Antidiabetic Potential of Sinigrin Against Streptozotocin-Induced Diabetes via Modulating Inflammation and Oxidative Stress

Diabetes mellitus (DM) is a common metabolic disorder which arises due to the improper carbohydrate metabolism, decreased secretion/activity of insulin, and genetic abnormalities, which result in the increased blood glucose level generally known as hyperglycemia. Diabetes holds an increased global prevalence in each year and is responsible for increased morbidity and mortality rates. Hence, the current investigation focusses to assess the antidiabetic potential of sinigrin on diabetic animal model through the suppression of inflammation. Diabetes was initiated to the animals via administering streptozotocin (STZ) and supplemented with the sinigrin at 25- and 50-mg/kg dose via oral route. The diabetic rats demonstrated the elevated glucose, food and water intake, kidney and liver weights, and reduced bodyweight and depleted insulin status. The sinigrin treatment remarkably improved and modulated these changes in diabetic animals. Additionally, the sinigrin supplementation also modulated the changes in glucose-6-phosphatase; fructose 1,6-bisphosphatase; AST; ALT; creatinine; and inflammatory mediators in the STZ-provoked diabetic animals. The levels of hexokinase, protein, and antioxidants also improved by the sinigrin treatment. The histological investigations of pancreas also witnessed the therapeutic actions of sinigrin, which is supported by the findings of biochemical examinations. Therefore, it was clear that the sinigrin supplementation displayed remarkable antidiabetic effect on STZ-initiated diabetic animals via modulating inflammation and other biochemical changes, which recommends that sinigrin could be a talented candidate for diabetes management in the future.

Sinigrin in combination with artesunate provides protection against lethal murine malaria via falcipain-3 inhibition and immune modulation

Plant-derived antimalarials are indispensable for malaria treatment and a platform for new drugs. The present study explores sinigrin, for malaria using in vitro, in silico and in vivo strategies and the immune response generated after administration. The compound exhibited promising activity against chloroquine (CQ)-resistant (RKL-9) IC₅₀ 5.14 μg/mL and CQ-sensitive (3D7) IC₅₀ 5.47 μg/mL strains of P. falciparum and was safe in both in vitro (CC₅₀ > 640 μg/mL) and in vivo (LD₅₀ > 2 g/kg) toxicity studies. In addition, virtual screening showed hydrogen bonding, hydrophobic and van der Waals interactions with amino acid residues of 3BPM (falcipain-3). In vivo studies revealed promising antimalarial activity of sinigrin (200 mg/kg) with 87.44% chemo-suppression on day 5 and significantly (p < 0.0001) enhanced the mean survival time (21 ± 4.74 days) in contrast to the infected control (5.4 ± 1.14 days). In combination therapy, sinigrin (100 mg/kg and 200 mg/kg) augmented the efficacy of artesunate (AS 50 mg/kg) with 100% survival and no recrudescence. These observations are further corresponded and supported by DLC, NO production, cytokine analysis, biochemical and histopathological studies. Treatment with the combination resulted in a regulated interplay of immune cells and cytokines aiding in parasite clearance in addition to its specific inhibitory activity. We report the antimalarial activity of sinigrin first time with best D-score against falcipain-3. These findings highlight sinigrin as a HIT molecule, which may potentially be used in drug and vaccine development approaches.

Preventive Effects of Sinigrin Against the Memory Deterioration in the Pentylenetetrazole-Kindled Male Wistar Rats: Possible Modulation of NLRP3 Pathway

Mainly found in brussels sprouts, broccoli, and black mustard seeds, sinigrin (2-propenyl glucosinolate) has enjoyed some attention currently for its effects on health and disease prevention. The present research design is aimed at investigating the effects of sinigrin on inflammation, oxidative stress (OS) and memory. Randomly, six groups of male Wistar rats were categorized into the control and experimental groups. The experimental groups were treated with sinigrin (10 and 20 mg/kg, orally). The control positive group was given the pentylenetetrazole (PTZ) treatment and the control negative one was given normal saline. All groups were kindled by the sub-threshold dose (35 mg/kg, i.p.) of PTZ for 12 times in one month. When the kindling procedure was done, the seizure behaviors and the behavioral function were evaluated. For cognitive parameters, the shuttle box test was employed. When the experiment was terminated, the rats were euthanized and their blood serum as well as brain samples were isolated for respective measuring of OS and gene expression parameters. The treatment with sinigrin significantly delayed the appearance of the seizure symptoms in comparison to that of the PTZ group. It also significantly increased the memory parameters like retention latency and the total time having been spent in the light compartment in the epileptic rats. In addition, sinigrin increased the superoxide dismutase and catalase levels. Treatment with sinigrin suppressed the Il1b and Nlrp3 gene expression at hippocampal level. In sum, sinigrin prevents inflammation, OS and memory impairment against the PTZ-kindling epilepsy in rats.

Development of HPLC Method for Quantification of Sinigrin from Raphanus sativus Roots and Evaluation of Its Anticancer Potential

Sinigrin, a precursor of allyl isothiocyanate, present in the Raphanus sativus exhibits diverse biological activities, and has an immense role against cancer proliferation. Therefore, the objective of this study was to quantify the sinigrin in the R. sativus roots using developed and validated RP-HPLC method and further evaluated its’ anticancer activity. To achieve the objective, the roots of R. sativus were lyophilized to obtain a stable powder, which were extracted and passed through an ion-exchange column to obtain sinigrin-rich fraction. The RP-HPLC method using C18 analytical column was used for chromatographic separation and quantification of sinigrin in the prepared fraction, which was attained using the mobile phase consisting of 20 mM tetrabutylammonium: acetonitrile (80:20%, v/v at pH 7.0) at a flow rate of 0.5 mL/min. The chromatographic peak for sinigrin was showed at 3.592 min for pure sinigrin, where a good linearity was achieved within the concentration range of 50 to 800 µg/mL (R² > 0.99), with an excellent accuracy (−1.37% and −1.29%) and precision (1.43% and 0.94%), for intra and inter-day, respectively. Finally, the MTT assay was performed for the sinigrin-rich fraction using three different human cancer cell lines, viz. prostate cancer (DU-145), colon adenocarcinoma (HCT-15), and melanoma (A-375). The cell-based assays were extended to conduct apoptotic and caspase-3 activities, to determine the mechanism of action of sinigrin in the treatment of cancer. MTT assay showed IC₅₀ values of 15.88, 21.42, and 24.58 µg/mL for DU-145, HCT-15, and A-375 cell lines, respectively. Increased cellular apoptosis and caspase-3 expression were observed with sinigrin-rich fraction, indicating significant increase in overexpression of caspase-3 in DU-145 cells. In conclusion, a simple, sensitive, fast, and accurate RP-HPLC method was developed for the estimation of sinigrin in the prepared fraction. The data observed here indicate that sinigrin can be beneficial in treating prostate cancer possibly by inducing apoptosis.

Effects of the Glucosinolate Sinigrin in Combination With a Noniodine Supplemented Diet on Serum Iodine and Thyroid Hormone Concentrations in Nonpregnant Mares

Exposure to plants containing glucosinolates (GSLs) affects thyroid function in many species, in horses is implicated in the birth of foals with congenital hypothyroidism. The present study was performed to determine the effect of feeding a GSL (sinigrin) in combination with a low-iodine diet for 12 weeks on thyroid hormones and serum iodine concentrations in nonpregnant mares. Nineteen mares aged 2-14 years were divided into control (n = 6), low (20 mmol/day) (n = 7) and high GSL (35 mmol/day) (n = 6) groups. Thyrotropin-releasing hormone (TRH) stimulation tests and serum iodine measurements were performed at 0 and 12 weeks. Total triiodothyronine (TT3), total thyroxine (TT4), and thyroid-stimulating hormone (TSH) concentrations were measured at the baseline and in post-TRH samples. The post-TRH value minus the basal value (Delta Δ) and fold change (FC) were calculated for TSH, TT3, and TT4. Data were analyzed at P < .05. Highlights included Delta Δ and FC TT4 and TT3 concentrations having a group and week interaction (P < .001) with week 12 control mares having higher values than mares in week 12 low and high GSL groups. TT4 FC values had a group (P < .001) and group by week interaction (P < .001) with week 12 control concentrations higher (P < .006) than all groups. Iodine concentrations decreased (P < .002) over time in GSL mares. In conclusion, feeding mares a low-iodine diet with 20 and 35 mmol sinigrin/day resulted in lower serum iodine concentrations.

Overexpression of the MYB29 transcription factor affects aliphatic glucosinolate synthesis in Brassica oleracea

KEY MESSAGE

Overexpression of BoMYB29 gene up-regulates the aliphatic glucosinolate pathway in Brassica oleracea plants increasing the production of the anti-cancer metabolite glucoraphanin, and the toxic and pungent sinigrin. Isothiocyanates, the bio-active hydrolysis products of glucosinolates, naturally produced by several Brassicaceae species, play an important role in human health and agriculture. This study aims at correlating the content of aliphatic glucosinolates to the expression of genes involved in their synthesis in Brassica oleracea, and perform functional analysis of BoMYB29 gene. To this purpose, three genotypes were used: a sprouting broccoli, a cabbage, and a wild genotype (Winspit), a high glucosinolate containing accession. Winspit showed the highest transcript level of BoMYB28, BoMYB29 and BoAOP2 genes, and BoAOP2 expression was positively correlated with that of the two MYB genes. Further analyses of the aliphatic glucosinolates also showed a positive correlation between the expression of BoAOP2 and the production of sinigrin and gluconapin in Winspit. The Winspit BoMYB29 CDS was cloned and overexpressed in Winspit and in the DH AG1012 line. Overexpressing Winspit plants produced higher quantities of alkenyl glucosinolates, such as sinigrin. Conversely, the DH AG1012 transformants showed a higher production of methylsulphinylalkyl glucosinolates, including glucoraphanin, and, despite an up-regulation of the aliphatic glucosinolate genes, no increase in alkenyl glucosinolates. The latter may be explained by the absence of a functional AOP2 gene in DH AG1012. Nevertheless, an extract of DH AG1012 lines overexpressing BoMYB29 provided a chemoprotective effect on human colon cells. This work exemplifies how the genetic diversity of B. oleracea may be used by breeders to select for higher expression of transcription factors for glucosinolate biosynthesis to improve its natural, health-promoting properties.

Kinetic and structural study of broccoli myrosinase and its interaction with different glucosinolates

Myrosinase is a glycosylated enzyme present in the Brassicaceae family that catalyzes the hydrolysis of glucoraphanin to yield sulforaphane, recognized as a health-promoting compound found in cruciferous foods. Broccoli myrosinase has been poorly characterized. In this work, the enzyme was purified from broccoli florets and its kinetic behaviour was analyzed. The cDNA of broccoli myrosinase was isolated and sequenced to obtain the amino acids sequence of the enzyme. A three-dimensional structural model of a broccoli myrosinase subunit was built and used to perform molecular docking simulations with glucoraphanin and other glucosinolates. Kinetic data were adjusted to the Two-Binding Sites Model that describes substrate inhibition, obtaining R² higher than 97%. The docking simulations confirmed the existence of two substrate-binding sites in the monomer, and allowed identifying the residues that interact with the substrate in each site. Our findings will help to design strategies to better exploit the health-promoting properties of broccoli.

Mechanistic insight in potential dual role of sinigrin against Helicoverpa armigera

The adverse effect of glucosinolates on diverse phytophagous insects is well documented, but its impact on insect physiology has remained enigmatic. Here we report insights into detrimental effects of plant glucosinolate molecule, sinigrin, on Helicoverpa armigera growth and development. In-silico screening of multiple glucosinolates predicted sinigrin as one of the potential inhibitor of H. armigera cathepsin B and L. Insects fed on sinigrin containing diet showed significantly reduced growth (20-30%), delayed pupation (10-15%), decreased fecundity (50-80%) and developmental abnormalities. Further, sinigrin showed 50-60% inhibition of ex-vivo cathepsin like activity which might be a reason for growth and development related abnormalities. In-vitro and mass spectrometry studies highlighted the cytotoxicity caused due to the hydrolysis of sinigrin, into toxic isothiocyanates, in presence of H. armigera whole body extract. In conclusion, insect cathepsin inhibition and isothiocyanate mediated cytotoxicity lead to the dual adverse effect of sinigrin on H. armigera.

Sinigrin attenuates the progression of atherosclerosis in ApoE-/- mice fed a high-cholesterol diet potentially by inhibiting VCAM-1 expression

Atherosclerosis is a complex inflammatory disease associated with elevated levels of atherogenic molecules for leukocyte recruitment. Sinigrin (2-propenylglucosinolate) is found mainly in broccoli, brussels sprouts, and black mustard seeds. Recently, sinigrin has received attention for its role in disease prevention and health promotion. In this study, we examined the effect of sinigrin on development of atherosclerosis in ApoE^-/- mice and the expression of adhesion molecules in vascular smooth muscle cells (VSMCs). The serum concentrations of lactate dehydrogenase (LDH), triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL), calcium (Ca²⁺), and pro-inflammatory cytokines were reduced by sinigrin treatment in ApoE^-/- mice. In addition, oral administration of sinigrin attenuated the mRNA expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), C-C motif chemokine ligand 2 (CCL2), and CCL5 on aorta tissues and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), liver X receptor (LXR), sterol regulatory element-binding protein-2 (SREBP-2), and low density lipoprotein receptor (LDLR) on liver tissues in ApoE^-/- mice. To provide a potential mechanism underlying the action of sinigrin, we evaluated the in vitro effect of sinigrin on the expression of the VCAM-1 in TNF-α-induced VSMCs. The increased expression of VCAM-1 by TNF-α stimulation was significantly suppressed by the treatment of sinigrin (1-100 μg/ml) and sinigrin inhibited the nuclear translocation of NF-κB and the phosphorylation of p38 MAPK and JNK pathways, suggesting that sinigrin decreases the TNF-α-stimulated VCAM-1 expression through the suppression of NF-κB and MAP kinases signaling pathways. Overall, sinigrin has the potential to be used in reducing the risks of atherosclerosis.

In vitro, in vivo and in silico anti-hyperglycemic inhibition by sinigrin

OBJECTIVE

To evaluate the anti-hyperglycemic potential of sinigrin using in vitro, in silico and in vivo streptozotocin (STZ) induced hyperglycemic zebrafish model.

METHODS

The in vitro enzyme inhibition assay was carried out to determine the IC₅₀ value against α-glucosidase and α-amylase, in silico molecular docking was performed against both enzymes with PyRx tool and simulations were performed using GROMACS tool. Hyperglycemia was induced in zebrafishes using three intraperitoneal injections on alternating days for 1 week at 350 mg/kg of STZ. Hyperglycemic fishes were treated intraperitoneally with 50, 100 and 150 mg of sinigrin/kg of body weight for 24 h and glucose levels were measured.

RESULTS

The sinigrin showed very strong inhibition against α-glucosidase and α-amylase with 0.248 and 0.00124 μM while reference drug acarbose showed IC₅₀ value of 73.0700 and 0.0017 μM against α-glucosidase and α-amylase, respectively. Kinetic analysis revealed that sinigrin has the mixed type mode of inhibition against α-glucosidase. Molecular docking results revealed its strong binding affinity with α-glucosidase (-10.00 kcal/mol) and α-amylase (-8.10 kcal/mol). Simulations graphs confirmed its stability against both enzymes. Furthermore, in hyperglycemic zebrafishes most significant (P < 0.001) reduction of glucose was occurred at 150 mg/kg, moderate significant reduction of glucose was observed at 100 mg/kg and no any significant reduction of glucose was measured at 50 mg/kg.

CONCLUSIONS

It can be evident from the present results that sinigrin has potent anti-hyperglycemic activity and it may prove to be effective treatment for the hyperglycemia.

Dynamics of glucosinolate-myrosinase system during Plutella xylostella interaction to a novel host Lepidium latifolium L

Plutella xylostella L. is a notorious pest of cruciferous crops causing worldwide losses of $4-5 billion per year. Developing classical biological control to this pest include an introduction of host plants that act as natural enemies showing deviation from the preference-performance regimen in the evolutionary ecology of plant-insect interactions. The present study was designed to understand the role of glucosinolate-myrosinase system during P. xylostella interactions with a novel host. Adult moth preference and larval performance study were conducted on a novel host Lepidium latifolium L. (LL) that has high sinigrin content and was compared with its laboratory host Arabidopsis thaliana (AT). The glucosinolate-myrosinase system was studied in a time course experiment during larval feeding in choice and no-choice experiments. Adult moths visit and prefers LL over AT for oviposition. Conversely, LL leaves were not preferred and proved detrimental for P. xylostella larvae. Aliphatic and indolic glucosinolates were found to decrease significantly (p≤0.05) in AT during initial 12h of P. xylostella challenge, whereas, they were not affected in LL. Also, MYB transcription factor expression and myrosinase activity in LL do not suggest a typical host response to a specialist insect. This preference-performance mismatch of P. xylostella on LL mediated by glucosinolate pattern suggests that this novel plant could be utilized in P. xylostella management.

In vitro wound healing and cytotoxic effects of sinigrin-phytosome complex

Sinigrin is a class of glucosinolates found naturally in plants of the Brassicaceae family. Lately, studies have shown that sinigrin possesses anticancer, antibacterial and anti-inflammatory activities. Since its efficacy has not been explored on wound healing, we examined the effect of sinigrin on HaCaT cells. We also aimed at formulating sinigrin into phytosome to form a sinigrin-phytosome complex and study the wound healing and cytotoxic activities on A-375 and HaCaT cells. Sinigrin was efficiently formulated into the phytosome with an average particle size of 153 ± 39 nm, zeta potential of 10.09 ± 0.98 mV and complex efficiency of 69.5 ± 5%. The formation of the sinigrin-phytosome complex was confirmed by DSC and FTIR analysis. The sinigrin-phytosome complex significantly exhibited wound healing effects when compared to sinigrin alone. After 42 h, the phytosome complex completely healed the wound, whereas sinigrin alone showed only 71% wound closure. The sinigrin-phytosome complex displayed minimal toxicity towards HaCaT cells and at higher concentrations, it showed potent activity towards A-375. The results indicated that sinigrin-phytosome complex augmented the therapeutic potential of sinigrin towards the wound healing activity and this approach should be explored further for cancerous wound treatment.

Influence of the antimicrobial compound allyl isothiocyanate against the Aspergillus parasiticus growth and its aflatoxins production in pizza crust

Aflatoxins (AFs) are secondary metabolites produced by different species of Aspergillus, such as Aspergillus flavus and Aspergillus parasiticus, which possess mutagenic, teratogenic and carcinogenic activities in humans. In this study, active packaging devices containing allyl isothiocyanate (AITC) or oriental mustard flour (OMF) + water were tested to inhibit the growth of A. parasiticus and AFs production in fresh pizza crust after 30 d. The antimicrobial and anti-aflatoxin activities were compared to a control group (no antimicrobial treatment) and to a group added with commercial preservatives (sorbic acid + sodium propionate). A. parasiticus growth was only inhibited after 30 d by AITC in filter paper at 5 μL/L and 10 μL/L, AITC sachet at 5 μL/L and 10 μL/L and OMF sachet at 850 mg + 850 μL of water. However, AFs production was inhibited by all antimicrobial treatments in a dose-dependent manner. More importantly, AITC in a filter paper at 10 μL/L, AITC sachet at 10 μL/L, OMF sachet at 850 mg + 850 μL of water and sorbic acid + sodium propionate at 0.5-2.0 g/Kg completely inhibited AFs formation. The use of AITC in active packaging devices could be a natural alternative to avoid the growth of mycotoxinogenic fungi in refrigerated bakery products in substitution of common commercial preservatives.

Role of glycoside hydrolase genes in sinigrin degradation by E. coli O157:H7

This work examined Escherichia coli O157:H7 strain 02-0304 for putative genes responsible for sinigrin hydrolysis. Sinigrin is a glucosinolate present in Oriental mustard (Brassica juncea), and its hydrolysis is mediated in plants by the enzyme myrosinase. Sinigrin hydrolysis by plant or bacterial myrosinase yields allyl isothiocyanate (AITC) which is bactericidal. In silico analysis using public databases found sequence similarity between plant myrosinase and enzymes encoded by genes from β-glucosidase families in E. coli O157:H7. Specifically, 6-phospho-β-glucosidase encoded by the genes bglA and ascB (family 1), and chbF (family 4) present in E. coli O157:H7 showed the highest similarity. Polymerase chain reaction (PCR) confirmed the presence of bglA, ascB, and chbF in the clinical E. coli strain tested. Disruption of these genes in wild-type E. coli O157:H7 strain 02-0304 using lambda-red replacement created single and double mutants. The relative importance of each gene in the hydrolysis of sinigrin by E. coli O157:H7 was also assessed by comparing gene expression and sinigrin degradation rates among the E. coli O157:H7 wild-type strain and its mutants. The results suggested that the genes bglA and ascB play a substantial role in the degradation of sinigrin by E. coli O157:H7 strain 02-0304.