MAAs occupy a unique niche in biology. To date, only cyanobacteria, phytoplankton, and algae are known to synthesize them, and more than 570 species of marine macroalgae are thought to harbor the compounds. Their chemical structures are diverse, their light and thermal stability is excellent, and they are considered non-toxic, qualities that have long made them attractive candidates for cosmetics and pharmaceuticals. Yet their antioxidant behavior has remained surprisingly understudied, particularly in comparison with the polysaccharides, phenols, and pigments that dominate the seaweed antioxidant literature. The Jiangsu team, led by Yingying Sun, set out to close that gap by focusing on six species that are common in Chinese waters and cuisine: Bangia fuscopurpurea, Gelidium amansii, Sargassum fusiforme, Palmaria palmata, Sargassum sp., and Undaria pinnatifida.

The first hurdle was cosmetic in the most literal sense. In the researchers’ earlier work, MAA extracts from several of these algae came out stained black-red or black-green by co-extracted pigments, which muddied subsequent activity assays and complicated any practical application. Their solution was elegantly simple: wash the dried, powdered algae with anhydrous ethanol before the real extraction begins, discarding the pigment-laden supernatant. Spectrophotometric scans confirmed the wash was pulling out chlorophyll, phycobiliproteins, and beta-carotene, the compounds responsible for the unwanted color. Only then did the team extract the MAAs themselves using 25 percent methanol at 45 degrees Celsius, followed by repeated rounds of cold ethanol precipitation to strip away remaining non-target material.

The results of this pretreatment were striking. The purified extracts emerged a transparent reddish hue rather than an opaque dark sludge, and for two species the yield actually improved rather than suffered. Bangia fuscopurpurea delivered 1.5 times its previous MAA output, reaching a yield of 23.62 percent of the dried algal powder, while Gelidium amansii improved by a factor of 1.1. For the brown algae, the trade-off was less favorable: yields of Sargassum fusiforme, Sargassum sp., and Undaria pinnatifida declined significantly, suggesting that some MAAs were lost during the extra purification steps and that the protocol will need species-specific refinement. High-performance liquid chromatography coupled with mass spectrometry showed that the cleanup did not alter the underlying chemistry. The extracts were dominated by four familiar MAAs: palythine, palythenic acid, shinorine, and porphyra-334. Notably, the team reports the first detection of palythenic acid in Palmaria palmata, a compound previously known mainly from phytoplankton and a handful of other macroalgal species.

With clean extracts in hand, the antioxidant testing began. Using a Trolox-based assay, the researchers found that the total antioxidant capacity of the extracts from Bangia fuscopurpurea and Sargassum fusiforme towered over the rest, running 1.8 to 5.1 times higher than the other four species. The superoxide anion scavenging assay told a similar story. At a concentration of 50 milligrams per milliliter, the extracts from Sargassum fusiforme, Bangia fuscopurpurea, and Sargassum sp. neutralized more than 93 percent of the superoxide radicals in solution, while the remaining three species still managed above 64 percent. The half-maximal effective concentrations for the two standouts hovered around 30 milligrams per milliliter. Vitamin C, it should be said, remains the benchmark, achieving over 96 percent scavenging at a mere 0.035 milligrams per milliliter, so the MAAs are not about to displace ascorbic acid on potency alone.

But potency is not the whole story, and the authors point to a mechanistic nuance that could change the calculus. Earlier studies have shown that although porphyra-334 and shinorine score modestly in DPPH radical assays, they are remarkably effective at quenching free radicals through hydrogen atom transfer, a different chemical pathway. The relatively low concentration of active MAAs within the crude extracts may also be masking their true capability, and the researchers anticipate that further purification could substantially boost performance. There is even suggestive evidence that MAA antioxidant activity contributes to inhibiting cancer cell activity, though that frontier remains exploratory.

Perhaps the most immediately practical finding concerns browning, the enzymatic discoloration that turns a sliced apple or yam an unappetizing brown within hours and drives consumer rejection of fresh-cut produce. When the team soaked yam slices and red Fuji apple slices in dilute MAA solutions and tracked them over three days, the untreated controls browned dramatically while the treated slices stayed visibly fresh. The extracts from Bangia fuscopurpurea and Sargassum fusiforme performed best, and a component isolated from the Bangia extract via silica gel chromatography outdid them all, suppressing browning in more than 52 percent of yam and apple slices after 48 hours. That performance exceeded what has been reported for green tea extract, a standard natural anti-browning agent. The researchers speculate the effect may be linked to the impressive moisture-absorption and retention properties previously documented for Bangia MAAs, though the precise mechanism awaits further study.

Safety and formulation matter just as much as activity for any food additive, and here the mineral analysis delivered reassuring news. Inductively coupled plasma optical emission spectrometry revealed that the extracts are rich in essential macro-elements such as calcium, potassium, magnesium, sodium, and phosphorus, along with beneficial trace elements including iron, zinc, copper, and molybdenum. Critically, no harmful heavy metals, lead, cadmium, arsenic, or mercury, were detected, and copper levels sat far below the limits set by the Chinese Pharmacopoeia. The team then stress-tested the two star extracts against five common food additives over 40 days at both 25 and 48 degrees Celsius. Citric acid proved destructive, cutting absorbance by more than 23 percent for the Bangia extract and over 40 percent for the Sargassum extract by the experiment’s end, while sodium glutamate also destabilized the Bangia extract. Agar and carrageenan, by contrast, actually enhanced stability, making them natural formulation partners.

The convergence of these findings, cleaner and higher-yielding extraction, demonstrated antioxidant and anti-browning activity, a benign mineral profile, and compatibility with common food hydrocolloids, sketches a credible path from laboratory bench to grocery shelf. The authors are careful to note the limitations: yields for the brown algae need improvement, antioxidant potency trails vitamin C, and the anti-browning mechanism remains unexplained. Future work will expand the evaluation to weight loss, texture, color, and visual quality of treated produce, and will probe the health-food applications of the Sargassum fusiforme and Bangia fuscopurpurea extracts in greater depth. Still, the study marks a first on several fronts, from the mineral content analysis to the food-additive stability data, and it strengthens the case that the ocean’s humble seaweeds, already hailed as biorefineries and super plants of sustainable development, hold molecules capable of keeping our food fresher and perhaps our bodies healthier.

Subject of Research: Optimized extraction and antioxidant application of mycosporine-like amino acids from marine macroalgae

Article Title: Research on the optimization of preparation and the application analysis of antioxidant activity of mycosporine-like amino acids derived from marine macroalgae

Article References: Li, Y., Wang, J., Wang, S., Jiang, X., Shi, S., & Sun, Y. (2025). Research on the optimization of preparation and the application analysis of antioxidant activity of mycosporine-like amino acids derived from marine macroalgae. Blue Biotechnology, 2(1), Article 2. https://doi.org/10.1186/s44315-025-00023-z

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00023-z

Keywords: mycosporine-like amino acids, marine macroalgae, antioxidant activity, seaweed, food preservation, anti-browning, palythine, shinorine, porphyra-334, extraction optimization, food additives, blue biotechnology

The biological rationale begins with reactive oxygen species, or ROS. These molecules, including superoxide anion, hydroxyl radical, and singlet oxygen, are unavoidable byproducts of oxidative metabolism, generated inside cells by electron leakage in mitochondria and outside them by ultraviolet radiation and pollution. At low levels, ROS act as legitimate signaling molecules in many cellular processes. But when their production outpaces the body’s antioxidant defenses, oxidative stress ensues, damaging DNA, proteins, and lipids, and driving cells toward apoptosis. The skin, as the body’s largest organ and its first line of contact with the environment, is particularly exposed. ROS accumulation triggered by ultraviolet light is considered a central event in photoaging, marked by collagen degradation, rupture of elastic fibers, and heightened activity of matrix metalloproteinases, the enzymes that dismantle the skin’s structural scaffolding.

Conventional skincare addresses oxidative stress with synthetic antioxidants and physical treatments, but these often irritate the skin, provoke photosensitivity, and deliver only temporary benefits. Natural antioxidants are generally less likely to cause irritation or allergy, and they align with the fast-growing consumer movement toward so-called clean beauty. What makes microalgae and cyanobacteria especially compelling is their evolutionary history. These are the oldest photosynthetic microorganisms on Earth, and populations living in hot springs, salt lakes, deserts, and high-irradiance intertidal zones have endured intense ultraviolet exposure, desiccation, and oxidative pressure for millions of years. Their response was to build elaborate chemical defenses, synthesizing structurally distinct antioxidants that terrestrial plants rarely produce, while also growing quickly and cultivable at scale on non-arable land.

The standout molecule is astaxanthin, a ketocarotenoid whose long chain of thirteen conjugated double bonds, capped by oxygenated ionone rings, gives it extraordinary capacity to quench singlet oxygen, outperforming other carotenoids as well as vitamins C and E. The green microalga Haematococcus pluvialis is the industrial workhorse, accumulating astaxanthin to five to eight percent of its dry cell weight, with annual production reaching tens of tons. In laboratory studies, concentrations of five to ten micromolar astaxanthin efficiently quenched UVA-induced ROS clusters in human dermal fibroblasts and lowered levels of malondialdehyde, a marker of lipid peroxidation. Mechanistically, astaxanthin also activates the cell’s own defenses: it promotes the release of the transcription factor Nrf2 from its cytoplasmic inhibitor Keap1, allowing Nrf2 to enter the nucleus and switch on genes for antioxidant enzymes such as glutathione S-transferases, glutathione peroxidase, superoxide dismutase, and NQO1.

Fucoxanthin, a polyunsaturated carotenoid with a reactive allenic bond and an epoxy group, delivers broad-spectrum radical scavenging and, in human keratinocytes, boosts glutathione through the same Nrf2 pathway. The diatom Phaeodactylum tricornutum and the haptophyte Tisochrysis lutea, which can reach nearly eighty milligrams of fucoxanthin per gram under optimized culture, are leading production candidates, and microalgae contain roughly ten to one hundred times more of the pigment than macroalgae. Beta-carotene, famously over-accumulated by the halotolerant green alga Dunaliella salina at up to fifteen percent of dry weight, quenches singlet oxygen through energy transfer and, in its 9-cis isomer form found uniquely in algae, exhibits strong antioxidant power. Lutein, currently harvested commercially only from marigold petals, could shift to algal sources that promise two to five times the per-hectare yield with eighty percent less water consumption and growth cycles as short as one to two weeks.

Beyond pigments, the review highlights polysaccharides, phycocyanin, polyphenols, mycosporine-like amino acids, and scytonemin as complementary actives. Sulfated exopolysaccharides from the red microalga Porphyridium cruentum and cyanobacterial EPS from Arthrospira and Nostoc scavenge radicals, chelate iron and copper ions that would otherwise fuel Fenton chemistry, and even form physical barriers against membrane lipid peroxidation. Phycocyanin, the brilliant blue pigment that makes up ten to twenty percent of Spirulina’s dry weight, directly eliminates ROS and reactive nitrogen species while enhancing intracellular antioxidant enzymes. Mycosporine-like amino acids, or MAAs, are especially elegant: these water-soluble molecules under four hundred daltons absorb UV-A and UV-B radiation with superb photostability, dissipating the energy harmlessly as heat rather than generating ROS, and compounds such as palythine and porphyra-334 rival ascorbic acid in radical-scavenging assays. Scytonemin, a lipophilic dimeric pigment produced in the extracellular sheaths of more than three hundred cyanobacterial species, absorbs across the UV-A, UV-B, and UV-C ranges.

What elevates these compounds above simple radical sponges is the breadth of their secondary effects on skin biology. Phycocyanin suppresses cyclooxygenase-2 and downstream prostaglandin E2, easing inflammation; fucoxanthin damps inflammatory cytokines through NF-kappaB signaling. On the anti-aging front, Spirulina polysaccharide complexes restore mitochondrial function in aged fibroblasts and spur collagen regeneration, while porphyra-334 increases procollagen, type I collagen, and elastin expression in UVA-irradiated skin fibroblasts. Several molecules inhibit the matrix metalloproteinases that degrade collagen and elastin: mycosporine-2-glycine from the halotolerant cyanobacterium Aphanothece halophytica matches the collagenase inhibitor aminoguanidine, C-phycocyanin reduces MMP-1 and MMP-9 in UVB-treated keratinocytes, and polysaccharides from Nostochopsis lobatus outperform the natural hyaluronidase inhibitor disodium cromoglycate. Microalgal polyphenols and phenolic acids also inhibit tyrosinase, the rate-limiting enzyme in melanin synthesis, offering safer alternatives to unstable or irritating whitening agents such as hydroquinone and kojic acid.

Commercial traction is already visible. Estee Lauder markets skincare lines featuring Chlorella extract for hydration and oil-water balance, while L’Oreal holds patents on marine polysaccharides for moisturizing and hair care. Astaxanthin appears in brightening serums and eye creams, and clinical trials suggest that oral doses of three to six milligrams per day reduce UV-induced wrinkles and enhance collagen synthesis. In the sunscreen space, Mibelle AG Biotechnology’s Helioguard 365, a porphyra-334 and shinorine complex from the red alga Porphyra umbilicalis, increased skin firmness by ten percent and reduced wrinkle depth by twelve percent over four weeks of application. Spirulina-derived extracts are found in anti-wrinkle and even antifungal formulations, and engineered microalgae-nanodrug delivery systems and live algal hydrogels are being explored for tissue repair, exploiting their capacity to produce oxygen through photosynthesis at wound sites.

Significant obstacles remain before these compounds reach their full potential. Extraction from tough algal cell walls is inefficient and often relies on polluting organic solvents, prompting interest in greener methods such as supercritical water extraction, ultrasound-assisted extraction, and enzyme-assisted processing. Stability is another vulnerability: carotenoids and phycobiliproteins degrade under light, heat, oxygen, and pH shifts, shortening shelf life, while hydrophilic and macromolecular ingredients struggle to cross the stratum corneum. Nanocarriers, including liposomes, nanoemulsions, and solid lipid nanoparticles, are emerging as solutions that shield actives and improve skin penetration, and the authors point to artificial intelligence-designed responsive delivery systems as a future frontier. Perhaps most critically, rigorous clinical evidence on biosafety, irritation, sensitization, and long-term effects remains thin for many novel species. The review calls for large-scale, multicenter, randomized, double-blind, placebo-controlled trials across diverse skin types and age groups, combined with omics-based mechanistic studies, to convert a promising laboratory story into the backbone of next-generation dermatological treatments and functional cosmeceuticals.

Subject of Research: Natural antioxidants from microalgae and cyanobacteria and their applications in skincare

Article Title: Natural antioxidants derived from microalgae and cyanobacteria and their applications in skincare

Article References: Natural antioxidants derived from microalgae and cyanobacteria and their applications in skincare. (n.d.). https://doi.org/10.1186/s44315-025-00050-w

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00050-w

Keywords: microalgae, cyanobacteria, antioxidants, skincare, astaxanthin, phycocyanin, mycosporine-like amino acids, carotenoids, photoaging, Nrf2 pathway, sunscreen, cosmetics