Kentucky State University

Poster Title

The Influence of Light Level on Annonaceous Acetogenin Activity in Pawpaw (Asimina triloba) Stem Tissue

Institution

Kentucky State University

Abstract

The pawpaw [Asimina triloba (L.) Dunal] is a native Kentucky tree fruit which contains Annonaceous acetogenins in the twigs and fruit which display antitumor and pesticidal effects. This tree is usually found in the forest understory and prefers growing in low light conditions. Our working hypothesis was that high light levels stress the pawpaw plant and induce high acetogenin activity in the stem tissue. Higher extractable acetogenin levels would be desirable for future product development. The objective of this study was to determine if there was a positive correlation between increased light level and acetogenin activity in the stems of pawpaw seedlings. Three month old greenhouse grown seedlings were subjected to three light treatments using no shade cloth (100% ambient light), 35% shade cloth (65% ambient light), and 80% shade cloth (20% ambient light). A randomized block design was used in the experiment with three replicate seedlings in each treatment in three replicate blocks (3 plants x 3 treatments x 3 blocks) for a total of 27 plants. The plants were destructively harvested after 6 weeks; stems were dried at 50o C, ground, and extracted with 95% ethanol. The Brine Shrimp Test (BST) was employed to assess acetogenin activity of the pawpaw extracts at 0, 5, 10, 50, and 100 ppm of extract after 48 hours exposure and the LC50 for each treatment was determined.

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The Influence of Light Level on Annonaceous Acetogenin Activity in Pawpaw (Asimina triloba) Stem Tissue

The pawpaw [Asimina triloba (L.) Dunal] is a native Kentucky tree fruit which contains Annonaceous acetogenins in the twigs and fruit which display antitumor and pesticidal effects. This tree is usually found in the forest understory and prefers growing in low light conditions. Our working hypothesis was that high light levels stress the pawpaw plant and induce high acetogenin activity in the stem tissue. Higher extractable acetogenin levels would be desirable for future product development. The objective of this study was to determine if there was a positive correlation between increased light level and acetogenin activity in the stems of pawpaw seedlings. Three month old greenhouse grown seedlings were subjected to three light treatments using no shade cloth (100% ambient light), 35% shade cloth (65% ambient light), and 80% shade cloth (20% ambient light). A randomized block design was used in the experiment with three replicate seedlings in each treatment in three replicate blocks (3 plants x 3 treatments x 3 blocks) for a total of 27 plants. The plants were destructively harvested after 6 weeks; stems were dried at 50o C, ground, and extracted with 95% ethanol. The Brine Shrimp Test (BST) was employed to assess acetogenin activity of the pawpaw extracts at 0, 5, 10, 50, and 100 ppm of extract after 48 hours exposure and the LC50 for each treatment was determined.