Development Program and is currently in use. In the present study, based on the data of Gene Expression Omnibus database (GEO), the gene expression profile of hepatocytes that were treated with SFN was analyzed. The ANOVA and Limma packets in R were used to analyze the differentially expressed genes (DEGs). On this basis, gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment were further analyzed. The core gene HSP90-α (cytosolic), class A member 1 (HSP90AA1) was screened by protein–protein interaction (PPI) network established by STRING and Cytoscape software for further study. Finally, miRNAs targeted HSP90AA1 were predicted by miRanda. All in all, based on the data of GSE20479 chip, the molecular mechanism of SFN on hepatocytes was studied by a series of bioinformatics analysis methods, and it indicated that SFN might effect on the hepatocyte by regulating HSP90AA1.