Arthralgia in midlife Singaporean women: the Integrated Women's Health Program (IWHP).

OBJECTIVE: Arthralgia is a common menopausal complaint in midlife women, and its causes remain unclear. We examined the prevalence of menopausal arthralgia with various factors including sleep quality, depression/anxiety, muscle strength and physical performance among midlife Singaporean women. METHODS: The Integrated Women's Health Program (IWHP) comprised 1120 healthy, community-dwelling women of Chinese, Malay or Indian ethnicities (aged 45-69 years) attending well-women clinics at the National University Hospital, Singapore. Sociodemographic, menopausal, reproductive and health data were obtained with validated questionnaires. Muscle strength, physical performance and dual-energy X-ray absorptiometry were measured. Women with moderate to very severe symptoms using the Menopause Rating Scale were classified as having arthralgia. Multivariable logistic regression analyses examined risk factors for arthralgia. RESULTS: One-third of the participants reported arthralgia, and 12.7%, 16.2% and 71.2% were in the premenopausal, perimenopausal and postmenopausal period, respectively. Menopausal symptoms, such as vaginal dryness (adjusted odds ratio [aOR]: 2.64, 95% confidence interval [CI]: 1.64, 4.24) and physical/mental exhaustion (aOR: 2.83, 95% CI: 1.79, 4.47), were independent risk factors for arthralgia. Poor muscle strength (aOR: 2.20, 95% CI: 1.29, 3.76), obesity (aOR: 1.94, 95% CI: 1.13, 3.32) and rheumatoid arthritis (aOR: 7.73, 95% CI: 4.47, 13.36) were also independently associated with arthralgia after adjustment for confounders. CONCLUSIONS: Arthralgia in midlife Singaporean women was associated with menopausal symptoms of vaginal dryness and physical and mental exhaustion. Women with poor muscle strength were more likely to experience menopausal arthralgia.

Excess mortality after hip fracture: fracture or pre-fall comorbidity?

Comorbidity and hip fracture independently increased mortality risk for 9 years in both sexes, with a significant additive interaction in the first year among women and through 6 years among men. INTRODUCTION: Hip fracture is associated with a persistently elevated mortality risk, but it is unknown whether the elevated risk is due to the fracture or to pre-fracture comorbidity. METHODS: In a population-based study in Singapore with 9 years of follow-up, patients age > 50 with first hip fracture from 2008 to 2017 were pair-matched to a cohort without hip fracture by age, sex, ethnicity, and pre-fracture Charlson Comorbidity Index (CCI). We investigated additive interaction using the relative excess risk due to interaction (RERI) and multiplicative interaction using the ratio of relative risks. RESULTS: Twenty-two thousand five hundred ninety of 22,826 patients with a first hip fracture in 2008-2017 were successfully matched. Hip fracture and comorbidity independently increased mortality risk for 9 years in both sexes. After adjustment for comorbidity, excess mortality risk continued to persist for 9 years post-fracture in both men and women. Women with a hip fracture and pre-fracture CCI > 4 had a higher relative risk (RR) of mortality at 9 years of 3.29 [95% confidence interval (CI) 3.01, 3.59] than those without comorbidity (RR 1.51, 95%CI 1.36, 1.68) compared to the referent without hip fracture or comorbidity. An additive interaction between hip fracture and pre-fracture CCI > 4 was observed in the first post-fracture year` [relative excess risk due to interaction (RERI) 1.99, 95%CI 0.97, 3.01]. For men with CCI ≥ 4, the positive additive interaction was observed through 6 years. CONCLUSIONS: Excess mortality risks post-fracture are attributable to both the fracture and pre-fracture comorbidity. Early interventions in hip fracture patients with high comorbidity could reduce their excess mortality.

Health information needs of 1000 midlife Singaporean women.

OBJECTIVES: Due to demographic changes, aging is a health priority. We aimed to identify midlife women's perceived health information needs and the preferred method(s) of information delivery. METHODS: A questionnaire was offered to women, aged 45-69 years, attending gynecological clinics during April/May 2016, collecting age and ethnicity data. Participants were asked to indicate important midlife health topics out of 26 topics, including 'other'. For each topic, six delivery options were offered. Age was stratified by 5-year intervals. Associations with age and ethnicity were examined using Pearson's chi-square tests (p < 0.05); analyses were performed with SPSS version 22.0. RESULTS: The top health topics chosen were gynecological cancer (66.0%), joint/muscle aches and pain (64.4%), bone health (63.2%), breast screening (55.9%), and heart health (55.3%). Adjusted results from the logistic regression model found that the odds of choosing the topics gynecological cancer, cervical screening, and complementary and alternative medicine for menopausal symptoms were significantly lower in age groups 55-59, 60-64 and 65-69 years compared to age group 45-49 years. Both Malay and Indian women were less likely to report bone health as important (odds ratio = 0.59, 95% confidence interval = 0.41-0.86) and (odds ratio = 0.64, 95% confidence interval = 0.42-0.98), respectively. Written leaflets were chosen by the majority (84.7%). CONCLUSION: This study of over 1000 midlife Asian women found that holistic health information is desired and requires tailoring by age, not ethnicity. Written information was preferred over support groups. These findings will guide clinical health services in delivering patient-centered information resources for midlife women.

Fecundity among women with polycystic ovary syndrome (PCOS)-a population-based study.

STUDY QUESTION: Does the long-term fecundity of women with polycystic ovary syndrome (PCOS) differ from those without PCOS? SUMMARY ANSWER: Cumulative probability of childbirth is similar between women with and without PCOS. WHAT IS KNOWN ALREADY: PCOS is the main cause of anovulatory infertility in women after menarche. Previous studies indirectly suggest that fecundity in women with PCOS over the longer term may not be lower than in women without PCOS. STUDY DESIGN, SIZE, DURATION: This is a population-based study using four linked Swedish national registries. A total of 45 395 women with PCOS and 217 049 non-PCOS women were included. Follow-up began at the age of 18 years and continued for a maximum of 26 years, from 1989 to the end of 2015. Childbirth was the main outcome, as identified from the Medical Birth Register. PARTICIPANTS/MATERIALS, SETTING, METHODS: All women born between 1971 and 1997 who were identified with a PCOS diagnosis in the Swedish Patient Registry between 1 January 2001 and 31 December 2016 were included in the study population. Five controls per women with PCOS were randomly drawn from the Total Population Registry. The control women were born in the same year and living in the same municipality as the patient. The fecundity ratio (FR) was calculated by clustered Cox regression using a robust variance, adjusted for maternal birth period, country of birth and level of education. MAIN RESULTS AND THE ROLE OF CHANCE: The cumulative probability of childbirth was 80.2% (95% CI, 79.5-80.9%) in women with PCOS and 78.2% (95% CI, 77.9-78.5%) in those without PCOS. Adjusted FR was 0.81 (95% CI, 0.80-0.82) for first childbirth and 0.58 (95% CI, 0.57-0.60) for first childbirth following a spontaneous pregnancy. The FR for second childbirth was 0.79 (95% CI, 0.77-0.80). Women with PCOS had more than one child less frequently than the comparison group. Within the PCOS group, early age at diagnosis, later birth year, Nordic country of origin and low educational level positively influenced the FR. LIMITATIONS, REASONS FOR CAUTION: Results are not adjusted for BMI, and time from intention to conceive to first childbirth could not be captured. Data on pregnancies, miscarriages or abortions and fertility treatment are unknown for women who did not give birth during the study period. Women with PCOS who did not seek medical assistance might have been incorrectly classified as not having the disease. Such misclassification would lead to an underestimation of the true association between PCOS and outcomes. WIDER IMPLICATIONS OF THE FINDINGS: While cumulative probability of childbirth is similar between groups, women with PCOS need longer time to achieve their first childbirth. Women with PCOS have a lower FR and give birth to fewer children per woman than women without PCOS. Early diagnosis of and information about PCOS may improve affected women's reproductive potential. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the Swedish Society of Medicine. Inger Sundström Poromaa has, over the past 3 years, received compensation as a consultant and lecturer for Bayer Schering Pharma, MSD, Gedeon Richter, Peptonics and Lundbeck A/S. The other authors declare no competing interests.

Hip fractures in Singapore: ethnic differences and temporal trends in the new millennium.

Despite an increase in absolute numbers, the age-standardized incidence of hip fractures in Singapore declined in the period 2000 to 2017. Among the three major ethnic groups, Chinese women had the highest fracture rates but were the only group to show a temporal decline. INTRODUCTION: A study published in 2001 predicted a 30-50% increase in Singapore hip fracture incidence rates over the ensuing 30 years. To test that prediction, we examined the incidence of hip fracture in Singapore from 2000 to 2017. METHODS: We carried out a population-based study of hip fractures among Singapore residents aged ≥ 50 years. National medical insurance claims data were used to identify admissions with a primary discharge diagnosis of hip fracture. Age-adjusted rates, based on the age distribution of the Singapore population of 2000, were analyzed separately by sex and ethnicity (Chinese, Malay, or Indian). RESULTS: Over the 18-year study period, 36,082 first hip fractures were recorded. Total hip fracture admissions increased from 1487 to 2729 fractures/year in the years 2000 to 2017. Despite this absolute increase, age-adjusted fracture rates declined, with an average annual change of - 4.3 (95% CI - 5.0, - 3.5) and - 1.1 (95% CI - 1.7, - 0.5) fractures/100,000/year for women and men respectively. Chinese women had 1.4- and 1.9-fold higher age-adjusted rates than Malay and Indian women: 264 (95% CI 260, 267) versus 185 (95% CI 176, 193) and 141 (95% CI 132, 150) fractures/100,000/year, respectively. Despite their higher fracture rates, Chinese women were the only ethnic group exhibiting a decline, most evident in those ≥ 85 years, in age-adjusted fracture rate of - 5.3 (95% CI - 6.0, - 4.5) fractures/100,000/year. CONCLUSION: Although the absolute number of fractures increased, steep drops in elderly Chinese women drove a reduction in overall age-adjusted hip fracture rates. Increases in the older population will lead to a rise in total number of hip fractures, requiring budgetary planning and new preventive strategies.

FRAX® based intervention thresholds for management of osteoporosis in Singaporean women.

Potential FRAX®-based major osteoporotic fracture (MOF) and hip fracture (HF) intervention thresholds (ITs) for postmenopausal Singaporean women were explored. Age-dependent ethnic-specific and weighted mean ITs progressively increased with increasing age. Fixed ITs were derived via discriminatory value analysis. MOF and HF ITs with highest the Youden index were chosen as optimal. INTRODUCTION: We aimed to explore FRAX®-based intervention thresholds (ITs) to potentially guide osteoporosis treatment in Singapore, a multi-ethnic nation. METHOD: One thousand and one Singaporean postmenopausal community-dwelling women belonging to Chinese, Malay and Indian ethnicities underwent clinical risk factor (CRF) and BMD assessment. FRAX® major osteoporotic fracture (MOF) and hip fracture (HF) probabilities were calculated using ethnic-specific models. We employed the translational logic adopted by NOGG (UK), whereby osteoporosis treatment is recommended to any postmenopausal woman whose fracture probability based on other CRFs is similar to or exceeds that of an age-matched woman with a fracture. Using the same logic, ethnic-specific and mean weighted age-dependent ITs were computed. Employing these age-dependent ITs as a reference, the performance of fixed (age-independent) ITs were examined using ROC curves and discriminatory analysis, with the highest Youden index (YI) (sensitivity + specificity - 1) used to identify the optimal MOF and HF ITs. RESULTS: The mean age was 58.9 (6.9) years. Seven hundred and eighty-nine (79%) women were Chinese, 136 (13.5%) Indian and 76 (7.5%) Malay. Age-dependent MOF ITs ranged from 3.1 to 33%, 2.5 to 17% and 2.5 to 16% whilst HF ITs ranged from 0.7 to 17%, 0.4 to 6% and 0.4 to 6.3% in Chinese, Malay and Indian women, respectively, between the ages of 50 and 90 years. The weighted age-dependent MOF and HF ITs ranged from 2.9% and 0.6%, respectively, at the age of 50, to 28% and 14% at 90 years of age. Fixed MOF/HF ITs of 5.5%/1%, 2.5%/1% and 2.5%/0.25% were identified as the most optimal by the highest YI in Chinese, Malay and Indian women, respectively. Fixed MOFP and HF ITs of 4% and 1%, respectively, were found to be most optimal on the weighted means analysis. CONCLUSION: The ITs for osteoporosis treatment in Singapore show marked variations across ethnicities. Weighted mean thresholds may overcome the dilemma of intervening at different thresholds for different ethnicities. Choosing fixed ITs may have to involve trade-offs between sensitivity and specificity. FRAX®-based age-dependent or the fixed intervention thresholds suggested as an alternative to be considered for use in Singapore though further studies on the societal and health economic impacts of choosing these thresholds in Singapore are needed.

STAT-3 regulation of CXCR4 is necessary for the prenylflavonoid Icaritin to enhance mesenchymal stem cell proliferation, migration and osteogenic differentiation.

Mesenchymal stem cell (MSC) dysfunction has been implicated in the pathogenesis of osteoporosis. MSCs derived from osteoporotic subjects demonstrate significant impairment in proliferation, adhesion and chemotaxis, and osteogenic differentiation, leading to reduced functional bone-forming osteoblasts and ultimately nett bone loss and osteoporosis. Epimedium herbs and its active compound Icaritin (ICT) have been used in Chinese ethnopharmacology for the treatment of metabolic bone diseases. Using an in-vitro cell culture model, we investigated the benefits of ICT treatment in enhancing MSC proliferation, migration and osteogenic differentiation, and provide novel data to describe its mechanism of action. ICT enhances MSC proliferation, chemotaxis to stromal cell-derived factor-1 (SDF-1) and osteogenic differentiation through the activation of signal transduction activator transcription factor 3 (STAT-3), with a consequential up-regulation in the expression and activity of cysteine (C)-X-C motif chemokine receptor 4 (CXCR4). These findings provide a strong basis for future clinical studies to confirm the therapeutic potential of ICT for the prevention and treatment of osteoporosis and fragility fractures.

The prenylflavonoid Icaritin enhances osteoblast proliferation and function by signal transducer and activator of transcription factor 3 (STAT-3) regulation of C-X-C chemokine receptor type 4 (CXCR4) expression.

In this study, we examined the effects of a natural prenylflavonoid Icaritin (ICT), on human osteoblast proliferation and osteogenic function. We observed that ICT dose-dependently enhanced osteoblast proliferation by ~15% over a 7day period. This increase in cell proliferation was associated with corresponding increases in osteoblast functions as measured by ALP secretion, intracellular calcium ions influx and calcium deposition. These anabolic effects were associated with a 4-fold increase in CXCR4 mRNA and protein expression. Silencing of CXCR4 protein expression using small interfering RNA reversed ICT-induced increase in cell proliferation, ALP activity and calcium deposition. Interestingly, we observed that ICT dose-dependently increased STAT-3 phosphorylation; and this resulted in increased binding of phosphorylated STAT-3 to the promoter region of the CXCR4 gene, to increase CXCR4 protein expression. Furthermore, we found that inhibition of STAT-3 phosphorylation resulted in a decrease in CXCR4 protein expression; whilst increasing phosphorylation of STAT-3 using a constitutive active STAT-3 vector significantly increased CXCR4 levels. Moreover, the chemical inhibition of STAT-3 phosphorylation annulled our previously observed ICT-induced increases of osteoblast proliferation and function. Finally, in a rat model of estrogen-deficient osteoporosis, ICT restored both osteoblasts numbers and CXCR4 expression. Taken together, both cellular and animal models support the novel findings that ICT; through the phosphorylation of STAT-3, up-regulated CXCR4, to increase osteoblast proliferation and function.

Chronic joint pain and handgrip strength correlates with osteoporosis in mid-life women: a Singaporean cohort.

This study aimed to identify novel correlates which may relate to low bone mass at lumbar spine in mid-life Asian women. The possibility of developing a prediction model for osteoporosis (OP) was explored which resulted in a risk assessment tool that performed better than currently available tools. INTRODUCTION: In order to identify novel correlates associated with low spinal bone mineral density (BMD) in mid-life women, we examined a large number of lifestyle and medical and performance measurements and developed a prediction model for triage to BMD scanning. METHODS: Women (n = 512) aged 45-69 years (mean 57.0 ± 6.3) attending gynecology clinics for "well woman" visits were recruited for this cross-sectional study from 2014 to 2015. We assessed symptoms, medical history, anthropometry, and physical performance. Stepwise multinomial logistic regressions were performed to examine significant associated covariates for pre-specified outcomes (normal [T-score ≥ -1.0], low bone mass [T-score between -1 and -2.5], and OP [T-score ≤ -2.5] at the lumbar spine). A new screening model was developed, and its performance was compared with the OP Screening Tool for Asians (OSTA) and Fracture Risk Assessment Tool (FRAX®). RESULTS: Spinal OP was found in 6.8%. Multivariate analysis indicated that chronic joint pain, the most common symptom reported by 37.5% of the women, was significantly associated with OP. Only age (Relative Risk Ratio [RRR] 1.63; 95%CI, 1.03-2.60), weight (RRR 0.14; 95% CI, 0.07-0.27), postmenopausal status (RRR 11.59, 95%CI, 1.15-116.73), chronic joint pain (RRR, 4.12; 95% CI, 1.53-11.07), and right handgrip strength (RRR 0.50; 95% CI, 0.31-0.80) were independently associated with spinal OP. Combining these five variables, our final model's area under curve (AUC) was significantly higher at 84% than both the OSTA [AUC; 79% (p value < 0.0231 'c' statistics)] and FRAX® [AUC 58% (p value < 0.0001 'c' statistic)]. CONCLUSION: A novel screening tool that combines age, weight, and menopausal status with chronic joint pain and right handgrip strength more reliably predicts spinal OP in mid-life Singaporean women.

Influenza A(H1N1)pdm09 infection in pregnant and non-pregnant women hospitalized in Singapore, May - December 2009.

OBJECTIVES: The aim of this study was to compare the demographic and clinical characteristics of pregnant women and non-pregnant women of childbearing age hospitalized with laboratory-confirmed influenza A(H1N1)pdm09 infection in Singapore, and to assess whether pregnancy was a risk factor associated with the development of influenza-related complications. STUDY DESIGN: Retrospective observational study. METHODS: We retrospectively identified and collected information from available medical records of all women admitted to three tertiary hospitals between 26 May 2009 and 31 December 2009 with laboratory-confirmed influenza A(H1N1)pdm09 infection who were either pregnant or non-pregnant and of childbearing age between 15 and 50 years. RESULTS: A total of 222 women, of whom 81 (36.5%) were pregnant, were hospitalized during the study period. Pregnant women were significantly more likely to be hospitalized with influenza A(H1N1)pdm09 infection than non-pregnant women of childbearing age (relative risk 26.3; 95% confidence interval: 20.1-34.6). Among those hospitalized, the proportion of pregnant women having at least one underlying medical condition that could predispose them to influenza-related complications was significantly lower than that of non-pregnant women (32.1% versus 56.0%, P < 0.001). The median time from onset of symptoms to administration of anti-viral drugs was significantly shorter among pregnant women than among non-pregnant women (three days versus five days, P < 0.001). The median length of stay in hospital was also significantly shorter among pregnant women than that of non-pregnant women (two days versus three days, P = 0.002). About 4.9% of pregnant women developed influenza-related complications, compared with 12.8% among non-pregnant women (P = 0.066). CONCLUSIONS: Pregnant women with influenza A(H1N1)pdm09 infection were at a higher risk of hospitalization. Upon hospitalization, they were not at a higher risk of developing influenza-related complications.

Phytoplankton blooms: an overlooked marine source of natural endocrine disrupting chemicals.

BACKGROUND: We had previously reported high androgenic and estrogenic activities in seawaters in confined clusters close to Singapore. Further investigations revealed a hitherto unsuspected link between estrogenic/androgenic activity and net phytoplankton count. OBJECTIVE: The primary objective of this study was to investigate the cause of a correlation between net phytoplankton and endocrine activity, and corroborate this observation, and rule out other possible confounding factors. Our secondary objective was to study if these estrogenic secretions can impact human health. METHODS: Five species of phytoplankton, Gymnodinium catenatum, Prorocentrum minimum, Alexandrium leei, Chattonella marina, and Fibrocapsa japonica, were isolated from Singapore waters and mass cultured and the cells and culture media screened for estrogenic and androgenic activity using human cell-based bioassays. RESULTS: The raphidophytes C. marina and F. japonica displayed significant estrogenic activity whilst the dinoflagellates G. catenatum and P. minimum displayed significant androgenic activity in both the cell extracts and the cell culture media extract. CONCLUSIONS: Our data shows that selected phytoplankton isolates are potent secretors of estrogenic and androgenic substances, which are potential endocrine disrupting chemicals (EDCs). As the harmful nature of EDCs is largely due to their bioaccumulation in the aquatic food chain our findings imply that the impact of these phytoplankton secretions needs to be investigated especially for seafoods, which are only a single trophic level away from phytoplankton. Alternatively, should these phytoplankton-origin EDCs not accumulate through marine food chains to significantly impact humans or marine mammals, our results indicate that functional assays could greatly over-estimate the risk from naturally occurring EDCs produced by marine phytoplankton. It remains to be determined if these EDCs affect zooplankton and other organisms that directly feed on marine phytoplankton, or if the secreted EDCs can directly impact other marine fauna.

Preparation and characterization of 4-isopropylcalix[4]arene-capped (3-(2-O-ß-cyclodextrin)-2-hydroxypropoxy)-propylsilyl-appended silica particles as chiral stationary phase for high-performance liquid chromatography.

A new type of 4-isopropylcalix[4]arene-capped (3-(2-O-ß-cyclodextrin)-2-hydroxypropoxy)propylsilyl-appended silica particles (IPC4CD-HPS) has been prepared by treatment of bromoacetate-substituted (3-(2-O-ß-cyclodextrin)-2-hydroxypropoxy)propylsilyl-appended silica particles (BACD-HPS) with 4-isopropylcalix[4]arene oxyanions in anhydrous N-methyl-2-pyrrolidone. The bonded silica IPC4CD-HPS has been successfully used as chiral stationary phase (CSP) in high-performance liquid chromatography (HPLC) for the first time. The synthetic stationary phase was characterized by means of elemental analysis and Fourier transform infrared spectroscopy. This new CSP has a chiral selector with two anchored functional moieties: 4-isopropylcalix[4]arene and ß-cyclodextrin. The chromatographic performance of IPC4CD-HPS was investigated by separation of positional isomers of several disubstituted benzenes and enantiomers of some chiral drug compounds under reversed-phase conditions. The results showed that IPC4CD-HPS had excellent selectivity for the separation of aromatic positional isomers and enantiomers of chiral compounds due to the cooperative functioning of the anchored 4-isopropylcalix[4]arenes and ß-cyclodextrins.

Serum free estradiol and estrogen receptor-α mediated activity are related to decreased incident hip fractures in older women.

There is paucity of data from Asian women on the association between serum estrogens and osteoporotic hip fracture risk. We conducted a case-control study nested within a population-based prospective cohort, The Singapore Chinese Health Study, to evaluate serum estrogens levels, ERα-mediated estrogenic activity and hip fracture risk in postmenopausal Asian women. Among 35,298 women who were recruited between 1993 and 1998, 15,410 women donated blood for research between 1999 and 2004. From this subcohort, we identified 140 cases who subsequently suffered hip fracture after blood donation, and 278 age-matched controls. Serum levels of total estrone, estradiol and sex hormone binding globulin levels were measured in a blinded fashion among cases and controls. ERα-mediated estrogenic activity of serum samples was quantified using a sensitive ERα-driven cell bioassay. Women with hip fracture had lower serum estrogens than control women. Compared to the lowest quintile, women in the highest quintile of free estradiol exhibited a statistically significant 57% reduction in risk of hip fracture (95% confidence interval (CI), 6-80%), with a dose-dependent relationship (p for trend=0.021). High levels of ERα-mediated estrogenic activity were also associated with decreased risk of hip fracture (p for trend=0.048). Overall, women with relatively high levels of both free estradiol and ERα-mediated estrogenic activity had a 55% reduction in hip fracture risk (95% CI, 17-76%) compared to women with low levels of both. High levels of free estradiol and ERα-mediated estrogen activity in sera were associated with reduced hip fracture risk in Chinese postmenopausal women.

Preparation and application of methylcalix[4]resorcinarene-bonded silica particles as chiral stationary phase in high-performance liquid chromatography.

Two new types of methylcalix[4]resorcinarene-bonded stationary phases, (3-(C-methylcalix[4]resorcinarene)-2-hydroxypropoxy)-propylsilyl-appended silica particles (MCR-HPS) and bromoacetate-substituted MCR-HPS particles (BAMCR-HPS), have been synthesized and used as chiral stationary phases for high-performance liquid chromatography (HPLC) for the first time. The synthetic stationary phases are characterized by means of elemental analysis and Fourier-transform infrared spectroscopy. The chromatographic behavior of MCR-HPS and BAMCR-HPS was studied with several disubstituted benzenes and some chiral drug compounds under both normal phase and reversed-phase conditions. The results show that MCR-HPS has excellent selectivity for the separation of aromatic positional isomers and BAMCR-HPS exhibits excellent performance for separation of enantiomers of chiral compounds.

Preparation and application of rifamycin-capped (3-(2-O-ß-cyclodextrin)-2-hydroxypropoxy)-propylsilyl-appended silica particles as chiral stationary phase for high-performance liquid chromatography.

Rifamycin-capped (3-(2-O-ß-cyclodextrin)-2-hydroxypropoxy)-propylsilyl-appended silica particles (RCD-HPS), a new type of substituted ß-cyclodextrin-bonded chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC), have been synthesized by the treatment of bromoacetate-substituted-(3-(2-O-ß-cyclodextrin)-2-hydroxypropoxy)-propylsilyl-appended silica particles (BACD-HPS) with rifamycin SV in anhydrous acetonitrile. The stationary phase is characterized by means of elemental analysis and Fourier-transform infrared spectroscopy. This new CSP has a chiral selector with two recognition sites: rifamycin and ß-cyclodextrin (ß-CD). The chromatographic behavior of RCD-HPS was studied with several disubstituted benzenes and some chiral drug compounds under reversed-phase HPLC mobile phase conditions. The results show that RCD-HPS has excellent selectivity for the separation of aromatic positional isomers and enantiomers of chiral compounds due to the cooperative functioning of rifamycin and ß-CD.

Application of bromoacetate-substituted beta-CD-bonded silica particles as chiral stationary phase for HPLC.

Bromoacetate-substituted [3-(2-O-beta-cyclodextrin)-2-hydroxypropoxy]propylsilyl-appended silica particles (BACD-HPS), an important and useful synthetic intermediate for preparation of novel types of macrocycles-capped beta-CD-bonded silica particles including crown ether/cyclam/calix[4]arene-capped beta-CD-bonded silica particles, have been prepared and used as chiral stationary phase for HPLC. This synthetic stationary phase is characterized by means of elemental analysis. For the first time, the chromatographic behavior of BACD-HPS was systematically evaluated with several disubstituted benzenes and some chiral drug compounds under both normal and RP conditions in HPLC. The results show that BACD-HPS has excellent selectivity for the separation of aromatic positional isomers and chiral isomers of some drug compounds when used as stationary phase in HPLC.