Diabetes
mellitus and its associated complications (cardiovascular, renal, hepatic,
ophthalmic, neurological, and osteopathic-, endothelial-, and
sexual-dysfunction, etc.) remain a burden worldwide in spite of the
availability of a number of anti-diabetic drugs, many of which have adverse
effects. There is a trend towards using natural products to control
hyperglycemia and associated pathologies. Propolis, an apiproduct used by the
honeybees as a sealant, has been rediscovered as a medicinal agent, reported
to be of benefit in the treatment of allergies, bruises, burns, ulcers,
sunburn, wounds, tumors, fatigue, sore throat, nasal congestion, respiratory
ailments, flu, colds, acne, skin disorders, and shingles. Propolis consists
of plant resins, balsams, wax, bee pollen and essential oils. The composition
of propolis (of different colors) depends on the phytogeographical location,
seasonal collection time, and botanical source. It is reported to contain
more than 300 natural compounds such as polyphenols, phenolic aldehydes,
sesquiterpene-quinones, coumarins, amino acids, steroids and inorganic
compounds. Propolis is reported to have anti-angiogenic,
antihypercholesterolemic, antihypertensive, anti-inflammatory, antimicrobial,
antioxidant, anti-parasitic, anti-septic, anti-tumor, antiulcer, anti-viral,
immune-stimulatory properties, and hepato-, cardio-, and neuro-protective
actions. Diabetes and pathologies associated with it are mainly due to
inflammation and oxidative stress, as a result of elevated levels of reactive
oxygen species (ROS), which cause lipid peroxidation and protein oxidation.
The anti-oxidant, oxygen radical scavenging activity of propolis (and its
extracts) is mainly due to the presence of phenolics and flavonoids.
The beneficial effects of
propolis in diabetes have been confirmed by a number of studies in
experimental animals. For example, propolis given orally to rats with streptozotocin (STZ)-induced diabetic
rats significantly decreased plasma insulin and insulin resistance, reduced glycated hemoglobin, suppressed
elevated hepatic enzymes, and increased hepato-renal glutathione peroxidase
levels. An
ethanolic extract of propolis administered to STZ-induced diabetic rats,
reversed body and kidney weight loss, improved serum glucose and lipid
profile, and renal function tests, as well as decreased oxidative damage
[increased superoxide dismutase, glutathione,
catalase and decreased malondialdehyde (MDA)] in the renal and pancreatic
tissue. Similar results were obtained by us using Moroccan propolis in
STZ-diabetic rats and diabetic 2 rats. The protective role of propolis against the
ROS induced damages in diabetic rats and nephrotoxicity models gives hope
that they may have similar protective action in humans.
These studies in humans and in
experimental model of diabetes in rats, provide a basis for therapeutic use
of beehive products. Furthermore, several studies, including ours, have
revealed that the observed beneficial effects of beehive products may be as a
result of synergistic action of several constituents.
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