Allyl isothiocyanate regulates caspase-1/receptor interacting protein-2 expression

[6]-Gingerol impedes 7,12-dimethylbenz(a)anthracene-induced inflammation and cell proliferation-associated hamster buccal pouch carcinogenesis through modulating Nrf2 signaling events

The present study examines the chemopreventive role of [6]-gingerol, an active component of ginger, on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis models. The HBP has been developed with an addition of 0.5% of DMBA to the HBP area three times per week, up to the end of the 16th experimental week. At the end of the experiment, we noticed 100% tumor incidence and precancerous lesions, such as dysplasia, hyperplasia, keratosis, and well-differentiated squamous cell carcinoma, in DMBA-induced HBP. Furthermore, we observed that [6]-gingerol inhibited the increased thiobarbituric acid-reactive substances and decreased antioxidant levels in DMBA-induced hamsters. Moreover, [6]-gingerol inhibits DMBA-exposed over expression of inflammatory markers (inducible nitric oxide synthase, interleukin [IL]-1β, IL-6, cyclooxygenase-2, and tumor necrosis factor-α) and cell proliferation markers (cyclin D1, proliferating cell nuclear antigen); induces proapoptotic markers in HBP. Nuclear factor erythroid-2-related factor-2 (Nrf2) is a major antioxidant transcription factor, which regulates the antioxidant gene-dependent scavenge of tumor proliferation and apoptosis. Overexpression of Nrf2 signaling plays a pivotal role and can be a novel target in preventing carcinogenesis. In this study, [6]-gingerol restores the DMBA-induced depletion of Nrf2 signaling and thereby prevents buccal pouch carcinogenesis in hamsters. These results point out that [6]-gingerol impedes the responses of inflammatory and cell proliferation-associated progression of cancer through the action of Nrf2 signaling.

Organic Isothiocyanates as Hydrogen Sulfide Donors

Significance: Hydrogen sulfide (H₂S), the "new entry" in the series of endogenous gasotransmitters, plays a fundamental role in regulating the biological functions of various organs and systems. Consequently, the lack of adequate levels of H₂S may represent the etiopathogenetic factor of multiple pathological alterations. In these diseases, the use of H₂S donors represents a precious and innovative opportunity. Recent Advances: Natural isothiocyanates (ITCs), sulfur compounds typical of some botanical species, have long been investigated because of their intriguing pharmacological profile. Recently, the ITC moiety has been proposed as a new H₂S-donor chemotype (with a l-cysteine-mediated reaction). Based on this recent discovery, we can clearly observe that almost all the effects of natural ITCs can be explained by the H₂S release. Consistently, the ITC function was also used as an original H₂S-releasing moiety for the design of synthetic H₂S donors and original "pharmacological hybrids." Very recently, the chemical mechanism of H₂S release, resulting from the reaction between l-cysteine and some ITCs, has been elucidated. Critical Issues: Available literature gives convincing demonstration that H₂S is the real player in ITC pharmacology. Further, countless studies have been carried out on natural ITCs, but this versatile moiety has been used only rarely for the design of synthetic H₂S donors with optimal drug-like properties. Future Directions: The development of more ITC-based synthetic H₂S donors with optimal drug-like properties and selectivity toward specific tissues/pathologies seem to represent a stimulating and indispensable prospect of future experimental activities.

Suppression of TRIF-dependent signaling pathway of toll-like receptors by allyl isothiocyanate in RAW 264.7 macrophages

Toll-like receptors (TLR) play a significant role in the induction of innate immune responses that are essential for host defense against invading microbial pathogens. In general, TLRs have two major downstream signaling pathways: myeloid differential factor 88 (MyD88)-dependent and toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent pathways. Allyl isothiocyanate (AITC) found in cruciferous vegetables has an effect on treatment of many chronic diseases. However, the exact molecular targets of AITC are still unidentified. Here, it was investigated whether AITC can modulate TLR signaling pathways and what is the molecular target of AITC in TLRs signaling pathways. AITC suppressed the activation of nuclear factor-κB by lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (poly[I:C]), but not by macrophage-activating lipopeptide of 2kDa (MALP-2) or cytosine-phosphate-guanine dinucleotide (CpG DNA). AITC also suppressed the activation of interferon regulatory factor 3 (IRF3) and the expression of interferon inducible protein-10 (IP-10) induced by LPS or poly[I:C]. These results suggest that AITC can modulate TRIF-dependent signaling pathways of TLRs leading to decreased inflammatory gene expression.