Two biologically important vitamins—vitamin C (ascorbic acid) and vitamin E (α-tocopherol)—have markedly different chemical structures. Vitamin C contains multiple hydroxyl (–OH) groups and a lactone ring, while vitamin E possesses a long non-polar hydrocarbon tail attached to a chromanol head that contains one –OH group.
A nutrition scientist is interested in how these structural differences affect the distribution of the two vitamins between the aqueous environment of blood plasma and the lipid-rich environment of adipose (fat) tissue at 37 °C.
(a) For each vitamin, predict whether it is more soluble in blood plasma or adipose tissue. Provide a brief structural rationale for each prediction.
(b) Draw a clear connection between the dominant intermolecular forces operating in blood plasma and those operating in adipose tissue, and relate these forces to the structural features of each vitamin.
(c) Propose one chemical modification to vitamin C that would increase its solubility in adipose tissue while minimally affecting its biological activity. Explain how your modification would alter intermolecular interactions.
(d) Discuss one potential physiological implication of the differing solubilities of vitamins C and E with respect to their storage and required dietary intake frequency.