Kojyl cinnamate esters are peroxisome proliferator-activated receptor α/γ dual agonists

New Insights into the Role of PPARγ in Skin Physiopathology

Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor expressed in many tissues, including skin, where it is essential for maintaining skin barrier permeability, regulating cell proliferation/differentiation, and modulating antioxidant and inflammatory responses upon ligand binding. Therefore, PPARγ activation has important implications for skin homeostasis. Over the past 20 years, with increasing interest in the role of PPARs in skin physiopathology, considerable effort has been devoted to the development of PPARγ ligands as a therapeutic option for skin inflammatory disorders. In addition, PPARγ also regulates sebocyte differentiation and lipid production, making it a potential target for inflammatory sebaceous disorders such as acne. A large number of studies suggest that PPARγ also acts as a skin tumor suppressor in both melanoma and non-melanoma skin cancers, but its role in tumorigenesis remains controversial. In this review, we have summarized the current state of research into the role of PPARγ in skin health and disease and how this may provide a starting point for the development of more potent and selective PPARγ ligands with a low toxicity profile, thereby reducing unwanted side effects.

Quantitative Analysis and Molecular Docking Simulation of Flavonols from Eruca sativa Mill. and Their Effect on Skin Barrier Function

Eruca sativa is a commonly used edible plant in Italian cuisine. E. sativa 70% ethanol extract (ES) was fractionated with five organic solvents, including n-hexane (EHex), chloroform (ECHCl3), ethyl acetate (EEA), n-butyl alcohol (EBuOH), and water (EDW). Ethyl acetate fraction (EEA) had the highest antioxidant activity, which was correlated with the total polyphenol and flavonoid content. ES and EEA acted as PPAR-α ligands by PPAR-α competitive binding assay. EEA significantly increased cornified envelope formation as a keratinocyte terminal differentiation marker in HaCaT cells. Further, it significantly reduced nitric oxide and pro-inflammatory cytokines (IL-6 and TNF-α) in lipopolysaccharide-stimulated RAW 264.7 cells. The main flavonol forms detected in high amounts from EEA are mono-and di-glycoside of each aglycone. The main flavonol form of EEA is the mono-glycoside of each aglycone detected, and the most abundant flavonol mono-glycoside is kaempferol 3-glucoside 7.4%, followed by quercetin-3-glucoside 2.3% and isorhamnetin 3-glucoside 1.4%. Flavonol mono-glycosides were shown to be a potent PPAR-α ligand using molecular docking simulation and showed the inhibition of nitric oxide. These results suggest that the flavonol composition of E. sativa is suitable for use in improving skin barrier function and inflammation in skin disorders, such as atopic dermatitis.

Research Progress in Skin Aging, Metabolism, and Related Products

In recent years, skin aging has received increasing attention. Many factors affect skin aging, and research has shown that metabolism plays a vital role in skin aging, but there needs to be a more systematic review. This article reviews the interaction between skin metabolism and aging from the perspectives of glucose, protein, and lipid metabolism and explores relevant strategies for skin metabolism regulation. We found that skin aging affects the metabolism of three major substances, which are glucose, protein, and lipids, and the metabolism of the three major substances in the skin also affects the process of skin aging. Some drugs or compounds can regulate the metabolic disorders mentioned above to exert anti-aging effects. Currently, there are a variety of products, but most of them focus on improving skin collagen levels. Skin aging is closely related to metabolism, and they interact with each other. Regulating specific metabolic disorders in the skin is an important anti-aging strategy. Research and development have focused on improving collagen levels, while the regulation of other skin glycosylation and lipid disorders including key membrane or cytoskeleton proteins is relatively rare. Further research and development are expected.

Discovery of Pan-peroxisome Proliferator-Activated Receptor Modulators from an Endolichenic Fungus, Daldinia childiae

Adiponectin-synthesis-promoting compounds possess therapeutic potential to treat diverse metabolic diseases, including obesity and diabetes. Phenotypic screening to find adiponectin-synthesis-promoting compounds was performed using the adipogenesis model of human bone marrow mesenchymal stem cells. The extract of the endolichenic fungus Daldinia childiae 047215 significantly promoted adiponectin production. Bioactivity-guided isolation led to 13 active polyketides (1-13), which include naphthol monomers, dimers, and trimers. To the best of our knowledge, trimers of naphthol (1-4) have not been previously isolated as either natural or synthetic products. The novel naphthol trimer 3,1',3',3″-ternaphthalene-5,5',5″-trimethoxy-4,4',4″-triol (2) and a dimer, nodulisporin A (12), exhibited concentration-dependent adiponectin-synthesis-promoting activity (EC₅₀ 30.8 and 15.2 μM, respectively). Compounds 2 and 12 bound to all three peroxisome proliferator-activated receptor (PPAR) subtypes, PPARα, PPARγ, and PPARδ. In addition, compound 2 transactivated retinoid X receptor α, whereas 12 did not. Naphthol oligomers 2 and 12 represent novel pan-PPAR modulators and are potential pharmacophores for designing new therapeutic agents against hypoadiponectinemia-associated metabolic diseases.

Application of kojic acid scaffold in the design of non-tyrosinase enzyme inhibitors

Kojic acid (KA) is a hydroxypyranone natural metabolite mainly known as tyrosinase inhibitor. Currently, this compound is used as a whitening agent in cosmetics and as an anti-browning agent in food industry. Given the easy-manipulation in different positions of the KA molecule, many investigations have been carried out to find new tyrosinase inhibitors derived from KA. Beside anti-tyrosinase activity, many KA-based compounds have been designed for targeting other enzymes including human neutrophil elastase, catechol-O-methyltransferase, matrix metalloproteinases, monoamine oxidase, human lactate dehydrogenase, endonucleases, D-amino acid oxidase, and receptors such as histamine H₃ and apelin (APJ) receptors. This review could help biochemists and medicinal chemists in designing diverse KA-derived enzyme inhibitors.

Perspectives on scaling production of adipose tissue for food applications

With rising global demand for food proteins and significant environmental impact associated with conventional animal agriculture, it is important to develop sustainable alternatives to supplement existing meat production. Since fat is an important contributor to meat flavor, recapitulating this component in meat alternatives such as plant based and cell cultured meats is important. Here, we discuss the topic of cell cultured or tissue engineered fat, growing adipocytes in vitro that could imbue meat alternatives with the complex flavor and aromas of animal meat. We outline potential paths for the large scale production of in vitro cultured fat, including adipogenic precursors during cell proliferation, methods to adipogenically differentiate cells at scale, as well as strategies for converting differentiated adipocytes into 3D cultured fat tissues. We showcase the maturation of knowledge and technology behind cell sourcing and scaled proliferation, while also highlighting that adipogenic differentiation and 3D adipose tissue formation at scale need further research. We also provide some potential solutions for achieving adipose cell differentiation and tissue formation at scale based on contemporary research and the state of the field.

Diallyl Biphenyl-Type Neolignans Have a Pharmacophore of PPARα/γ Dual Modulators

Adiponectin secretion-promoting compounds have therapeutic potentials in human metabolic diseases. Diallyl biphenyl-type neolignan compounds, magnolol, honokiol, and 4-O-methylhonokiol, from a Magnolia officinalis extract were screened as adiponectin-secretion promoting compounds in the adipogenic differentiation model of human bone marrow mesenchymal stem cells (hBM-MSCs). In a target identification study, magnolol, honokiol, and 4-O-methylhonokiol were elucidated as PPARα and PPARγ dual modulators. Diallyl biphenyl-type neolignans affected the transcription of lipid metabolism-associated genes in a different way compared to those of specific PPAR ligands. The diallyl biphenyl-type neolignan structure provides a novel pharmacophore of PPARα/γ dual modulators, which may have unique therapeutic potentials in diverse metabolic diseases.

Synthetic Retinoid Seletinoid G Improves Skin Barrier Function through Wound Healing and Collagen Realignment in Human Skin Equivalents

The outer epidermal skin is a primary barrier that protects the body from extrinsic factors, such as ultraviolet (UV) radiation, chemicals and pollutants. The complete epithelialization of a wound by keratinocytes is essential for restoring the barrier function of the skin. However, age-related alterations predispose the elderly to impaired wound healing. Therefore, wound-healing efficacy could be also considered as a potent function of an anti-aging reagent. Here, we examine the epidermal wound-healing efficacy of the fourth-generation retinoid, seletinoid G, using HaCaT keratinocytes and skin tissues. We found that seletinoid G promoted the proliferation and migration of keratinocytes in scratch assays and time-lapse imaging. It also increased the gene expression levels of several keratinocyte proliferation-regulating factors. In human skin equivalents, seletinoid G accelerated epidermal wound closure, as assessed using optical coherence tomography (OCT) imaging. Moreover, second harmonic generation (SHG) imaging revealed that seletinoid G recovered the reduced dermal collagen deposition seen in ultraviolet B (UVB)-irradiated human skin equivalents. Taken together, these results indicate that seletinoid G protects the skin barrier by accelerating wound healing in the epidermis and by repairing collagen deficiency in the dermis. Thus, seletinoid G could be a potent anti-aging agent for protecting the skin barrier.

Theaflavin-Enriched Fraction Stimulates Adipogenesis in Human Subcutaneous Fat Cells

Skin provides the first defense line against the environment while preserving physiological homeostasis. Subcutaneous tissues including fat depots that are important for maintaining skin structure and alleviating senescence are altered during aging. This study investigated whether theaflavin (TF) in green tea (GT) has skin rejuvenation effects. Specifically, we examined whether high ratio of TF contents can induce the subcutaneous adipogenesis supporting skin structure by modulating lipid metabolism. The co-fermented GT (CoF-GT) fraction containing a high level of TF was obtained by co-fermentation with garland chrysanthemum (Chrysanthemum coronarium) and the conventionally fermented GT (F-GT) fraction was also obtained. The effects of the CoF- or F-GT fractions on adipogenesis were assessed using primary human subcutaneous fat cells (hSCF). Adipogenesis was evaluated based on lipid droplet (LD) formation, as visualized by Oil Red O staining; by analyzing of adipogenesis-related factors by real-time quantitative polyperase chain reaction (RT-qPCR); and by measuring the concentration of adiponectin released into the culture medium by enzyme-linked immunosorbent assay. TF-enriched CoF-GT fraction did not adversely affect hSCF cell viability but induced their adipogenic differentiation, as evidenced by LD formation, upregulation of adipogenesis-related genes, and adiponectin secretion. TF and TF-enriched CoF-GT fraction promoted differentiation of hSCFs and can therefore be used as an ingredient in rejuvenating agents.