Hydrophilic vitamins ascorbic acid vitamin

The second system involves numerous hydrophilic or lipophilic molecules like ascorbic acid (AH-) (vitamin C) and a-tocopherol (aT-OH) (vitamin E). These low-molecular-weight antioxidants (LMWA) reduce ROS by oxido-reduction reactions ... 

One of the main problems of topical application of vitamin C is that it is extremly unstable, so hydrophilic derivatives like sodium ascorbyl phosphate and lipophilic esters with fatty acids were synthesized to improve stability.43,44 However, an efficient increase in vitamin C levels after topical application of different ascorbic acid derivatives including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehydroascorbic acid to porcine skin could not be shown.42... 

For example, when 02 is formed in the hydrophilic stage, vitamin C (18, L-ascorbic acid present in hydrophilic stage) assists the hydrogen atoms to form dehydroascorbic acid (19) via monodehydroascorbic acid, and hydrogen peroxide (eq. 1.9). 

Ascorbic Acid and Ascorbic Acid Esters and Saits Vitamin C or ascorbic acid is widespread in nature but sparingly associated with fats of oils because of its hydrophilic nature (95). Ascorbic acid in the free form, salts of sodium and calcium, and esters of stearic and palmitic are commonly used as antioxidants in foods. Erythorbic acid is the D-isomer of naturally present L-ascorbic acid (Figure 10) and is often used as an antioxidant in dried fruits and a cure... 

Isol. from baechu kimchi. Stable hydrophilic vitamin C deriv. Skin antioxidant used as a medical additive in commercial cosmetics. [a]o +189.6 (c, 5.0 in H2O). 2-O-P-D-Glucopyranoside Ascorbic acid 2-fl -D-glucoside C12H18O11 338.268 Constit. of the fruit of Lycium barbarum (box thorn). Amorph. cryst. 6-Hexadecanoyl Ascorbyl palndtate, USAN. E304 [137-66-6]... 

In its reactions with free radicals, vitamin E is converted to the a-tocopheroxyl radical. By regenerating vitamin E, ascorbic acid becomes involved in protecting the membranes indirectly. The mechanism whereby water-soluble ascorbic acid regenerates fat-soluble vitamin E has not yet been elucidated. Regeneration reactions would have to take place at the interface between hydrophilic and hydrophobic sites (Lambe-let et aL, 1985). It is suggested that ascorbate functions to recycle vitamin E... 

All the above contributions are presented as self-contained independent chapters. This has inevitably led to some element of repetition and overlap of content. In my opinion, this contributes positively to the book by providing alternative data, literature, opinions, and interpretations. Many partly answered and unanswered questions remain. Perhaps the most pertinent lie within the context of the antioxidant/prooxidant balance of ascorbic acid within different tissues and disease situations and the detailed understanding of the hydrophilic/hydrophobic interface between water-soluble ascorbic acid and the lipid-soluble antioxidants, vitamins E and A. Thus, the door remains wide open for many future investigations. 

In pharmaceutical preparations and fruit juices, ascorbic acid is readily separated from other compounds by TLC on silica gel and quantified directly by absorption at 254 nm. Serum and plasma may be deproteinized with twice its volume of methanol or ethanol. Various ascorbic acid compounds in plant extracts and foods have been separated on cellulose layers and detected by spraying with 2,S dichlorophenol indophenol (36). Heulandite, a natural zeolite (particle size 45 p) has successfully been employed as an adsorbent and ascorbic acid and other hydrophilic vitamins have separated within 5 cm by ascending chromatography in dimethylformamide (37). HPTLC and OPLC methods have been developed to improve the separation of ascorbic acid from other water soluble vitamins, with mixed success (11). 

Hydrophilic vitamins, I047-1QS4 ascorbic acid (vitamin C), 1052-1033 biotin. 1051-1052... 

Ascorbyl palmitate, a derivative of ascorbic acid, is actually a lipophilic vitamin C and has been shown to be as biologically active as its original hydrophilic counterpart. Since both vitamin C and palmitate esters are natural food ingredients, ascorbyl palmitate is widely used in the food industry as a natural preserver of oils and fats. 

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