RESUMEN
3,6-Anhydro-l-galactose (l-AHG) is a bioactive sugar that is a major component of agarose. Recently, l-AHG was reported to have anti-melanogenic potential in human epidermal melanocytes (HEMs) and B16F10 melanoma cells; however, its underlying molecular mechanisms remain unknown. At noncytotoxic concentrations, l-AHG has been shown to inhibit alpha-melanocyte-stimulating hormone-induced melanin synthesis in various cell models, including HEMs, melan-a cells, and B16F10 cells. Although l-AHG did not inhibit tyrosinase activity in vitro, reverse transcription-polymerase chain reaction results demonstrated that the anti-melanogenic effect of l-AHG was mediated by transcriptional repression of melanogenesis-related genes, including tyrosinase, tyrosinase-related protein-1 (TRP-1), tyrosinase-related protein-2 (TRP-2), and microphthalmia-associated transcription factor (MITF) in HEMs. Western blot analysis showed that l-AHG effectively attenuated α-melanocyte-stimulating hormone-induced melanogenic proteins by inhibiting cyclic adenosine monophosphate/cyclic adenosine monophosphate-dependent protein kinase, mitogen-activated protein kinase, and Akt signaling pathways in HEMs. Topical application of l-AHG significantly ameliorated melanin production in a 3D pigmented human skin model. Collectively, these results suggest that l-AHG could be utilized as novel cosmetic compounds with skin-whitening efficacy.
Asunto(s)
Galactosa/análogos & derivados , Melaninas/metabolismo , Melanocitos/citología , alfa-MSH/metabolismo , Administración Tópica , Animales , Línea Celular Tumoral , Supervivencia Celular , Células Cultivadas , Galactosa/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Oxidorreductasas Intramoleculares/genética , Melanocitos/efectos de los fármacos , Melanocitos/metabolismo , Glicoproteínas de Membrana/genética , Ratones , Factor de Transcripción Asociado a Microftalmía/genética , Modelos Biológicos , Oxidorreductasas/genéticaRESUMEN
The main carbohydrate of red macroalgae is agarose, a heterogeneous polysaccharide composed of D-galactose and 3,6-anhydro-L-galactose. When saccharifying agarose by enzymes, the unique physical properties of agarose, namely the sol-gel transition and the near-insolubility of agarose in water, limit the accessibility of agarose to the enzymes. Due to the lower accessibility of agarose to enzymes in the gel state than to the sol state, it is important to prevent the sol-gel transition by performing the enzymatic liquefaction of agarose at a temperature higher than the sol-gel transition temperature of agarose. In this study, a thermostable endo-type ß-agarase, Aga16B, originating from Saccharophagus degradans 2-40T, was characterized and introduced in the liquefaction process. Aga16B was thermostable up to 50 °C and depolymerized agarose mainly into neoagarooligosaccharides with degrees of polymerization 4 and 6. Aga16B was applied to enzymatic liquefaction of agarose at 45 °C, which was above the sol-gel transition temperature of 1 % (w/v) agarose (â¼35 °C) when cooling agarose. This is the first systematic demonstration of enzymatic liquefaction of agarose, enabled by determining the sol-gel temperature of agarose under specific conditions and by characterizing the thermostability of an endo-type ß-agarase.
Asunto(s)
Glicósido Hidrolasas/metabolismo , Sefarosa/química , Sefarosa/metabolismo , Clonación Molecular , Estabilidad de Enzimas , Gammaproteobacteria/enzimología , Glicósido Hidrolasas/genética , Glicósido Hidrolasas/aislamiento & purificación , Cinética , Transición de Fase , Proteínas Recombinantes/metabolismo , Algas Marinas/química , Temperatura de TransiciónRESUMEN
The significance for anticariogenic sugar substitutes is growing due to increasing demands for dietary sugars and rising concerns of dental caries. Xylitol is widely used as an anticariogenic sugar substitute, but the inhibitory effects of xylitol on Streptococcus mutans, the main cause of tooth decay, are exhibited only at high concentrations. Here, the inhibitory effects of 3,6-anhydro-l-galactose (AHG), a rare sugar from red macroalgae, were evaluated on S. mutans, in comparison with those of xylitol. In the presence of 5g/l of AHG, the growth of S. mutans was retarded. At 10g/l of AHG, the growth and acid production by S. mutans were completely inhibited. However, in the presence of xylitol, at a much higher concentration (i.e., 40g/l), the growth of S. mutans still occurred. These results suggest that AHG can be used as a new anticariogenic sugar substitute for preventing dental caries.
Asunto(s)
Agar/química , Caries Dental/prevención & control , Galactosa/análogos & derivados , Streptococcus mutans/efectos de los fármacos , Edulcorantes/farmacología , Galactosa/análisis , Galactosa/farmacología , Humanos , Edulcorantes/análisis , Xilitol/farmacologíaRESUMEN
Red macroalgae are currently considered as renewable resources owing to their high carbohydrate and low lignin and hemicellulose contents. However, utilization of red macroalgae has been limited owing to the lack of established methods for pretreatment and an effective saccharification system. Furthermore, marine red macroalgae consist of the non-favorable mixed sugars for industrial microorganisms. In this review, we suggest strategies for converting red macroalgae to bio-based products, focusing on the pretreatment and saccharification of red macroalgae to produce fermentable sugars and the microbial fermentation of these sugars by industrial microorganisms. In particular, some recent breakthroughs for the efficient utilization of red macroalgae include the discovery of key enzymes for the complete monomerization of red macroalgal carbohydrate and the catabolic pathway of 3,6-anhydro-l-galactose, the most abundant sugar in red macroalgae. This review provides a comprehensive perspective for the efficient utilization of red macroalgae as sustainable resources to produce bio-based products.