Naphthalene, a versatile platform in medicinal chemistry: Sky-high perspective

Naphthalene, a cytotoxic moiety, is an extensively explored aromatic conjugated system with applications in various pathophysiological conditions viz. anticancer, antimicrobial, anti-inflammatory, antiviral, antitubercular, antihypertensive, antidiabetic, anti-neurodegenerative, antipsychotic, anticonvulsant, antidepressant. Naphthalene epoxides and naphthoquinones are most reactive metabolites of naphthalene and are responsible for the covalent interaction with cysteine amino acid of cellular proteins for cytotoxic nature. Many naphthalene derived bioactive phytoconstituents are present in nature including podophyllotoxins (Etoposide, teniposide), bis-ANS 82, Rifampicin, Justiprocumin A, B, Patentiflorin A. The naphthalene-based molecules, viz. Naphyrone, tolnaftate, naftifine, nafcillin, terbinafine, propranolol, nabumetone, nafimidone, naproxen, duloxetine, lasofoxifene, bedaquiline etc. have also been approved by FDA and are being marketed as therapeutics. Thus, the naphthalene scaffold emerges as an important building block in drug discovery owing to its broad spectrum of biological activities through varying structural modifications. This review incorporates the pharmacological aspects of different types of chemically modified naphthalene-based molecules along with their activity profile. This compiled information may serve as a benchmark for the alteration of existing ligands to design novel potent molecules with lesser side effects.