Can a single compound alleviate most of the biological functions decreased with aging?

If one has to propose a compound, it is probably “retinol” or one for retinoids. Retinoids work and their effect has been demonstrated on the molecular and clinical levels by many researchers. For example, Retinol addresses all three major skin care/ treatment issues - reversing aging, protecting skin from further damage, and improving problem skin, such as acne. The results are not just cosmetic.

Retinoic acid and its synthetic analogs are potent regulators of a diverse group of biological processes. Both experimental and clinical studies have revealed that retinoids regulate a wide variety of essential biological processes, such as vertebrate embryonic morphogenesis and organogenesis, cell growth arrest, differentiation and apoptosis, and homeostasis, as well as their disorders.

Although retinol’s benefits are undeniable, it has numerous shortcomings restricting its universal use in cosmetic products. To name a few: its instability, formulation difficulty, skin irritancy, and skin sensitization. The use of Retinol can make one's skin look red and irritated and increase skin sensitivity to sunlight. If retinol is not used correctly, there can be scaling of the skin, dryness, and itching. Other retinoids e.g. synthetic analogs developed for skincare preparations are more stable, have less irritation potential, and are almost equally effective. So, those ingredients are more often used in modern antiaging skincare formulations.
Bakuchiol is a derivative from the psoralea corylifolia plant used in oriental medicine. The first natural alternative to retinol.
This carotenoid is found primarily in carrots and is used to give personal care products a yellow to orange-red color. The body converts beta-carotene into vitamin A.
A stabilized form of Vitamin A, Encapsulated Retinol supports skin's natural immune system function to hydrate, diminish fine lines and wrinkles, and reveal a radiant glow.

Hydroxypinacolone Retinoate is a pure ester form of Tretinoin (all-trans-Retinoic acid) that works similarly to Retin-A but without the irritation of Tretinoin.

Retinol is one of the forms of vitamin A (also called vitamin A1) that plays a critical role in maintaining essential functions in the body.
Retinyl Palmitate is a stable form of vitamin A that acts as a skin normalizer, this nutrient helps remind the cells of what they "did" when they were young. In addition, it nourishes the skin when applied topically.
Retinyl Propionate is an ester of retinol and propionic acid, one of the stable forms of vitamin A.
Vitamin A in cosmetic preparations is intended for all skin types. Mature skin becomes supple and radiant, and wrinkles are reduced.