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Innovation and Challenges in the Development of Functional and Medicinal Beverages
Published in Debarshi Kar Mahapatra, Cristóbal Noé Aguilar, A. K. Haghi, Natural Products Pharmacology and Phytochemicals for Health Care, 2021
Dayang Norulfairuz Abang Zaidel, Ida Idayu Muhamad, Zanariah Hashim, Yanti Maslina Mohd Jusoh, Eraricar Salleh
Vitamin D is abundant consists of dairy foods and beverages. It presents in nature in several forms, which are Vitamin D2 and Vitamin D3. The dietary vitamin D occurs predominantly in animal products with a very small amount gained from plant sources. Vitamin D2 or ergocalciferol is produced by the ultraviolet irradiation of ergosterol. This vitamin is widely distributed in plants and fungi. Vitamin D3, also known as cholecalciferol, is derived from ultraviolet irradiation of 7-dehydrocholesterol and can be found in the skin of animals, including humans. Human requirements for this vitamin are obtained both from the endogenous production in the skin and from dietary sources [127]. Vitamin D is essential for the formation of teeth and bones. It helps the body to absorb and use calcium in an effective manner [33].
Photochemical Reactions as a Useful and Easy to Implement and Scale-Up, New Method for the Synthesis of Chemicals
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
As within skin cells, precursor 7-dehydrocholesterol (achieved in four steps from cholesterol) generates previtamin D3 by ring-opening of the cyclohexadiene moiety upon absorption of light. On mild heating, this intermediate rearranges to previtamin D3 via a sigmatropic 1,7-hydrogen shift. A thorough investigation of the irradiation conditions has been required since previtamin D3 can easily rearrange to undesired tachysterols and lumisterols upon irradiation. Moreover, mercury lamp emission and 7-dehydrocholesterol absorption spectra overlap poorly, leading to great radiant energy waste. Thus, proper light filters and a two-step irradiation sequence are usually adopted,15 see Scheme 5.18.
Hormonal Regulation of Sodium, Potassium, Calcium, and Magnesium Ions
Published in Robert B. Northrop, Endogenous and Exogenous Regulation and Control of Physiological Systems, 2020
The calcium system is interesting because it is regulated through the action of two hormones: parathyroid hormone (PTH), which is an 84-amino-acid protein, and calcitonin, a 32-amino-acid polypeptide secreted by the thyroid glands’ parafollicular “C” cells. The rate of release of both hormones is controlled by IF [Ca++]. The rate of release of PTH is decreased by high [Ca4”1”]. Conversely, high [Ca++] increases the release rate of calcitonin from the thyroid. The normal concentration of PTH ranges from 1 00 to 300 ng/1, and calcitonin concentration in the blood is normally less than 100 ng/1, with a half-life of about 10 min.141 Of the two hormones, PTH is the most potent; the bones and the kidneys are its principal target organs. Figure 6.13 illustrates the major relationships in the [Ca++] regulatory system. Figure 6.14 shows how PTH acts on certain kidney tissues to cause them to increase the rate of conversion of 25-hydroxycholecalciferol (HCC) to the active hormone 1,25-dihydroxycholecalciferol (DHCC), which acts on the intestinal epithelium to increase the level of calcium-binding protein and the enzymes calcium-stimulated ATPase and alkaline phosphatase. The net result of these actions is an increase in the rate of [Ca++] absorption from the gut, Q˙CaD. Note that vitamin D (cholecalcif-erol |CC|) can come either from diet or the action of ultraviolet light on the skin to convert 7-dehydrocholesterol to CC. CC is converted in the liver to HCC. There is a high-gain, biochemical, negative feedback loop whereby the concentration of HCC inhibits the liver conversion of CC to more HCC. Figure 6.15 illustrates how this local feedback loop stabilizes the concentration of HCC against variation in the rate of vitamin D intake. Only at very low vitamin D intake rates does the regulation fail.
Temperature stability of vitamin D2 and color changes during drying of UVB-treated mushrooms
Published in Drying Technology, 2018
Nils Nölle, Dimitrios Argyropoulos, Joachim Müller, Hans Konrad Biesalski
Vitamin D belongs to the fat-soluble vitamins and could be identified in some of the oldest, still living phytoplankton species.[1] Not only it is mainly known for its role in the calcium and phosphate metabolism but also induces cell differentiation and modulates the immune system.[2] Owing to different reasons, vitamin D deficiency can be found in both developed and developing countries.[3,4] To maintain a vitamin D status necessary for good health, a daily intake of 400 IU for infants and 800 IU for children and adults (1 IU equals 25 ng vitamin D) is recommended.[5] Endogenous synthesis of vitamin D through exposure of 7-dehydrocholesterol to UV light covers most of the daily requirements but can be diminished by factors like dark skin, clothing habits, and age.[6] Therefore, dietary sources are important for supplying vitamin D, but only few foods are naturally rich in vitamin D such as fatty sea fish and dairy products.[7] Mushrooms represent the only nonanimal food source of vitamin D. The explanation for this is that their cell membranes are composed of ergosterol, which is converted by UV light into vitamin D2.