Fake tan products work through a chemical reaction involving dihydroxyacetone (DHA), a small sugar molecule that penetrates the outer layer of skin. Unlike bronzers that sit on the skin's surface, DHA reacts with amino acids in the stratum corneum to form brown pigments that remain trapped within the skin. This process mirrors the Maillard reaction that occurs when cooking, which is responsible for browning in foods like toast and seared meat. The characteristic 'biscuity' smell comes from volatile compounds produced during this reaction, similar to the aromas released when browning food. Factors such as skin thickness, temperature, and sweat can affect how evenly the tan develops, leading to patchy results on areas like elbows, knuckles, and ankles. Formulators often add green pigments to neutralise orange tones, while some products include erythrulose for a more natural reddish hue. The development time for DHA-based tans varies, with 'one-hour' products relying on higher concentrations or penetration enhancers to speed up the reaction. However, faster formulas may produce stronger odours or uneven results. Proper preparation, including exfoliation before application and using barrier creams on sensitive areas, can help achieve a more even tan. The article explains that fake tan does not involve UV exposure, making it a safer alternative to sunbathing or tanning beds, which increase skin cancer risk. It also clarifies that the tan fades as dead skin cells naturally shed, rather than being washed off like makeup. The chemistry behind fake tan is a fascinating example of how everyday science applies to personal care products, blending food chemistry with skincare innovation.

by Dan Drecktrah, Laura S. Hall, Britney Cheff, Crystal Richards, Sandra J. Raffel, Michael Wulf, Ian T. Bailey, Frank Gherardini, D. Scott Samuels The carbonyl stress pathway in bacteria is mediated by the enigmatic metabolite methylglyoxal and is thought to be activated in response to cellular carbohydrate and phosphate imbalance. Methylglyoxal, produced from dihydroxyacetone phosphate by methylglyoxal synthase, covalently modifies nucleophilic groups of amino acid residues, such as lysine, arginine and cysteine, to yield advanced glycation end products. In this work, we have identified several environmental signals, including glycerol and peptides, which activate carbonyl stress in the Lyme disease spirochete Borrelia (Borreliella) burgdorferi. We establish that methylglyoxal production and protein glycation is dependent on the mgsA gene (bb0364) product and show that this pathway is active in Lyme disease spirochetes, but not relapsing fever Borrelia or in B. mayonii. Furthermore, we have investigated the role of carbonyl stress in the tick-mouse model of Lyme disease and provide evidence that production of methylglyoxal and glycation of proteins is not necessarily lethal, as previously believed, at least in Lyme disease spirochetes. Finally, we show that expression of the B. burgdorferi mgsA and carbonyl stress pathway in the relapsing fever spirochete B. hermsii significantly reduces the peak level of spirochetemia during the relapse phase of murine infection. Together, our results identify a new post-translation modification system in Lyme disease spirochetes that appears to be important in governing the lifestyle of this pathogen and seems to be selected against in spirochetes that reach high numbers in the blood.

by Dan Drecktrah, Laura S. Hall, Britney Cheff, Crystal Richards, Sandra J. Raffel, Michael Wulf, Ian T. Bailey, Frank Gherardini, D. Scott Samuels The carbonyl stress pathway in bacteria is mediated by the enigmatic metabolite methylglyoxal and is thought to be activated in response to cellular carbohydrate and phosphate imbalance. Methylglyoxal, produced from dihydroxyacetone phosphate by methylglyoxal synthase, covalently modifies nucleophilic groups of amino acid residues, such as lysine, arginine and cysteine, to yield advanced glycation end products. In this work, we have identified several environmental signals, including glycerol and peptides, which activate carbonyl stress in the Lyme disease spirochete Borrelia (Borreliella) burgdorferi. We establish that methylglyoxal production and protein glycation is dependent on the mgsA gene (bb0364) product and show that this pathway is active in Lyme disease spirochetes, but not relapsing fever Borrelia or in B. mayonii. Furthermore, we have investigated the role of carbonyl stress in the tick-mouse model of Lyme disease and provide evidence that production of methylglyoxal and glycation of proteins is not necessarily lethal, as previously believed, at least in Lyme disease spirochetes. Finally, we show that expression of the B. burgdorferi mgsA and carbonyl stress pathway in the relapsing fever spirochete B. hermsii significantly reduces the peak level of spirochetemia during the relapse phase of murine infection. Together, our results identify a new post-translation modification system in Lyme disease spirochetes that appears to be important in governing the lifestyle of this pathogen and seems to be selected against in spirochetes that reach high numbers in the blood.

Continuous-flow biocatalysis can decouple enzymatic productivity from the cellular growth constraints inherent to fermentation, but exploiting this advantage requires a reactor design framework that l...

Many of us love a summer glow on our skin. But we also know sun tanning and tanning beds are bad for our health. Are spray tans a good alternative? A dermatologist weighs in on the comparative pros an...

Links for the day

Links for the day

DHA & UV Essentials https://x.com/nikshahxai/status/1885837401739739216 https://nikhil.blog/2025/01/21/mastering-dihydroxyacetone-dha-uva-uvb-radiation-harnessing-ai-to-stimulate-the-production-of-m...