Assessing the Protein Quality, In Vitro Intestinal Iron Absorption and Human Faecal Microbiota Impacts of Plant-Based Mince.

The nutritional quality of plant-based meat analogues compared to traditional meat products has been questioned in recent commentary, particularly in relation to protein quality and micronutrient bioavailability. However, the attributes of specific products within this category are unclear. We therefore undertook a comprehensive assessment of the compositional and functional attributes of v2food® (Sydney, Australia) plant-based mince, including an assessment of the effects of reformulation, including the addition of amino acids, ascorbic acid, and different forms of elemental iron. The protein digestibility and protein quality of v2food® plant-based mince were comparable to beef mince in the standardized INFOGEST system, and favourable effects on microbiota composition and short-chain fatty acid (SCFA) production were demonstrated in an in vitro digestion system. The use of ferrous sulphate as an iron source improved in vitro intestinal iron absorption by ~50% in comparison to other forms of iron (p < 0.05), although levels were ~3-fold lower than beef mince, even in the presence of ascorbic acid. In conclusion, the current study identified some favourable nutritional attributes of plant-based v2food® mince, specifically microbiota and SCFA changes, as well as other areas where further reformulation could be considered to further enhance the bioavailability of key nutrients. Further studies to assess the effect of plant-based meat analogues on health measures in vivo will be important to improve knowledge in this area.

Impact of polyphenol-rich extracts of Terminalia ferdinandiana fruits and seeds on viability of human intestinal and liver cells in vitro.

Terminalia ferdinandiana (Kakadu plum) is a native Australian fruit consumed by Indigenous Australians for centuries. Commercial interest in T. ferdinandiana has increased in recent years due to its high vitamin C content, however, food safety assessments are lacking. To explore the safety of extracts prepared from T. ferdinandiana using different solvents, in vitro cell viability of undifferentiated and differentiated Caco-2, HT29-MTX-E12, and HepG2 cells was measured using the CyQUANT® NF Cell Proliferation Assay. Changes to cell viability produced IC50 values between 3650 and 14400 µg/mL for all extracts and cell lines tested with HepG2 cells impacted the most by T. ferdinandiana extracts, followed by HT29-MTX-E12 cells, and undifferentiated and differentiated Caco-2 cells. Different solvents also produced extracts with variable effects on cell viability that were dependent on tissue source, however, extracts from seedcoats appeared to impact cell viability less than fruit extracts. The IC50 values for ellagic acid, an abundant phytochemical in T. ferdinandiana, varied from 1190 to 2390 µg/mL across different cells and were significantly lower than extract IC50 values. Findings from this study will help to inform future safety studies, select which solvents to use when preparing T. ferdinandiana extracts, and decide whether fruit flesh should be separated from seeds during extract preparation.

Indospicine cytotoxicity and transport in human cell lines.

Indospicine, a non-proteinogenic analogue of arginine, occurs only in Indigofera plant species and accumulates in the tissues of animals grazing on Indigofera. Canine deaths have resulted from the consumption of indospicine-contaminated meat but only limited information is available regarding indospicine toxicity in humans. In this study three human cell lines, Caco-2 (colorectal adenocarcinoma), HT29-MTX-E12 (colorectal adenocarcinoma) and HepG2 (hepatocellular carcinoma), were used to investigate the cytotoxicity of indospicine and its metabolite 2-aminopimelic acid in comparison to arginine. Indospicine and 2-aminopimelic acid were more cytotoxic than arginine, displaying the highest toxicity in HepG2 liver cells. Intestinal transport in vitro also revealed a 2-fold higher transport rate of indospicine compared to arginine. The sensitivity of HepG2 cells to indospicine is consistent with observed canine hepatotoxicity, and considering the higher in vitro transport of indospicine across an intestinal barrier, it is possible that similar ill effects could be seen in humans consuming contaminated meat.

In vitro transport and satiety of a beta-lactoglobulin dipeptide and beta-casomorphin-7 and its metabolites.

Understanding the digestive behaviour and biological activities of dairy proteins may help to develop model dairy products with targeted health outcomes including increased satiety and healthy weight maintenance. Caseins and whey proteins constitute over 95% of milk proteins with consumption of these proteins associated with increased satiety and a decreased prevalence of metabolic disorders. To investigate the in vitro digestive behaviour and satiety of dairy proteins at the intestinal epithelium, the in vitro transport and hydrolysis of 500-2000 µM ß-casomorphin-7 (YPFPGPI or ß-CM7) and a ß-lactoglobulin (ß-Lg) dipeptide (YL) was measured using Caco-2 cell monolayers grown on transwells as a model of the intestinal epithelium. Transport of YL was concentration dependent and ranged from 0.37-5.26 × 10(-6) cm s(-1), whereas transport of ß-CM7 was only detected at 2000 µM and was significantly lower at 0.13 × 10(-6) cm s(-1). Rapid hydrolysis of ß-CM7 in the apical chamber by the Caco-2 cells produced three peptide metabolites: YP, GPI and FPGPI. All of these metabolites were detected in the basolateral chamber after 30 min with both the YP and GPI peptides transporting at a higher rate than intact ß-CM7. In vitro satiety was indicated by the secretion of cholecystokinin [26-33] (CCK-8) and glucagon-like peptide 1 (GLP-17-36NH2) in the STC-1 enteroendocrine cell model. CCK-8 secretion was highest in response to ß-CM7 followed by the ß-CM7 metabolite FPGPI. CCK-8 secretion however was not significantly stimulated by the tri- or dipeptides. Secretion of GLP-1 was not significantly stimulated by ß-CM7 or YL. These in vitro results suggest that dairy peptide size enhances CCK-8 secretion, whilst limiting transport across Caco-2 monolayers.

Small-molecule inhibitors of the cancer target, isoprenylcysteine carboxyl methyltransferase, from Hovea parvicalyx.

Isoprenylcysteine carboxyl methyltransferase (Icmt) is enzyme target in anticancer drug discovery. An Icmt natural product high-throughput screening campaign was conducted and a hit extract from the roots of Hovea parvicalyx was identified. 2'-Methoxy-3'-prenyl-licodione and 2'-methoxy-3',3''-diprenyl-licodione, two prenylated beta-hydroxychalcone compounds, together with the known flavanone (S)-glabrol, were isolated and identified as bioactive constituents. Their structures were determined largely by 1D and 2D NMR spectroscopy.

Aplysamine 6, an alkaloidal inhibitor of Isoprenylcysteine carboxyl methyltransferase from the sponge Pseudoceratina sp.

The anticancer target isoprenylcysteine carboxyl methyltransferase (Icmt) was the focus of a natural product high-throughput screening campaign. The Australian marine sponge Pseudoceratina sp. yielded aplysamine 6, a new bromotyrosine derivative with an alpha,beta-unsaturated amide linkage, as the bioactive constituent. Its structure was determined by 1D and 2D NMR spectroscopy.

Niphatoxin C, a cytotoxic tripyridine alkaloid from Callyspongia sp.

As part of our studies to discover P2X 7 receptor antagonists, the sponge Callyspongia sp. was investigated. A new tripyridine alkaloid niphatoxin C ( 1) was isolated and had P2X 7 receptor antagonism; however, cytotoxicity of THP-1 cells was the predominant biological effect at higher concentrations. Its structure was determined by 1- and 2-D NMR spectroscopy.

Psammaplysenes C and D, cytotoxic alkaloids from Psammoclemma sp.

The sponge Psammoclemma sp. was investigated as part of our studies to discover P2X 7 receptor antagonists for the treatment of inflammatory disease. The biological activity of this extract was found to be due to the cytotoxicity of two new bromotyrosine alkaloids, psammaplysenes C (1) and D (2), and not P2X 7-specific activity. Their structures were determined by 1D and 2D NMR spectroscopy.

Spermatinamine, the first natural product inhibitor of isoprenylcysteine carboxyl methyltransferase, a new cancer target.

Isoprenylcysteine methyltransferase (Icmt) catalyzes the carboxyl methylation of oncogenic proteins in the final step of a series of post-translational modifications. The inhibition of Icmt provides an attractive and novel anticancer target. A natural product high-throughput screening campaign was conducted to discover inhibitors of Icmt. The Australian marine sponge, Pseudoceratina sp., yielded spermatinamine, a novel alkaloid with a bromotyrosyl-spermine-bromotyrosyl sequence, as the bioactive constituent. Its structure was determined by 1D and 2D NMR spectroscopy. Spermatinamine is the first natural product inhibitor of Icmt.