Kentucky State University
Heat Stability of Annonaceous Acetogenin Activity in Pawpaw (Asimina triloba) Fruit Pulp
Institution
Kentucky State University
Faculty Advisor/ Mentor
Kirk Pomper; Jeremiah Lowe; Sheri Crabtree
Abstract
The North American pawpaw [Asimina triloba (L.) Dunal] is a tree fruit that is native to Kentucky which contains Annonaceous acetogenins in the twigs and ripe fruit. Annonaceous acetogenins are a large class of unique structurally homogenous polyketide (C32 or C34 fatty acid) compounds found in plants in the Annonaceae family. They are potent inhibitors of mitochondrial (complex I) as well as cytoplasmic (anaerobic) production of adenosine triphosphate (ATP) and related nucleotides. Acetogenins have antitumor, pesticidal, antimalarial, antiviral, and antimicrobial activity, suggesting many potentially useful applications. There has been a concern that these acetogenin compounds may not be stable with heating above 50 C; heating of extracts with sugars from the fruit could also lead to problems of caramelization. Our working hypothesis was that heating pawpaw fruit extracts above 50 C would reduce acetogenin activity in the extracts. The objective of this study was to determine the heat stability of acetogenin compounds. Ripe pawpaw pulp was extracted with 95% ethanol or 95% ethanol followed by a long enrichment protocol to increase acetogenin concentration and reduce sugar content; thereby reducing caramelization. The extracts were heated to 30, 65, or 100 C for 16 hours. The Brine Shrimp Test (BST) bioassay was employed to assess acetogenin activity of the extracts. Brine shrimp mortality at 0, 0.5, 5, and 10 ppm of extract were determined after 48 hours and the LC50 for each treatment determined.
Heat Stability of Annonaceous Acetogenin Activity in Pawpaw (Asimina triloba) Fruit Pulp
The North American pawpaw [Asimina triloba (L.) Dunal] is a tree fruit that is native to Kentucky which contains Annonaceous acetogenins in the twigs and ripe fruit. Annonaceous acetogenins are a large class of unique structurally homogenous polyketide (C32 or C34 fatty acid) compounds found in plants in the Annonaceae family. They are potent inhibitors of mitochondrial (complex I) as well as cytoplasmic (anaerobic) production of adenosine triphosphate (ATP) and related nucleotides. Acetogenins have antitumor, pesticidal, antimalarial, antiviral, and antimicrobial activity, suggesting many potentially useful applications. There has been a concern that these acetogenin compounds may not be stable with heating above 50 C; heating of extracts with sugars from the fruit could also lead to problems of caramelization. Our working hypothesis was that heating pawpaw fruit extracts above 50 C would reduce acetogenin activity in the extracts. The objective of this study was to determine the heat stability of acetogenin compounds. Ripe pawpaw pulp was extracted with 95% ethanol or 95% ethanol followed by a long enrichment protocol to increase acetogenin concentration and reduce sugar content; thereby reducing caramelization. The extracts were heated to 30, 65, or 100 C for 16 hours. The Brine Shrimp Test (BST) bioassay was employed to assess acetogenin activity of the extracts. Brine shrimp mortality at 0, 0.5, 5, and 10 ppm of extract were determined after 48 hours and the LC50 for each treatment determined.