| Summary: | 碩士 === 國立中興大學 === 農藝學系所 === 102 === St. John''s wort has been a vary important medicinal plant to alleviate depression and other disorders owing to its abundance of several active ingredients. In order to investigate the optimal conditions for accumulation of active ingredients of St. John''s wort, the variation of
hyperforin, hypericin, melatonin, quercetin and rutin contents of two month-old plants cultivated under 3 levels of temperature, light and nutrient solution have been analysed by HPLC. It reveals that the contents of hyperforin, melatonin and rutin of St. John''s wort has been influenced significantly by temperature and light, whereas with no signifacant effects by nutrient solution. It should be related with applied levels and kinds of nutrient. Based on Response Surface Methodology, the best-fit future direction of optimal conditions for cultivation of St. John''s wort can be derived, respectively.
In the experiments of microwave-assisted extraction, the highest amounts of hyperforin ,hypericin, melatonin, quercetin, and rutin can be obtained from leaves of St. John''s wort under 550 W×60 min ; 300 W× 80 min ; 750 W×40 min ; 1000W×10 min and 100 W×40 min, respectively. The amounts of active ingredients of stems, leaves and flowers of St. John''s wort have been analysed by afore-mentioned method. Besides rutin, the other active compounds occur mainly in leaf and flower tissues of St. John''s wort, especially in flowers. Among different
solvents, methanol and ethanol have shown to be better with microwave-assisted extraction of active ingredients of St. John''s wort.
In addition, three endophytic fungi designated as S-3-A, L-3-B and L-3-C have been isolated from stem and leaf parts of St. John''s wort in bloom. The isolated endophytes were grown in liquid culture with PDB and YMB media for about 50 days. It has been found that these endophytes might posses potential to produce hyperforin and melatonin and other secondary metabolites. It exhibits that this medicinal herb can use this proposed mode of co-existence with endophytes to increase accumulation of certain active ingrediants for
antibacterial and pathogen defense purposes.
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