Differentiating Dyes: A Spectroscopic Investigation into the Composition of Scarlet Bloodroot (Haemodorum coccineum R.Br.) Rhizome.

Haemodorum coccineum, commonly known as scarlet bloodroot, is a plant native to New Guinea and the northern most parts of Australia. The highly coloured H. coccineum is used by communities in Larrakia country for dyeing garments and occasionally to treat snake bites. Previous studies into H. coccineum have focused on its taxonomic classification, with this being the first evaluation of the chemical composition of the plant. Haemodoraceae plants are reported to contain phenylphenalenones (PhPs), which are highly conjugated polycyclic oxygenated aromatic hydrocarbons. We report the characterisation of 20 compounds extracted from the rhizome of H. coccineum: four sugars and 16 compounds belonging to the PhP family. The compounds include five aglycones and seven glycosylated compounds, of which four contain malonate esters in their structures. Characterisation of these compounds was achieved through 1D and 2D NMR, MS analysis and comparison to the known phytochemistry of other species from the Haemodorum genus. Preliminary anti-microbial activity of the crude extract shows significant inhibition of the growth of both gram-positive and gram-negative bacteria, but no activity against Candida albicans.

Design, synthesis and evaluation of alpha lipoic acid derivatives to treat multiple sclerosis-associated central neuropathic pain.

Multiple sclerosis-associated central neuropathic pain (MS-CNP) is difficult to alleviate with clinically used pain-killers and so there is a large unmet medical need for novel treatments for alleviating MS-CNP. Although (R)-alpha lipoic acid (ALA) evoked significant pain relief efficacy in a mouse model of multiple sclerosis-associated central neuropathic pain (MS-CNP), this dietary supplement has poor oral bioavailability due to low gastric stability. Eight ester prodrugs of the R enantiomer of ALA [(R)-ALA] were designed encompassing a range of biocompatible hydrophobic and hydrophilic features and synthesized in an effort to identify a prodrug candidate that was stable at gastric and upper gastrointestinal tract (GIT) pH, and that could be released (hydrolyzed by esterases) in the blood to (R)-ALA immediately after absorption into the portal vein (i.e., highly desirable features for pain relief development). These biocompatible hydrophobic and hydrophilic (R)-ALA pro-dugs underwent comprehensive preliminary screening to reveal PD-ALA4 HCl salt (10) as a promising candidate and PD-ALA 7 (8) could be a viable substitute, utilizing enzyme-free gastric and intestinal stability assessments, LogP evaluations, in vitro plasma stability and caco-2 cell monolayer permeability.

Feeding Sugars to Stingless Bees: Identifying the Origin of Trehalulose-Rich Honey Composition.

The beneficial disaccharide, trehalulose, is a feature of stingless bee honey, while not dominant in any other foods. By experimentally feeding sugar solutions to confined colonies of the Australian stingless bee Tetragonula carbonaria, the origin of trehalulose has now been established. Complete conversion of fed sucrose was observed, by analysis of the honey, forming trehalulose (64-72%) with lesser erlose (18-23%), fructose (9-12%), and minor glucose detected. Remarkably, feeding solutions of glucose/fructose (1:1) mixtures did not result in trehalulose/erlose formation. Hence, stingless bees with natural access to floral nectar high in sucrose will produce honey high in trehalulose, with its associated beneficial properties. Any temptation to artificially increase trehalulose content by feeding sucrose to stingless bees would produce "fake" honey lacking key natural phytochemicals available to the foraging bee. The sucrose-fed fake and natural honey were however readily distinguished via isotope ratio mass spectrometry δ13C values, to combat such potential indirect adulteration.

The Inactivation by Curcumin-Mediated Photosensitization of Botrytis cinerea Spores Isolated from Strawberry Fruits.

Photosensitization is a novel environmentally friendly technology with promising applications in the food industry to extend food shelf life. In this study, the natural food dye curcumin, when combined with visible light (430 nm), was shown to be an effective photosensitizer against the common phytopathogenic fungi Botrytis cinerea (the cause of grey mould). Production of the associated phytotoxic metabolites botrydial and dihydrobotrydial was measured by our newly developed and validated HRAM UPLC-MS/MS method, and was also shown to be reduced by this treatment. With a light dose of 120 J/cm2, the reduction in spore viability was directly proportional to curcumin concentrations, and the overall concentration of both botrydial and dihydrobotrydial also decreased with increasing curcumin concentration above 200 µM. With curcumin concentrations above 600 µM, the percentage reduction in fungal spores was close to 100%. When the dye concentration was increased to 800 µM, the spores were completely inactive and neither botrydial nor dihydrobotrydial could be detected. These results suggest that curcumin-mediated photosensitization is a potentially effective method to control B. cinerea spoilage, and also to reduce the formation of these phytotoxic botryane secondary metabolites.

Stingless bee honey, a novel source of trehalulose: a biologically active disaccharide with health benefits.

Stingless bee (Meliponini) honey has long been considered a high-value functional food, but the perceived therapeutic value has lacked attribution to specific bioactive components. Examination of honey from five different stingless bee species across Neotropical and Indo-Australian regions has enabled for the first time the identification of the unusual disaccharide trehalulose as a major component representing between 13 and 44 g per 100 g of each of these honeys. Trehalulose is an isomer of sucrose with an unusual α-(1 → 1) glucose-fructose glycosidic linkage and known acariogenic and low glycemic index properties. NMR and UPLC-MS/MS analysis unambiguously confirmed the identity of trehalulose isolated from stingless bee honeys sourced across three continents, from Tetragonula carbonaria and Tetragonula hockingsi species in Australia, from Geniotrigona thoracica and Heterotrigona itama in Malaysia and from Tetragonisca angustula in Brazil. The previously unrecognised abundance of trehalulose in stingless bee honeys is concrete evidence that supports some of the reported health attributes of this product. This is the first identification of trehalulose as a major component within a food commodity. This study allows the exploration of the expanded use of stingless bee honey in foods and identifies a bioactive marker for authentication of this honey in associated food standards.

Pyrrolizidine Alkaloids of Blue Heliotrope (Heliotropium amplexicaule) and Their Presence in Australian Honey.

Blue heliotrope (Heliotropium amplexicaule) is an invasive environmental weed that is widely naturalized in eastern Australia and has been implicated as a source of pyrrolizidine alkaloid (PA) poisoning in livestock. Less well-documented is the potential of such carcinogenic alkaloids to contaminate honey from bees foraging on this plant species. In this study, the PA profile of H. amplexicaule plant material, determined by HRAM LC-MS/MS, revealed the presence of nine PAs and PA-N-oxides, including several PAs and PA-N-oxides of the indicine class, which have not previously been reported. The predominant alkaloid, indicine, represents 84% of the reduced PA content, with minor alkaloids identified as intermedine and the newly reported helioamplexine, constituting 7 and 9%, respectively. NMR analysis confirmed the identity of helioamplexine as a previously unreported indicine homologue. This is the first report of the isolation of intermedine, helioamplexine, and 3'-O-angelylindicine from H. amplexicaule. Also described is the identification of N-chloromethyl analogues of the major alkaloids as isolation-derived artifacts from reactions with dichloromethane. Analysis of regional-market honey samples revealed a number of honey samples with PA profiles analogous to that seen in H. amplexicaule, with measured PA contents of up to 2.0 µg of PAs per gram of honey. These results confirm the need for honey producers to be aware of H. amplexicaule as a potential PA source, most particularly in products where honey is sourced from a single location.