Catalytic asymmetric carbenoid α-C-H insertion of ether.

Significant advancements have been made in catalytic asymmetric α-C-H bond functionalization of ethers via carbenoid insertion over the past decade. Effective asymmetric catalytic systems, featuring a range of chiral metal catalysts, have been established for the enantioselective synthesis of diverse ether substrates. This has led to the generation of various enantioenriched, highly functionalized oxygen-containing structural motifs, facilitating their application in the asymmetric synthesis of bioactive natural products.

Modulation of innate immune response to viruses including SARS-CoV-2 by progesterone.

Whether and how innate antiviral response is regulated by humoral metabolism remains enigmatic. We show that viral infection induces progesterone via the hypothalamic-pituitary-adrenal axis in mice. Progesterone induces downstream antiviral genes and promotes innate antiviral response in cells and mice, whereas knockout of the progesterone receptor PGR has opposite effects. Mechanistically, stimulation of PGR by progesterone activates the tyrosine kinase SRC, which phosphorylates the transcriptional factor IRF3 at Y107, leading to its activation and induction of antiviral genes. SARS-CoV-2-infected patients have increased progesterone levels, and which are co-related with decreased severity of COVID-19. Our findings reveal how progesterone modulates host innate antiviral response, and point to progesterone as a potential immunomodulatory reagent for infectious and inflammatory diseases.

Genetic diversity and main functional composition of Lingzhi strains from main producing areas in China.

In this study, we used genotyping by sequencing (GBS) to examine the genetic diversity of 22 strains of Lingzhi and the quality differences in 15 fruit bodies of Lingzhi from different Chinese regions. The phylogenetic trees of 22 strains were constructed based on ITS (Internal transcribed spacer) and SNP (single nucleotide polymorphism). Moisture, ash, water-soluble extracts, alcohol-soluble extracts, polysaccharides, and triterpenoids from 15 fruit bodies of Lingzhi were detected and analyzed based on Chinese Pharmacopoeia and the US Pharmacopoeia references. Moreover, the monosaccharide composition of polysaccharides was studied using PMP-HPLC, and the effect of polysaccharides on the proliferation rate of splenocytes was investigated in vitro. The identification results of these strains by the phylogenetic trees which were constructed based on ITS sequences and SNPs showed that most of the strains applied in the main producing areas of Lingzhi in China were accurate except for a few inaccurate strains. The moisture, ash, water and alcohol soluble extractive, polysaccharide and triterpenoid content of all samples were meet the requirements of the Chinese Pharmacopoeia, while the polysaccharide and triterpenoid content of less than half of the samples meet the requirements of the U.S. Pharmacopoeia. The polysaccharide extracted from these samples have different effects on the proliferation rate of spleen cells. To sum up, this is the first study that reported on the differences in Lingzhi strains from the main producing areas in China. The quality of some fruit bodies did not meet the pharmacopeia requirements, and wrong strains were used in some production areas; thus, strains should be given special attention before legal processing.

Oxidative Indole Dearomatization for Asymmetric Furoindoline Synthesis by a Flavin-Dependent Monooxygenase Involved in the Biosynthesis of Bicyclic Thiopeptide Thiostrepton.

The interest in indole dearomatization, which serves as a useful tool in the total synthesis of related alkaloid natural products, has recently been renewed with the intention of developing new methods efficient in both yield and stereoselective control. Here, we report an enzymatic approach for the oxidative dearomatization of indoles in the asymmetric synthesis of a variety of furoindolines with a vicinal quaternary carbon stereogenic center. This approach depends on the activity of a flavin-dependent monooxygenase, TsrE, which is involved in the biosynthesis of bicyclic thiopeptide antibiotic thiostrepton. TsrE catalyzes 2,3-epoxidation and subsequent epoxide opening in a highly enantioselective manner during the conversion of 2-methyl-indole-3-acetic acid or 2-methyl-tryptophol to furoindoline, with up to >99 % conversion and >99 % ee under mild reaction conditions. Complementing current chemical methods for oxidative indole dearomatization, the TsrE activity-based approach enriches the toolbox in the asymmetric synthesis of products possessing a furoindoline skeleton.

Recent applications of solid-phase strategy in total synthesis of antibiotics.

Antibiotics produced by soil microorganisms have been widespread and have cured the most prevalent diseases since 1940s. However, recent bacterial resistance to existing antibacterial drugs is causing a public health crisis. The structure-activity relationship of antibiotics needs to be established to search for existing antibiotics-based next-generation drug candidates that can conquer the challenge of bacterial resistance preparedness, which relies on the development of highly efficient total synthesis strategies. The solid-phase strategy has become important to circumvent tedious intermediate isolation and purification procedures with simple filtrations. This review will give a brief overview of recent applications of solid-phase strategy in the total synthesis of antibiotics.

Total synthesis of natural products using photocycloaddition reactions of arenes.

The photocycloaddition reaction of benzene with alkenes has become a significant approach for organic chemists and thus has been frequently utilized as a key step in the total synthesis of natural products. In this mini-review, the recent developments in [4 + 2] and [2 + 2] photocycloaddition reactions will be emphasized in constructing core scaffolds of complex natural products. By combining them together, we aim to demonstrate the utility and reinstate the importance of this methodology.

[Impact of the freezing-thawing process on human sperm mitochondria].

OBJECTIVE: To study the structure and function of human sperm mitochondria before and after the freezing-thawing process. METHODS: Human sperm from healthy donors were subjected to the slow freezing-thawing process, and the sperm mitochondrion-related indexes compared before and after cryopreservation. The ultrastructural changes of the mitochondria were observed under the projection electron microscope, the mitochondrial membrane potential (MMP) and seminal adenosine triphosphate (ATP) content measured by immunofluorescence labeling and ELISA, respectively, and the sperm oxidative stress related indexes detected before and after sperm cryopreservation. RESULTS: Electron microscopy showed loose structures and widened crests of the sperm mitochondria, some with vacuole-like changes after the freezing-thawing process. The sperm after cryopreservation, compared with those before it, exhibited significantly increased contents of oxygen free radicals (ï¼»11.6 ± 3.8ï¼½% vs ï¼»9.6 ± 4.1ï¼½%, P < 0.05) and malondialdehyde (ï¼»3.2 ± 1.4ï¼½ vs ï¼»2.3 ± 1.2ï¼½ nmol/108, P < 0.05), but decreased antioxidant capacity (ï¼»0.6 ± 0.4ï¼½ vs ï¼»0.9 ± 0.4ï¼½ nmol/108, P < 0.05), superoxide dismutase activity (ï¼»0.9 ± 0.4ï¼½ vs ï¼»9.1 ± 3.9ï¼½ nmol/108, P < 0.05), MMP (ï¼»52.2 ± 6.2ï¼½% vs ï¼»55.7 ± 4.9ï¼½%, P = 0.026) and ATP production (ï¼»56.5 ± 9.0ï¼½ vs ï¼»61.3 ± 10.4ï¼½ pmol/106, P = 0.014). CONCLUSIONS: The freezing-thawing process can cause ultrastructural disorder of human sperm mitochondria, reduce their membrane potential and decrease their ATP production.

Enantioselective Synthesis of Arene cis-Dihydrodiols from 2-Pyrones.

An enantioselective chemical synthesis of arene cis-dihydrodiols has been realized from 2-pyrones through sequential ytterbium-catalyzed asymmetric inverse-electron-demand Diels-Alder (IEDDA) reaction of 2-pyrones and retro-Diels-Alder extrusion of CO2 . By using this strategy, a series of substituted arene cis-dihydrodiols can be obtained efficiently with high enantioselectivity (>99 % ee in many cases). Based on this strategy, efficient and concise asymmetric total syntheses of (+)-MK7607 and 1-epi-(+)-MK7607 were accomplished.

In the human sperm nucleus, nucleosomes form spatially restricted domains consistent with programmed nucleosome positioning.

In human sperm, a fraction of its chromatin retains nucleosomes that are positioned on specific sequences containing genes and regulatory units essential for embryonic development. This nucleosome positioning (NP) feature provides an inherited epigenetic mark for sperm. However, it is not known whether there is a structural constraint for these nucleosomes and, if so, how they are localized in a three-dimensional (3D) context of the sperm nucleus. In this study, we examine the 3D organization of sperm chromatin and specifically determine its 3D localization of nucleosomes using structured illumination microscopy. A fraction of the sperm chromatin form nucleosome domains (NDs), visible as microscopic puncta ranging from 40 µm to 700 µm in diameter, and these NDs are precisely localized in the post acrosome region (PAR), outside the sperm's core chromatin. Further, NDs exist mainly in sperm from fertile men in a pilot survey with a small sample size. Together, this study uncovers a new spatially-restricted sub-nuclear structure containing NDs that are consistent with NPs of the sperm, which might represent a novel mark for healthy sperm in human.

[Status quo of autologous sperm preservation in the human sperm bank in Beijing].

OBJECTIVE: To comprehensively analyze the status quo of autologous sperm preservation in the human sperm bank in Beijing and better utilize the existing resources for the preservation of male fertility. METHODS: We retrospectively analyzed the geographical data and semen quality of 251 males with autologous sperm preservation in the Human Sperm Bank, Science and Technology Research Institute, National Health and Family Planning Commission of China from July 2006 to December 2016. RESULTS: The rate of autologous sperm preservation in the Human Sperm Bank was as low as 8.76% between July 2006 and December 2010 but increased annually by 119% on average from 2011 to 2013. Of the 251 males involved, 204 (81.27%) were aged 20－39 years, 175 (69.72%) had bachelor's or master's degree, 223 (88.84%) had no child, 69 (27.49%) got less than 10 tubes of semen samples frozen, and 26 (10.36%) had their semen samples cryopreserved only once. The utilization rate of the cryopreserved sperm was only 5.58 % (n = 14). The main reason for autologous sperm preservation was carcinoma (55.78% ï¼»n = 140ï¼½), including blood cancer (22.31% ï¼»n = 66ï¼½), testicular cancer (13.15% ï¼»n = 33ï¼½) and other cancers (16.33% ï¼»n = 41ï¼½). Compared with the non-cancer males, the cancer patients had a significantly reduced mean sperm concentration (90.45 vs 60.53 ×106/ml, P < 0.05), total sperm count (311.3 vs 175.8 ×106, P < 0.05), percentage of progressively motile sperm (PMS) (49.21% vs 43.55%, P < 0.05) and recovery rate of PMS (68.13% vs 52.17%, P < 0.05). In the subgroups of testicular, blood and other cancers, the sperm concentration averaged 37.68, 57.98 and 90.69 ×106/ml, the semen volume 2.73, 2.82 and 3.41 ml, the total sperm count 93.29, 158.41 and 349.49 ×106, the percentage of PMS 45.32%, 43.47% and 44.49%, and the recovery rate of PMS 48.32%, 50.07% and 61.09%, respectively, the sperm concentration and total sperm count significantly lower in the testicular cancer patients than in the other two groups (P < 0.05). CONCLUSIONS: The number of the cases of autologous sperm preservation in Beijing is increasing year by year, and the majority of them are cancer patients. As most of the cancer patients have missed the best period for sperm preservation, sperm bank workers should endeavor to increase the public awareness of autologous sperm preservation.

Manipulation of Spiroindolenine Intermediates for Enantioselective Synthesis of 3-(Indol-3-yl)-Pyrrolidines.

By manipulating the reactivity of spiroindolenine species, a sequential Michael/retro-Mannich/Mannich reaction of ω-indol-3-yl α,ß-unsaturated ketones was developed. In the presence of 10 mol % of a chiral phosphoric acid as the catalyst, a series of 3-(indol-3-yl)-pyrrolidines were synthesized in high yields (up to 91 %) with excellent stereoselectivities (up to 92 % ee, >19:1 d.r.). The products obtained here undergo diverse functional-group transformations. The mechanistic proposal of this reaction is supported by DFT calculations.

Obesity impairs male fertility through long-term effects on spermatogenesis.

OBJECTIVE: This study aimed to investigate the effect and possible underlying mechanisms of high-fat diet-induced obesity on spermatogenesis in male rats. METHODS: A total of 45 male rats were randomly divided into control (n = 15, normal diet) and obesity groups (n = 30, high-fat diet) and were fed for 16 weeks. Body weight and organ indexes were determined after sacrifice. Indicators of reproductive function, including sperm count, sperm motility, apoptosis of spermatogenic cells, and oxidative stress levels, were measured. Serum metabolic parameters and reproductive hormones were also assayed. RESULTS: Compared with the control group, epididymal sperm motility in the obese rats was significantly decreased (P < 0.01). Morphological analysis of the obesity group showed vacuolar changes in seminiferous tubules, spermatogenic cell dysfunction, and increased apoptosis of spermatogenic cells in testicular tissue (P < 0.05). The calculated free testosterone (cFT) concentration in serum was decreased (P < 0.05), whereas the serum sex hormone-binding globulin (SHBG) level was significantly increased (P < 0.01). The superoxide dismutase (SOD) concentration decreased and the malondialdehyde (MDA) concentration increased in testis tissues; however, neither changes were statistically significant (P > 0.05). RESULTS: Nutritional obesity can damage spermatogenesis in male rats due to long-term effects on spermatogenesis.

[L-carnitine protects the motion parameters and mitochondrial function of human sperm in cryopreservation].

OBJECTIVE: To study the effects of L-carnitine (LC) on cryopreserved human sperm. METHODS: Ten semen samples were collected from normal sperm donors, each divided into six groups, fresh ejaculate (FE), non-LC cryopreservation (non-LC), and cryopreservation with LC at 1 mmol/L (LC-1), 2.5 mmol/L (LC-2), 5 mmol/L (LC-3) and 10 mmol/L (LC-4), respectively. The optimal concentration of LC was identified based on the motility and motion parameters of the post-thaw sperm. The plasma membrane integrity (PMI) of the sperm was assessed by eosin-nigrosin staining, their mitochondrial membrane potential (MMP) monitored by JC-1 assay, and the level of sperm ROS measured by the fluorescent probe DCFH-DA, followed by analysis of the mechanisms of LC protecting sperm against cryopreservation injury. RESULTS: Compared with the sperm in the FE group, the post-thaw sperm in the non-LC and LC groups showed significantly decreased progressive motility, average path velocity (VAP), straight line velocity (VSP) and curvilinear velocity (VCP) (P < 0.05). In comparison with the non-LC group, the LC-3 group exhibited a remarkably higher percentage of progressively motile sperm (ï¼»41.9 ± 4.6ï¼½ vs ï¼»47.0 ± 4.3ï¼½%, P = 0.0261) and VAP (ï¼»34.9 ± 2.6ï¼½ vs ï¼»38.9 ± 4.2ï¼½ µm/s, P = 0.0152), indicating that the optimal concentration of LC was 5 mmol/L. Both PMI and MMP were significantly lower in the non-LC than in the FE group (ï¼»52.7 ± 5.7ï¼½ vs ï¼»75.5 ± 5.4ï¼½%, P < 0.01 and ï¼»44.5 ± 3.5ï¼½ vs ï¼»57.3 ± 4.4ï¼½%, P < 0.01), but higher in the LC groups (ï¼»70.1 ± 8.2ï¼½% and ï¼»50.3 ± 3.4ï¼½%) than in the non-LC group (P < 0.01 and P < 0.05). The level of sperm ROS, however, was markedly higher in the non-LC than in the FE group (ï¼»12.5 ± 3.9ï¼½ vs ï¼»6.8 ± 2.4ï¼½, P < 0.01) but lower in the LC groups (ï¼»8.4 ± 5.3ï¼½%) than in the non-LC group (P = 0.05). CONCLUSIONS: L-carnitine can improve the motility and motion parameters of cryopreserved human sperm by reducing sperm ROS, enhancing sperm mitochondrial membrane potential and protecting the sperm plasma membrane.

[Levels of serum reproductive hormones and metabolic syndrome in adult males].

OBJECTIVE: To investigate the prevalence of metabolic syndrome (MS) and its relationship with reproductive hormones in adult males in China. METHODS: Using the cluster and stratified sampling methods, we conducted an investigation among 3 600 adult males aged over 20 years in Hebei, Shaanxi and Jiangsu provinces. We obtained their reproductive hormone levels, biochemical indicators and basic body indexes and compared them between the two groups of subjects. RESULTS: A total of 3 332 valid serum samples were collected, which revealed a prevalence rate of MS of 38.5% in the adult males. Compared with the non-MS subjects, the MS males showed a significantly higher free testosterone index (FTI, 0.39 ± 0.15 vs 0.45 ± 0.19, P < 0.01) but lower levels of total testosterone (TT, ï¼»16.35 ± 4.78ï¼½ vs ï¼»13.37 ± 4.23ï¼½ nmo/L, P < 0.01) and sex hormone-binding globulin (SHBG, ï¼»47.13 ± 20.50ï¼½ vs ï¼»33.32 ± 14.91ï¼½ nmol/L, P < 0.01) and testosterone secretion index (TSI, 3.64 ± 1.92 vs 3.14 ± 1.80, P < 0.01). There were no statistically significant differences between the two groups in the levels of calculated free testosterone (cFT) and LH (P > 0.05). Spearman rank correlation analysis showed that the levels of serum TT and SHBG were correlated with all the indicators of MS (P < 0.01) except systolic blood pressure (SBP), while that of cFT only with the levels of high-density lipoprotein (HDL), fasting blood glucose (FBG) and SBP (P < 0.01). After adjusted for age, smoking, drinking, and body mass index (BMI), all the MS indicators were significantly associated with the SHBG level (P < 0.01), but not high blood pressure with the serum TT level (P > 0.05). After adjusted for the age, smoking, drinking, BMI and TT, the serum SHBG level was the main independent risk factor for MS (OR: 0.965, 95% CI: 0.958－0.973, P < 0.01). CONCLUSIONS: The level of serum cFT is not correlated with while that of SHBG is the main independent risk factor for metabolic syndrome in adult males in China.

Asymmetric fluorinative dearomatization of tryptamine derivatives.

An asymmetric fluorinative dearomatization reaction of tryptamine derivatives was developed by using a chiral anion phase transfer catalyst (PTC) system, and the preliminary results of the reaction mechanistic study were achieved. This method is characterized by a simple operation, facile introduction of a fluorine atom in a highly enantioselective manner and construction of two contiguous quaternary stereogenic centers.

[Protective effect of Qilin Pills on the reproductive function of oligoasthenospermia rats].

OBJECTIVE: To study the protective effect of Qilin Pills (QLP) on the reproductive function of rats with oligoasthenospermia (OAS) induced by tripterygium glycosides. METHODS: Twenty-eight male SD rats were randomly divided into a normal control, an OAS model control, a low-dose QLP, and a high-dose QLP group of equal number. OAS models were made in the latter three groups by intragastrical administration of tripterygium glycosides at 40 mg per kg of the body weight per day, and meanwhile the animals in the low- and high-dose QLP groups were treated with QLP at 1.62 and 3.24 g per kg of the body weight per day, respectively, while those in the OAS model group with normal saline, all for 30 consecutive days. Then all the rats were executed for obtaining the testis weight, testis viscera index, epididymal sperm concentration and motility, reproductive hormone levels, and antioxidation indexes and observation of the histomorphological changes of the testis tissue by HE staining. RESULTS: After 30 days of intervention, the low- and high-dose QLP groups, as compared with the OAS model controls, showed significantly improved epididymal sperm concentration (ï¼»14.57 ± 3.95ï¼½ and ï¼»39.71 ± 11.31ï¼½ vs ï¼»4.71 ± 1.25ï¼½ ×106/ml, P <0.05) and motility (ï¼»3.71 ± 1.11ï¼½ and ï¼»4.29 ± 1.80ï¼½ vs ï¼»0.57 ± 0.53ï¼½%, P <0.05), increased levels of sex hormone binding globulin (SHBG) (ï¼»94.83 ± 11.17ï¼½ and ï¼»88.05 ± 9.21ï¼½ vs ï¼»56.74 ± 8.29ï¼½ nmol/L, P <0.05) and free testosterone (FT) (ï¼»27.27 ± 3.63ï¼½ and ï¼»32.80 ± 2.51ï¼½ vs ï¼»22.81 ± 2.75ï¼½ nmol/L, P <0.05), decreased level of follicle-stimulating hormone (FSH) (ï¼»1.49 ± 0.62ï¼½ and ï¼»1.12 ± 0.83ï¼½ vs ï¼»1.71 ± 0.52ï¼½ mIU/ml, P <0.05), but no significant change in the total testosterone (TT) level. Meanwhile, the level of superoxide dismutase (SOD) was markedly elevated in the low- and high-dose QLP groups in comparison with the OAS model control group (ï¼»277.14 ± 15.84ï¼½ and ï¼»299.60 ± 20.83ï¼½ vs ï¼»250.04 ± 31.06ï¼½ U/ml, P <0.05) while that of reactive oxygen species (ROS) remarkably reduced (ï¼»397.61 ± 62.71ï¼½ and ï¼»376.84 ± 67.14ï¼½ vs ï¼»552.20 ± 58.07ï¼½ IU/ml, P <0.05). HE staining showed that QLP intervention significantly increased the layers and quantity of spermatogenic cells in the testicular seminiferous tubules of the OAS rats. CONCLUSIONS: QLP can effectively protect the reproductive system of oligoasthenospermia rats by raising sperm quality, elevating reproductive hormone levels, reducing oxidative stress injury, and improving histomorphology of the testis.

Dearomatization through Halofunctionalization Reactions.

Recent advances in dearomatization through halofunctionalization reactions are summarized in this Minireview. Two general categories of strategies are currently employed in this field. On one hand, the reaction can be initiated with electrophilic halogenation at an alkyne or alkene moiety. The resulting halonium ion intermediate is then captured by a pendant aromatic ring at the ipso position, affording the dearomatization product. On the other hand, electrophilic halogenation can directly take place at a substituted arene, and the final dearomatization product is furnished by deprotonation or intramolecular nucleophilic trap. Highly enantioselective variants have been realized in the latter case by organocatalysis or transition metal catalysis. By applying these methods, various valuable halogenated polycyclic molecular architectures have been obtained from readily available starting materials.

Copper(I)-Catalyzed Asymmetric Dearomatization of Indole Acetamides with 3-Indolylphenyliodonium Salts.

The rapid and direct asymmetric synthesis of 3-(3a-indolyl)hexahydropyrroloindoline motifs is an extremely important part of the total synthesis of several alkaloid structures. Herein, an intermolecular, asymmetric cascade dearomatization reaction of indole acetamides with 3-indolylphenyliodonium salts has been developed. This protocol provides a straightforward access to 3-(3a-indolyl)hexahydropyrroloindolines bearing an all-carbon quaternary stereocenter at the C3 position of the indoline ring with high enantioselectivities. The utility of the protocol has been demonstrated by the formal asymmetric synthesis of folicanthine.

Serum homocysteine and metabolic syndrome in middle-aged and elderly men / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the relationship among serum reproductive hormone levels, serum homocysteine (Hcy) levels, metabolic syndrome (MS), and the components of MS in middle-aged and elderly males.</p><p><b>METHODS</b>Using the cluster and stratified sampling methods and a unified structured questionnaire, we conducted a survey among 948 men aged 40 - 80 years in the rural community, measured their basic physical parameters, and obtained their reproductive hormone levels, serum Hcy concentrations, and metabolism-related indicators. We collected 868 valid questionnaires along with their serum samples, divided the subjects into an MS and a non-MS control group in a 1:1 ratio, and measured their serum Hcy concentrations.</p><p><b>RESULTS</b>Among the subjects included, 132 were diagnosed with MS. Nonparametric tests showed statistically significant differences between the MS and non-MS groups in the waist circumference (WC), waist-hip ratio (WHR), body mass index (BMI), systolic blood pressure (SBP), and diastolic blood pressure (DBP) (P < 0.05), but not in age (P > 0.05). Significant differences were also observed between the two groups in the levels of serum tT, SHBG, LH, and FTI (P < 0.05) , but not in the concentrations of serum Hcy (P > 0.05). The concentration of serum Hcy exhibited no correlation with BMI, SBP, DBP, FBG, TG, and HDL-C (P > 0.05) and had no influence on MS.</p><p><b>CONCLUSION</b>The concentration of serum Hcy is not significantly correlated with MS, nor with its components. The levels of male serum reproductive hormones are associated both with MS and with its components.</p>

Is serum sex hormone-binding globulin a dominant risk factor for metabolic syndrome?

This multi-center, cross-sectional study investigated the association between serum testosterone (T) levels, serum sex hormone-binding globulin (SHBG) levels, and the risk of metabolic syndrome (MS) in 3332 adult Chinese men. The prevalence of MS was 34.7%, and men with MS had lower serum levels of total T (TT) and SHBG than those without MS (P < 0.001). There was no significant difference in serum free T (FT) levels between subjects with and without MS (P = 0.627). In logistic regression analysis, the association between MS and serum SHBG levels persisted after adjusting for age, body mass index (BMI), smoking and drinking status, and serum TT (odds ratio [OR] 0.962, 95% confidence interval [95% CI] 0.954-0.969, P< 0.01). However, the association between serum TT level and the risk of MS was weak after adjusting for age, BMI, SHBG level, and smoking and drinking status (OR 0.981, 95% CI 0.960-1.007). Our study reveals that both serum TT and SHBG levels, but not serum FT, are inversely associated with the prevalence of MS and that serum SHBG is an independent and dominant risk factor for MS.