Chemical Analyses and Antimicrobial Activity of Nine Kinds of Unifloral Chinese Honeys Compared to Manuka Honey (12+ and 20+)

Honey has good antimicrobial properties and can be used for medical treatment. The antimicrobial properties of unifloral honey varieties are different. In this study, we evaluated the antimicrobial and antioxidant activities of nine kinds of Chinese monofloral honeys. In addition, headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) technology was used to detect their volatile components. The relevant results are as follows: 1. The agar diffusion test showed that the diameter of inhibition zone against Staphylococcus aureus of Fennel honey (21.50 ± 0.41 mm), Agastache honey (20.74 ± 0.37 mm), and Pomegranate honey (18.16 ± 0.11 mm) was larger than that of Manuka 12+ honey (14.27 ± 0.10 mm) and Manuka 20+ honey (16.52 ± 0.12 mm). The antimicrobial activity of Chinese honey depends on hydrogen peroxide. 2. The total antioxidant capacity of Fennel honey, Agastache honey, and Pomegranate honey was higher than that of other Chinese honeys. There was a significant positive correlation between the total antioxidant capacity and the total phenol content of Chinese honey (r = 0.958). The correlation coefficient between the chroma value of Chinese honey and the total antioxidant and the diameter of inhibition zone was 0.940 and 0.746, respectively. The analyzed dark honeys had better antimicrobial and antioxidant activities. 3. There were significant differences in volatile components among Fennel honey, Agastache honey, Pomegranate honey, and Manuka honey. Hexanal-D and Heptanol were the characteristic components of Fennel honey and Pomegranate honey, respectively. Ethyl 2-methylbutyrate and 3-methylpentanoic acids were the unique compounds of Agastache honey. The flavor fingerprints of the honey samples from different plants can be successfully built using HS-GC-IMS and principal component analysis (PCA) based on their volatile compounds. Fennel honey, Agastache honey, and Pomegranate honey are Chinese honey varieties with excellent antimicrobial properties, and have the potential to be developed into medical grade honey.

Royal jelly attenuates nonalcoholic fatty liver disease by inhibiting oxidative stress and regulating the expression of circadian genes in ovariectomized rats

Nonalcoholic fatty liver disease (NAFLD) has a high incidence in postmenopausal women and is accompanied by insulin resistance, obesity, and dyslipidemia. Royal jelly (RJ), a natural substance derived from hive, possesses numerous health-beneficial properties. Here, we evaluated the effects of RJ (150, 300, and 450 mg kg^-1  day^-1 , 8 weeks) on NAFLD in ovariectomized (OVX) rats. Based on the results, RJ ameliorated the degree of anxiety, improved serum lipid profile, and attenuated the hepatic steatosis and liver injury in OVX rats. Furthermore, the protective effects of RJ could be attributed to its antioxidant properties, which enhance the levels of hepatic antioxidant enzymes. The qRT-PCR results also suggest that RJ improves the disturbances of circadian genes by downregulating their expression, including that of Per1 and Per 2, in the liver of OVX rats. Altogether, our findings suggest that RJ may be a promising agent for the treatment of NAFLD. PRACTICAL APPLICATIONS: Postmenopausal women are at an increased risk of NAFLD. Currently, there are no licensed therapies for NAFLD. Although hormone replacement therapy (HRT) is reported to inhibit the development of NAFLD, it causes unexpected adverse effects. As HRT is controversial, the use of natural supplements to counteract the detrimental effects of menopause has recently attracted more attention. RJ is a natural product secreted from the hypopharyngeal and mandibular glands of worker bees. The present study illustrates the protective effect of the natural product, RJ, and its underlying mechanisms on NAFLD. This is the first study to assess the effect of RJ on NAFLD under estrogen deficiency. Such findings contribute to the further utilization of RJ, which might serve as a promising therapeutic option and natural food for the treatment of NAFLD.

Ethanol Extract of Chinese Propolis Attenuates Early Diabetic Retinopathy by Protecting the Blood-Retinal Barrier in Streptozotocin-Induced Diabetic Rats

Propolis has been shown to reduce the level of blood glucose and suppress the histopathological changes in diabetics. However, it still remains unknown if propolis has a similar effect on diabetic retinopathy (DR). Our study aimed to evaluate the effect of the ethanol extract of Chinese propolis (EECP) on early DR in streptozotocin (STZ)-induced diabetic rats. EECP was given to diabetic rats by oral intubation for 12 weeks. The concentrations of fasting blood glucose (FBG), glycated hemoglobin (HbA1c), malondialdehyde (MDA), reactive oxygen species (ROS), and reactive nitrogen species (RNS) were measured. Pathological examinations, including hematoxylin and eosin (HE) staining, transmission electron microscopy (TEM), and immunofluorescence, were also conducted to provide further evidence of EECP's effect on early DR. EECP was able to attenuate diabetes via directly decreasing the levels of FBG and HbA1c, which also resulted in the reduction of MDA, ROS, and RNS. Furthermore, EECP could protect against the damages of photoreceptor cells, as well as retinal thickening. And the inhibition of blood-retinal barrier (BRB) leakage was also observed in EECP-treated diabetic rats, along with the inhibition the loss of tight junction proteins (occludin, ZO-1). These results suggest that EECP has an ameliorating effect on early DR by inhibition of blood-retinal barrier breakdown. PRACTICAL APPLICATION: This study sheds light on the protective effect of the ethanol extract of Chinese propolis on early diabetic retinopathy and the molecular actions underlying the inhibition of blood-retinal barrier breakdown. Our study suggests that ethanol extract of Chinese propolis can be considered as a potential therapeutic agent in the treatment of early diabetic retinopathy.

Authentication of Apis cerana Honey and Apis mellifera Honey Based on Major Royal Jelly Protein 2 Gene

In Asia, honey is mainly produced by Apis mellifera and Apis cerana. However, the price of A. cerana honey is usually much higher than A. mellifera honey. Seeing considerable profits, some dishonest companies and beekeepers mislabel A. mellifera honey as A. cerana honey or incorporate A. mellifera honey into A. cerana honey. In the present study, we developed methods to discriminate A. cerana honey from A. mellifera honey based on the MRJP2 (major royal jelly protein 2) gene. Two pairs of species-specific primers were designed. The amplification products of A. cerana and A. mellifera were 212 and 560 bp, respectively. As little as one percent incorporation of A. mellifera honey in the mixture can be detected by duplex PCR. Additionally, another method based on the melt curve analysis using the same primers was also developed, allowing a rapid discrimination of real-time PCR product of different species. Our study shows that the entomological authentication of honey samples can be identified by nuclear genes other than mitochondrial genes and this extends the possibility of gene selection in identification. The authentication system we proposed could be a useful tool for discriminating A. cerana honey from A. mellifera honey.