Cerumen of Australian stingless bees (Tetragonula carbonaria): gas chromatography-mass spectrometry fingerprints and potential anti-inflammatory properties

Abstract

Cerumen, or propolis, is a mixture of plant resins enriched with bee secretions. In Australia, stingless bees are important pollinators that use cerumen for nest construction and possibly for colony's health. While extensive research attests to the therapeutic properties of honeybee (Apis mellifera) propolis, the biological and medicinal properties of Australian stingless bee cerumen are largely unknown. In this study, the chemical and biological properties of polar extracts of cerumen from Tetragonula carbonaria in South East Queensland, Australia were investigated using gas chromatography-mass spectrometry (GC-MS) analyses and in vitro 5-lipoxygenase (5-LOX) cell-free assays. Extracts were tested against comparative (commercial tincture of A. mellifera propolis) and positive controls (Trolox and gallic acid). Distinct GC-MS fingerprints of a mixed diterpenic profile typical of native bee cerumen were obtained with pimaric acid (6.31 ± 0.97%, w/w), isopimaric acid (12.23 ± 3.03%, w/w), and gallic acid (5.79 ± 0.81%, w/w) tentatively identified as useful chemical markers. Characteristic flavonoids and prenylated phenolics found in honeybee propolis were absent. Cerumen extracts from T. carbonaria inhibited activity of 5-LOX, an enzyme known to catalyse production of proinflammatory mediators (IC₅₀ 19.97 ± 2.67 μg/ml, mean ± SEM, n = 4). Extracts had similar potency to Trolox (IC₅₀ 12.78 ± 1.82 μg/ml), but were less potent than honeybee propolis (IC₅₀ 5.90 ± 0.62 g/ml) or gallic acid (IC₅₀ 5.62 ± 0.35 μg/ml, P < 0.001). These findings warrant further investigation of the ecological and medicinal properties of this stingless bee cerumen, which may herald a commercial potential for the Australian beekeeping industry.

Mechanisms of action underlying the anti-inflammatory and immunomodulatory effects of propolis: a brief review

“…However, oral administration of the extracts did not affect the ex vivo production of PGE 2 , but increased the production of leukotrienes and prostaglandins by peritoneal macrophages (Mirzoeva & Calder, 1996). Massaro et al (2011) suggests a potential of cerumen (stingless bees propolis) for preventing the lipid oxidation of linoleic acid, thus protecting the integrity of cell membranes.…”

“…Some specific effects of the aqueous extract of propolis have been demonstrated, such as the inhibition of platelet aggregation, inhibition of prostaglandin biosynthesis in vitro, prevention of formaldehyde-induced paw edema and arthritis and inhibition of 5-lipoxygenase (5-LOX) activity (Dobrowolski et al, 1991;Khayyal et al, 1993;Massaro et al, 2011). In addition, propolis has shown in vitro free radical scavenging activity and a hepatoprotective effect on TNF-α-induced cell death (Banskota et al, 2000;Alencar et al, 2007).…”

In vitro and in vivo characterization of the anticancer activity of Thai stingless bee (Tetragonula laeviceps) cerumen

“…4 Cerumen is not only the main component of storage pots and brood cells, but it is also the material used for involucrum, a cerumen sheet that covers the brood section to control the temperature and protect the brood cells. The products of honey bees, including stingless bees, such as honey, propolis, wax, pollen, and venom, have been reported to have many bioactivities and pharmaceutical benefits, including anti-viral, 5 antimicrobial, 6 anti-oxidant, 7 anti-inflammatory, 8 anti-cholesterol, 9 and antiproliferative activities. 10 In addition, interest in the potential bioactivity of mixed bee products, such as geopropolis and cerumen, has increased.…”

Stingless Bee Honey, the Natural Wound Healer: A Review

“…The functions of these products are slightly different, where the cerumen is used as a storage pot for the honey and to mummify trespassers as well as to ensure that the environment in the hive is sterile, while the propolis is used as an internal layer and for sealing the extra space surrounding the hexagon-shaped nest combs. Consequently, due to the storage of honey in the cerumen pots, the quality of the stingless bee honey is influenced by the infiltration of phytochemicals from the cerumen [10,11]. …”