In-vitro Antimicrobial Effects and Phytochemical Contents of Stingless Bee Meliponula beccarii Honey and Pollen from Baringo County, Kenya

Abstract

Background: Afro-tropical stingless bees produce several products including honey, propolis, cerumen and pollen, which are widely used as traditional medicine and food. In Baringo County, Kenya stingless bee honey in particular is widely used as a traditional remedy for respiratory disorders, stomach disorders and oral thrush, commonly associated with bacterial and fungal infections. However, scientific data on the antimicrobial activities and phytochemical content of stingless bee products from Baringo is scarce. Objectives: The objective of this study was to investigate the in vitro antimicrobial activities and phytochemical content of Meliponula beccarii stingless bee honey and pollen from Baringo County. Materials and methods: Eleven honey and pollen samples were conveniently sampled from eleven wild occurring stingless bee nests in three ecologically distinct areas. Increasing concentrations of honey and pollen samples were then prepared and tested against H. influenzae, E. coli, MRSA and C. albicans using agar well diffusion assay. The broth microdilution test was further performed to determine the Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs). Standard qualitative methods were used to analyse the phytochemical contents of the honey and pollen samples. Data was analysed by two-way ANOVA and Tukey’s post-hoc tests. Results: in comparison to distilled water (negative control), the honey samples had a significantly higher mean zones of inhibition at concentration of 100% v/v against E. coli (9.0±4.7 mm vs 0 mm, p<0.0001, N=11), H. influenzae (11.1±5.0 mm vs 0 mm, p<0.0001, N=11), and MRSA (10.8±5.9 mm vs 0 mm, p>0.0001, N=11). However, compared to ciprofloxacin standard (30ug/ml), all the concentrations of honey samples had significantly lower mean zones of inhibition against H. influenzae (8.8±2.4 mm vs 25±0.58 mm, p<0.0001, N=11), E. coli (5.7±3.4 mm vs 31.7±1.5 mm, p<0.0001, N=11) and MRSA (8.1±2.8 mm vs 27±0 mm). All the honey samples did not exhibit activity against C. albicans even at 100% (v/v). The mean MICs against E. coli, H. influenzae and MRSA were 9.38% (v/v), 18.75% (v/v) and 18.75% (v/v), respectively. Notably, the honey samples exhibited bactericidal activity, only against MRSA with a mean MBC of 60.94% (v/v). All the pollen samples showed no antibacterial and antifungal activities against the tested micro-organisms. Qualitative analyses revealed that the honey and pollen samples of Meliponula beccarii contain alkaloids, phenolics, triterpenoids, flavonoids, saponins, tannins, glycosides and steroids, but not terpenoids. Conclusion: Some but not all Meliponula beccarii honey samples from Baringo County has antibacterial activities. The honey and pollen are rich in various phytochemical compounds. Our findings validate the use of Meliponula beccarii honey in traditional treatment of bacterial infections and its further investigation as a potential source of novel agents against drug resistant pathogenic bacteria.