cis-4,7,10,13,16,19-Docosahexaenoic acid
[CAS 6217-54-5]

Identification

• Classification: Analytical chemistry >> Standard >> Clinical standard
• Name: cis-4,7,10,13,16,19-Docosahexaenoic acid
• Synonyms: DHA
• Molecular Formula: C₂₂H₃₂O₂
• Molecular Weight: 328.49
• CAS Registry Number: 6217-54-5
• EC Number: 612-950-9
• SMILES: CC/C=CC/C=CC/C=CC/C=CC/C=CC/C=CCCC(=O)O

Properties

• Density: 0.9±0.1 g/cm³ Calc.^*
• Boiling point: 446.7±24.0 °C 760 mmHg (Calc.)^*
• Flash point: 343.4±18.0 °C (Calc.)^*
• Index of refraction: 1.521 (Calc.)^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H227-H315-H319-H335-H413
• Safety Statements: P210-P261-P264-P271-P273-P280-P302+P352-P304+P340+P312-P305+P351+P338-P332+P313-P337+P313-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413

chemBlink Chemical Story

Docosahexaenoic acid (DHA), chemically designated all-cis-4,7,10,13,16,19-docosahexaenoic acid, is a naturally occurring omega-3 polyunsaturated fatty acid with the molecular formula C₂₂H₃₂O₂. Containing twenty-two carbon atoms and six cis double bonds, DHA is one of the most highly unsaturated fatty acids found in nature. Although present in relatively small quantities in the human body, it is indispensable for normal brain function, vision, and nervous system development, making it one of the most extensively studied nutritional lipids of the modern era.

The scientific history of DHA began with investigations into marine oils during the first half of the twentieth century. Fish oils had long been recognized as nutritionally valuable, but the identity and physiological significance of their individual fatty acids remained largely unknown. Improvements in chromatographic analysis during the 1950s and 1960s enabled researchers to isolate and characterize DHA, revealing that it was particularly abundant in marine fish and mammalian neural tissues. This discovery marked the beginning of intensive research into the biological functions of long-chain omega-3 fatty acids.

A major turning point came when scientists recognized that DHA is not merely an energy source but a structural lipid concentrated in cell membranes, especially those of the brain and retina. The exceptionally high degree of unsaturation contributes to membrane fluidity, allowing membrane proteins, receptors, and ion channels to function efficiently. These findings transformed DHA from a little-known component of fish oil into a molecule of central importance in neuroscience and developmental biology.

Interest in DHA increased further as epidemiological studies suggested that populations consuming diets rich in marine fish exhibited lower rates of cardiovascular disease than expected. Although many factors contribute to these observations, research stimulated worldwide interest in omega-3 fatty acids and their physiological roles. Subsequent investigations demonstrated that DHA participates in neuronal development, synaptic function, visual signaling, and the formation of specialized lipid mediators involved in the resolution of inflammation.

During pregnancy and infancy, DHA assumes particular importance because large amounts accumulate in the developing brain and retina. Clinical and nutritional studies have therefore supported the inclusion of DHA in infant formulas, frequently together with arachidonic acid (ARA), to better approximate the lipid composition of human milk. This combination reflects the complementary physiological functions of omega-3 and omega-6 long-chain polyunsaturated fatty acids during early development.

Commercial production of DHA has undergone remarkable evolution. Early supplies depended almost entirely on fish oil extraction, raising concerns regarding sustainability, product variability, and marine contaminants. Advances in industrial biotechnology have since enabled the cultivation of microalgae capable of producing high-purity DHA through controlled fermentation. Microalgal DHA has become an important source for infant nutrition, dietary supplements, and functional foods, while reducing dependence on wild fish resources.

Today, DHA remains a major focus of research in nutrition, neuroscience, ophthalmology, cardiovascular medicine, and healthy aging. Scientists continue to investigate its roles in cognitive development, neurodegenerative disorders, retinal function, and inflammatory regulation. At the same time, increasing attention has been directed toward maintaining an appropriate balance between omega-3 and omega-6 fatty acids rather than emphasizing any single nutrient in isolation.

The development of DHA research illustrates how progress in analytical chemistry, marine biology, nutrition, and molecular medicine can converge to reveal the biological significance of a naturally occurring molecule. From an obscure constituent of marine oils to a globally recognized nutritional ingredient, DHA has become one of the defining examples of how chemical discovery can influence both scientific understanding and public health.

**References**

1. Sinclair, A.J. and Crawford, M.A. (1972) 'The accumulation of arachidonate and docosahexaenoate in the developing brain', *Journal of Neurochemistry*, 19, pp. 1753–1758.

2. Innis, S.M. (2007) 'Dietary (n-3) fatty acids and brain development', *Journal of Nutrition*, 137(4), pp. 855–859.

3. Ratledge, C. (2004) 'Fatty acid biosynthesis in microorganisms being used for Single Cell Oil production', *Biochimie*, 86(11), pp. 807–815.