Using a global diversity panel of Cannabis sativa L. to develop a near InfraRed-based chemometric application for cannabinoid quantification.

C. sativa has gained renewed interest as a cash crop for food, fibre and medicinal markets. Irrespective of the final product, rigorous quantitative testing for cannabinoids, the regulated biologically active constituents of C. sativa, is a legal prerequisite across the supply chains. Currently, the medicinal cannabis and industrial hemp industries depend on costly chromatographic analysis for cannabinoid quantification, limiting production, research and development. Combined with chemometrics, Near-InfraRed spectroscopy (NIRS) has potential as a rapid, accurate and economical alternative method for cannabinoid analysis. Using chromatographic data on 12 therapeutically relevant cannabinoids together with spectral output from a diffuse reflectance NIRS device, predictive chemometric models were built for major and minor cannabinoids using dried, homogenised C. sativa inflorescences from a diverse panel of 84 accessions. Coefficients of determination (r2) of the validation models for 10 of the 12 cannabinoids ranged from 0.8 to 0.95, with models for major cannabinoids showing best performance. NIRS was able to discriminate between neutral and acidic forms of cannabinoids as well as between C3-alkyl and C5-alkyl cannabinoids. The results show that NIRS, when used in conjunction with chemometrics, is a promising method to quantify cannabinoids in raw materials with good predictive results.

A sensitive, high-throughput fluorescent method for the determination of lactoperoxidase activities in milk and comparison in human, bovine, goat and camel milk.

Lactoperoxidase (LPO) is one of the major antibacterial ingredients in milk and an extensively employed indicator for milk heat treatment. The traditional method for LPO activity measurement using ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonate) cannot achieve high sensitivity and is affected by indigenous milk thiocyanate. A more sensitive microplate fluorescent assay was developed by monitoring generation of red-fluorescent resorufin from LPO catalysed oxidation of Amplex® Red (1-(3,7-dihydroxyphenoxazin-10-yl)ethanone) in this study. The assay is particularly suitable for milk LPO activity measurement as it eliminates the influences of indigenous milk hydrogen peroxide and thiocyanate. The method limit of detection was 7.1x10-6 U/mL of LPO in milk and good intra-run and inter-run precision was obtained. The LPO activities ranked as bovine > goat > camel > human in the four types of milk analysed. The high sensitivity and low cost of this assay makes it suitable for LPO activity analyses in both laboratory and commercial scales.

A sensitive and high-throughput fluorescent method for determination of oxidase activities in human, bovine, goat and camel milk.

Milk oxidases are an integral part of milk immune system, and good indicators for milk thermal history. Current assay methods for milk oxidases are either insensitive, tedious or not cost-effective. In this study, a high-throughput fluorescence assay method for determination of xanthine oxidase (XO) and polyamine oxidase (PAO) activities in milk samples was developed. The hydrogen peroxide generated by XO catalysed oxidation of hypoxanthine, and PAO catalysed oxidation of spermine, was coupled to horseradish peroxidase conversion of Amplex® Red (1-(3,7-dihydroxyphenoxazin-10-yl)ethanone) to the fluorescent product resorufin. The assay was highly sensitive, with limits of detection of activity in milk being 3 × 10-7 and 7 × 10-7 U/mL for XO and PAO, respectively. Intra-run and inter-run results showed good assay repeatability and reproducibility. The assay was successfully applied to survey the XO and PAO activities in human, bovine, goat and camel milk samples, and it can be readily adapted for measurements of other oxidase activities.

Bio-Guided Fractionation of Papaya Leaf Juice for Delineating the Components Responsible for the Selective Anti-proliferative Effects on Prostate Cancer Cells.

Alternative therapies against cancer cells with minimal or no effect on healthy tissues are highly sought after. Prostate cancer (PCa) is the second most frequently diagnosed malignancy in males. The Carica papaya L. leaf extract has been traditionally used by Australian aboriginal people for anticancer properties. In this study, medium polar fraction of papaya leaf extract that had shown anti-proliferative activity in PCa cell lines in vitro, in earlier studies, was further fractionated to 28 fractions by semi-preparative HPLC. Nine of these fractions were identified to possess selective anti-proliferative responses on PCa cells in comparison to non-cancerous cells of prostate gland origin. When these nine sub-fractions were mixed in various combinations, a combination containing six of the specific fractions (FC-3) showed the best potency. FC3 inhibited the growth of BPH-1, PC-3, and LNCaP cells in a concentration-dependent manner with an IC50 value <20 µg/mL, while (unlike paclitaxel, the positive control) minimal effect was observed on the proliferation of non-cancerous, WPMY-1 and RWPE-1cells. Furthermore, synergistic interaction of FC-3 with paclitaxel was observed with combination index values in the range of 0.89-0.98 and 0.85-1.10 on PC-3 and LNCaP cells, respectively. Untargeted qualitative analysis using UHPLC (Ultra High-Performance Liquid Chromatography)-QToF (Quadrupole Time of-Flight) mass spectrometry and screening against the METLIN database indicated presence of multiple known anticancer compounds in the FC-3 extract. These outcomes show that the potent and selective anti-proliferative effects are due to a range of bio-active compounds within the medium polar fraction of papaya leaf juice.

Separation of highly charged compounds using competing ions with hydrophilic interaction liquid chromatography - Application to assay of cellular nucleotides.

Separation of highly charged compounds has always been a challenge in chromatography. Ion-pair reversed phase chromatography has been the most successful approach to date. Although polar reversed phase and HILIC columns have been introduced, they have limitations with highly charged compounds. Competing ions have been used, in addition to ion-pair reagent, to achieve better resolution with reversed phase columns. Herein, we explored the use of competing ions with HILIC columns to demonstrate the effects on retention and separation of mono-, di-, and tri-nucleotides, introducing a new tool to improve resolution with HILIC columns. HILIC columns that had irreversibly retained highly charged tri-nucleotides became capable of successfully separating the same compounds, by using this approach. The optimised method was used to successfully resolve a mixture of 12 nucleotides with charges ranging from 1- to 3-. The method was applied to quantify nucleotides in blood cell extracts.

Standard addition with internal standardisation as an alternative to using stable isotope labelled internal standards to correct for matrix effects-Comparison and validation using liquid chromatography-​tandem mass spectrometric assay of vitamin D.

With mass spectrometric detection in liquid chromatography, co-eluting impurities affect the analyte response due to ion suppression/enhancement. Internal standard calibration method, using co-eluting stable isotope labelled analogue of each analyte as the internal standard, is the most appropriate technique available to correct for these matrix effects. However, this technique is not without drawbacks, proved to be expensive because separate internal standard for each analyte is required, and the labelled compounds are expensive or require synthesising. Traditionally, standard addition method has been used to overcome the matrix effects in atomic spectroscopy and was a well-established method. This paper proposes the same for mass spectrometric detection, and demonstrates that the results are comparable to those with the internal standard method using labelled analogues, for vitamin D assay. As conventional standard addition procedure does not address procedural errors, we propose the inclusion of an additional internal standard (not co-eluting). Recoveries determined on human serum samples show that the proposed method of standard addition yields more accurate results than the internal standardisation using stable isotope labelled analogues. The precision of the proposed method of standard addition is superior to the conventional standard addition method.

Simultaneous determination of 12 vitamin D compounds in human serum using online sample preparation and liquid chromatography-tandem mass spectrometry.

The development and validation of a method to simultaneously quantify 12 vitamin D compounds in human serum by LC-MS/MS is described. The main challenge was that of extracting and chromatographing vitamin D compounds with a range of polarities, both lipophilic and hydrophilic, in a single analytical procedure. The extractions of all 12 vitamin D compounds were achieved by an optimised protein precipitation method using acetonitrile as the precipitant, and the separation was accomplished by using a pentafluorophenyl (PFP) column. The sensitivity was increased by minimising matrix effects in MS detector rather than using a lengthy derivatisation procedure; an online solid phase extraction (SPE) using a PFP guard column was used for cleanup. Detection limits for all compounds were in the picomole range when using a 500µL sample volume. Recovery percentages ranged from 92% to 99%. LC-MS/MS resolution of all 12 vitamin D compounds, including the chromatographic separation of 25(OH)D3 from the isomer 3-epi-25(OH)D3 was achieved. Stable isotope labelled vitamin D compounds were used as internal standards for the quantification of all 12 vitamin D compounds. This is a simple yet accurate, selective, and sensitive method for the quantification of 12 major vitamin D compounds, including the sulfated forms, in human serum. The method is sufficiently robust to offer potential for use in routine analysis in a pathology laboratory setting.

Selective anti-proliferative activities of Carica papaya leaf juice extracts against prostate cancer.

BACKGROUND: Prostate cancer (PCa) is the leading cause of cancer related deaths in men. Carica papaya is a popular tropical plant that has been traditionally used for its nutritional and medicinal properties. METHODS: We investigated the anti-proliferative responses of papaya leaf juice (LJP) and its various extracts ("biological"- in vitro digested, "physical"- size exclusion, and "chemical"-solvent extraction) on a range of cell lines representing benign hyperplasia, tumorigenic and normal cells of prostate origin. RESULTS: Time course analysis (by 24h, 48h and 72h) of LJP (1-0.1mg/mL) before and after in vitro digestion, and of molecular weight based fractions of LJP showed anti-proliferative responses. The medium polarity fraction of LJP (0.03-0.003mg/mL) after 72h exposure showed potent growth inhibitory (IC50=0.02-0.07mg/mL) and cytotoxic activities on all prostate cells, with the exception of the normal (RWPE-1 and WPMY-1) cells. Flow cytometry analysis showed S phase cell cycle arrest and apoptosis as a possible mechanism for these activities. Medium polar fraction of LJP also inhibited migration and adhesion of metastatic PC-3 cells. CONCLUSION: This is the first report suggesting selective anti-proliferative and anti-metastatic attributes of LJP extract against prostatic diseases, including PCa.

Production of N-acyl homoserine lactones by the sponge-associated marine actinobacteria Salinispora arenicola and Salinispora pacifica.

The structures of acyl homoserine lactone (AHL) compounds and their quantification were accomplished using an integrated liquid chromatography-mass spectrometry approach. The precursor and product ions, along with retention times of peaks, were searched against an in-house database of AHLs and structures confirmed by accurate mass and by comparison with authentic AHL standards. The two compounds, N-(3-oxodecanoyl)-L-homoserine lactone and N-(3-oxododecanoyl)-L-homoserine lactone, were characterised and quantified in Salinispora sp. cultures.

EFFECT OF PASTEURISATION ON THE CONCENTRATIONS OF VITAMIN D COMPOUNDS IN DONOR BREAST MILK.

AIM: Breastmilk is considered the most important nutrient and source of supplementation for both term and preterm infants.1 It is composed of many important nutrients, including vitamin D.2 The content of this vitamin in breast milk is usually low, even for lactating mothers with adequate vitamin D status.2 3 Preterm infants are at the great risk of vitamin D deficiency due to decreased transplacental transfer.4 Premature infants are the main recipients of pasteurised donor human milk (PDHM), when their mothers are unable to provide their own.This study aims to evaluate the effect of pasteurisation on the concentrations of vitamin D compounds in donor breast milk. METHOD: A total of 16 participants, who donated breast milk to the RBWH milk bank, were recruited in this study. Milk samples were obtained pre- and post-Holder pasteurisation. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to analyse the samples for vitamins D2 and D3 and 25-hydroxyvitamins D2 and D3 (25(OH)D2 and 25(OH)D3). The significance of differences in vitamin D concentrations between the two groups of milk samples was assessed using the Wilcoxon matched-pairs signed rank test, in which P<0.05 was considered significant. RESULTS: Pasteurisation resulted in a significant reduction (P<0.05) in the content of D2, D3, 25(OH)D2 and 25(OH)D3, with P values of 0.0001 for all targeted analytes. The concentrations of the vitamin D analogues in non-pasteurised milk ranged from 3.6 to 5.0 pM (D2), 1.0 to 9.8 pM (D3), 1.4 to 2.1 pM (25(OH)D2) and 1.2 to 9.3 pM (25(OH)D3). The concentrations of the vitamin D analogues in post-pasteurised milk ranged from 3.0 to 4.0 pM (D2), 0.6 to 9.5 pM (D3), 1.2 to 1.7 pM (25(OH)D2) and 1.1 to 9.1 pM (25(OH)D3). Losses of vitamin D compounds resulting from the pasteurisation process ranged from 10% to 20%. CONCLUSION: Pasteurisation significantly affected the concentration of vitamin D compounds in pasteurised donor breast milk.

TO INVESTIGATE THE EFFECT OF THE PASTEURISATION PROCESS ON TRACE ELEMENTS IN DONOR BREAST MILK.

AIM: To investigate the effect of the pasteurisation process on trace elements in donor breast milk. METHOD: Premature infants often receive donor breast milk when the mother is unable to produce sufficient breast milk. It is widely accepted that donor milk has considerable advantages over formula milk.1 The Royal Brisbane and Women's Hospital (RBWH) has a milk bank that receives milk donated by women which undergoes a pasteurisation process.2 This study investigated the effect of pasteurisation on a range of trace elements in donor milk.A total of 14 participants who donated to the milk bank were recruited in this study. A 2 ml sample was collected pre- and post- pasteurisation, and frozen at -80 °C. Post-natal age of the milk was documented. Inductively-coupled plasma mass-spectrometry was used to analyse the following trace elements - zinc (Zn), copper (Cu), selenium (Se), manganese (Mn), iodine (I), iron (Fe), molybdenum (Mo) and bromine (Br). The study received ethical approval from RBWH and The University of Queensland Ethics Committee. RESULTS: No significant difference was found between the levels of any of the trace elements tested pre- and post-pasteurisation. The following p-values were calculated - Zn (0.82), Cu (0.80), Se (0.97), Mn (0.63), I (0.99), Fe (0.05), Mo (0.41), Br (0.59). The following ranges in mcg/L of trace elements were calculated - Zn (365.4-5460.0), Cu (157.6-820.5), Se (10.6-23.7), Mn (0.55-3.24), I (66.4-215.3), Fe (101.5-473.1), Mo (0.20-5.45), Br (704.9-3379.0). Spearman's rank correlation analysis showed significant correlations between post-natal age of milk and trace elements - Zn (ρ=-0.578), Se (ρ=-0.627). Fe (ρ=-0.704), and Mo (ρ=-0.534). No significant correlation was found for Cu, Mn, I, and Br. CONCLUSION: This study found that the pasteurisation process had minimal effect on trace element levels in donor breast milk. However, it was noted that there was a correlation between post-natal age of donor milk and Zn, Se, Fe and Mo. Further work is needed to establish factors that may influence levels of trace elements in donor milk such as post-natal age.

Anti-inflammatory and immunomodulatory properties of Carica papaya.

Chronic inflammation is linked with the generation and progression of various diseases such as cancer, diabetes and atherosclerosis, and anti-inflammatory drugs therefore have the potential to assist in the treatment of these conditions. Carica papaya is a tropical plant that is traditionally used in the treatment of various ailments including inflammatory conditions. A literature search was conducted by using the keywords "papaya", "anti-inflammatory and inflammation" and "immunomodulation and immune" along with cross-referencing. Both in vitro and in vivo investigation studies were included. This is a review of all studies published since 2000 on the anti-inflammatory activity of papaya extracts and their effects on various immune-inflammatory mediators. Studies on the anti-inflammatory activities of recognized phytochemicals present in papaya are also included. Although in vitro and in vivo studies have shown that papaya extracts and papaya-associated phytochemicals possess anti-inflammatory and immunomodulatory properties, clinical studies are lacking.

Traditional Aboriginal Preparation Alters the Chemical Profile of Carica papaya Leaves and Impacts on Cytotoxicity towards Human Squamous Cell Carcinoma.

Carica papaya leaf decoction, an Australian Aboriginal remedy, has been used widely for its healing capabilities against cancer, with numerous anecdotal reports. In this study we investigated its in vitro cytotoxicity on human squamous cell carcinoma cells followed by metabolomic profiling of Carica papaya leaf decoction and leaf juice/brewed leaf juice to determine the effects imparted by the long heating process typical of the Aboriginal remedy preparation. MTT assay results showed that in comparison with the decoction, the leaf juice not only exhibited a stronger cytotoxic effect on SCC25 cancer cells, but also produced a significant cancer-selective effect as shown by tests on non-cancerous human keratinocyte HaCaT cells. Furthermore, evidence from testing brewed leaf juice on these two cell lines suggested that the brewing process markedly reduced the selective effect of Carica papaya leaf on SCC25 cancer cells. To tentatively identify the compounds that contribute to the distinct selective anticancer activity of leaf juice, an untargeted metabolomic approach employing Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry followed by multivariate data analysis was applied. Some 90 and 104 peaks in positive and negative mode respectively were selected as discriminatory features from the chemical profile of leaf juice and >1500 putative compound IDs were obtained via database searching. Direct comparison of chromatographic and tandem mass spectral data to available reference compounds confirmed one feature as a match with its proposed authentic standard, namely pheophorbide A. However, despite pheophorbide A exhibiting cytotoxic activity on SCC25 cancer cells, it did not prove to be the compound contributing principally to the selective activity of leaf juice. With promising results suggesting stronger and more selective anticancer effects when compared to the Aboriginal remedy, Carica papaya leaf juice warrants further study to explore its activity on other cancer cell lines, as well as investigation to confirm the identity of compounds contributing to its selective effect, particularly those compounds altered by the long heating process applied during the traditional Aboriginal remedy preparation.

Simultaneous quantitative analysis of nine vitamin D compounds in human blood using LC-MS/MS.

AIM: It has been suggested that each member of the family of vitamin D compounds may have different function(s). Therefore, selective quantification of each compound is important in clinical research. MATERIALS & METHODS: Development and validation attempts of a simultaneous determination method of 12 vitamin D compounds in human blood using precolumn derivatization followed by LC-MS/MS is described. Internal standard calibration with 12 stable isotope labeled analogs was used to correct for matrix effects in MS detector. RESULTS & CONCLUSION: Nine vitamin D compounds were quantifiable in blood samples with detection limits within femtomole levels. Serum (compared with plasma) was found to be a more suitable sample type, and protein precipitation (compared with saponification) a more effective extraction method for vitamin D assay.

Effect of pasteurisation on the concentrations of vitamin D compounds in donor breastmilk.

Premature infants are the main recipients of pasteurised donor human milk (PDHM), when their mothers are unable to provide their own. In this study, we evaluated the effect of pasteurisation on the concentrations of vitamin D compounds in donor breastmilk. Milk samples were obtained pre- and post-Holder pasteurisation. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyse the samples for vitamins D2 and D3 (D2 and D3) and 25-hydroxyvitamins D2 and D3 (25(OH)D2 and 25(OH)D3). The significance of differences in vitamin D concentrations between the two groups of milk samples was assessed using the Wilcoxon matched-pairs signed rank test, in which p < 0.05 was considered significant. Pasteurisation resulted in a significant reduction (p < 0.05) in the content of D2, D3, 25(OH)D2 and 25(OH)D3. The losses ranged from 10% to 20% following pasteurisation.

Determination of four sulfated vitamin D compounds in human biological fluids by liquid chromatography-tandem mass spectrometry.

The determination of both the water-soluble and lipid-soluble vitamin D compounds in human biological fluids is necessary to illuminate potentially significant biochemical mechanisms. The lack of analytical methods to quantify the water-soluble forms precludes studies on their role and biological functions; currently available liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods are able to determine only a single sulfated form of Vitamin D. We describe here a highly sensitive and specific LC-MS/MS method for the quantification of four sulfated forms of vitamin D: vitamins D2- and D3-sulfate (D2-S and D3-S) and 25-hydroxyvitamin D2- and D3-sulfate (25(OH)D2-S and 25(OH)D3-S). A comparative evaluation showed that the ionization efficiencies of underivatized forms in negative ion mode electrospray ionisation (ESI) are superior to those of the derivatized (using 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD)) forms in positive ion mode ESI. Separation was optimised to minimise co-elution with endogenous matrix compounds, thereby reducing ion suppression/enhancement effects. Isotopically labelled analogues of each compound were used as internal standards to correct for ion suppression/enhancement effects. The method was validated and then applied for the analysis of breastmilk and human serum. The detection limits, repeatability standard deviations, and recoveries ranged from 0.20 to 0.28fmol, 2.8 to 10.2%, and 81.1 to 102%, respectively.

Chemical Characterization and in Vitro Cytotoxicity on Squamous Cell Carcinoma Cells of Carica papaya Leaf Extracts.

In traditional medicine, Carica papaya leaf has been used for a wide range of therapeutic applications including skin diseases and cancer. In this study, we investigated the in vitro cytotoxicity of aqueous and ethanolic extracts of Carica papaya leaves on the human oral squamous cell carcinoma SCC25 cell line in parallel with non-cancerous human keratinocyte HaCaT cells. Two out of four extracts showed a significantly selective effect towards the cancer cells and were found to contain high levels of phenolic and flavonoid compounds. The chromatographic and mass spectrometric profiles of the extracts obtained with Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds identified were flavonoids or flavonoid glycosides, particularly compounds from the kaempferol and quercetin families, of which several have previously been reported to possess anticancer activities. These results confirm that papaya leaf is a potential source of anticancer compounds and warrant further scientific investigation to validate the traditional use of papaya leaf to treat cancer.

Breastmilk-Saliva Interactions Boost Innate Immunity by Regulating the Oral Microbiome in Early Infancy.

INTRODUCTION: Xanthine oxidase (XO) is distributed in mammals largely in the liver and small intestine, but also is highly active in milk where it generates hydrogen peroxide (H2O2). Adult human saliva is low in hypoxanthine and xanthine, the substrates of XO, and high in the lactoperoxidase substrate thiocyanate, but saliva of neonates has not been examined. RESULTS: Median concentrations of hypoxanthine and xanthine in neonatal saliva (27 and 19 µM respectively) were ten-fold higher than in adult saliva (2.1 and 1.7 µM). Fresh breastmilk contained 27.3 ± 12.2 µM H2O2 but mixing baby saliva with breastmilk additionally generated >40 µM H2O2, sufficient to inhibit growth of the opportunistic pathogens Staphylococcus aureus and Salmonella spp. Oral peroxidase activity in neonatal saliva was variable but low (median 7 U/L, range 2-449) compared to adults (620 U/L, 48-1348), while peroxidase substrate thiocyanate in neonatal saliva was surprisingly high. Baby but not adult saliva also contained nucleosides and nucleobases that encouraged growth of the commensal bacteria Lactobacillus, but inhibited opportunistic pathogens; these nucleosides/bases may also promote growth of immature gut cells. Transition from neonatal to adult saliva pattern occurred during the weaning period. A survey of saliva from domesticated mammals revealed wide variation in nucleoside/base patterns. DISCUSSION AND CONCLUSION: During breast-feeding, baby saliva reacts with breastmilk to produce reactive oxygen species, while simultaneously providing growth-promoting nucleotide precursors. Milk thus plays more than a simply nutritional role in mammals, interacting with infant saliva to produce a potent combination of stimulatory and inhibitory metabolites that regulate early oral-and hence gut-microbiota. Consequently, milk-saliva mixing appears to represent unique biochemical synergism which boosts early innate immunity.

Simultaneous quantitative analysis of eight vitamin D analogues in milk using liquid chromatography-tandem mass spectrometry.

Milk is an important source of nutrients for various risk populations, including infants. The accurate measurement of vitamin D in milk is necessary to provide adequate supplementation advice for risk groups and to monitor regulatory compliance. Currently used liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods are capable of measuring only four analogues of vitamin D in unfortified milk. We report here an accurate quantitative analytical method for eight analogues of vitamin D: Vitamin D2 and D3 (D2 and D3), 25-hydroxy D2 and D3, 24,25-dihydroxy D2 and D3, and 1,25-dihydroxyD2 and D3. In this study, we compared saponification and protein precipitation for the extraction of vitamin D from milk and found the latter to be more effective. We also optimised the pre-column derivatisation using 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD), to achieve the highest sensitivity and accuracy for all major vitamin D forms in milk. Chromatography was optimised to reduce matrix effects such as ion-suppression, and the matrix effects were eliminated using co-eluting stable isotope labelled internal standards for the calibration of each analogue. The analogues, 25-hydroxyD3 (25(OH)D3) and its epimer (3-epi-25(OH)D3) were chromatographically resolved, to prevent over-estimation of 25(OH)D3. The method was validated and subsequently applied for the measurement of total vitamin D levels in human, cow, mare, goat and sheep milk samples. The detection limits, repeatability standard deviations, and recovery ranges were from 0.2 to 0.4 femtomols, 6.30-13.5%, and 88.2-105%, respectively.

LC-MS-based metabolomics study of marine bacterial secondary metabolite and antibiotic production in Salinispora arenicola.

An LC-MS-based metabolomics approach was used to characterise the variation in secondary metabolite production due to changes in the salt content of the growth media as well as across different growth periods (incubation times). We used metabolomics as a tool to investigate the production of rifamycins (antibiotics) and other secondary metabolites in the obligate marine actinobacterial species Salinispora arenicola, isolated from Great Barrier Reef (GBR) sponges, at two defined salt concentrations and over three different incubation periods. The results indicated that a 14 day incubation period is optimal for the maximum production of rifamycin B, whereas rifamycin S and W achieve their maximum concentration at 29 days. A "chemical profile" link between the days of incubation and the salt concentration of the growth medium was shown to exist and reliably represents a critical point for selection of growth medium and harvest time.