| The Honeycomb is a part of the hive,and it is an important place for bees to inhabit,breed,and store and brew food.Propolis plays an important role in maintaining the clean environment of the honeycombs and the health of bees.Apis cerana does not produce propolis.Its mechanism to inhibit the reproduction of microorganisms,keep the environment clean,and maintain the healthy growth of eggs and larvae has not been reported in the literature.We speculate that compared with A.mellifera hongycomb(AMC),the specific or higher content of compounds in A.ceranae honeycomb(ACC)may play a role in keeping the honeycomb clean and inhibiting the reproduction of microorganisms.Therefore,this paper used ACC and AMC as research materials.Solid-phase microextraction-gas mass spectrometry(SPME-GC-MS),high-performance liquid chromatography(HPLC-UV),ultra-high liquid chromatography-Quadrupole time-of-flight mass spectrometry(UPLC-QTOF-MS),ultraviolet-visible spectrophotometer were used to identify the volatile and non-volatile matter in ACC and AMC.Combining fingerprints,principal component analysis(PCA),and orthogonal partial least square discriminant analysis(OPLS-DA)to explore the difference in chemical composition between ACC and AMC.The anti-oxidation ability of ACC and AMC were evaluated by DPPH method.The antibacterial activity of ACC,AMC,and tricoumaroyl spermidine were measured by filter paper diffusion method.The main conclusions are as follows:1.A total of 114 volatile components(VOCs)were found and identified in the honeycomb by SPME-GC-MS,including 11 aldehydes,13 hydrocarbons,11 ketones,26 ester,38 terpenes,3 alcohols,12 others.The main components of ACC included 2-phenylethanol,trans-linalool oxide,and linalool oxide.The main components of AMC included octanal,linalool oxide.PCA and OPLS-DA analysis found a total of 20 different components of ACC and AMC.Among them,the contents of linalool,lilac aldehyde A,ocimene,α-terpineol,limonene,decanal,benzaldehyde,ethyl octoate,octanal,dehydro-ar-ionene,acetyl furan,and α-cedrene in AMC were significantly higher than those in ACC(p<0.05).The content of 2-phenylethanol,dihydrooxophorone,ethyl phenacetate,ethyl palmitate,betula,phenethyl acetate,isophorone,and 4-Oxoisophorone in ACC was significantly higher than that in AMC(p<0.05).2.The total phenols and total flavonoids in AMC are higher than ACC.HPLC-UV combined with 25 standard for qualitative and quantitative analysis,3,4-dimethoxycinnamic acid,apigenin,chrysin,galangin,biochanin A,phenethyl caffeate,chlorogenic acid,p-hydroxybenzoic acid and trans-4-hydroxycinnamic acid were significantly higher than ACC in AMC(p<0.05).Fingerprint and PCA analysis show that there is a significant difference in chemical composition between ACC and AMC.Among them,tricoumaroyl spermidine is the main component of ACC,which is significantly higher than AMC(156.84 μg/g)in ACC(296.40 μg/g)(p<0.05).3.UPLC-QTOF-MS combined 43 standards,literature and online databases,and identified 88 compounds from two kinds of honeycomb,including 18 phenolic acids and derivatives,35 flavonoids,14 fatty acids,16 nitrogen compounds and 5 other compounds.PCA and OPLS-DA were used to analyze the difference.When ANOVA p≤0.05,Max fold change ≥2 and VIP≥2,ACC and AMC have 10 different compounds.The content of AMP and tricoumarol spermidine were higher in ACC.Glucose-1-phosphate,uridine diphosphate glucose,sakuranetin,apigenin,pinobanksin,chrysoeriol,pinocembrin,phenethyl caffeate,pinobanksin-3-acetate and galangin-5-methyl ether are higher in AMC.4.The results of DPPH free radical scavenging ability show that the DPPH free radical scavenging ability of AMC is better than that of ACC,and the antioxidant capacity is positively correlated with the total phenol content.The results of the antibacterial activity test showed that ACC and AMC have certain antibacterial effects on Escherichia coli,Pseudomonas fluorescens,Staphylococcus aureus and Bacillus subtilis.The antibacterial effect of AMC on E.coli and P.fluorescens is significantly stronger than ACC(p<0.05),but there is no significant difference between ACC and AMC on S.aureus,B.subtilis.tricoumarol spermidine has an inhibitory effect on E.coli,B.subtilis and P.fluorescens,and may be one of the effective antibacterial compounds of ACC.In summary,A.mellifera produces propolis.Propolis will increase the total phenols,total flavonoids and phenolic compounds in AMC,and at the same time enhance the antioxidant and antibacterial capabilities of AMC.A.ceranae does not produce propolis,and ACC also had strong antioxidant and antibacterial activities.ACC contains higher content of volatile and non-volatile substances such as 2-phenylethanol,phenethyl acetate,tricoumarol spermidine,AMP,etc.These compounds may play an important role in maintaining the cleanliness of ACC and enhancing the immunity of bees. |
