Components of royal jelly: I. Identification of the organic acids

Exploring fatty acids from royal jelly as a source of histone deacetylase inhibitors: from the hive to applications in human well-being and health

A differential diet with royal jelly (RJ) during early larval development in honeybees shapes the phenotype, which is probably mediated by epigenetic regulation of gene expression. Evidence indicates that small molecules in RJ can modulate gene expression in mammalian cells, such as the fatty acid 10-hydroxy-2-decenoic acid (10-HDA), previously associated with the inhibition of histone deacetylase enzymes (HDACs). Therefore, we combined computational (molecular docking simulations) and experimental approaches for the screening of potential HDAC inhibitors (HDACi) among 32 RJ-derived fatty acids. Biochemical assays and gene expression analyses (Reverse Transcriptase - quantitative Polymerase Chain Reaction) were performed to evaluate the functional effects of the major RJ fatty acids, 10-HDA and 10-HDAA (10-hydroxy-decanoic acid), in two human cancer cell lines (HCT116 and MDA-MB-231). The molecular docking simulations indicate that these fatty acids might interact with class I HDACs, specifically with the catalytic domain of human HDAC2, likewise well-known HDAC inhibitors (HDACi) such as SAHA (suberoylanilide hydroxamic acid) and TSA (Trichostatin A). In addition, the combined treatment with 10-HDA and 10-HDAA inhibits the activity of human nuclear HDACs and leads to a slight increase in the expression of HDAC-coding genes in cancer cells. Our findings indicate that royal jelly fatty acids collectively contribute to HDAC inhibition and that 10-HDA and 10-HDAA are weak HDACi that facilitate the acetylation of lysine residues of chromatin, triggering an increase in gene expression levels in cancer cells.

Sterol and lipid metabolism in bees

BACKGROUND

Bees provide essential pollination services for many food crops and are critical in supporting wild plant diversity. However, the dietary landscape of pollen food sources for social and solitary bees has changed because of agricultural intensification and habitat loss. For this reason, understanding the basic nutrient metabolism and meeting the nutritional needs of bees is becoming an urgent requirement for agriculture and conservation. We know that pollen is the principal source of dietary fat and sterols for pollinators, but a precise understanding of what the essential nutrients are and how much is needed is not yet clear. Sterols are key for producing the hormones that control development and may be present in cell membranes, where fatty-acid-containing species are important structural and signalling molecules (phospholipids) or to supply, store and distribute energy (glycerides).

AIM OF THE REVIEW

In this critical review, we examine the current general understanding of sterol and lipid metabolism of social and solitary bees from a variety of literature sources and discuss implications for bee health.

KEY SCIENTIFIC CONCEPTS OF REVIEW

We found that while eusocial bees are resilient to some dietary variation in sterol supply the scope for this is limited. The evidence of both de novo lipogenesis and a dietary need for particular fatty acids (FAs) shows that FA metabolism in insects is analogous to mammals but with distinct features. Bees rely on their dietary intake for essential sterols and lipids in a way that is dependent upon pollen availability.

The royal food of termites shows king and queen specificity

Society in eusocial insects is based on the reproductive division of labor, with a small number of reproductive individuals supported by a large number of nonreproductive individuals. Because inclusive fitness of all colony members depends on the survival and fertility of reproductive members, sterile members provide royals with special treatment. Here, we show that termite kings and queens each receive special food of a different composition from workers. Sequential analysis of feeding processes demonstrated that workers exhibit discriminative trophallaxis, indicating their decision-making capacity in allocating food to the kings and queens. Liquid chromatography tandem-mass spectrometry analyses of the stomodeal food and midgut contents revealed king- and queen-specific compounds, including diacylglycerols and short-chain peptides. Desorption electrospray ionization mass spectrometry imaging analyses of ¹³C-labeled termites identified phosphatidylinositol and acetyl-l-carnitine in the royal food. Comparison of the digestive tract structure showed remarkable differences in the volume ratio of the midgut-to-hindgut among castes, indicating that digestive division of labor underlies reproductive division of labor. Our demonstration of king- and queen-specific foods in termites provides insight into the nutritional system that underpins the extraordinary reproduction and longevity of royals in eusocial insects.

The volatile chemistry of orchid pollination

Covering: up to September 2022Orchids are renowned not only for their diversity of floral forms, but also for their many and often highly specialised pollination strategies. Volatile semiochemicals play a crucial role in the attraction of a wide variety of insect pollinators of orchids. The compounds produced by orchid flowers are as diverse as the pollinators they attract, and here we summarise some of the chemical diversity found across orchid taxa and pollination strategies. We focus on compounds that have been experimentally demonstrated to underpin pollinator attraction. We also highlight the structural elucidation and synthesis of a select subset of important orchid pollinator attractants, and discuss the ecological significance of the discoveries, the gaps in our current knowledge of orchid pollination chemistry, and some opportunities for future research in this field.

The adult lifespan of the female honey bee (Apis mellifera): Metabolic rate, AGE pigment and the effect of dietary fatty acids

Female honey bees can be queens or workers and although genetically identical, workers have an adult lifespan of weeks while queens can live for years. The mechanisms underlying this extraordinary difference remain unknown. This study examines three potential explanations of the queen-worker lifespan difference. Metabolic rates were similar in age-matched queens and workers and thus are not an explanation. The accumulation of fluorescent AGE pigment has been successfully used as a good measure of cellular senescence in many species. Unlike other animals, AGE pigment level reduced during adult life of queens and workers. This unusual finding suggests female honey bees can either modify, or remove from their body, AGE pigment. Another queen-worker difference is that, as adults, workers eat pollen but queens do not. Pollen is a source of polyunsaturated fatty acids. Its consumption explains the queen-worker difference in membrane fat composition of female adult honey bees which has previously been suggested as a cause of the lifespan difference. We were able to produce "queen-worker" membrane differences in workers by manipulation of diet that did not change worker lifespan and we can, thus, also rule out pollen consumption by workers as an explanation of the dramatic queen-worker lifespan difference.

Royal jelly fatty acids bioprofiling using TLC-MS and digital image analysis coupled with chemometrics and non-parametric regression for discovering efficient biomarkers against melanoma

A comprehensive approach of untargeted and targeted fatty acid bioprofiling of different royal jelly commercial and pharmaceutical products based on HPTLC-image analysis and melanoma cytotoxic activity together with chemometric analysis was applied in this study for discovering efficient biomarkers. Principal component analysis based on HPTLC-image analysis fingerprints of fatty acid loading plots were used to determine the chemical markers responsible for classification of royal jelly samples into fresh and lyophilized ones. These markers were identified using the HPTLC-MS technique as 8-hydroxyoctanoic acid, 3,10-dihydroxydecanoic acid, 10-hydroxy-2-decenoic acid, decanedioic acid and 10-hydroxydecanoic acid. These discriminating markers were quantified via the HPTLC-imaging technique for targeted profiling using two different methods: parametric and non-parametric regression. The non-parametric regression method exhibited superiority in terms of linearity, accuracy and precision. Biomarkers were determined from the 3D-loading plot of orthogonal projection to latent structures model based on the fatty acid quantitative data together with the melanoma cytotoxic activity data. 10-Hydroxy-2-decenoic acid showed the greatest reduction in melanoma cell viability followed by decanedioic acid then 8-hydroxyoctanoic acid. The present study is considered the first attempt to discriminate fresh and lyophilized royal jelly samples based on their holistic lipidomic profile to discover efficient fatty acid reducing melanoma cell viability.

Mechanistic Insight into Royal Protein Inhibiting the Gram-Positive Bacteria

Royal jelly (RJ), a natural honeybee product, has a wide range of antibacterial activities. N-glycosylated major royal jelly protein 2 (N-MRJP2), purified from RJ, can inhibit the growth of Paenibacillus larvae (P. larvae, Gram-positive), a contagious etiological agent of the American foulbrood disease of honeybees. However, the inhibitory mechanism is largely unknown. Antibacterial assay and membrane proteome were conducted to investigate the inhibition capacity of RJ from different instar larvae and P. larvae treated by N-MRJP2, respectively. The similar antibacterial efficiency of RJ from different larval instar indicates that RJ is vital for the adaptive immune defense of small larvae. The killing of P. larvae by N-MRJP2 is achieved by disturbing the cell wall biosynthesis, increasing the permeability of cell membrane, hindering aerobic respiration, restraining cell division and inducing cell death. This demonstrates that RJ is critical for the passive immunity of immature larvae and N-MRJP2 can be used as natural antibiotic substance to resist P. larvae, even for other gram-positive bacteria. This constitutes solid evidence that RJ and N-MRJP2 have potentials as novel antibacterial agents.

10-HDA, A Major Fatty Acid of Royal Jelly, Exhibits pH Dependent Growth-Inhibitory Activity Against Different Strains of Paenibacillus larvae

Paenibacillus larvae (P. larvae) is a bacterial pathogen causing American foulbrood (AFB), the most serious disease of honeybee larvae. The food of young larvae could play an important role in the resistance of larvae against AFB. It contains antibacterial substances produced by honeybees that may inhibit the propagation of the pathogen in larval midguts. In this study, we identified and investigated the antibacterial effects of one of these substances, trans-10-hydroxy-2-decenoic acid (10-HDA), against P. larvae strains including all Enterobacterial Repetitive Intergenic Consensus (ERIC) genotypes. Its inhibitory activities were studied by determining the minimum inhibitory concentrations (MICs). It was found that 10-HDA efficacy increases substantially with decreasing pH; up to 12-fold differences in efficacy were observed between pH = 5.5 and pH = 7.2. P. larvae strains showed different susceptibility to 10-HDA; up to 2.97-fold differences existed among various strains with environmentally important ERIC I and ERIC II genotypes. Germinating spores of the pathogen were generally more susceptible to 10-HDA than vegetative cells. Our findings suggest that 10-HDA could play significant role in conferring antipathogenic activity to larval food in the midguts of young larvae and contribute to the resistance of individual larvae to P. larvae.

Royal jelly supplementation reduces skeletal muscle lipotoxicity and insulin resistance in aged obese rats

BACKGROUND

Consumption of a high-fat diet (HFD) in aged rats is associated with several metabolic disorders. The mechanism of skeletal muscle lipotoxicity and insulin resistance (IR) is multi-factorial, but the exact mechanism of how aging affects these processes unknown. Royal jelly (RJ) is a dietary supplement with many physiological and pharmacological properties. No previous studies have demonstrated the protective effects and mechanism of RJ in aged obese rats.

OBJECTIVES

The study was carried to investigate the effects of aging and HFD on skeletal muscles, and adipose tissue metabolism and inflammation, in aged rats, and whether RJ could combat such adverse effects.

METHODOLOGY

A total of 40 male rats were divided into5 groups; young rats fed a standard diet, aged rats fed a standard diet, aged rats fed RJ, aged rats fed a HFD, and aged rats fed both a HFD and RJ for 8 weeks. We investigated changes in body weights (BW), abdominal fat weights, total cholesterol, triglycerides (TG), low density lipoprotein-cholesterol (LDL-c), high density lipoprotein-cholesterol (HDL-c), muscle TG, and IR levels. Also, concentrations of TNF-α receptor 1(TNFR1) were estimated in the serum and adipose tissues.

RESULTS

Aged, obese rats showed increased BW, adipose weights, IR, and disturbed serum and muscle lipids. Also, TNFR1 was increased. Rats fed RJ showed decreased adiposity, improved lipids' profiles, improved IR, and decreased TNFR1.

CONCLUSION

Aging and HFD were associated with disturbed metabolism, and muscle lipotoxicity and inflammation, while RJ could counteract muscle lipotoxicity in rats and reduce IR, most likely due to an anti-inflammatory effect.

Transgenic silkworms secrete the recombinant glycosylated MRJP1 protein of Chinese honeybee, Apis cerana cerana

Major royal jelly protein-1 (MRJP1) is the most abundant glycoprotein of royal jelly (RJ) and is considered a potential component of functional foods. In this study, we used silkworm transgenic technology to obtain five transgenic silkworm lineages expressing the exogenous recombinant Chinese honeybee, Apis cerana cerana, protein-1 (rAccMRJP1) under the control of a fibroin light chain (Fib-L) promoter in the posterior silk glands. The protein was successfully secreted into cocoons; specifically, the highest rAccMRJP1 protein content was 0.78% of the dried cocoons. Our results confirmed that the protein band of the exogenous rAccMRJP1 protein expressed in the transgenic silkworm lineages was a glycosylated protein. Therefore, this rAccMRJP1 protein could be used as an alternative standard protein sample to measure the freshness of RJ. Moreover, we also found that the overall trend between the expression of the endogenous and exogenous genes was that the expression level of the endogenous Fib-L gene declined as the expression of the exogenous rAccMRJP1 gene increased in the transgenic silkworm lineages. Thus, by employing genome editing technology to reduce silk protein expression levels, a silkworm bioreactor expression system could be developed as a highly successful system for producing various valuable heterologous proteins, potentially broadening the applications of the silkworm.

Royal jelly lipophilic fraction induces antiproliferative effects on SH-SY5Y human neuroblastoma cells

Royal jelly (RJ) is one the most important bee product because it strongly influences the larval development in the hive, including the queen bee. In literature, RJ is known for its antioxidant, immunoregulatory, antifungal, antibiotical, erythropoietic, hypoglycemic, anticholesteremic, antithyroidic, anti-osteoporotic and estrogenic properties. However, it is surprising how rare the scientific evidence about RJ antineoplastic capacity are. That being said, we investigated, for the first time, the in vitro bioactivity of six different RJs on the growth of three different mammalian cell lines: immortalized murine myoblasts (C2C12), human prostate cancer (PC3) and human neuroblastoma (SH-SY5Y). These studies were performed treating the cells with the only lipophilic, or hydrophilic, fraction of the RJs, a scientific approach never performed before. Moreover, chemical and protein profiles of all RJs were finely characterized, in qualitative and quantitative terms, by GC-MS and 1D-SDS-PAGE, respectively, in order to give a complete framework to the research. Despite the deep differences we found in the composition of each sample, unexpectedly, RJs showed comparable or very similar biological effects. In particular, our attention was captured by the extraordinary antiproliferative activity of the lipophilic extract of all RJs against SH-SY5Y cells, suggesting a potential medical application of this bee product to prevent the onset and slow down the growth of human neuroblastoma.

Royal jelly decreases corticosterone levels and improves the brain antioxidant system in restraint and cold stressed rats

Restraint and cold stress induces the hypothalamic-pituitary-adrenal (HPA) axis to release corticosterone from the adrenal gland, which can worsen the antioxidant defense system in the central nervous system. Here, we investigated the corticosterone levels and the antioxidant defense system in the cerebellum and brain, as well as in its isolated regions, such as cerebral cortex, striatum and hippocampus of stressed rats supplemented with royal jelly (RJ). Wistar rats were supplemented with RJ for 14days and the stress induction started on the 7th day. Stressed rats increased corticosterone levels, glycemia and lipid peroxidation in the brain and cerebellum, cerebral cortex and hippocampus besides reduced glutathione defense system in the brain and striatum. Rats supplemented with RJ decreased corticosterone, maintained glycemia and decreased lipid peroxidation in the brain, cerebellum, as well as striatum and hippocampus, besides improved glutathione defense system in cerebral cortex and striatum. This study suggests an anti-stress and neuroprotective effect of RJ under stress conditions.

In Vitro Anti-Inflammatory Effects of Three Fatty Acids from Royal Jelly

Trans-10-hydroxy-2-decenoic acid (10-H2DA), 10-hydroxydecanoic acid (10-HDAA), and sebacic acid (SEA) are the three major fatty acids in royal jelly (RJ). Previous studies have revealed several pharmacological activities of 10-H2DA and 10-HDAA, although the anti-inflammatory effects and underlying mechanisms by which SEA acts are poorly understood. In the present study, we evaluated and compared the in vitro anti-inflammatory effects of these RJ fatty acids in lipopolysaccharide-stimulated RAW 264.7 macrophages. The results showed that 10-H2DA, 10-HDAA, and SEA had potent, dose-dependent inhibitory effects on the release of the major inflammatory-mediators, nitric oxide, and interleukin-10, and only SEA decreased TNF-α production. Several key inflammatory genes have also been modulated by these RJ fatty acids, with 10-H2DA showing distinct modulating effects as compared to the other two FAs. Furthermore, we found that these three FAs regulated several proteins involved in MAPK and NF-κB signaling pathways. Taken together, these findings provide additional references for using RJ against inflammatory diseases.

Royal Jelly: An ancient remedy with remarkable antibacterial properties

Royal Jelly (RJ), a honeybee hypopharyngeal gland secretion of young nurse and an exclusive nourishment for bee queen, has been used since ancient times for care and human health and it is still very important in traditional and folkloristic medicine, especially in Asia within the apitherapy. Recently, RJ and its protein and lipid components have been subjected to several investigations on their antimicrobial activity due to extensive traditional uses and for a future application in medicine. Antimicrobial activities of crude Royal Jelly, Royalisin, 10-hydroxy-2-decenoic acid, Jelleines, Major Royal Jelly Proteins against different bacteria have been reported. All these beehive products showed antimicrobial activities that lead their potential employment in several fields as natural additives. RJ and its derived compounds show a highest activity especially against Gram positive bacteria. The purpose of this Review is to summarize the results of antimicrobial studies of Royal Jelly following the timescale of the researches. From the first scientific applications to the isolation of the single components in order to better understand its application in the past years and propose an employment in future studies as a natural antimicrobial agent.

Anti-inflammatory effects of royal jelly on ethylene glycol induced renal inflammation in rats

Objective:

In this study, anti-inflammatory effects of Royal Jelly were investigated by inducing renal inflammation in rats with the use of ethylene glycol. For this purpose, the calcium oxalate urolithiasis model was obtained by feeding rats with ethylene glycol in drinking water.

Materials and Methods:

The rats were divided in five study groups. The 1^st group was determined as the control group. The rats in the 2^nd group received ethylene glycol (1%) in drinking water. The rats in the 3^rd group were daily fed with Royal Jelly by using oral gavage. The 4^th group was determined as the preventive group and the rats were fed with ethylene glycol (1%) in drinking water while receiving Royal Jelly via oral gavage. The 5^th group was determined as the therapeutic group and received ethylene glycol in drinking water during the first 2 weeks of the study and Royal Jelly via oral gavage during the last 2 weeks of the study.

Results:

At the end of the study, proinflammatory/anti-inflammatory cytokines, TNF-α, IL-1β and IL-18 levels in blood and renal tissue samples from the rats used in the application were measured.

Conclusion:

The results have shown that ethylene glycol does induce inflammation and renal damage. This can cause the formation of reactive oxygen species. Royal Jelly is also considered to have anti-inflammatory effects due to its possible antiradical and antioxidative effects. It can have positive effects on both the prevention of urolithiasis and possible inflammation during the existing urolithiasis and support the medical treatment.

Recipe for a busy bee: microRNAs in Honey Bee caste determination

Social caste determination in the honey bee is assumed to be determined by the dietary status of the young larvae and translated into physiological and epigenetic changes through nutrient-sensing pathways. We have employed Illumina/Solexa sequencing to examine the small RNA content in the bee larval food, and show that worker jelly is enriched in miRNA complexity and abundance relative to royal jelly. The miRNA levels in worker jelly were 7-215 fold higher than in royal jelly, and both jellies showed dynamic changes in miRNA content during the 4(th) to 6(th) day of larval development. Adding specific miRNAs to royal jelly elicited significant changes in queen larval mRNA expression and morphological characters of the emerging adult queen bee. We propose that miRNAs in the nurse bee secretions constitute an additional element in the regulatory control of caste determination in the honey bee.

Effect of royal jelly in ovo injection on embryonic growth, hatchability, and gonadotropin levels of pullet breeder chicks

The objectives of this study were to compare the following: (1) hatchability, (2) chicks' body and internal organs weights, and (3) plasma gonadotropin levels of hatchlings after in ovo administration of royal jelly (RJ) on Day 7 of incubation. Fertile eggs (n = 270) were injected into the air sac or yolk sac with 0.5 mL normal saline solution consisting of four formulations (normal saline solution with antibiotics, ultrafiltrate RJ, pure RJ, and RJ with antibiotics). The eggs were randomly divided into nine groups of 30 eggs each: (i) C: the control eggs received no injection, (ii) ASA: air sac-injected eggs received normal saline solution with antibiotics, (iii) ARJ: air sac-injected eggs received pure RJ, (iv) ARJA: air sac-injected eggs received RJ with antibiotics, (v) ARJF: air sac-injected eggs received RJ ultrafiltrate solution, (vi) YSA: yolk sac-injected eggs received normal saline solution with antibiotics, and (vii) YRJ: yolk sac-injected eggs received pure RJ, (viii) YRJA: yolk sac-injected eggs received RJ with antibiotics, and (ix) YRJF: yolk sac-injected eggs received ultrafiltrate RJ solution. Hatchability rate was lower in ARJ (46.7%), ARJA (43.3%), ARJF (43.3%), and YRJF (46.7%) groups than in the control (80.0%; P < 0.05). Hatchability rate in ASA (70.0%), YSA (66.7%), YRJ (66.7%), and YRJA (63.3%) groups were comparable to the control (P > 0.05). In ovo injection of RJ and or RJ with antibiotics in both sacs increased chicks' body weight (CWT), heart weight (HWT), and liver weight (LWT) and FSH and LH levels compared with control (P < 0.05). CWT in YRJ (37.02 g), YRJA (37.03 g), ARJ (36.82 g), and ARJA (36.89 g) groups were higher than control (34.9 g; P < 0.05). Similarly, HWT significantly increased in YRJ (0.22 g), YRJA (0.21 g), ARJ (0.20 g), and ARJA (0.20 g) in comparison to control (0.18 g; P < 0.05). In addition, LWT were higher in YRJ (0.83 g), YRJA (0.82g), ARJ (0.81g), and ARJA (0.81g) than control (0.72 g; P < 0.05). Six hours post-hatch, the mean plasma FSH and LH levels in ARJ (1.13 and 2.80 mIu/mL), YRJ (1.32 and 3.36 mIu/mL), ARJA (1.23 and 2.95 mIu/mL), and YRJA (1.31 and 3.28 mIu/mL) groups were higher than in the control (0.56 and 1.48 mIu/mL, P < 0.05). We concluded that in ovo administration of RJ or RJ with antibiotics might be an effective method to increase CWT, chicks' internal organs weights, and LH and FSH secretion rate without deleterious effect on hatchability. However, further research should be conducted to determine the putative endocrine disruptive effects of RJ and its byproducts.

Characterization of markers of botanical origin and other compounds extracted from unifloral honeys

The possibility of tracing the botanical and geographical origin of products such as honey has become more important because of market globalization. As a consequence, numerous analytical methods have been applied to the determination of honey authenticity. The scope of the present work is to chromatographically purify and characterize 23 compounds from organic extracts of unifloral (chestnut, linden, orange, acacia, eucalyptus, honeydew) and polyfloral honeys. Of these compounds, 17 were identified as specific markers and were used for botanical discrimination in a previous study based on multivariate statistical analysis of proton nuclear magnetic resonance ((1)H NMR) data. Together with the botanical markers, 6 other substances were isolated and characterized using NMR and mass spectrometry. These phytochemicals belong to several classes, that is, terpenes, organic acids, flavonoids, and others. For the first time, a diacylglyceryl ether and 5 other compounds present in different types of honey were identified and characterized.

Towards posttranslational modification proteome of royal jelly

Royal jelly (RJ) is a secretory protein from the hypopharyngeal glands of nurse honeybee workers, which contains a variety of proteins of which major royal jelly proteins (MRJPs) are some of the most important. It plays important roles both for honeybee and human. Each family of MRJP 1-5 displays a string of modified protein spots in the RJ proteome profile, which may be caused by posttranslational modifications (PTMs) of MRJPs. However, information on the RJ PTMs is still limited. Therefore, the PTM status of RJ was identified by using complementary proteome strategies of two-dimensional gel electrophoresis (2-DE), shotgun analysis in combination with high performance liquid chromatography-chip/electrospray ionization quadrupole time-of-flight/tandem mass spectrometry and bioinformatics. Phosphorylation was characterized in MRJP 1, MRJP 2 and apolipophorin-III-like protein for the first time and a new site was localized in venom protein 2 precursor. Methylation and deamidation were also identified in most of the MRJPs. The results indicate that methylation is the most important PTM of MRJPs that triggers the polymorphism of MRJP 1-5 in the RJ proteome. Our data provide a comprehensive catalog of several important PTMs in RJ and add valuable information towards assessing both the biological roles of these PTMs and deciphering the mechanisms underlying the beneficial effects of RJ for human health.

Gas chromatographic-mass spectrometric investigation of volatile and extractable compounds of crude royal jelly

Using headspace solid-phase microextraction (HS-SPME) followed by diethyl ether and methanol extraction, it was possible to isolate as many as 185 organic compounds out of 17 samples of crude royal jelly (RJ). Of the above compound number, 169 compounds were positively identified by means of gas chromatography-mass spectrometry. The volatile fraction of RJ consists of 25 different compounds where approximately 47% of the total ion current (TIC) of volatile compound chromatograms were composed of substances characterized by bactericidal (phenols) and repelling (octanoic acid and 2-heptanone) activities. Preliminary investigations have shown that RJ stored for 10 months at -18°C and 4°C keeps its composition of volatile compounds unchanged, however, at the same time at room temperature RJ phenol contents is decreased twice, whereas the fraction of aliphatic acids is increased 2.8 times due to the presence of both acetic and butyric acids. The chromatogram of RJ ether extracts showed 85 different compounds, however about 88% of TIC consisted exclusively of 8 compounds, i.e. 10-hydroxy-2-decenoic, 10-hydroxydecanoic, 3,10-dihydroxydecanoic, 8-hydroxyoctanoic, 2-decene-1,10-dioc and (Z)-9-hydroxy-2-decenoic acids. Nine aliphatic acids, which were detected for the first time, are the homologues of hydroxy- and oxo-acids identified earlier in RJ. In the RJ methanol extracts 82 compounds were identified, mainly carbohydrates and their derivatives. Approximately 87% of TIC consisted of fructose, glucose and sucrose. Special attention was paid to discrepancies between obtained and literature data concerning the presence of free amino acids in RJ. It was suggested that these inconsistencies can be explained by the differences in the methods of RJ collection and/or sample preparation.

Fatty acids derived from royal jelly are modulators of estrogen receptor functions

Royal jelly (RJ) excreted by honeybees and used as a nutritional and medicinal agent has estrogen-like effects, yet the compounds mediating these effects remain unidentified. The possible effects of three RJ fatty acids (FAs) (10-hydroxy-2-decenoic-10H2DA, 3,10-dihydroxydecanoic-3,10DDA, sebacic acid-SA) on estrogen signaling was investigated in various cellular systems. In MCF-7 cells, FAs, in absence of estradiol (E₂), modulated the estrogen receptor (ER) recruitment to the pS2 promoter and pS2 mRNA levels via only ERβ but not ERα, while in presence of E₂ FAs modulated both ERβ and ERα. Moreover, in presence of FAs, the E₂-induced recruitment of the EAB1 co-activator peptide to ERα is masked and the E₂-induced estrogen response element (ERE)-mediated transactivation is inhibited. In HeLa cells, in absence of E₂, FAs inhibited the ERE-mediated transactivation by ERβ but not ERα, while in presence of E₂, FAs inhibited ERE-activity by both ERβ and ERα. Molecular modeling revealed favorable binding of FAs to ERα at the co-activator-binding site, while binding assays showed that FAs did not bind to the ligand-binding pocket of ERα or ERβ. In KS483 osteoblasts, FAs, like E₂, induced mineralization via an ER-dependent way. Our data propose a possible molecular mechanism for the estrogenic activities of RJ's components which, although structurally entirely different from E₂, mediate estrogen signaling, at least in part, by modulating the recruitment of ERα, ERβ and co-activators to target genes.

Gas chromatographic and mass spectrometric characterization of the organic acids extracted from some preparations containing lyophilized royal jelly

Thirty-five aliphatic acids were identified by gas chromatography-mass spectrometry from the ether extract of commercial preparations containing lyophilized royal jelly. The article presents linear-programmed retention indices on capillary columns with non-polar and low-polar stationary phases and mass spectra for identified compounds which were not characterized earlier by these parameters. Nine compounds are reported for the first time as royal jelly constituents.

Effects of sodium fluoride exposure on some biochemical parameters in mice: evaluation of the ameliorative effect of royal jelly applications on these parameters

Forty eight male Balb/c mice, each weighing 30-35 g, were used in the present study. The animals were divided into four equal groups. The first group served as the control group, and the second group was administered royal jelly at a dose of 50 mg/kg bw by gavage for a period of 7 days. The third group received 200 ppm fluoride, as sodium fluoride, for a period of 7 days, in drinking water. Lastly, the fourth group was given 200 ppm fluoride in drinking water, in association with royal jelly at a dose of 50 mg/kg bw by gavage, for a period of 7 days. At the end of the seventh day, blood samples were collected from all groups into heparinised and dry tubes, and liver samples were taken concurrently. Erythrocyte and liver tissue malondialdehyde (MDA) levels and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were evaluated in the blood and tissue samples obtained. Furthermore, serum cholesterol, triglyceride, glucose, total protein and albumin levels, and aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alcaline phosphatase (ALP) activities were evaluated. In conclusion, fluoride was determined to cause adverse effects in mice, and the administration of royal jelly to these animals alleviated the adverse effects of fluoride.

Honeybee royal jelly inhibits autoimmunity in SLE-prone NZB x NZW F1 mice

Royal jelly (RJ) is a gelatinous secretion from young nurse worker bees (Apis mellifera), which serves as the sole food for the queen bee. Because of its pleiotropic functions for queen bees, RJ has also been used as a dietary supplement with various health benefits for humans. Because RJ is being indicated to have immunomodulatory potential for humans, we undertook the study to determine whether the oral administration of RJ could alter the development of systemic autoimmunity in New Zealand Black (NZB) x New Zealand White (NZW) F1 mice that genetically exhibit many manifestations similar to human systemic lupus erythematosus (SLE). We herein reported that mice administered with RJ showed a significant delay in the onset of the disease, as manifested by decreased proteinuria and a prolongation of lifespan. In addition, RJ administration after the onset of the disease significantly improved the renal symptoms, leading to an extended lifespan. RJ administration to mice caused a significant decrease in the serum level of IL-10, and in the autoantibodies against ssDNA, dsDNA and erythrocytes, as well as a reduction in the number of splenic autoreactive B cells. In conclusion, our data suggest that the use of RJ may be beneficial in the prevention of the early onset of SLE and in the control of the active progression of the manifestations of SLE.

Antioxidant properties of royal jelly associated with larval age and time of harvest

This study aimed to evaluate the antioxidant properties of royal jelly (RJ) collected from larvae of different ages that were transferred in artificial bee queen cells for 24, 48, and 72 h. RJ harvested from the 1 day old larvae 24 h after the graft displayed predominant antioxidant properties, including scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, inhibition of linoleic acid peroxidation, and reducing power. Regardless of the initial larval age, lower antioxidant activities were observed in the RJ harvested later than 24 h except for the activity of superoxide dismutase. In addition, higher contents of proteins and polyphenolic compounds were determined in the RJ harvested 24 h than that harvested 48 or 72 h after the graft. It implied that the polyphenolic compounds may be the major component for giving the antioxidant activities in RJ. In summary, the time of harvest and the initial larval age did affect the antioxidant potencies in RJ, and RJ collected 24 h after the larval transfer showed the most substantial antioxidant activities.

The effects of royal jelly on liver damage induced by paracetamol in mice

The present study was undertaken to investigate the protective effect of royal jelly against paracetamol-induced liver damage. The study was conducted in 90 female Swiss Albino mice, and six groups were established. While the first group was maintained as control, Groups 2-6 were administered 200mg/kg RJ for 1 day, 200mg/kg RJ for 7 days, 400mg/kg PAR for 1 day, 200mg/kg RJ plus 400mg/kg PAR for 1 day and 200mg/kg RJ for 7 days and then second 400mg/kg PAR on the 7th day, orally, respectively. It was shown that PAR significantly increased serum ALT, AST, ALP, liver MDA levels and significantly decreased liver GSH-Px activity, when compared to the control group (Group 1). On the other hand, meaningful changes were observed in the biochemical parameters of the group which was administered long-term RJ (Group 6). The aforementioned parameters which were statistically significant were determined to have drawn closer to values of the control group, and among these, the existing statistical differences for MDA level and GSH-Px activity between the trial group (Group 6) and the control group disappeared (Group 1). Compared to the pathological changes observed in the liver parenchyma, remark cords, sinusoids and hepatocytes in the group which was administered paracetamol alone (Group 4), lesions were determined to be less severe particularly in the group (Group 6) which received royal jelly for 7 days prior to paracetamol. In conclusion, the administration of royal jelly as a hepatoprotective agent for 7 days against paracetamol-induced liver damage was determined to exhibit marked protective effect on liver tissue.

Evaluation of the immunomodulatory activities of royal jelly components in vitro

In this work the effect of different components isolated from royal jelly (RJ) was studied using an in vitro rat T-cell proliferation assay. We found that lower concentrations of MEL 174 (final water extract of RJ) and MEL 147 (3-10-dihydroxydecanoic acid) stimulated T-cell proliferation, triggered by concanavalin A (Con-A) and the process was followed by an increase in the production of interleukin-2 (IL-2). Higher concentrations of MEL 174, MEL 247 (dry powder of RJ) and MEL 138 (trans-10-hydroxydec-2-enoic acid) inhibited T-cell proliferation. The inhibition of T-cell proliferation in the presence of MEL 174 was followed by a decrease in IL-2 production, which was partly abrogated by exogenous IL-2, a decrease in nitric oxide (NO) production and increased apoptosis. In conclusion, our results showed the complexity of biological activity of RJ and suggest that its water extract possesses the most potent immunomodulatory activity in vitro.

Determination of (E)-10-hydroxy-2-decenoic acid content in pure royal jelly: a comparison between a new CZE method and HPLC

A new CZE method was developed and compared with HPLC for the determination of (E)-10-hydroxy-2-decenoic acid (10-HDA) in royal jelly (RJ) samples of different geographical origin. The results obtained with the CZE method were highly correlated with those of HPLC (p < 0.01). Under optimized conditions, CZE employed minimal amounts of 50 mM tetraborate buffer as BGE, without the addition of organic solvents, EOF or pH modifiers. The CZE method showed a wide linear response range (0.006-0.808 mg 10-HDA/mL), a good sensitivity (LOD and LOQ were 0.002 and 0.004 mg/mL, respectively) and a satisfactory instrumental repeatability with respect to migration time and peak area (RSD% less than 1.0 and 2.0% on migration time for intra- and interday assay, respectively and less than 2.0 and for 4.0% on peak area for intra- and interday assay, respectively). The 10-HDA content in RJ ranged from 0.8 to 3.2 g/100 g of RJ and a significant difference (p < 0.05) was found between the Italian and extra-European average values: 2.5 and 1.6 g/100 g of RJ, respectively, according to the CZE data. The possibility of application of CZE for routine analyses on RJ and RJ based products to verify their authenticity is highlighted here.

Fatty acids isolated from royal jelly modulate dendritic cell-mediated immune response in vitro

Royal jelly (RJ), especially its protein components, has been shown to possess immunomodulatory activity. However, almost nothing is known about the influence of RJ fatty acids on the immune system. In this work we studied the effect of 10-hydroxy-2-decanoic acid (10-HDA) and 3,10-dihydroxy-decanoic acid (3,10-DDA), isolated from RJ, on the immune response using a model of rat dendritic cell (DC)-T-cell cocultures. Both fatty acids, at higher concentrations, inhibited the proliferation of allogeneic T cells. The effect of 10-HDA was stronger and was followed by a decrease in interleukin-2 (IL-2) production and down-regulation of IL-2 receptor expression. Spleen DC, cultivated with 10 microg/ml of fatty acids down-regulated the expression of CD86 and the production of IL-12, but up-regulated the production of IL-10. In contrast, DC, pretreated with 100 microg/ml of 3,10-DDA, up-regulated the expression of CD86 and augmented the proliferation of allogeneic T cells. The highest dose (200 microg/ml) of both fatty acids which was non-apoptotic for both T cells and DC, down-regulated the expression of MHC class II and CD86, decreased the production of IL-12 and made these DC less allostimulatory. The immunosuppressive activity of 3,10-DDA was also confirmed in vivo, using a model of Keyhole lymphet hemocyanine immunization of rats. In conclusion, our results showed the immunomodulatory activity of RJ fatty acids and suggest that DC are a significant target of their action.

Extended longevity of queen honey bees compared to workers is associated with peroxidation-resistant membranes

In the honey bee (Apis mellifera), depending on what they are fed, female eggs become either workers or queens. Although queens and workers share a common genome, the maximum lifespan of queens is an order-of-magnitude longer than workers. The mechanistic basis of this longevity difference is unknown. In order to test if differences in membrane composition could be involved we have compared the fatty acid composition of phospholipids of queen and worker honey bees. The cell membranes of both young and old honey bee queens are highly monounsaturated with very low content of polyunsaturates. Newly emerged workers have a similar membrane fatty acid composition to queens but within the first week of hive life, they increase the polyunsaturate content and decrease the monounsaturate content of their membranes, probably as a result of pollen consumption. This means their membranes likely become more susceptible to lipid peroxidation in this first week of hive life. The results support the suggestion that membrane composition might be an important factor in the determination of maximum lifespan. Assuming the same slope of the relationship between membrane peroxidation index and maximum lifespan as previously observed for mammal and bird species, we propose that the 3-fold difference in peroxidation index of phospholipids of queens and workers is large enough to account for the order-of-magnitude difference in their longevity.

From the linden flower to linden honey--volatile constituents of linden nectar, the extract of bee-stomach and ripe honey

Honey is produced by honeybees (Apis mellifera), which collect nectar from flowers, digest it in their bodies, and deposit it in honeycombs, where it develops into ripe honey. We studied the evolution of the volatile constituents from the nectar of linden blossoms (Tilia cordata) to honey via the 'intermediate' honeybee. The sampling of the contents of the honey stomach or honey sack of the bee is unique. Extracts were prepared from nectar, from the liquid of the honey stomach, and from ripe honey. The chemistry is extremely complex, and compounds spanning from monoterpenes (hydrocarbons, ethers, aldehydes, acids, and bifunctional derivatives), isoprenoids, aromatic compounds (phenylpropanoids, phenols), and products degraded from fatty acids to alkaloids, were identified. Some compounds definitely stem from the plants, whereas other interesting constituents can be attributed to animal origin. Two derivatives of decanoic acid, 9-oxodec-2-enoic acid (12) and 9-hydroxydec-2-enoic acid, identified in the honey are known to be constituents of the so-called 'Queen's pheromone'. Two metabolites of these acids were identified in the extract of the honey stomach: 8-oxononanal (10), a new natural product, and 8-oxononanol (11). There structures were confirmed by synthesis. Nectar and honey stomach contain many aldehydes, which, due to the highly oxidative atmosphere in the honeycomb, are found as corresponding acids in the honey. Two acids were newly identified as 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid (14) and 4-(1-hydroxy-1-methylethyl)-cyclohexa-1,3-diene-1-carboxylic acid (15).

Isolation and characterization of some hydroxy fatty and phosphoric acid esters of 10-hydroxy-2-decenoic acid from the royal jelly of honeybees (Apis mellifera)

The present work characterizes novel FA in the royal jelly of honeybees (Apis mellifera). TLC analysis showed that the chloroform/methanol extract obtained from royal jelly consists mainly of FA. The FABMS spectrum of this extract gave several ion peaks due to compounds with higher M.W. than those of the FA so far reported. The methanol extract was found to contain unknown phospholipids. By means of reversed-phase HPLC with various solvent systems, 13 compounds were obtained in pure state. Their structures including absolute configurations were determined by chemical, NMR, and MS spectral analysis. Six compounds were identified as novel mono- or di-esters of 10-hydroxy-2E-decenoic acid in which the hydroxyl group was esterified by another FA unit, and one was hydroxy-2E-decenoic acid 10-phosphate. In addition, we demonstrated that 9-hydroxy-2E-decenoic acid exists as a mixture of optical isomers.

Towards royal jelly proteome

The recent availability of the honey-bee Apis mellifera genome and trascriptome of both the female castes, has stimulated new efforts in investigating the protein composition of royal jelly (RJ), its role in caste differentiation and its quality and typicality by a proteomic approach. This study is aimed both to separate and identify proteins of royal jelly and to detect some of them in honey-bee pollen-bread by using two-dimensional gel electrophoresis, mass spectrometry and by de novo sequencing. All the identified proteins belonged to the Apis mellifera genome. Apalbumin 1 was also confirmed to be present in honey-bee pollen-bread where the presence of apalbumin 2 was also found. In addition several fragments of apalbumin 1 and apalbumin 3 were also found in RJ. These could be the result of protease activity other than that of serine-protease. This study is a contribution to the description of royal jelly proteome.

Components of Honeybee Royal Jelly as Deterrents of the Parasitic Varroa Mite, Varroa destructor

The parasitic mite Varroa destructor Anderson & Trueman reproduces on the immature stage of the honeybee, Apis mellifera L. Mites are found more often on drone brood than worker brood and only infrequently on queen brood. We investigated the chemical basis for the low incidence of mites on queen brood. V. destructor mites were deterred by a crude extract of royal jelly, a glandular secretion produced by nurse bees and fed to queen larvae. Bioassay-driven fractionation of the crude extract via column chromatography resulted in one active fraction that was as active as the crude extract. Compounds in the active fraction were identified using gas chromatography (GC) and coupled gas chromatography/mass spectrometry (GC-MS). Before injection, compounds were esterified with MeOH/sulfuric acid, followed by silylation of any hydroxyl groups present. The active fraction contained at least 22 compounds, all fatty acids, several of which contained an additional hydroxyl group on the alkyl chain. Synthesis of some of these compounds that are not commercially available is described. A synthetic mixture containing most of the compounds in the active fraction was as active as the active fraction in the bioassay.