Nam Joo Kang

The human microbiome plays a fundamental role in health and disease through dynamic interactions with the host. Accumulating evidence demonstrates that these interactions are essential for the deve...

Background/Objectives: Dioscorea batatas Decne (yam), which contains various bioactive compounds, has been utilized in the cosmetics industry, while most of the peel of D. batatas (DBP) is discarded without further use. Recent studies have shown that DBP contains higher levels of bioactive substances than the rhizome flesh. The aim of this study was to evaluate the skin biological activities of DBP extracts obtained using 70% ethanol (70% EtOH DBP), 95% ethanol (95% EtOH DBP), and ethyl acetate (EA DBP), with particular attention to their antioxidant-associated protective effects. Methods: Skin-related bioactivities of DBP extracts prepared using ultrasonic extraction were evaluated using in vitro tyrosinase and matrix metalloproteinase-1 (MMP-1) assays, alpha-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis in B16F10 cells, ultraviolet B (UVB)-irradiated HaCaT viability assays, and Western blot analysis of pro-collagen type I alpha 1(Pro-COL1A1) and MMP-1 in HDF cells. In addition, the ABTS and DPPH radical scavenging activities of DBP extracts and representative DBP derivatives were assessed. Results: DBP extracts inhibited tyrosinase activity in vitro and reduced melanogenesis in B16F10 cells. DBP extracts also protected skin cells from UVB by increasing the viability of UVB-irradiated HaCaT cells. In UVB-irradiated HDF cells, DBP extracts restored Pro-COL1A1 expression and suppressed MMP-1 levels. Additionally, DBP extracts inhibited MMP-1 activity in a concentration-dependent manner. The DBP extracts themselves exhibited ABTS and DPPH radical scavenging activities, with EA DBP showing the highest vitamin C equivalent antioxidant capacity among the tested extracts. Representative DBP-derived phenanthrene compounds also showed radical scavenging activities, supporting the antioxidant potential of peel-derived phytochemicals. Conclusions: These findings indicate that DBP extracts possess skin-whitening and anti-photoaging effects and suggest that these protective activities may be associated with the antioxidant potential of both DBP extracts and DBP derivatives.

Direct epithelial-microbial interactions occur across a steep aerobic-anaerobic interface in the intestine, yet mechanistic analysis has been limited by the difficulty of sustaining oxygen-dependent epithelial cells together with strictly anaerobic microbes in vitro . Here, we establish a dual oxygen-partitioned co-culture system that reproducibly maintains aerobic intestinal epithelial cells and obligate anaerobic gut bacteria, enabling controlled analysis of epithelial responses under physiologically relevant oxygen architecture. Using Mediterraneibacter gnavus and Lacticaseibacillus casei as contrasting microbial partners, we identify distinct epithelial programs. M. gnavus induces epithelial stress characterized by tight-junction disruption, suppression of mitochondrial respiration, and activation of chromatin-associated and innate immune regulatory pathways, whereas L. casei preserves barrier integrity and supports mitochondrial capacity with restrained immune modulation. Integrated transcriptomic and proteomic analyses reveal a shared epithelial energy-conserving response to microbial proximity, upon which microbe-specific stress or homeostatic programs are imposed. In vivo analysis using a dextran sodium sulfate-induced colitis model demonstrates that these epithelial programs become physiologically relevant under inflammatory conditions, with L. casei promoting epithelial repair and immune rebalancing. Together, these findings define oxygen-partitioned epithelial-microbial interactions as a determinant of microbe-specific epithelial states.

Agarobiose (AB; d-galactose-β-1,4-AHG), produced by one-step acid hydrolysis of agarose of red seaweed, is considered a promising cosmetic ingredient due to its skin-moisturizing activity. In this study, the use of AB as a cosmetic ingredient was found to be hampered due to its instability at high temperature and alkaline pH. Therefore, to increase the chemical stability of AB, we devised a novel process to synthesize ethyl-agarobioside (ethyl-AB) from the acid-catalyzed alcoholysis of agarose. This process mimics the generation of ethyl α-glucoside and glyceryl α-glucoside by alcoholysis in the presence of ethanol and glycerol during the traditional Japanese sake-brewing process. Ethyl-AB also showed in vitro skin-moisturizing activity similar to that of AB, but showed higher thermal and pH stability than AB. This is the first report of ethyl-AB, a novel compound produced from red seaweed, as a functional cosmetic ingredient with high chemical stability.

Eun Ji Baek, Yu-Bin Ha, Ji Hye Kim, Ki Won Lee, Soon Sung Lim, and Nam Joo Kang. J. Microbiol. Biotechnol. 2022;32:982-8. https://doi.org/10.4014/jmb.2207.07043

Inflammatory bowel disease (IBD) is an idiopathic inflammatory disease. Environmental sanitization, modern lifestyles, advanced medicines, ethnic origins, host genetics and immune systems, mucosal barrier function, and the gut microbiota have been delineated to explain how they cause mucosal inflammation. However, the pathogenesis of IBD and its therapeutic targets remain elusive. Recent studies have highlighted the importance of the human gut microbiota in health and disease, suggesting that the pathogenesis of IBD is highly associated with imbalances of the gut microbiota or alterations of epithelial barrier function in the gastrointestinal (GI) tract. Moreover, diet-induced alterations of the gut microbiota in the GI tract modulate immune responses and perturb metabolic homeostasis. This review summarizes recent findings on IBD and its association with diet-induced changes in the gut microbiota; furthermore, it discusses how diets can modulate host gut microbes and immune systems, potentiating the impact of personalized diets on therapeutic targets for IBD.

The gut microbiome influences the development of allergic diseases during early childhood. However, there is a lack of comprehensive understanding of microbiome-host crosstalk. Here, we analyzed the influence of gut microbiome dynamics in early childhood on atopic dermatitis (AD) and the potential interactions between host and microbiome that control this homeostasis. We analyzed the gut microbiome in 346 fecal samples (6–36 months; 112 non-AD, 110 mild AD, and 124 moderate to severe AD) from the Longitudinal Cohort for Childhood Origin of Asthma and Allergic Disease birth cohort. The microbiome-host interactions were analyzed in animal and in vitro cell assays. Although the gut microbiome maturated with age in both AD and non-AD groups, its development was disordered in the AD group. Disordered colonization of short-chain fatty acids (SCFA) producers along with age led to abnormal SCFA production and increased IgE levels. A butyrate deficiency and downregulation of GPR109A and PPAR-γ genes were detected in AD-induced mice. Insufficient butyrate decreases the oxygen consumption rate of host cells, which can release oxygen to the gut and perturb the gut microbiome. The disordered gut microbiome development could aggravate balanced microbiome-host interactions, including immune responses during early childhood with AD.

Resveratrol (RES) and oxyresveratrol (OXYRES) are considered and utilized as active ingredients of anti-aging skin cosmetics. However, these compounds are susceptible to oxidative discoloration and unpleasant odor in solutions, limiting their use in cosmetics. Accordingly, RES and OXYRES were chemically modified to acetylated derivatives with enhanced stability, and their anti-aging effect on the skin and detailed molecular mechanism of their acetylated derivatives were investigated. Acetylated RES and OXYRES lost their acetyl group and exerted an inhibitory effect on H₂O₂-induced ROS levels in human dermal fibroblast (HDF) cells. In addition, RES, OXYRES, and their acetylated derivatives suppressed UVB-induced matrix metalloproteinase (MMP)-1 expression via inhibition of mitogen-activated protein kinases (MAPKs) and Akt/mTOR signaling pathways. Furthermore, RES, OXYRES, and their acetylated derivatives suppressed type I collagen in TPA-treated HDF cells. Collectively, these results suggest the beneficial effects and underlying molecular mechanisms of RES, OXYRES, and their acetylated derivatives for anti- skin aging applications.

Numerous health benefits of diets containing red seaweeds or agar-derived sugar mixtures produced by enzymatic or acid hydrolysis of agar have been reported. However, among various agar-derived sugars, the key components that confer health-beneficial effects, such as prebiotic and anti-colon cancer activities, remain unclear. Here, we prepared various agar-derived sugars by multiple enzymatic reactions using an endo-type and an exo-type of β-agarase and a neoagarobiose hydrolase and tested their in vitro prebiotic and anti-colon cancer activities. Among various agar-derived sugars, agarotriose exhibited prebiotic activity that was verified based on the fermentability of agarotriose by probiotic bifidobacteria. Furthermore, we demonstrated the anti-colon cancer activity of 3,6-anhydro-l-galactose, which significantly inhibited the proliferation of human colon cancer cells and induced their apoptosis. Our results provide crucial information regarding the key compounds derived from red seaweeds that confer beneficial health effects, including prebiotic and anti-colon cancer activities, to the host.

7,3′,4′-Trihydroxyisoflavone (7,3′,4′-THIF) is a metabolite of daidzein which is a representative isoflavone found in soybean. Recent studies suggested that 7,3′,4′-THIF exerts a hypopigmentary effect in B16F10 cells, however, its underlying molecular mechanisms and specific target protein remain unknown. Here, we found that 7,3′,4′-THIF, but not daidzein, inhibited α-melanocyte-stimulating hormone (MSH)-induced intracellular and extracellular melanin production in B16F10 cells by directly targeting melanocortin 1 receptor (MC1R). Western blot data showed that 7,3′,4′-THIF inhibited α-MSH-induced tyrosinase, tyrosinase-related protein-1 (TYRP-1), and tyrosinase-related protein-2 (TYRP-2) expressions through the inhibition of Microphthalmia-associated transcription factor (MITF) expression and cAMP response element-binding (CREB) phosphorylation. 7,3′,4′-THIF also inhibited α-MSH-induced dephosphorylation of AKT and phosphorylation of p38 and cAMP-dependent protein kinase (PKA). cAMP and Pull-down assays indicated that 7,3′,4′-THIF strongly inhibited forskolin-induced intracellular cAMP production and bound MC1R directly by competing with α-MSH. Moreover, 7,3′,4′-THIF inhibited α-MSH-induced intracellular melanin production in human epidermal melanocytes (HEMs). Collectively, these results demonstrate that 7,3′,4′-THIF targets MC1R, resulting in the suppression of melanin production, suggesting a protective role for 7,3′,4′-THIF against melanogenesis.