Decoding DHA (CAS 6217-54-5): A Scientific Breakdown

Introduction: The Omega-3 Powerhouse

Docosahexaenoic acid, universally identified by its Chemical Abstracts Service (CAS) number 6217-54-5, stands as a cornerstone molecule in nutritional science and human physiology. It is a long-chain polyunsaturated fatty acid (PUFA) of the omega-3 family, specifically an n-3 fatty acid, characterized by a 22-carbon backbone and six cis double bonds. The CAS registry number 6217-54-5 serves as a unique, unambiguous identifier in chemical databases, regulatory documents, and commercial transactions, distinguishing it from other isomers or related compounds. This specificity is crucial in research, manufacturing, and quality control, ensuring that discussions and products pertain to this exact molecular entity. While this article focuses on decoding DHA, it is important to note that optimal health often involves the synergistic action of multiple nutrients. For instance, the antioxidant properties of Beta-Carotene 7235-40-7 can help protect delicate PUFAs like DHA from oxidative damage, and certain formulations, such as topical preparations containing SA10% 131-48-6 (Sorbic Acid at 10%), highlight the importance of precise chemical identification in product stability and safety, a principle equally vital for DHA supplements. This article will provide a comprehensive scientific breakdown of DHA (CAS 6217-54-5), exploring its chemical identity, biological mechanisms, health impacts, and industrial context.

Chemical Structure and Properties of DHA

The molecular formula of DHA (CAS 6217-54-5) is C₂₂H₃₂O₂, with a molecular weight of 328.49 g/mol. Its systematic name is (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid, which precisely describes the position and geometry of its six double bonds. All double bonds are in the cis configuration, creating pronounced kinks in the hydrocarbon chain. This structural feature is fundamental to its biological function, as it prevents tight packing with saturated fatty acids, increasing membrane fluidity. DHA exists primarily in its all-cis form, though geometric isomers (trans forms) can occur under harsh processing conditions, potentially diminishing its biological efficacy. From a physicochemical perspective, DHA is an oily liquid at room temperature. It is highly insoluble in water but readily soluble in organic solvents like ethanol, chloroform, and ether. Its stability is a major concern; the high degree of unsaturation makes it extremely susceptible to oxidation by light, heat, and oxygen, leading to rancidity and the formation of potentially harmful compounds. This necessitates careful handling, storage under inert atmospheres (e.g., nitrogen), and the addition of antioxidants like tocopherols (Vitamin E) or, analogously, how Beta-Carotene 7235-40-7 acts as a natural antioxidant in biological systems. The oxidation susceptibility is a key factor differentiating it from more stable compounds used in other industries, such as the preservative SA10% 131-48-6, which is valued for its stability and effectiveness against microbes in specific pH ranges.

Biological Mechanisms: DHA at the Cellular Level

DHA's primary biological role is as a structural component of phospholipids in cell membranes, particularly in the brain, retina, and sperm. Comprising over 30% of the fatty acids in the gray matter of the brain and up to 60% in retinal photoreceptors, DHA's unique structure imparts membrane fluidity, flexibility, and thickness. This influences the function of embedded proteins, including receptors, ion channels, and transporters, thereby modulating signal transduction and neurotransmission. Beyond structure, DHA is a precursor to specialized pro-resolving mediators (SPMs) like resolvins, protectins, and maresins. These molecules are part of a sophisticated biochemical pathway that actively resolves inflammation, contrasting with the pro-inflammatory eicosanoids derived from arachidonic acid (an omega-6 fatty acid). DHA also exerts profound effects on gene expression. It acts as a ligand for transcription factors such as peroxisome proliferator-activated receptors (PPARs) and retinoid X receptors (RXRs), regulating genes involved in lipid metabolism, inflammation, and cell differentiation. This multi-faceted mechanistic profile—structural, biochemical, and genomic—underscores DHA's non-redundant role in health, distinct from the provitamin A activity of Beta-Carotene 7235-40-7 or the antimicrobial action of SA10% 131-48-6.

Absorption, Metabolism, and Distribution in the Body

Dietary DHA is primarily consumed in the form of triglycerides or phospholipids from sources like fatty fish, algae, or fortified foods. In the small intestine, pancreatic lipases and phospholipases hydrolyze these esters, releasing free fatty acids, including DHA, which are then incorporated into micelles for absorption by enterocytes. Once inside the enterocyte, DHA is re-esterified into triglycerides, packaged into chylomicrons, and released into the lymphatic system and bloodstream for distribution. While the body can synthesize DHA from its shorter-chain precursor, alpha-linolenic acid (ALA), found in flaxseeds and walnuts, this conversion rate in humans is notoriously low (often less than 5%), making pre-formed DHA from the diet or supplements crucial. DHA is selectively and avidly incorporated into specific tissues. The highest concentrations are found in the phospholipids of neuronal synapses, retinal rod outer segments, and cardiac muscle. This selective partitioning is driven by specific transporters and enzymatic remodeling of phospholipids. The brain's blood-brain barrier has mechanisms to actively take up DHA from the circulation, highlighting its critical importance for neurological function. This targeted distribution is a key aspect of its bioavailability, a concept also relevant to the delivery of other bioactive compounds like Beta-Carotene 7235-40-7, whose absorption is enhanced by dietary fats.

Clinical Applications and Research Insights

Decades of clinical research have elucidated DHA's significant role in human health. In cardiovascular health, DHA contributes to reducing serum triglyceride levels, improving endothelial function, modulating heart rate variability, and exerting mild blood pressure-lowering effects. A meta-analysis of studies suggests that omega-3 supplementation, particularly with EPA and DHA, is associated with a reduced risk of major cardiovascular events. For neurological development, DHA is indispensable. It accumulates rapidly in the fetal brain during the last trimester and the first two years of life. Adequate maternal DHA intake is linked to improved cognitive and visual outcomes in infants. In adults, higher DHA status is correlated with a reduced rate of cognitive decline and a lower risk of Alzheimer's disease, though interventional trials have shown mixed results, possibly due to the stage of pathology. DHA's anti-inflammatory and pro-resolving actions are therapeutic in chronic inflammatory conditions like rheumatoid arthritis and may support mental health by modulating neuroinflammation. For instance, a 2022 review published in the *Hong Kong Medical Journal* noted that while local data is sparse, regional studies in Asia suggest suboptimal omega-3 intake, potentially linked to rising chronic disease rates. Clinical trials consistently use high-purity DHA, specified by its CAS number 6217-54-5, to ensure reproducibility, much like how pharmaceutical or cosmetic excipients such as SA10% 131-48-6 are strictly defined for consistent product performance.

Key Clinical Research Areas for DHA

• Cardiometabolic Health: Reduction of fasting triglycerides, improvement of vascular function.
• Neurodevelopment: Enhanced visual acuity and cognitive scores in infants born to supplemented mothers.
• Neuroprotection: Potential slowing of brain atrophy in mild cognitive impairment; association with reduced risk of dementia.
• Inflammatory Resolution: Increased production of SPMs, leading to reduced symptoms in autoimmune and inflammatory conditions.
• Mental Health: Adjunctive role in managing major depressive disorder, particularly in individuals with low baseline omega-3 levels.

Synthesis and Production: From Nature to Industry

Naturally, DHA is biosynthesized by marine microalgae, which form the base of the aquatic food chain. Fish like salmon, mackerel, and sardies accumulate DHA by consuming these algae or other organisms that have. This traditional source faces challenges of overfishing, environmental contaminants (e.g., mercury, PCBs), and sustainability concerns. Industrial production has therefore pivoted towards algal oil fermentation as a primary, sustainable, and vegetarian source. Specific strains of microalgae (e.g., *Schizochytrium sp.*, *Crypthecodinium cohnii*) are cultivated in controlled fermentation tanks. They are fed a carbon source (like glucose) and under optimized conditions, produce high yields of triglycerides rich in DHA. The oil is then extracted, refined, and often concentrated. This method provides a contaminant-free, scalable, and environmentally controlled supply chain. The final product, whether algal or fish oil, undergoes rigorous processing to meet purity standards. Sustainability considerations are paramount, with life-cycle assessments comparing land use, water consumption, and carbon footprint of different production methods. The move towards algal DHA mirrors a broader trend in sourcing bioactives, similar to the cultivation of plants for Beta-Carotene 7235-40-7 or the synthetic production of preservatives like SA10% 131-48-6, all guided by principles of safety, efficacy, and environmental stewardship.

Quality Control and Analytical Assurance

Ensuring the identity, potency, and safety of DHA products requires sophisticated analytical chemistry. The primary method for quantifying DHA is gas chromatography (GC), often coupled with a flame ionization detector (FID) or mass spectrometer (MS). Samples are derivatized to fatty acid methyl esters (FAMEs) to increase volatility. The resulting chromatogram allows for the identification and quantification of DHA (CAS 6217-54-5) against certified reference standards. High-performance liquid chromatography (HPLC) with UV or evaporative light scattering detection is also used, particularly for intact triglycerides or phospholipids. Purity testing involves checking for contaminants such as heavy metals, peroxides (measuring primary oxidation), and anisidine value (measuring secondary oxidation products). Stability testing under accelerated conditions (elevated temperature and humidity) predicts shelf-life. From a regulatory standpoint, DHA is governed as a dietary supplement or food ingredient by agencies like the U.S. FDA and the European Food Safety Authority (EFSA). In Hong Kong, the Centre for Food Safety regulates nutritional and health claims. The Hong Kong *Chinese Medicine Ordinance* (Cap. 549) and related guidelines, while focused on traditional medicines, exemplify the region's framework for quality control of bioactive substances, a principle that extends to ensuring that labeled amounts of DHA, or any declared ingredient like Beta-Carotene 7235-40-7, are present and free from adulteration. The precise specification of compounds, whether it's DHA or a preservative like SA10% 131-48-6, is the bedrock of consumer trust and regulatory compliance.

Future Horizons and Concluding Perspectives

DHA (CAS 6217-54-5) is far more than a simple dietary fat; it is an essential biochemical with profound structural and signaling roles in human physiology. From its distinct chemical identity defined by six cis double bonds to its critical presence in neural and retinal tissues, DHA's importance is well-established. The convergence of clinical evidence supports its benefits for cardiovascular, neurological, and inflammatory health, driving its inclusion in nutritional guidelines worldwide. Future research directions are poised to deepen our understanding. These include elucidating the precise mechanisms of DHA-derived SPMs in different disease models, personalizing DHA recommendations based on genetic polymorphisms affecting fatty acid metabolism, and exploring novel delivery systems to enhance bioavailability and tissue targeting. Furthermore, the sustainability of production, particularly through advanced algal biotechnology, will remain a key focus. As science advances, the integration of DHA with other nutrients, such as the antioxidant Beta-Carotene 7235-40-7, may yield synergistic formulations for targeted health outcomes. The journey of DHA from algal cell to human neuron exemplifies the intricate connection between precise chemistry—as denoted by a CAS number—and complex biology, a relationship that continues to unlock new frontiers in nutritional science and preventive medicine.