β-Carotene oxidation products - Function and safety

Assessing the impact of temperature, pH, light and chemical oxidation on fucoxanthin colour changes, antioxidant activity and the resulting metabolites

BACKGROUND

The present study evaluated the effects of temperature, pH, light and chemical oxidation on fucoxanthin changes in terms of colour, antioxidant activity and metabolomic profile. Additionally, the correlation between antioxidant activity and identified metabolites was analysed.

RESULTS

It was found that colour change was significantly reduced at elevated heat (100 °C, *∆E = 0.81 ± 0.05), reduced pH (pH 3, *∆E = 0.59 ± 0.04) and length of light exposure (*∆E = 3.16 ± 0.04). Antioxidant activity decreased under all treatments. Among the temperatures tested, fucoxanthin exhibited the highest activity at 60 °C, ranging from 0.92 to 3.04 mg Trolox equivalents (TE) g-1. Significant activity reductions (P < 0.05) were observed as a result of pH changes in the 2,2-diphenyl-1-picrylhydrazyl and β-carotene bleaching assays. Exposure to light 2: warm white lamp for 120 h significantly reduced antioxidant activity (0.01 to 1.70 mg TE g-1). Chemical oxidation also led to reduced activity, ranging from 0.18 to 0.29 mg TE g-1. Multivariate data analysis revealed distinct profiles for temperature, pH, light and chemical oxidation treatments. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics analysis identified 10 metabolites, and significant correlations (P < 0.05) indicate that these metabolites contributed to the samples' antioxidant activities.

CONCLUSION

In conclusion, fucoxanthin tolerates well at 60 °C, within pH range 3-9, and within 8 h of light exposure, as indicated by its consistent antioxidant activity and minimal colour change. Each treatment resulted in distinct metabolite concentrations, as shown by LC-MS/MS-based metabolomics analysis. Further research into these metabolites could advance the understanding of their roles and aid in optimising processing conditions to favour beneficial metabolites. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of the Salt Stress Duration and Intensity on Developmental and Physiological Features of the Moss Polytrichum formosum

The two accessions of the polytrichaceous moss species Polytrichum formosum, namely German and Serbian genotypes, were subjected to salt stress, aiming to study the species' developmental and physiological features. Various concentrations of sodium chloride were applied to an axenic in vitro culture of the two moss genotypes, and the growth parameters as well as physiological feature changes were followed. As inferred by the morpho-developmental parameters and survival index, the Serbian genotype showed higher resistance to salt stress as compared to the German one. However, both moss genotypes survived the highest applied concentration (500 mM). As expected, short exposures to salt were rather easily overcome. No clear patterns in sugar content and changes were observed during the stress, but they are surely included in salt stress response and tolerance in P. formosum. Longer stress increased total chlorophyll content in both genotypes. In short-term applied salt stress, the Serbian genotype had a higher total chlorophyll concentration to control unstressed plants, while the German genotype decreased the total amount of chlorophyll. Similarly, carotenoids were shown to be significantly higher in the Serbian genotype, both in unstressed and treated plants, compared to the German one. The contents of tocopherols were higher in the Serbian genotype in controlled unstressed and subsequently short- and long-stressed plantlets compared to the German accession. In general, we can assume that P. formosum is unexpectedly tolerant to salt stress and that there are differences within various accessions of overall European populations, as referred by two randomly selected genotypes, which is most probably a consequence of different genetic structure.

Rhodotorula sp. as a cell factory for production of valuable biomolecules

Rhodotorula sp. are well-known for their ability to biosynthesize a diverse range of valuable biomolecules, including carotenoids, lipids, enzymes, and polysaccharides. Despite the high number of studies conducted using Rhodotorula sp. at the laboratory scale, most of these do not address all processual aspects necessary for scaling up these processes for industrial applications. This chapter explores the potential of Rhodotorula sp. as a cell factory for the production of distinct biomolecules, with a particular emphasis on exploring their use from a biorefinery perspective. Through in-depth discussions of the latest research and insights into non-conventional applications, we aim to provide a comprehensive understanding of Rhodotorula sp.'s ability to produce biofuels, bioplastics, pharmaceuticals, and other valuable biochemicals. This book chapter also examines the fundamentals and challenges associated with the optimizing upstream and downstream processing of Rhodotorula sp-based processes. We believe that through this chapter, readers with different levels of expertise will gain insights into strategies for enhancing the sustainability, efficiency, and effectiveness of producing biomolecules using Rhodotorula sp.

Oxidized β-Carotene Is a Novel Phytochemical Immune Modulator That Supports Animal Health and Performance for Antibiotic-Free Production

Oxidized β-carotene (OxBC), a phytochemical that occurs naturally in plants, is formed by the spontaneous reaction of β-carotene with ambient oxygen. Synthetic OxBC, obtained by full oxidation of β-carotene with air, shows considerable promise as an in-feed antimicrobial alternative additive that enhances health and performance in livestock. OxBC is predominantly composed of β-carotene-oxygen copolymers that have beneficial immune-modulating effects that occur within the innate immune system by priming it to face microbial challenges and by mitigating the inflammatory response. OxBC does not have any direct anti-bacterial activity. Further, unlike traditional immune stimulants, OxBC modulates but does not stimulate and utilize the animal's energy stores unless directly stress-challenged. These immune effects occur by mechanisms distinct from the provitamin A or antioxidant pathways commonly proposed as explanations for β-carotene's actions. Trials in poultry, swine, and dairy cows with low parts-per-million in-feed OxBC supplementation have shown performance benefits over and above those of feeds containing regular vitamin and mineral premixes. Through its ability to enhance immune function, health, and performance, OxBC has demonstrated utility not only as a viable alternative to in-feed antimicrobials but also in its ability to provide tangible health and performance benefits in applications where antimicrobial usage is precluded.

Effect of Oxidized β-Carotene on Swine Growth Performance under Commercial Production Conditions in Vietnam

The effects of oxidized β-carotene (OxBC) were determined upon the growth performance of swine through their full growth cycle under commercial production conditions in Vietnam. Five hundred 28-day-old-weaned barrows and gilts were used in a 140-day complete wean-to-finish feeding trial. Animals were randomized by weight, and each pen contained 20 pigs with the same ratio of barrows to gilts. There were five dietary treatment groups with five replicate pens per treatment: Control basal diet, no antibiotics or OxBC; Basal diet with antibiotics; no OxBC; Basal diet supplemented with 2, 4, or 8 mg OxBC/kg of diet, no antibiotics. Growth performance parameters were calculated for each production stage (Starter: Days 1−28, Grower: Days 29−84, Finisher: Days 85−140) and for the overall study (Days 1−140). OxBC and antibiotics each improved growth rate, feed efficiency, and body weight compared to the unsupplemented control (p < 0.001). Animals receiving 4 and 8 mg/kg OxBC performed better than animals on antibiotics (p < 0.001). In Starter pigs, OxBC reduced the occurrence of diarrhea dose-dependently (2, 4, and 8 mg/kg) and more so than did antibiotics (p < 0.001). These findings support the concept that oxidized β-carotene can facilitate swine growth and health in the absence of in-feed antibiotics.

The effects of β-carotene on osteoporosis: a systematic review and meta-analysis of observational studies

PURPOSE

The aim is to evaluate the effect of β-carotene for osteoporosis and provide quantitative evidence.

METHOD

PubMed, Embase, Web of Science, and Cochrane Library were searched for eligible studies. Fifteen studies were included. Random-effect model was applied to pool the odds ratio (OR). The risk of osteoporosis and fracture were compared between low β-carotene intake group and high β-carotene intake group.

RESULT

The intake of β-carotene was unassociated with the overall risk of osteoporosis [OR = 0.733, 95% Cl (0.528, 1.018), p = 0.064]. Subgroup analysis showed that the intake of β-carotene was negatively associated with the risk of osteoporosis in both male subgroup [OR = 0.7, 95% Cl (0.549, 0.893), I² = 40.40%, p = 0.004] and female subgroup [OR = 0.684, 95% Cl (0.487, 0.960), I² = 86.40%, p = 0.028]. There was also a negative association between β-carotene intake and osteoporosis in Asia subgroup [OR = 0.512, 95% Cl (0.403, 0.650), I² = 0.00%, p = 0], whereas no association was observed in Western subgroup [OR = 1.107, 95% Cl (0.908, 1.350), I² = 2.30%, p = 0.314]. In addition, random-effect model was adopted to pool the standard mean difference (SMD), and the results showed that β-carotene intake was positively associated with overall bone mineral density (BMD) [SMD =  - 0.213, 95% Cl (- 0.391, - 0.034), I² = 87.30%, p = 0.019]. Subgroup analysis showed that β-carotene intake was positively associated with BMD in Asian participants [SMD =  - 0.394, 95% Cl (- 0.461, - 0.328), I² = 0, p = 0], while unassociated in Western participants [SMD =  - 0.047, 95% Cl (- 0.314, 0.219), I² = 78.9%, p = 0.727].

CONCLUSION

β-carotene may improve BMD and reduce the risk of osteoporosis and fracture. However, these effects could vary by gender and race and need to be further validated by longitudinal studies.

Safety and uptake of fully oxidized β-carotene

Spontaneous oxidation of β-carotene yields a polymer-rich product (OxBC) together with minor amounts of many apocarotenoids. OxBC's activity extends β-carotene's benefits beyond vitamin A, finding utility in supporting health in livestock, pets, and humans. Although the naturally occurring form of OxBC is consumed in foods and feeds, a direct demonstration of synthetic OxBC's safety provides additional support for its usage. A toxicological study in rats showed a maximum tolerated single oral dose of 5000 mg/kg, an LD₅₀ of more than 10,000 mg/kg, and a NOAEL of 1875 mg/kg body weight. A repeat-dose 90-day oral toxicity study showed no adverse physiological or pathological effects. A study of OxBC uptake by mice over 2-5 days showed OxBC already was naturally present. The highest levels were in liver, lung, and hamstring. Dosing did not increase levels in liver, kidney, lung, and muscle. Increases occurred in urine, intestinal content, plasma, feces, spleen, and cecum with preferential elimination of polymer, consistent with processing of OxBC. Compared to the 4:1 polymer: apocarotenoid ratio of OxBC, polymer was enriched in liver and spleen and depleted in lung, kidney, hamstring, and abdominal muscle. The apparent control of OxBC in major tissues further supports its safety.