Novel trisaccharide fatty acid ester identified from the fruits of Morinda citrifolia (Noni)

Two known glycosides and a novel trisaccharide fatty acid ester were isolated from the n-butanol-soluble fraction of the fruits of Morinda citrifolia (noni). Structure determination was carried out by spectral techniques such as MS, IR, NMR, and 2D-NMR. The novel trisaccharide fatty acid ester was elucidated as 2, 6-di-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose. The known compounds were identified as rutin and asperulosidic acid.

Evaluation of resveratrol derivatives as potential antioxidants and identification of a reaction product of resveratrol and 2, 2-diphenyl-1-picryhydrazyl radical

Resveratrol (3,4',5-trihydroxy-trans-stilbene), an antioxidant from grapes, and five other polyhydroxystilbenes were synthesized. Their antioxidative properties were evaluated in two model systems [pure lipid oxidation using the Rancimat method and 2, 2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging model.] 3, 3',4,5'-Tetrahydroxystilbene, 3,3',4,5,5'-pentahydroxystilbene, and 3,4,4',5-tetrahydroxystilbene were found to be more active than resveratrol in both models. A dimer of resveratrol was identified as the major radical reaction product when resveratrol was reacted with DPPH radicals.

Thermal degradation of sulforaphane in aqueous solution

Sulforaphane, a cancer chemopreventive agent identified from broccoli, was degraded in an aqueous solution at 50 and 100 degrees C. The reaction mixtures were extracted with methylene chloride and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Dimethyl disulfide, S-methyl methylthiosulfinate, S-methyl methylthiosulfonate, methyl (methylthio)methyl disulfide, 1,2,4-trithiolane, 4-isothiocyanato-1-(methylthio)-1-butene, and 3-butenyl isothiocyanate were identified as volatile decomposition products. After methylene chloride extraction, the aqueous layer was dried and silica gel column chromatography was used to separate and purify the nonvolatile decomposition products. The major thermal degradation compound was determined by (1)H NMR, (13)C NMR, and FAB-MS as N, N'-di(4-methylsulfinyl)butyl thiourea. A possible mechanism for the formation of these products is proposed.

2,2-Diphenyl-1-picrylhydrazyl radical-scavenging active components from Polygonum multiflorum thunb

An activity-directed fractionation and purification process was used to identify the antioxidative components of Polygonum multiflorum Thunb. (PM). Dried root of PM was extracted with 95% ethanol and then separated into water, ethyl acetate, and hexane fractions. Among these only the ethyl acetate phase showed strong antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test when compared with water and hexane phases. The ethyl acetate fraction was then subjected to separation and purification using silica gel column chromatography and Sephadex LH-20 chromatography. Three compounds showing strong antioxidant activity were identified by spectral methods ((1)H NMR, (13)C NMR, and MS) and by comparison with authentic samples to be gallic acid, catechin, and 2,3,5, 4'-tetrahydroxystilbene 2-O-beta-D-glucopyranoside.

Acetophenone glycosides from thyme (Thymus vulgaris L.)

Four acetophenone glycosides were isolated from the butanol-soluble fraction of thyme extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR). Among them, two new compounds, 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D -gl ucopyranoside (1) and 4-hydroxyacetophenone 4-O-[5-O-(4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D-+ ++gluc opyranoside (2), were determined. Compound 1 showed weak cytotoxicity, inhibiting DNA synthesis of human leukemia cells.

Suppression of extracellular signals and cell proliferation by the black tea polyphenol, theaflavin-3,3'-digallate

Previous studies in our laboratory have shown that the major green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), suppressed autophosphorylation of epidermal growth factor (EGF) receptor induced by EGF in human A431 epidermoid carcinoma cells. In this study, we examined the inhibitory effects of black tea polyphenols, including theaflavin (TF-1), a mixture (TF-2) of theaflavin-3-gallate (TF-2a) and theaflavin-3'-gallate (TF-2b), theaflavin-3,3'-digallate (TF-3) and the thearubigin fraction on the autophosphorylation of the EGF and PDGF receptors in A431 cells and mouse NIH3T3 fibroblast cells, respectively. First, we examined the effects of these polyphenols on the proliferation of A431 and NIH3T3 cells. Both EGCG and TF-3 strongly inhibited the proliferation of A431 and NIH3T3 cells more than the other theaflavins did. In cultured cells with pre-treatment of tea polyphenol, TF-3 was stronger than EGCG on the reduction of EGF receptor and PDGF receptor autophosphorylation induced by EGF and PDGF, respectively. Other theaflavins slightly reduced the autophosphorylation of the EGF and PDGF receptors; furthermore, TF-3 could reduce autophosphorylation of the EGF receptor (or PDGF receptor) even with co-treatment with EGF (or PDGF) and TF-3, but EGCG was inactive under these conditions. In addition, TF-3 was stronger than EGCG in blocking EGF binding to its receptor. These results suggest that not only the green tea polyphenol, EGCG, but also the black tea polyphenol, TF-3, have an antiproliferative activity on tumor cells, and the molecular mechanisms of antiproliferation may block the growth factor binding to its receptor and thus suppress mitogenic signal transduction.

Inhibition of TPA-induced protein kinase C and transcription activator protein-1 binding activities by theaflavin-3,3'-digallate from black tea in NIH3T3 cells

Tea is one of the most popular beverages in the world. Several reports have shown that both green tea and black tea were able to inhibit tumor cell proliferation in animal models. In this study, we investigated the inhibitory effects of black tea polyphenols including theaflavin (TF-1), the mixture (TF-2) of theaflavin-3-gallate (TF-2a), and theaflavin-3'-gallate (TF-2b), theaflavin-3,3'-digallate (TF-3), thearubigin (TR), and a major green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) on 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced protein kinase C (PKC) and transcription activator protein-1 (AP-1) binding activities in NIH3T3 cells. On analysis of PKC activity with partial purified preparation, TPA (100 ng/mL) treatment was able to elevate membrane-associated PKC activity approximately 3-fold, and treatment with TF-3 (20 microM) and EGCG (20 microM) showed 94.5% and 9.4% suppression on TPA-induced PKC activity, respectively. Translocation of PKCalpha protein from cytosol to membrane was detected in TPA-treated NIH3T3 cells, and TF-3 was able to block its translocation. By in vitro kinase assay using myelin basic protein (MBP) as a PKC-specific substrate, we found that TPA treatment was able to increase PKC kinase activity by detection of phosphorylated MBP protein and TF-3 showed strongest inhibitory effect on its phosphorylation while EGCG was shown to be less effective. We also analyzed the AP-1 binding activity by electrophoretic mobility shift assay and c-Jun gene expression by northern blot and western blot, the results showed that TF-3 is the most potent inhibitor on TPA-induced AP-1 binding activity and c-Jun gene expression among these five tea polyphenols. Our results might provide new molecular basis for understanding the inhibitory effects of tea polyphenols on TPA-mediated tumor promotion.

Antioxidative phenolic glycosides from sage (Salvia officinalis)

An investigation of Salvia officinalis L. has led to the isolation of three new phenolic glycosides, 6-O-caffeoyl-beta-D-fructofuranosyl-(2-->1)-alpha-D-glucopyranosid e (1), 1-O-caffeoyl-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyrano side (2), and 1-O-p-hydroxybenzoyl-beta-D-apiofuranosyl-(1-->6)-beta-D-glucop yranos ide (3). Elucidation of the structures of 1-3 was based on the interpretation of FABMS and 1D and 2D NMR spectra. Compounds 1 and 2 were found to be moderately active as antioxidants in the DPPH test and metmyoglobin test.

Theaflavin-3,3'-digallate from black tea blocks the nitric oxide synthase by down-regulating the activation of NF-kappaB in macrophages

Nitric oxide (NO) plays an important role in inflammation and also in multiple stages of carcinogenesis. We investigated the effects of various tea polyphenols, including theaflavin, a mixture of theaflavin-3-gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate, thearubigin, and (-)-epigallocatechin-3-gallate on the induction of NO synthase in lipopolysaccharide-activated murine macrophages, RAW 264.7 cells. Theaflavin-3,3'-digallate was found to be stronger than (-)-epigallocatechin-3-gallate in inhibiting NO generation and inducible NO synthase protein in activated macrophages, while theaflavin, a mixture of theaflavin-3-gallate and theaflavin-3'-gallate and thearubigin were less effective. Inhibition of NO production was observed when cells were cotreated with theaflavin-3,3'-digallate and lipopolysaccharide. Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses demonstrated that significantly reduced 130-kDa protein and mRNA levels of inducible NO synthase were expressed in lipopolysacchride-activated macrophages with theaflavin-3,3'-digallate, compared to those without theaflavin-3,3'-digallate. Electrophoretic mobility shift assay (EMSA) indicated that theaflavin-3,3'-digallate blocked the activation of nuclear factor kappaB (NF-kappaB), a transcription factor necessary for inducible NO synthase induction. Theaflavin-3,3'-digallate also blocked phosphorylation of IkappaB from cytosolic fraction and reduced lipopolysacchride-induced nuclear accumulation of transcription factor NF-kappaB p65 and p50 subunits. These results suggest that theaflavin-3,3'-digallate decreases the protein levels of inducible NO synthase by reducing the expression of inducible NO synthase mRNA, and the reduction could be via preventing the activation of NF-kappaB, thereby inhibiting the induction of inducible NO synthase transcription. It was also demonstrated that the gallic acid moiety of theaflavin-3,3'-digallate is essential for their potent anti-inflammation activity.

Comparison of volatile generation in serine/threonine/glutamine-ribose/glucose/fructose model systems

Thermal generation of volatiles in nine model reactions was studied and compared. Each of the model systems contained one amino acid and one monosaccharide. The amino acid was serine, threonine, or glutamine, and the monosaccharide was ribose, glucose, or fructose. More unsubstituted pyrazine was generated in serine-sugar systems than threonine-sugar systems. The formation of several furfuryl-substituted pyrazines and pyrroles was observed in some of the studied systems. Total pyrazines were generated more in glutamine-containing systems than in serine- and threonine-containing systems, and the reverse was true for generation of furfuryl-substituted compounds. Acetylpyrazine was generated in serine/threonine/glutamine-glucose and serine/glutamine-fructose systems.

Two novel beta-carboline compounds from the Maillard reaction between xylose and tryptophan

Two nonvolatile beta-carboline alkaloids were isolated from the Maillard reaction between xylose and tryptophan by solvent extraction and flash silica gel column chromatography. Their structures were elucidated by spectral methods (UV, MS, and NMR) as 1-(1,4-dihydroxybutyl)-beta-carboline and 1-(1,3, 4-trihydroxybutyl)-beta-carboline.

Characterization of volatile compounds from the reaction of 3-hydroxy-2-butanone and ammonium sulfide model system

The reactions between 3-hydroxy-2-butanone and ammoniun sulfide at 25, 50, 75, 100, 125, and 150 degrees C were studied. Four well-known flavor compounds, 2,4,5-trimethyloxazole, 2,4, 5-trimethyl-3-oxazoline, 2,4,5-trimethylthiazole, and 2,4, 5-trimethyl-3-thiazoline, were identified. Another four interesting intermediate compounds, 2-(1-hydroxyethyl)-2,4, 5-trimethyl-3-oxazoline, 2-(1-mercaptoethyl)-2,4, 5-trimethyl-3-oxazoline, 2-(1-hydroxyethyl)-2,4, 5-trimethyl-3-thiazoline, and 2-(1-mercaptoethyl)-2,4, 5-trimethyl-3-thiazoline, were also identified by GC-EIMS and GC-CIMS. All these intermediate compounds were formed at 25 degrees C. On the other hand, tetramethylpyrazine was the major product with a reaction temperature higher than 100 degrees C.

Safety of hormonal replacement therapy in postmenopausal patients with systemic lupus erythematosus

It remains controversial whether administration of exogenous estrogens is safe in systemic lupus erythematosus (SLE). The current study was undertaken to determine the effect of hormone replacement therapy (HRT) on the rate and magnitude of flares in a cohort of postmenopausal SLE patients. Thirty-four patients were prospectively followed. The frequency and severity of disease exacerbations in 11 patients who received HRT was compared with 23 patients who did not receive HRT. Our results showed that both users and non-users of HRT had a comparable age of disease onset, duration of disease, clinical manifestations, and duration of follow-up. No significant increase in the rate (0.12 relapses/patient-year in HRT group vs 0.16 relapses/patient-year in the non-HRT group, p = 0.90) or magnitude (total SLEDAI score increase during flares/patient-year in the HRT and non-HRT groups were 0.55 and 1.22, respectively, p = 0.57) of flares could be demonstrated in patients who received HRT over a median follow-up period of 35 months. We concluded that HRT appeared to be well tolerated and safe in postmenopausal SLE patients. Its potential beneficial effect may outweigh its deleterious effect on disease activity.

Dietary administration of an extract from rosemary leaves enhances the liver microsomal metabolism of endogenous estrogens and decreases their uterotropic action in CD-1 mice

We evaluated the effects of a methanol extract from the leaves of the plant Rosmarinus officinalis L. (rosemary) on the metabolism and action of estradiol and estrone. Treatment of female CD-1 mice with 2% rosemary in AIN-76A diet for 3 weeks increased the liver microsomal 2-hydroxylation of estradiol and estrone by approximately 150%, increased their 6-hydroxylation by approximately 30% and inhibited the 16alpha-hydroxylation of estradiol by approximately 50%. Treatment of female CD-1 mice with 2% rosemary diet for 3 weeks also stimulated the liver microsomal glucuronidation of estradiol and estrone by 54-67% and 37-56%, respectively. In additional studies, feeding 2% rosemary diet to ovariectomized CD-1 mice for 3 weeks inhibited the uterotropic action of estradiol and estrone by 35-50% compared with animals fed a control diet. The results of this study showed that feeding female mice a 2% rosemary diet increased the liver microsomal oxidation and glucuronidation of estradiol and estrone and inhibited their uterotropic action.

Inhibition of lung carcinogenesis by black tea in Fischer rats treated with a tobacco-specific carcinogen: caffeine as an important constituent

Here, we examined the effect of black tea and caffeine on lung tumorigenesis in F344 rats induced by the nicotine-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in a 2-year bioassay. NNK was administered s.c. at a dose of 1.5 mg/kg body weight three times weekly for 20 weeks. Animals were given either black tea as drinking water at concentrations of 2%, 1%, or 0.5%, or caffeine in drinking water at concentrations identical to those in 2% and 0.5% tea infusions for 22 weeks. The treatment period began 1 week before and ended 1 week after the NNK administration. The animals were sacrificed on week 101 for the examination of tumors in target organs, including lung, liver, nasal cavity, and other major organs. The NNK-treated group, given 2% black tea, showed a significant reduction of the total lung tumor (adenomas, adenocarcinomas, and adenosquamous carcinomas) incidence from 47% to 19%, whereas the group given 1% and 0.5% black tea showed no change. The 2% tea also reduced liver tumor incidence induced by NNK from 34% in the group given only deionized water to 12%. The tumor incidence in the nasal cavity, however, was not affected by either black tea or caffeine at any of the concentrations tested. The most unexpected finding was the remarkable reduction of the lung tumor incidence, from 47% to 10%, in the group treated with 680 ppm caffeine, a concentration equivalent to that found in the 2% tea. This incidence is comparable to background levels seen in the control group. This study demonstrated for the first time in a 2-year lifetime bioassay that black tea protects against lung tumorigenesis in F344 rats, and this effect appears to be attributed, to a significant extent, to caffeine as an active ingredient of tea.

Green tea epigallocatechin gallate shows a pronounced growth inhibitory effect on cancerous cells but not on their normal counterparts

(-)-Epigallocatechin gallate (EGCG), a catechin polyphenol compound, represents the main ingredient of green tea extract. Although EGCG has been shown to be growth inhibitory in a number of tumor cell lines, it is not clear whether the effect is cancer-specific. In this study we compared the effect of EGCG on the growth of SV40 virally transformed WI38 human fibroblasts (WI38VA) with that of normal WI38 cells. The IC50 value of EGCG was estimated to be 120 and 10 microM for WI38 and WI38VA cells, respectively. Thus, EGCG at 40 microM completely inhibited the growth of WI38VA cells, but had little or no inhibitory effect on the growth of WI38 cells. Similar differential growth inhibition was also observed between a human colorectal cancer cell line (Caco-2), a breast cancer cell line (Hs578T) and their respective normal counterparts. EGCG at a concentration range of 40-200 microM induced a significant amount of apoptosis in WI38VA cultures, but not in WI38 cultures, as determined by terminal deoxynucleotidyl transferase assay. After exposure to EGCG at 200 microM for 8 h, more than 50% of WI38VA cells in a confluent culture became apoptotic. In contrast, less than 1% of WI38 cells displayed apoptotic labeling under the same condition. EGCG did not affect the serum-induced expression of c-fos and c-myc genes in normal WI38 cells. However, it significantly enhanced their expression in transformed W138VA cells. It is possible that differential modulation of certain genes, such as c-fos and c-myc, may cause differential effects of EGCG on the growth and death of cancer cells.

Effect of dietary curcumin and dibenzoylmethane on formation of 7,12-dimethylbenz[a]anthracene-induced mammary tumors and lymphomas/leukemias in Sencar mice

Female Sencar mice (6 weeks old) were administered 1 mg of 7,12-dimethylbenz[a]anthracene (DMBA) by oral gavage once a week for 5 weeks. At 20 weeks after the first dose of DMBA, 68% of mice developed mammary tumors (the average 1.08 tumors per mouse) and 45% had lymphomas/leukemias. Feeding 1% dibenzoylmethane (DBM) in AIN 76A diet, starting at 2 weeks before the first dose of DMBA and continuing until the end of the experiment, inhibited both the multiplicity and incidence of DMBA-induced mammary tumor by 97%. The incidence of lymphomas/leukemias was completely inhibited by 1% DBM diet. In contrast, feeding 2% curcumin diet had little or no effect on the incidence of mammary tumors, and the incidence of lymphomas/leukemias was reduced by 53%.

Green tea epigallocatechin gallate shows a pronounced growth inhibitory effect on cancerous cells but not on their normal counterparts

(-)-Epigallocatechin gallate (EGCG), a catechin polyphenol compound, represents the main ingredient of green tea extract. Although EGCG has been shown to be growth inhibitory in a number of tumor cell lines, it is not clear whether the effect is cancer-specific. In this study we compared the effect of EGCG on the growth of SV40 virally transformed WI38 human fibroblasts (WI38VA) with that of normal WI38 cells. The IC50 value of EGCG was estimated to be 120 and 10 microM for WI38 and WI38VA cells, respectively. Thus, EGCG at 40 microM completely inhibited the growth of WI38VA cells, but had little or no inhibitory effect on the growth of WI38 cells. Similar differential growth inhibition was also observed between a human colorectal cancer cell line (Caco-2), a breast cancer cell line (Hs578T) and their respective normal counterparts. EGCG at a concentration range of 40-200 microM induced a significant amount of apoptosis in WI38VA cultures, but not in WI38 cultures, as determined by terminal deoxynucleotidyl transferase assay. After exposure to EGCG at 200 microM for 8 h, more than 50% of WI38VA cells in a confluent culture became apoptotic. In contrast, less than 1% of WI38 cells displayed apoptotic labeling under the same condition. EGCG did not affect the serum-induced expression of c-fos and c-myc genes in normal WI38 cells. However, it significantly enhanced their expression in transformed W138VA cells. It is possible that differential modulation of certain genes, such as c-fos and c-myc, may cause differential effects of EGCG on the growth and death of cancer cells.

Late onset systemic lupus erythematosus in southern Chinese

OBJECTIVE

Systemic lupus erythematosus (SLE) is a multisystem disorder that predominately affects women of the reproductive age. Onset of the disease beyond the age of 50 years is unusual. This study was undertaken to compare retrospectively the clinical and laboratory features between early and late onset (onset of disease beyond the age of 50 years) SLE patients in a Chinese population.

METHODS

Case records of all SLE patients who attended our rheumatology clinics between 1971 and 1997 were reviewed. Patients with a disease onset beyond the age of 50 years were identified. One hundred consecutive SLE patients who had their disease onset before the age of 50 were recruited as controls. The presenting clinical features, autoantibody profile, number of major organs involved, number of major relapses, and the use of cytotoxic agents in the two groups of patients were obtained and compared.

RESULTS

25 patients with late onset SLE were identified. All the female patients in the late onset group were postmenopausal. The female to male ratio was 3.2 to 1, compared with 13.3 to 1 in the control group (p < 0.02). Both groups had a comparable duration of disease. There were no significant differences in the presenting features between the two groups except for a lower prevalence of malar rash (24% v 86%, p < 0.0001) and a higher prevalence of rheumatoid factor (32% v 1%, p < 0.0001) in the late onset patients. On subsequent visits, the late onset group had a lower prevalence of lupus nephritis (4% v 51%, p < 0.001), fewer major organs involved (mean number of major organs involved; 0.3 v 0.9, p < 0.02), fewer major relapses (mean number of major relapses/patient; 0.08 v 0.47, p < 0.002, number of major relapses/patient year; 0.009 v 0.12, p < 0.001), and required fewer cytotoxic agents for disease control (percentage of patients on cytotoxic agents; 32% v 79%, p < 0.002).

CONCLUSION

Late onset SLE in Chinese tends to run a more benign course with fewer major organ involvement and fewer major relapses. The significantly higher incidence of male sex in late onset SLE and the milder disease course in the postmenopausal female patients suggest that oestrogen status may influence disease activity.

Photochemical reactions of flavor compounds

Photochemical reaction is a chemical reaction which is initiated by light. In addition to light, photosensitizer and oxygen are the two important factors which contribute to the formation of photochemical products. In this contribution, photochemical reactions of flavor compounds are classified into four categories according to the factors of photosensitizer and oxygen. Photochemical reaction with or without sensitizer in the absence of oxygen and unsensitized photochemical reaction in the presence of oxygen usually involve free radical reactions; while in the presence of oxygen and sensitizer, the singlet oxygen can be generated that then reacts with flavor compounds which contain double bonds to give the oxygenated products.

Process-induced chemical changes in foods. An overview

Processing of foods induces changes in their physical, chemical and sensory characteristics. Many researchers have shown the chemical consequences of food processing on acceptability and sensory attributes, nutritive value and wholesomeness of foods. A cursory account of these changes is provided.

Inhibitory activity of boswellic acids from Boswellia serrata against human leukemia HL-60 cells in culture

Four major triterpene acids including beta-boswellic acid (1), 3-O-acetyl-beta-boswellic acid (2), 11-keto-beta-boswellic acid (3), and 3-O-acetyl-11-keto-beta-boswellic acid (4) were isolated from the gum resin of Boswellia serrata and examined for their in vitro antitumor activity. They inhibited the synthesis of DNA, RNA and protein in human leukemia HL-60 cells in a dose dependent manner with IC50 values ranging from 0.6 to 7.1 microM. Among them, compound 4 induced the most pronounced inhibitory effects on DNA, RNA and protein synthesis with IC50 values of 0.6, 0.5, and 4.1 microM, respectively. The effect of 4 on DNA synthesis was found to be irreversible. Compound 4 significantly inhibited the cellular growth of HL-60 cells, but did not affect cell viability.

Mechanistic Studies on the Formation of Thiazolidine and Structurally Related Thiazines in a Cysteamine/2,3-Butanedione Model System

Phosphate was found to dramatically enhance the formation of 2-methyl-2-acetylthiazolidine from a cysteamine/2,3-butanedione model system. In addition to the major component, 2-methyl-2-acetylthiazolidine, significant amounts of two structurally closely related compounds, 2-acetyl-2,3,5,6-tetrahydro-1,4-thiazine and 5-acetyl-2,3-dihydro-1,4-thiazine, were characterized by using GC/MS (CI and EI). There was an oxidative transformation of 2-acetyl-2,3,5,6-tetrahydro-1,4-thiazine to 5-acetyl-2,3-dihydro-1,4-thiazine in the presence of azodicarbonamide. A formation mechanism for 2-methyl-2-acetylthiazolidine and structurally related 2-acetyl-2,3,5,6-tetrahydro-1,4-thiazine and 5-acetyl-2,3-dihydro-1,4-thiazine is proposed.