Kamehameha Schools, Kapālama Campus, Grade 12

 

The purpose of phase II of this project is to isolate and pursue the identification of the biologically active component in Vaccinium reticulatum, commonly known as ‘ōhelo, responsible for significant inhibition of bacterial growth. Historical accounts confirm that the leaves of ‘ōhelo were made into a tea and administered to patients to treat throat congestion by Hawaiian medicinal practitioners or kahuna la‘au lapa‘au. Therefore, the leaves were the source for the extract solubilized in ethanol (EtOH) used for biological and analytical testing in phase I. The ‘ōhelo extract produced prominent inhibition zones against both gram-positive and gram-negative bacteria, some of which surpassed the inhibiting abilities of penicillin. These results in relation to the emerging concern that gram-positive antibacterial agents are rare and those bacteria that can be subdued are developing an increasing resistance to those antibiotics led to the second phase. Thin layer chromatograms (TLC) were conducted to separate the individual banding using partitioning which make up the ‘ōhelo extract. Individual fractionated extracts from TLC plates are removed, resolubilized in EtOH and the silica removed using a centrifuge, creating individual extracts per fraction. Using suspension cultures of B. subtilis, the six fractions were tested for biological activity. Of six fractions, one fraction produced an absorbance reading and thus similar inhibiting capabilities as the original ‘ōhelo extract against Bacillus subtilis, indicating the bioactive component is within that particular fraction. Current experimentation regards attempting to concentrate this fraction in order to identify the molecular structure of the component(s) responsible for the inhibition of bacterial growth using nuclear magnetic resonance and mass spectrometry. If the component of interest can be identified and synthetically replicated, it could significantly reduce the growing epidemic of antibiotic-resistant bacteria.