Pimaricin
[CAS# 7681-93-8]

Identification

• Classification: API >> Antibiotics >> Other antibiotics
• Name: Pimaricin
• Synonyms: Natamycin
• Molecular Formula: C₃₃H₄₇NO₁₃
• Molecular Weight: 665.73
• CAS Registry Number: 7681-93-8
• EC Number: 231-683-5
• SMILES: C[C@@H]1C/C=C/C=C/C=C/C=C/[C@@H](C[C@H]2[C@@H]([C@H](C[C@](O2)(C[C@H](C[C@@H]3[C@H](O3)/C=C/C(=O)O1)O)O)O)C(=O)O)O[C@H]4[C@H]([C@H]([C@@H]([C@H](O4)C)O)N)O

Properties

• Density: 1.4±0.1 g/cm³, Calc.^*
• Index of Refraction: 1.620, Calc.^*
• Boiling Point: 952.2±65.0 °C (760 mmHg), Calc.^*
• Flash Point: 529.7±34.3 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Discovery and Applications

Pimaricin, also known as natamycin, is a polyene antifungal compound first discovered in 1955 from a strain of *Streptomyces natalensis*. It was identified during a screening process for natural antifungal agents and has since become widely used due to its effectiveness against molds and yeasts. The isolation of pimaricin marked a significant advancement in antifungal treatments, particularly in the food and pharmaceutical industries.

The synthesis of pimaricin occurs naturally in *Streptomyces natalensis* through a polyketide biosynthetic pathway. The process involves the assembly of a macrolide lactone ring, which is characteristic of polyene antibiotics. The compound's structure enables it to bind to ergosterol, a key component of fungal cell membranes, thereby disrupting membrane integrity and leading to cell death. Unlike some other polyene antibiotics, pimaricin does not significantly affect mammalian cells, making it a safe and selective antifungal agent.

One of the primary applications of pimaricin is as a food preservative, particularly in dairy products such as cheese and yogurt, where it prevents mold and yeast contamination without affecting bacterial cultures used in fermentation. It is also used in meat products and fruit coatings to extend shelf life. Due to its low toxicity and stability, pimaricin is approved for use in many countries as a natural food additive.

Beyond food preservation, pimaricin has medical applications, primarily in ophthalmology for the treatment of fungal keratitis and other ocular infections caused by filamentous fungi. Its ability to target fungal pathogens without promoting bacterial resistance makes it a valuable alternative to synthetic antifungal drugs. In veterinary medicine, pimaricin is also utilized to treat fungal infections in livestock.

Environmental concerns related to pimaricin's use have been minimal, as it exhibits low persistence and limited impact on non-target organisms. However, research continues into optimizing its production through fermentation and genetic engineering to enhance yield and cost-effectiveness. Advances in biotechnology have enabled modifications to the biosynthetic pathway, improving strain efficiency and reducing production costs.

The continued application of pimaricin in food safety and medicine underscores its importance as a natural antifungal agent. Its discovery and development have provided significant benefits in preserving food quality and treating fungal infections, making it an indispensable compound in multiple industries.

References

1987. [Effect of 1% pimaricin ophthalmic ointment in the treatment of keratomycosis]. Nippon Ganka Gakkai zasshi, 91(2).
https://pubmed.ncbi.nlm.nih.gov/3496742

2005. Comparison of Topical Itraconazole 1% With Topical Natamycin 5% for the Treatment of Filamentous Fungal Keratitis. Cornea, 24(4).
DOI: 10.1097/01.ico.0000151539.92865.3e

2017. [Contact lens-associated Paecilomyces lilacinus keratitis]. Der Ophthalmologe: Zeitschrift der Deutschen Ophthalmologischen Gesellschaft, 114(1).
DOI: 10.1007/s00347-016-0255-3