Cytotoxic and Antioxidant Activity of 4-Methylthio-3-butenyl Isothiocyanate from Raphanus sativus L. (Kaiware Daikon) Sprouts

Abstract

There is high current interest in the chemopreventive potential of Brassica vegetables (cruciferae), particularly due to their content in glucosinolates (GL), which upon myrosinase hydrolysis release the corresponding isythiocyanates (ITC). Some ITCs, such as sulforaphane (SFN) from broccoli ( Brassica oleacea italica), have been found to possess anticancer activity through induction of apoptosis in selected cell lines, as well as indirect antioxidant activity through induction of phase II detoxifying enzymes. Japanese daikon ( Raphanus sativus L.) is possibly the vegetable with the highest per capita consumption within the Brassicaceae family. Thanks to a recently improved gram scale production process, it was possible to prepare sufficient amounts of the GL glucoraphasatin (GRH) as well as the corresponding ITC 4-methylthio-3-butenyl isothiocyanate (GRH-ITC) from its sprouts. This paper reports a study on the cytotoxic and apoptotic activities of GRH-ITC compared with the oxidized counterpart 4-methylsulfinyl-3-butenyl isothiocyanate (GRE-ITC) on three human colon carcinoma cell lines (LoVo, HCT-116, and HT-29) together with a detailed kinetic investigation of the direct antioxidant/radical scavenging ability of GRH and GRH-ITC. Both GRH-ITC and GRE-ITC reduced cell proliferation in a dose-dependent manner and induced apoptosis in the three cancer cell lines. The compounds significantly ( p < 0.05) increased Bax and decreased Bcl2 protein expression, as well as producing caspase-9 and PARP-1 cleavage after 3 days of exposure in the three cancer cell lines. GRH-ITC treatment was shown to have no toxicity with regard to normal human lymphocytes (-15 +/- 5%) in comparison with SFN (complete growth inhibition). GRH and GRH-ITC were able to quench the 2,2-diphenyl-1-picrylhydrazyl radical, with second-order rate constants of 14.0 +/- 2.8 and 43.1 +/- 9.5 M(-1) s(-1), respectively (at 298 K in methanol), whereas the corresponding value measured here for the reference antioxidant alpha-tocopherol was 425 +/- 40 M (-1) s (-1). GRH reacted with H2O2 and tert-butyl hydroperoxide in water (pH 7.4) at 37 degrees C, with rate constants of 1.9 +/- 0.3 x 10(-2) and 9.5 +/- 0.3 x 10(-4) M(-1) s (-1) (paralleling recently developed synthetic antioxidants) being quantitatively (>97%) converted to GRE. It is demonstrated that GRH-ITC has interesting antioxidant/radical scavenging properties, associated with a selective cytotoxic/apoptotic activity toward three human colon carcinoma cell lines, and very limited toxicity on normal human T-lymphocytes.

Sulforaphane is Superior to Glucoraphanin in Modulating Carcinogen-Metabolising Enzymes in Hep G2 Cells

“…*p<0.05 as compared to control (0 µM) were affected following exposure of the cells line to the glucosinolate (Figure 2). When myrosinase was added to the glucosinolate-containing incubations, the inductive this enzyme at pH 7.4 allows to its complete hydrolysis to produce the isothiocyanate (Papi et al, 2008).…”

Mitochondria-mediated Apoptosis in Human Lung Cancer A549 Cells by 4-Methylsulfinyl-3-butenyl Isothiocyanate from Radish Seeds

“…Alessio Papi reported that Sulforaphane (SFN) caused a complete growth inhibition at 50 μM, whereas MTBITC showed only 15 (±5)% inhibition. It showed MTBITC with limited toxicity to normal human T-lymphocytes (Papi et al, 2008).…”

“…(Karen-Ng et al, 2013;Zhu et al, 2013; MTBITC is a major phytochemical constituent of radish as well as other cruciferous vegetables with known chemopreventive properties. MTBITC has been shown to modulate the activity of phase II detoxification enzymes (Hanlon et al, 2007), suppress proliferation, and induce apoptosis in cancer cells (Papi et al, 2008), via pathways that have been suggested to be involved in anticarcinogenic processes. However, few studies have been carried out to ascertain the effects of MTBITC treatment in lung adenocarcinoma.…”

“…Moreover, MTBITC has shown more specificity and sensitivity toward tumor cells compared with normal cells (Hanlon et al, 2007;Papi et al, 2008). MTBITC has been shown to induce detoxification enzymes in the human hepatocyte HepG2 cell line (Hanlon et al, 2007), and has interesting antioxidant/radical scavenging properties associated with a selective cytotoxic/apoptotic activity toward three human colon carcinoma cell lines (LoVo, HCT-116, and HT-29) (Papi et al, 2008). However, the mechanisms of how MTBITC induces apoptosis of human lung cancer cells are still not defined.…”

First Total Synthesis of 4-Methylthio-3-butenyl Glucosinolate

“…1,2) More recently, MTBI and its bioprecursor, 4-methylthio-3-butenyl glucosinolate (MTBG, 1), have been found to possess unique antioxidant and cytotoxic activities, boosting intense research interest in them. 3) Kosemura et al (1993) suggested that MTBI is released from MTBG via myrosinase (thioglucosidase) action (Fig. 1).…”