gamma-butyrolactone (GBL), also known as  Butyrolactone, is a cyclic ester commonly used as a solvent and a chemical intermediate in various industrial and cosmetic applications. This ingredient is valued for its excellent solvency properties, making it effective in dissolving a wide range of compounds. In cosmetic formulations, Butyrolactone functions as a solvent, humectant, and stabilizer, enhancing the texture and performance of products while contributing to skin hydration.

Chemical Composition and Structure

Butyrolactone consists of:

• Lactone Structure: A cyclic ester that contains a carbonyl group (C=O) and an ether link (C-O) within a ring structure.
• Butyric Acid: Derived from butyric acid, which contributes to its chemical properties and functionality.

The structure allows Butyrolactone to effectively interact with various ingredients in formulations, improving solubility and stability.

Physical Properties

• Appearance: Typically a colorless to pale yellow liquid.

• Solubility: Highly soluble in water and a wide range of organic solvents.

• pH: Generally neutral, compatible with various cosmetic formulations.

• Odor: Mild, often considered slightly sweet or characteristic of lactones.

• Stability: Stable under normal storage conditions; should be kept away from excessive heat and moisture.

Production Process

1. Synthesis: Butyrolactone is synthesized through the oxidation of 1,4-butanediol or through other chemical processes that involve the condensation of butyric acid.

2. Purification: The product is purified to remove any impurities or unreacted materials, ensuring a high-quality ingredient.

3. Formulation: Purified Butyrolactone is incorporated into various cosmetic products to enhance their solubility, texture, and performance.

Applications

• Medical: Occasionally used in topical formulations for its solvent properties and ability to enhance the delivery of active ingredients.

• Cosmetics: Commonly found in creams, lotions, and hair care products for its moisturizing, stabilizing, and solvent properties. It helps improve product texture and overall skin feel.

• Industrial Uses: Employed in various applications, including coatings, adhesives, and as a solvent for resins and polymers.

Environmental and Safety Considerations

Butyrolactone is generally regarded as safe for use in cosmetics when applied according to recommended guidelines. However, it is essential to handle it with care due to its solvent properties. 

Responsible sourcing and formulation practices are necessary to ensure that the ingredient is free from harmful contaminants and produced sustainably.

Molecular Formula  C₄H₆O₂

Molecular Weight  86.09 g/mol 

CAS     96-48-0

UNII    OL659KIY4X

EC Number  202-509-5

DTXSID6020224

Synonyms:

gamma-Butyrolactone

1,4-Butanolide

References__________________________________________________________________________

Hur J, Jang J, Sim J. A Review of the Pharmacological Activities and Recent Synthetic Advances of γ-Butyrolactones. Int J Mol Sci. 2021 Mar 9;22(5):2769. doi: 10.3390/ijms22052769. 

Abstract. γ-Butyrolactone, a five-membered lactone moiety, is one of the privileged structures of diverse natural products and biologically active small molecules. Because of their broad spectrum of biological and pharmacological activities, synthetic methods for γ-butyrolactones have received significant attention from synthetic and medicinal chemists for decades. Recently, new developments and improvements in traditional methods have been reported by considering synthetic efficiency, feasibility, and green chemistry. In this review, the pharmacological activities of natural and synthetic γ-butyrolactones are described, including their structures and bioassay methods. Mainly, we summarize recent advances, occurring during the past decade, in the construction of γ-butyrolactone classified based on the bond formation in γ-butyrolactone between (i) C5-O1 bond, (ii) C4-C5 and C2-O1 bonds, (iii) C3-C4 and C2-O1 bonds, (iv) C3-C4 and C5-O1 bonds, (v) C2-C3 and C2-O1 bonds, (vi) C3-C4 bond, and (vii) C2-O1 bond. In addition, the application to the total synthesis of natural products bearing γ-butyrolactone scaffolds is described.

Du YL, Shen XL, Yu P, Bai LQ, Li YQ. Gamma-butyrolactone regulatory system of Streptomyces chattanoogensis links nutrient utilization, metabolism, and development. Appl Environ Microbiol. 2011 Dec;77(23):8415-26. doi: 10.1128/AEM.05898-11. 

Abstract. Gamma-butyrolactones (GBLs) produced by several Streptomyces species have been shown to serve as quorum-sensing signaling molecules for activating antibiotic production. The GBL system of Streptomyces chattanoogensis L10, a producer of antifungal agent natamycin, consists of three genes: scgA, scgX, and scgR. Both scgA and scgX contribute to GBL production, while scgR encodes a GBL receptor. ΔscgA and ΔscgX mutants of S. chattanoogensis behaved identically: they had a growth defect in submerged cultures and delayed or abolished the morphological differentiation and secondary metabolites production on solid medium. ScgR could bind to the promoter region of scgA and repress its transcription. Moreover, scgA seems also to be controlled by a GBL-mediated negative-feedback system. Hence, it is apparent that GBL biosynthesis is tightly controlled to ensure the correct timing for metabolic switch. An additional direct ScgR-target gene gbdA was identified by genomic SELEX and transcriptional analysis. Comparative proteomic analysis between L10 and its ΔscgA mutant revealed that the GBL system affects the expression of more than 50 proteins, including enzymes involved in carbon uptake system, primary metabolism, and stress response, we thus conclude that scgR-scgA-scgX constitute a novel GBL regulatory system involved in nutrient utilization, triggering adaptive responses, and finally dictating the switch from primary to secondary metabolism.

Natsume R, Ohnishi Y, Senda T, Horinouchi S. Crystal structure of a gamma-butyrolactone autoregulator receptor protein in Streptomyces coelicolor A3(2). J Mol Biol. 2004 Feb 13;336(2):409-19. doi: 10.1016/j.jmb.2003.12.040. 

Abstract. The gamma-butyrolactone-type autoregulator/receptor systems in the Gram-positive bacterial genus Streptomyces regulate morphological differentiation or antibiotic production, or both. The autoregulator receptors act as DNA-binding proteins, and on binding their cognate ligands (gamma-butyrolactones) they are released from the DNA, thus serving as repressors. The crystal structure of CprB in Streptomyces coelicolor A3(2), a homologue of the A-factor-receptor protein, ArpA, in Streptomyces griseus, was determined. The overall structure of CprB shows that the gamma-butyrolactone receptors belong to the TetR family. CprB is composed of two domains, a DNA-binding domain and a regulatory domain. The regulatory domain contains a hydrophobic cavity, which probably serves as a ligand-binding pocket. On the basis of the crystal structure of CprB and on the analogy of the characteristics of ligand-TetR binding, the binding of gamma-butyrolactones to the regulatory domain of the receptors is supposed to induce the relocation of the DNA-binding domain through conformational changes of residues located between the ligand-binding site and the DNA-binding domain, which would result in the dissociation of the receptors from their target DNA.

Lepoittevin JP, Berl V, Giménez-Arnau E. Alpha-methylene-gamma-butyrolactones: versatile skin bioactive natural products. Chem Rec. 2009;9(5):258-70. doi: 10.1002/tcr.200900013. PMID: 19937861.

Hamann HJ, Abutaleb NS, Pal R, Seleem MN, Ramachandran PV. β,γ-Diaryl α-methylene-γ-butyrolactones as potent antibacterials against methicillin-resistant Staphylococcus aureus. Bioorg Chem. 2020 Nov;104:104183. doi: 10.1016/j.bioorg.2020.104183. Epub 2020 Aug 28. PMID: 32971415.