From Antiseptics to Azoles: 130 Years of Synthetic Antifungal Drugs

Natural products helped establish modern antifungal therapy; synthetic chemistry tells the other half of the story. Following our review of natural product-inspired antifungal drugs, Rob Capon and I have now published a companion review examining synthetic antifungals introduced or approved for human use also published in Antibiotics. The review covers 70 therapeutic entities across 19 structural classes from late 19th century topical antiseptics to 21st century oral and intravenous medicines used against serious invasive fungal infections. For each, we trace its clinical introduction, chemistry, modes of action, resistance and evidence of continuing use.

Before modern antifungal medicines. The earliest synthetic agents emerged in a very different therapeutic and regulatory environment. Hydroxyquinolines, gentian violet and other antiseptics entered practice when treatment largely focused on superficial infections. Some were adapted from compounds developed for other purposes; others combined antibacterial and antifungal activity without the fungal-selective targets we now seek in drug discovery. Their histories also require careful terminology. “Introduced into human use” is not synonymous with “approved” under a modern regulatory system. Nor does historical use establish that a medicine remains available today. Our review distinguishes these questions rather than treating them as interchangeable.

The azole transformation. Post the discovery and development of the polyenes in the 1950s, the rise of the synthetic azoles is one the most important advances in antifungal therapy. Our dataset includes 31 azole agents: one benzimidazole, 20 imidazoles, nine triazoles and one tetrazole. From 1970 onwards, azoles accounted for 30 of the 43 synthetic entities approved for human use. Their importance extends beyond the number of compounds. Broad-spectrum activity and the availability of oral and, for selected agents, intravenous, formulations substantially expanded treatment options for systemic and invasive mycoses.

Beyond the azoles. The synthetic contribution is broader than this dominant class. Thiocarbamates, hydroxypyridones, benzylamines, morpholines and oxaboroles illustrate the chemical diversity explored in developing antifungal medicines. The review places these agents alongside less familiar historical classes, including diamidines and benzothiazoles, to document the wider development of the field. This longer view matters as a history based only on medicines familiar today misses both earlier therapeutic approaches and compounds subsequently displaced by more useful treatments.

Natural products and synthetics: two complementary histories. Our reviews document 30 natural product-inspired and 70 synthetic antifungal therapeutic entities; overall, an even 100 therapeutics. Together, they trace the development of human antifungal treatment from 19th century preparations to contemporary medicines, while distinguishing chemical origin, historical introduction and continuing use.

Rethinking Natural Products: What’s Next for Nature-Inspired Drug Discovery?

Introduction. Nature has been humanity’s pharmacy for millennia—think traditional herbal remedies, or blockbuster drugs like morphine and quinine. However, in recent decades, drug discovery focused has on alternative lead discovery methods and engineered biologics. In our new review (January 2014–June 2025) published in Natural Product Reports we ask: what is the current role of natural-product-derived (NP-D) compounds in drug approvals and clinical pipelines?

Link: https://doi.org/10.1039/D5NP00031A

The Big Picture:
– We identified 58 NP-related drugs launched globally between January 2014 and June 2025 (45 NCEs and 13 ADCs).
– Between 2014 and 2024, of the 579 drugs approved globally (388 NCEs, 191 NBEs) we found 56 (≈ 9.7 %) could be classified as NP or NP-D drugs.
– At the end of December 2024, there were 125 NP or NP-D compounds undergoing clinical trials or in the registration phase, including 33 new pharmacophores not previously seen in approved drugs. However, only one of these new pharmacophores in active clinical development has been discovered in the last 15 years.

Key Take-aways.

(1) Despite the decline in emphasis on natural products, they still contribute meaningfully (~10 %) to approved drugs.

(2) The pipeline is active—but innovation (in terms of new pharmacophores) is slow. – To unlock future NP-derived success, renewed emphasis on bioassay-guided isolation and mode-of-action elucidation is needed.

Why it Matters. For researchers, entrepreneurs and policymakers: natural products offer chemical diversity and biological relevance that synthetic libraries often struggle to match. Our review suggests that while NP-D compounds aren’t dominating the field, they remain a valuable strategic option. Re-investing in the foundational work (isolation, mechanism, natural-source exploration) could yield the next generation of breakthrough therapeutics.

Looking Ahead:

(1) Better integration of genomics, metabolomics and modern analytics with natural product discovery.

(2) Strategic partnerships between academia, industry and natural-source repositories to accelerate NP pipelines.

(3) Encourage early-phase investment in NP scaffolds and biologically-rich extracts.

(4) Further integration of machine learning, genomics, metabolomics and modern analytics with NP discovery.

Conclusion. Nature still holds surprises—and in the era of multi-drug resistant pathogens, complex diseases and the need for new therapeutic modalities, NP-derived drugs will continue to play an important role for the foreseeable future. I hope this review spurs renewed interest, investment and collaboration across the NP drug discovery ecosystem.