Mary T. Fletcher

The analysis of rare or atypical sugars is not encompassed by standard sugar methodology. With greater selectivity, this new method covers 80 sugars for their analysis.

This paper provides a decadal review of literature describing the analysis of simple saccharides and oligosaccharides in food by ion chromatography pulsed amperometric detection (IC/PAD) and ion chromatography mass spectrometry (IC/MS) as emerging techniques. The concentrations of these saccharides in food have important health implications and affect technical attributes of food quality. Saccharides have been analyzed over many decades using a diverse range of physical, chemical, and chromatographic techniques, each with their own advantages and disadvantages. In the past decade, ion chromatography (IC) has appeared as a contender with substantial benefits over established techniques. It is conducted without sample derivatization, unlike other techniques of comparable accuracy. Limits of detection (LOD) are also comparable, typically 20 μg/L when coupled with a pulsed amperometric detector or 1 mg/kg food using ion chromatography single quadrupole mass spectrometry. This compares to LODs of 2 g/kg food by high performance/liquid chromatography refractive index detector and 2 mg/kg food for gas chromatography/mass spectrometry. The main strength of ion chromatography is the specificity/differentiation of simple saccharides, that has resulted in the discoveries of several unreported saccharides in foods. Examples include isomaltose in flour, erlose in stingless bee honey and arabinose, ribose, rhamnose, xylose, mannose, trehalose, maltose and raffinose in paprika. Evolving future advantages of ion chromatography in saccharide analysis include the increasing utilization of mass spectrometry, more work towards a standardized analytical methodology, and the need to investigate new, novel and admixed food types so that instrumentation continues to demonstrate relevance at the cutting edge of food research.

Metabolic anticancer therapy based on enzymatic arginine (Arg) deprivation (ADT) is currently being evaluated in clinical trials. The combination of ADT with low doses of the plant cytotoxic analogs of Arg, canavanine (Cav) or indospicine (Isp), have been proposed as being more efficient and selective against malignant cells. The leguminous plant Indigofera spicata contains one of the highest known amounts of Isp. Here we demonstrate for the first time that the Isp-containing ethanolic extract from I. spicata is growth-inhibiting and toxic for cultured human colorectal and ovarian carcinoma cells. The extract reduces the viability of colorectal carcinoma cells two-fold under Arg-deficient conditions and entirely abrogates their residual proliferative potential (growth recovery) after the treatment. Pre-exposure of the extract to recombinant human arginase I (rhARGI) as a therapeutic Arg-depleting agent did not impact the extract’s efficacy. Further development of Isp as a component of combinatorial anticancer metabolic targeting strategies is discussed.

Pimelea is one of the highly toxic plants in Australia, particularly affecting cattle. It contains simplexin, a potent toxin that can cause Pimelea poisoning (St. George Disease) in livestock. A survey was conducted to assess the current impact of Pimelea on livestock production, pasture systems, and financial losses among agricultural producers. In addition, information was also sought about the environmental conditions that facilitate its growth and the effectiveness of existing management strategies. The survey responses were obtained from producers affected by Pimelea across nine different Local Government Areas, through three States, viz., Queensland, New South Wales, and South Australia. Pimelea was reported to significantly affect animal production, with 97% of producers surveyed acknowledging its detrimental effects. Among livestock, cattle were the most severely affected (94%), when compared to sheep (13%), goats (3%), and horses (3%). The presence of Pimelea was mostly observed in spring (65%) and winter (48%), although 29% of respondents indicated that it could be present all year-round under favorable rainfall conditions. Germination was associated with light to moderate rainfall (52%), while only 24% linked it to heavy rainfall. Pimelea simplex F. Muell. was the most frequently encountered species (71%), followed by Pimelea trichostachya Lindl. (26%). Infestations were reported to occur annually by 47% of producers, with 41% noting occurrences every 2 to 5 years. Financially, producers estimated average annual losses of AUD 67,000, with 50% reporting an average of 26 cattle deaths per year, reaching up to 105 deaths in severe years. Some producers were spending up to AUD 2100 per annum to manage Pimelea. While chemical and physical controls were commonly employed, integrating competitive pastures and alternative livestock, such as sheep and goats, was considered as a potential management strategy. This study reiterates the need for further research on sustainable pasture management practices to reduce Pimelea-related risks to livestock and agricultural production systems.

Pimelea poisoning of cattle is caused by the toxin simplexin present in native Pimelea plant species. Surface weathering and burial of Pimelea plant material under soil in Pimelea-infested pastures previously showed simplexin degradation, suggesting soil microbial metabolism and/or abiotic degradation of simplexin in the field. This current study investigated whether soil from a Pimelea-infested paddock was capable of simplexin degradation in the laboratory. The effects of temperature on isolated simplexin levels and simplexin levels in Pimelea plant material treated with field-collected soil, acid-washed sand or bentonite were determined. Pimelea plant material incubated in field-collected soil at 22 °C for seven days did not show any simplexin degradation. Isolated simplexin preadsorbed to field-collected soil, acid-washed sand or bentonite showed simplexin decrease after one hour of incubation at 100 °C with three breakdown products identified by UPLC-MS/MS, indicating that toxin breakdown can be a heat-induced process rather than a microbial-based metabolism. Decreased simplexin levels were observed in Pimelea plant material mixed with acid-washed sand under similar incubation conditions. Overall, the study showed the field-collected soil did not contain soil microorganisms capable of simplexin metabolism within a short period of time. However, the co-exposure to high temperature resulted in significant abiotic simplexin breakdown, without microorganism involvement, with the product structures suggesting that the degradation was a heat promoted acid hydrolysis/elimination process. Overall, this study demonstrated that simplexin breakdown in the field could be a thermal abiotic process with no indication of microbial involvement.

Pasture lands, while appearing uniform in species diversity, exhibit notable variations upon closer examination. The study on Pimelea (or riceflower) seedbank dynamics revealed significant variations in seed density and distribution across soil depths, sites, years, and between pasture and cultivated paddocks in the same region of western Queensland. For the total number of germinable riceflower seeds across both the years 2019 and 2020, there is a clear distinction between pasture and cultivated paddocks. Pasture paddocks exhibited a gradual increase in total seed count from 108 seeds m⁻² in 2019 to 121 seeds m⁻² in 2020, resulting in a combined total of 229 seeds m⁻² over the 2 years across both depths. In contrast, cultivated paddocks showed a more substantial increase, with seed counts rising from 146 seeds m⁻² in 2019 to 255 seeds m⁻² in 2020, resulting in a combined total of 401 seeds m⁻² across both depths. Additionally, the Shannon–Wiener index at Site 1 indicated increased species diversity in the topsoil of pasture paddocks in 2020 compared to 2019, while deeper soil diversity decreased. Cultivated paddocks showed a declining trend, while pasture sites exhibited stable or increasing diversity. Pasture management generally maintained or enhanced diversity better than cultivation, especially in the topsoil layer. These findings highlight site-specific differences influenced by soil properties, land management practices, and local environmental conditions, shaping riceflower seedbank dynamics. Understanding these patterns is crucial for developing targeted management strategies to control riceflower in affected areas. Long-term field studies focusing on seedbanks are essential to develop sustainable control strategies.

Context: Pastures growing on low phosphorus (P) soils are often P deficient, particularly for lactating cows. Aim: To examine the effects of P-deficient diets on the performance of lactating multiparous cows. Methods: From parturition, mature Bos indicus cross cows (n = 32, initially 474 kg liveweight (LW) and body condition score 3.5) were fed ad libitum for 14 weeks one of four diets: (i) high P (HP-HCa), (ii) low P with low calcium (LP-LCa), (iii) low P with high Ca (LP-HCa), or (iv) the LP-LCa diet with ammonium chloride (LP-LCa+ac). Results: Voluntary feed intakes were higher for cows fed the HP-HCa than the three LP diets (23.1 vs 17.4–19.6 g DM/kg LW.day; P < 0.001). The HP-HCa cows gained 0.15 kg LW/day, whereas LP cows lost 0.14–0.51 kg LW/day; P < 0.05). The cows fed LP diets generally maintained milk production and calf growth comparable to that of HP-HCa cows (5.8 kg/day and 0.70 kg/day). The HP-HCa cows retained 6.0–6.4 g P/day from weeks 1–8, but P retention was negligible at week 14. The LP cows mobilised 4.9–9.1 g body P/day. Rib cortical bone shortly after parturition was 634 ± 127 (337–848) μg P/mm2 in the 12th rib, and indicated that the bone P reserves were deficient, marginal and adequate in 27, 37 and 37% of the cows, respectively. During lactation, rib bone P increased 23% in HP-HCa cows, changed little in the LP-LCa and LP-HCa cows (−4 and +7%), and decreased 13% (P < 0.05) in LP-LCa+ac cows. The change in rib cortical bone P during lactation was correlated with this measurement at parturition; the P per unit surface area of rib cortical bone of cows with low bone P at parturition did not change, but in cows with high bone P it decreased up to 16%. Plasma inorganic P averaged 1.49 mmol/L in the HP-HCa cows and <0.8 mmol/L in the LP cows. Plasma Ca, Ca/inorganic P ratio, 1,25-dihydroxy vitamin D3, bone alkaline phosphatase, and carboxy-terminal telepeptides of type 1 collagen increased during lactation (P < 0.05 to P < 0.001) in the LP cows. Conclusions: When fed acutely P-deficient diets, mature cows of moderate LW and with body condition scores at parturition generally maintained milk secretion and calf growth by mobilisation of body reserves. Implications: The capacity of beef cows to maintain lactation when ingesting P-deficient diets provides opportunities for improved herd management.

This study assessed the effectiveness of four competitive pasture species—Premier digit grass (Digitaria eriantha Steud. var. Premier), Rhodes grass (Chloris gayana Kunth.), sabi grass (Urochloa mosambicensis Hack.), and buffel grass (Pennisetum ciliare L.) against the toxic annual riceflower (Pimelea trichostachya Lindl.) at varying planting densities and ratios. At six plants pot⁻¹, with a 66:33 grass-to-weed ratio, riceflower biomass decreased by 73.7%, 82.5%, 73.7%, and 60.6% when grown alongside Premier digit, Rhodes, sabi, and buffel grasses, respectively. Similarly, with four plants pot⁻¹ at a 75:25 ratio, reductions were 69.1%, 79.8%, 71.0%, and 44.5%, respectively. Annual riceflower experienced the greatest suppression when grown with Rhodes grass, showing aggressivity index (AI) values of −60.2 and −67.2 and relative crowding coefficient (RCC) values of 0.4 for both six and four plants pot⁻¹. Premier digit grass also suppressed riceflower effectively, with riceflower AI values of −35.6 and −36.7 and RCC values of 0.5 and 0.6. Buffel grass had the least impact, with riceflower AI values of −41.1 and −27.9 and RCC values of 0.9 and 2.0. Sabi grass also demonstrated good suppressive effects, though slightly less than the top two species. Higher planting densities generally resulted in stronger riceflower suppression. The results highlight the importance of considering planting density, arrangement, and key plant traits when selecting pasture species for successful weed control. Based on these findings, we conclude that Premier digit grass and Rhodes grass show promising potential for effective suppression of annual riceflower growth.