Journal of Cosmetic Science and Trichology

(Annual (One issue per year))

ABSTRACT

Solar radiation has profoundly influenced the evolution of life by serving both as a primary energy source and as a continuous photochemical force that generates molecular diversity and imposes environmental selection. Although ultraviolet (UV) radiation is commonly associated with DNA damage, mutagenesis, photoaging, and carcinogenesis, its constructive role in shaping natural-product chemistry has received less attention. This review examines four major carbocyclic ring systems cyclopropane (C3), cyclobutane (C4), cyclopentane (C5), and cyclohexane (C6) and considers how ring size influences strain energy, molecular geometry, conformational flexibility, stereochemical organization, chemical reactivity, and biological function. These ring systems are presented as a comparative physicochemical continuum rather than as a strictly chronological evolutionary sequence. Cyclopropane is associated mainly with specialized functions such as membrane adaptation and stress resistance, whereas cyclopentane and cyclohexane provide comparatively stable scaffolds for signaling, hormonal regulation, molecular recognition, and metabolism. Particular attention is given to cyclobutane because its combination of structural rigidity, controlled strain, chemical stability, and photochemical accessibility has supported its repeated occurrence in natural products from plants, fungi, bacteria, marine organisms, and animals. The review further evaluates the relevance of carbocyclic natural products to cosmetic science and trichology. Plant- and marine-derived terpenoids, steroids, iridoids, cyclitols, and related metabolites exhibit antioxidant, anti-inflammatory, antimicrobial, photoprotective, pigmentation-modulating, and barrier-supporting properties that may be useful in skin-care, anti-aging, scalp-care, and hair-protection formulations. However, evidence ranges from traditional use and in vitro observations to limited clinical evaluation, and substantial uncertainties remain regarding skin penetration, photostability, bioavailability, sensitization, endocrine activity, formulation compatibility, and long-term safety. By integrating photochemistry, natural-product chemistry, skin and hair biology, and formulation science, this review identifies current research gaps and proposes priorities for translating structurally diverse carbocyclic metabolites into safe and effective cosmetic and trichological ingredients.

Keywords: Sunlight; Photochemistry; Carbocyclic Natural Products; Cyclobutane; Cyclopropane; Cyclopentane; Cyclohexane; Molecular Evolution; Functional Differentiation; Natural Selection; Medicinal Chemistry; Cosmetics