Royal Jelly Protects against Epidermal Stress through Upregulation of the NQO1 Expression

Royal jelly (RJ) is secreted by honeybees and has been used as an apitherapy to obtain healthy skin since ancient times. However, the mechanism of the protective effects of RJ against skin aging and skin diseases caused by skin stress and its components have not been clarified. In this study, we attempted to understand the effect of RJ on epidermal function and observed that NAD(P)H quinone dehydrogenase 1 (NQO1) is significantly induced by RJ in keratinocytes. The expression of NQO1 was also increased in the 3D epidermal skin model. NQO1 is involved in antioxidation and detoxification metabolism, and we found that RJ protects against the epidermal stress caused by UVB and menadione through the upregulation of NQO1. We identified 10-hydroxy-2-decenoic acid (10H2DA), a major fatty acid in RJ, as an active compound in this reaction as it induced the expression of NQO1 and protected the skin against oxidative stress. We demonstrated that the protective effect of RJ against epidermal stress is mediated through the upregulation of NQO1 by 10H2DA.

Anti-Tumor Effects of Queen Bee Acid (10-Hydroxy-2-Decenoic Acid) Alone and in Combination with Cyclophosphamide and Its Cellular Mechanisms against Ehrlich Solid Tumor in Mice

Queen bee acid or 10-hydroxy-2-decenoic acid (10-HDA) is one of the main and unique lipid components (fatty acids) in royal jelly. Previous studies have demonstrated that 10-HDA has various pharmacological and biological activities. The present study aims to evaluate the anti-tumor effects of 10-HDA alone and combined with cyclophosphamide (CP), as an alkylating agent which widely used for the treatment of neoplastic cancers, against the Ehrlich solid tumors (EST) in mice. Methods: A total of 72 female Swiss albino mice were divided into eight groups. EST mice were treated with 10-HDA (2.5 and 5 mg/kg) alone and combined with CP (25 mg/kg) orally once a day for 2 weeks. Tumor growth inhibition, body weight, the serum level of alpha-fetoprotein (AFP) and carcinoembryonic antigen tumor (CAE), liver and kidney enzymes, tumor lipid peroxidation (LPO) and nitric oxide (NO), antioxidant enzymes (e.g. glutathione reductase (GR), glutathione peroxidase (GPx), catalase enzyme (CAT)), tumor necrosis factor alpha level (TNF-α), and the apoptosis-regulatory genes expression were assessed in tested mice. Results: the findings exhibited that treatment of EST-suffering mice with 10-HDA at the doses of 2.5 and 5 mg/kg especially in combination with CP significantly (p < 0.001) decreased the tumor volume and inhibition rate, tumor markers (AFP and CEA), serum level of liver and kidney, LPO and NO, TNF-α level, as well as the expression level of Bcl-2 in comparison with the mice in the C2 group; while 10-HDA at the doses of 2.5 and 5 mg/kg especially in combination with CP significantly (p < 0.001) improved the level of antioxidant enzymes of GPx, CAT, and SOD and the expression level of caspase-3 and Bax genes. Conclusions: According to the results of the present investigations, 10-HDA at the doses of 2.5 and 5 mg/kg especially in combination with CP showed promising antitumor effects against EST in mice and can be recommended as a new or alternative anticancer agent against tumor; nevertheless, further investigations, particularly in clinical setting, are required to confirm these results.

Antiproliferative and Cytotoxic Efficacy of 10-Hydroxy-2-Decenoic Acid, Compared to Doxorubicin, on MCF-7 Breast Cancer Cells

Exploration of effective chemotherapy is needed for cancer treatment. 10-hydroxy-2-decenoic acid (10-H2DA), a unique fatty acid from royal jelly (RJ), is reported to have antitumor activities. However, its mechanisms remain under-examined. This study investigated the antiproliferative and cytotoxic efficacy of 10-H2DA treatments and their underlying mechanisms, compared to doxorubicin (DXR), on MCF-7 breast cancer cells. The antiproliferative effect was determined using the MTS tetrazolium assay. Cytotoxic activity was performed using a modified MTS assay. Cell cycle progression and cell apoptosis were analyzed by flow cytometry. Pivotal protein expressions were detected by Western blot. Results revealed that 125 µg/mL 10-H2DA treatment significantly inhibited cancer cell growth by 65 %, better than 0.54 µg/mL DXR treatment (48 %), compared to the medium control (p<0.05). The 50 % lethal concentration (LC50) values of 10-H2DA were 190 µg/mL, representing cytotoxic activity. The underlying antiproliferative and cytotoxic mechanisms of 125 µg/mL 10-H2DA treatment demonstrated that it extensively suppressed c-MYC/BAX and slightly activated p53/BAX, leading to G0/G1 cell cycle arrest (decreased cyclin D1 and CDK4) and cell apoptosis (decreased BCL2/BAX). It slightly limited lifespan extension (decreased hTERT/BAX). Nevertheless, it strongly activated HO-1/BAX and NRF2/BAX, possibly inducing chemoresistance and cell invasion later on. Our findings suggested that 10-H2DA treatments induced antiproliferative effects on MCF-7 breast cancer cells via suppression of c-MYC, CDK4, and cyclin D1, leading to cell cycle arrest and cell apoptosis. However, long-term treatment may increase chemoresistance and cell invasion due to induction of antioxidative power, NRF2/BAX, and HO-1/BAX. Therefore, aggressive treatment for a short period would be recommended for using 10-H2DA as a chemotherapeutic compound to prevent chemoresistance and cell invasion. Further long-term in vitro and in vivo studies are necessary to confirm its strength and weakness. HIGHLIGHTS 10-hydroxy-2-decenoic acid (10-H2DA), a marker royal jelly acid, effectively inhibited MCF-7 breast cancer cells proliferation and induced cytotoxicity The inhibitory mechanisms involved the high suppression of c-MYC, cyclin D1, and CDK4, which induced cell cycle arrest and cell apoptosis 10-H2DA treatment at proper dose induced high antioxidative potency via activation of NRF2/BAX and HO-1/BAX Limitation of 10-H2DA treatment is that it might induce chemoresistance GRAPHICAL ABSTRACT

Synthesis and Characterization of 2-Decenoic Acid Modified Chitosan for Infection Prevention and Tissue Engineering

Chitosan nanofiber membranes are recognized as functional antimicrobial materials, as they can effectively provide a barrier that guides tissue growth and supports healing. Methods to stabilize nanofibers in aqueous solutions include acylation with fatty acids. Modification with fatty acids that also have antimicrobial and biofilm-resistant properties may be particularly beneficial in tissue regeneration applications. This study investigated the ability to customize the fatty acid attachment by acyl chlorides to include antimicrobial 2-decenoic acid. Synthesis of 2decenoyl chloride was followed by acylation of electrospun chitosan membranes in pyridine. Physicochemical properties were characterized through scanning electron microscopy, FTIR, contact angle, and thermogravimetric analysis. The ability of membranes to resist biofilm formation by S. aureus and P. aeruginosa was evaluated by direct inoculation. Cytocompatibility was evaluated by adding membranes to cultures of NIH3T3 fibroblast cells. Acylation with chlorides stabilized nanofibers in aqueous media without significant swelling of fibers and increased hydrophobicity of the membranes. Acyl-modified membranes reduced both S. aureus and P. aeruginosa bacterial biofilm formation on membrane while also supporting fibroblast growth. Acylated chitosan membranes may be useful as wound dressings, guided regeneration scaffolds, local drug delivery, or filtration.

Does the Presence and Absence of Queen Bee in the Production of Royal Jelly Affect the Amount of Soluble Protein and Ratio of 10-Hydroxy-2-Decenoic Acid?

Royal jelly (RJ), is one of the important honey bee products and a functional food item in the regulation of diets and in the cosmetic industry. RJ has a potential towards various human disease treatments. The chemical content of RJ is influenced by some factors. In this study, the effect of the presence or absence of the queen on the amount of 10-hydroxy-2-decenoic acid (10-HDA) and soluble protein in RJ is determined. For this reason, colonies were prepared as queenless, queenright and starter-finisher. RJ yields in colonies queenless, queenright and starter-finisher were determined as 15.2 ± 0.89 g, 12.0 ± 0.90 g and 9.6 ± 0.72 g, respectively. Group queenless was different from the other two groups. While 10-HDA values of the groups were similar (queenless, queenright and starter-finisher, respectively; 2.0 ± 0.06%, 2.1 ± 0.06% and 2.0 ± 0.05%), the soluble protein amounts of the groups (queenless, queenright and starter-finisher, respectively, 9.65 ± 0.179%, 7.68 ± 0.184%, 7.50 ± 0.203%) were found different and significant from each other. As a result, the RJ production colony queenless or queenright affected the amount of soluble protein. The worker bees of queenless colonies secreted RJ containing more soluble protein.

The Effects of Royal Jelly Acid, 10-Hydroxy-Trans-2-Decenoic Acid, on Neuroinflammation and Oxidative Stress in Astrocytes Stimulated with Lipopolysaccharide and Hydrogen Peroxide

The increased prevalence of neurodegenerative diseases, especially during the COVID-19 outbreak, necessitates the search for natural immune- and cognitive-enhancing agents. 10-Hydroxy-trans-2-decenoic acid (10-H2DA), the main fatty acid of royal jelly, has several pharmacological activities. Given the fundamental role of astrocytes in regulating immune responses of the central nervous system, we used cortical astrocytes to examine the effect of 10-H2DA on the expression of genes associated with neuroinflammation and the production of neurotrophins, as well as cellular resistance to H2O2-induced cytotoxicity. Astrocytes, pretreated with a range of concentrations of 10-H2DA for 24 h, were exposed to lipopolysaccharide (LPS) for 3 h, after which the expression of proinflammatory cytokines (IL-1β, IL-6, and tumor necrosis factor-α (TNF-α)) and neurotrophic factors (BDNF, GDNF, and IGF-1) was evaluated. In the absence of LPS, 10-H2DA had no significant effect on the mRNA expression of neurotrophins or cytokines except for IL-1β, which significantly increased with low doses of 10-H2DA (3 µM). 10-H2DA (10 µM) pretreatment of LPS-stimulated cells did not significantly inhibit the expression of cytokine encoding genes; however, it significantly lowered the mRNA expression of GDNF and tended to decrease BDNF and IGF-1 expression compared with LPS alone. Additionally, 10-H2DA did not protect astrocytes against H2O2-induced oxidative stress. Our data indicate no anti-inflammatory, antioxidant, or neurotrophic effect of 10-H2DA in astrocytes undergoing inflammation or oxidative stress. The effect of IGF-1 inhibition by 10-H2DA on neuronal ketogenesis needs investigation.

2-Heptylcyclopropane-1-Carboxylic Acid Disperses and Inhibits Bacterial Biofilms

Fatty-acid signaling molecules can inhibit biofilm formation, signal dispersal events, and revert dormant cells within biofilms to a metabolically active state. We synthesized 2-heptylcyclopropane-1-carboxylic acid (2CP), an analog of cis-2-decenoic acid (C2DA), which contains a cyclopropanated bond that may lock the signaling factor in an active state and prevent isomerization to its least active trans-configuration (T2DA). 2CP was compared to C2DA and T2DA for ability to disperse biofilms formed by Staphylococcus aureus and Pseudomonas aeruginosa. 2CP at 125 μg/ml dispersed approximately 100% of S. aureus cells compared to 25% for C2DA; both 2CP and C2DA had significantly less S. aureus biofilm remaining compared to T2DA, which achieved no significant dispersal. 2CP at 125 μg/ml dispersed approximately 60% of P. aeruginosa biofilms, whereas C2DA and T2DA at the same concentration dispersed 40%. When combined with antibiotics tobramycin, tetracycline, or levofloxacin, 2CP decreased the minimum concentration required for biofilm inhibition and eradication, demonstrating synergistic and additive responses for certain combinations. Furthermore, 2CP supported fibroblast viability above 80% for concentrations below 1 mg/ml. This study demonstrates that 2CP shows similar or improved efficacy in biofilm dispersion, inhibition, and eradication compared to C2DA and T2DA and thus may be promising for use in preventing infection for healthcare applications.

10-hydroxy-2E-decenoic acid (10HDA) does not promote caste differentiation in Melipona scutellaris stingless bees

In bees from genus Melipona, differential feeding is not enough to fully explain female polyphenism. In these bees, there is a hypothesis that in addition to the environmental component (food), a genetic component is also involved in caste differentiation. This mechanism has not yet been fully elucidated and may involve epigenetic and metabolic regulation. Here, we verified that the genes encoding histone deacetylases HDAC1 and HDAC4 and histone acetyltransferase KAT2A were expressed at all stages of Melipona scutellaris, with fluctuations between developmental stages and castes. In larvae, the HDAC genes showed the same profile of Juvenile Hormone titers—previous reported—whereas the HAT gene exhibited the opposite profile. We also investigated the larvae and larval food metabolomes, but we did not identify the putative queen-fate inducing compounds, geraniol and 10-hydroxy-2E-decenoic acid (10HDA). Finally, we demonstrated that the histone deacetylase inhibitor 10HDA—the major lipid component of royal jelly and hence a putative regulator of honeybee caste differentiation—was unable to promote differentiation in queens in Melipona scutellaris. Our results suggest that epigenetic and hormonal regulations may act synergistically to drive caste differentiation in Melipona and that 10HDA is not a caste-differentiation factor in Melipona scutellaris.