A Preliminary Study of Chemical Profiles of Honey, Cerumen, and Propolis of the African Stingless Bee Meliponula ferruginea

Abstract

Recently, the honey and propolis of stingless bees have been attracting growing attention because of their health-promoting properties. However, studies on these products of African Meliponini are still very scarce. In this preliminary study, we analyzed the chemical composition of honey, two cerumen, and two resin deposits (propolis) samples of Meliponula ferruginea from Tanzania. The honey of M. ferruginea was profiled by NMR and indicated different long-term stability from Apis mellifera European (Bulgarian) honey. It differed significantly in sugar and organic acids content and had a very high amount of the disaccharide trehalulose, known for its bioactivities. We suggested trehalulose to be a potential marker for African stingless bee honey analogously to the recent proposal for Meliponini honey from Asia, South America, and Australia and demonstrated its easy discrimination by ¹³C NMR. Propolis and cerumen were studied by GC-MS (gas chromatography-mass spectometry). The samples contained mainly terpenoids (di-and triterpenes) but demonstrated qualitative and quantitative differences. This fact was an indication that possibly M. ferruginea has no strict preferences for resins used to construct and protect their nests. The antimicrobial and anti-quorum sensing properties of the two materials were also tested. These first results demonstrated that the honey, cerumen, and propolis of African stingless bees were rich in biologically active substances and deserved further research.

Keywords: African Meliponini; anti-quorum sensing; antimicrobial; cerumen; chemical profiling; pot-honey; propolis; stingless bees.

Figure 1

Quantities of honey components (in g/100 g) in M. ferruginea honey (TZ_1), M. ferruginea honey after 18 months of storage (TZ_18), and Bulgarian honey (BG) (average values of 10 samples). Acronyms: Ala—Alanine; Gln—Glutamine; Glp—Pyroglutamic acid; Ile—Isoleucine; Pro—Proline; Tyr—Tyrosine; Val—Valine; AA—Acetic acid; CitA—Citric acid; FoA—Formic acid; LA—Lactic acid; MalA—Malic acid; PyrA—Pyruvic acid; ShA—Shikimic acid; SucA—Succinic acid; 2,3Bd—2,3 Butanediol; EtOH—Ethanol; Q—Quercitol; F—Fructose; G—Glucose; Gb—Gentiobiose; Ima—Isomaltose; IMu—Isomaltulose; Kb—Kojibiose; Lu—Leucrose; Ma—Maltose; Mu—Maltulose; Ng—Nigerose; Su—Sucrose; Tru—Trehalulose; Tu—Turanose; ααTr—ααTrehalose; αβTr—αβTrehalose; Er—Erlose; 1-Ks—1-Kestose; Mr—Maltotriose; Mz—Melezitose; Pa—Panose; Rf—Raffinose; HMF—5-Hydroxymethylfurfural; Tri—Trigonelline; Urd—Uridine; U—Unknown.

Figure 2

Antibiofilm activity of propolis and cerumen extracts. Note: S. a. (S. aureus ATCC 25923); E. f. (E. faecalis ATCC 29212); L. m. (L. monocytogenes ATCC 7644); C. a. (C. albicans ATCC 10239); E. c. (E. coli ATCC 25922); P. a. (P. aeruginosa ATCC 27853); S. t. (S. typhi ATCC 14028).

Figure 3

Nightingale’s diagrams for the average content of studied components in M. ferruginea (TZ) and Bulgarian A. mellifera honeys (BG). Acronyms according to Figure 1.

Figure 4

Anomeric ¹³C NMR signals in the region 96–105 ppm of M. ferruginea honey (TZ_1) and A. mellifera honey (BG_P5) with anomeric signals of trehalulose indicated.

Figure 5

Nightingale’s diagrams illustrating the change in the quantities of the components studied in M. ferruginea honey after 18 months (TZ_1 vs. TZ_18). Acronyms according to Figure 1.

Figure 6

(A). Principal component analysis (PCA) score plot of honey samples based on chemical composition. (B). Dendrogram of honey samples constructed in chemical composition.

Figure 6

(A). Principal component analysis (PCA) score plot of honey samples based on chemical composition. (B). Dendrogram of honey samples constructed in chemical composition.