Delphinidin.

Ascorbic acid and anthocyanins co-degrade in aqueous systems, with the ascorbate radical and hydrogen peroxide products opening the pyrylium ring of the anthocyanin. This is one reason berry juices lose colour faster when vitamin C is added. In a dry capsule the two sit apart and the reaction is slow, but in a liquid or a gummy the pairing is a stability question worth designing around.

Colourless flavonols such as quercetin stack face to face with the flat flavylium cation of delphinidin, shielding it from water attack at position 2. The result is a deeper and more stable colour, which is the copigmentation effect described across anthocyanin chemistry. It is a physical association in solution rather than a shared biological pathway.

Adding phenolic copigments to an anthocyanin-rich food raised measured colour intensity and slowed pigment loss during frozen storage. The measurements are colour and pigment retention in the food, not anything measured in a person. The pairing belongs to formulation stability rather than to nutrition.

Delphinidin carries three adjacent hydroxyls on its B ring, a pyrogallol arrangement that binds iron and other transition metals and shifts the pigment towards blue. The same binding means a polyphenol-rich extract taken with an iron dose can lower how much of that iron is taken up, which is the general polyphenol effect on non-haem iron. Separating the two by a couple of hours is the usual formulation answer.

Zinc ions complex with the ortho-hydroxyl groups on the anthocyanidin B ring, which changes both the pigment colour and the availability of the free ion. In a mixed capsule this is a compatibility point rather than a demonstrated absorption effect in people. The effect size in a human meal has not been measured for delphinidin specifically.

Only a small percentage of ingested anthocyanin is absorbed intact; most reaches the colon where bacterial glycosidases release the aglycone, which then breaks down at the C ring to gallic acid and phloroglucinaldehyde. Those metabolites, not the parent pigment, account for much of what circulates. The microbial community therefore sets how much of a dose is converted at all.

Epigallocatechin gallate and delphinidin both carry a trihydroxylated ring and both end up as small phenolic acids after colonic breakdown. In solution the catechin also copigments with the flavylium cation. Overlapping metabolism means the two compete for the same conjugating enzymes rather than simply adding up.

Anthocyanins are polar and poorly absorbed, and food matrix work has repeatedly shown that a fat-containing meal changes their plasma appearance. A medium-chain triglyceride vehicle is one way formulators apply that. The evidence base for the effect is stronger for carotenoids than for anthocyanins, so read this as a design choice with mechanistic support rather than a measured delphinidin result.

Delphinidin and resveratrol are both extensively glucuronidated and sulfated at first pass, and both draw on the same limited pool of UDP-glucuronic acid and PAPS. Taken together at high doses they compete for that capacity, which can raise the free fraction of either. The direction is predictable from the enzymology; the magnitude in people has not been quantified for this pair.

Tocopherol quenches a lipid peroxyl radical and becomes a tocopheroxyl radical, which a water-soluble phenol can reduce back to the active form. Anthocyanidins sit at a redox potential that allows this in model lipid systems. The recycling is well demonstrated in vitro; whether it translates into a measurable difference in a person is a separate question.

In berry and fruit matrices, pigment classes with different polarities buffer one another against oxidation, which shows up as slower colour and carotenoid loss. Reviews of berry composition describe delphinidin sitting alongside carotenoids in this way. The measurement is pigment retention in the food, not an outcome in a person.