Teas made from the leaves of North American species of Rhododendron have traditionaly been used as medicines by First Nations tribes. Several species have been found to contain potent antioxidants and flavonoids, but further pharmacological research remains to be done. For this reason, Rhododendron flowers were investigated for their anti-bacterial, anti-fungal, hyaluronidase inhibiting, and possible anti-cancer activity. Material from petals, pistils, and stamens was extracted and separated repeatedly using flash chromatography. Antibacterial activity of fractions was assessed by plating against Staphylococcus aureus and Escherichia coli, using ampicillin as a control. Initial tests indicate at least 8 compounds exhibit bactericidal or bacteriostatic activity against S. aureus. Anti-fungal and possible anti-cancer activity was assessed by small-scale culture with Pythium ultimum. Three fractions entirely prevented P. ultimum growth after 5 days. General hyaluronidase inhibition may slow some cancers, and PH20 inhibition in particular may aid in the remyelination of spinal nerve lesions. Hyaluronidase inhibition was tested by determining the relative molecular weight of hyaluronic acid via gel electrophoresis after digestion with bovine testicular hyaluronidase in the presence of extract fractions. Only flavonoid-containing fractions were tested for hyaluronidase inhibition, and 91% of tested fractions showed some inhibition. Active fractions are continuing to be separated using flash chromatography and HPLC. When active compounds are isolated, assays will determine effective concentrations for antibacterial, anti-fungal, or hyaluronidase-inhibiting activity. Those compounds exhibiting hyaluronidase inhibition will be tested in nerve cell cultures for in vivo inhibition and for toxicity levels to human cells.

Antibiotic and hyaluronidase-inhibiting fractions from the Rhododendron flower

253rd National Meeting (2017)

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