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We thank Dr. Jerry McLaughlin for help with understanding acetogenin compound action.

Downloaded by UNIV OF KENTUCKY on September 16, 2009 | http://pubs.acs.org Publication Date (Web): August 27, 2009 | doi: 10.1021/jf9018239

fruit tissues (2, 3), but have not previously been reported in the ripe fruit pulp. Pawpaw fruit pulp could serve as a large renewable source of biomass for the extraction of acetogenin compounds. Fruit biomass of >35 lb of fruit fresh weight (9.9 lb of dry weight)/mature tree/year versus about 5 lb of fresh weight (1.8 lb of dry weight) of young twig tissue/mature tree/year (unpublished data) would be possible for some pawpaw genotypes. Additionally, Gu et al. (18) reported seasonal fluctuations in twig acetogenin levels that limited the harvest period for maximum yield of acetogenin compounds. Ripe fruit would provide a renewable source of biomass for extraction of these compounds, and predictable fruit harvest times would facilitate the procurement of large amounts of biomass for extraction. Therefore, ripe pawpaw fruit could represent a more cost-effective source than twigs for extractable acetogenin compounds for commercial products.

There are recent scientific papers suggesting a possible link between the long-term frequent consumption of Annonaceae family fruit and tea in Guadeloupe (20–24), New Caledonia (25), and Caribbean origin populations (26) and a higher rate of atypical Parkinsonism in later life. Acetogenin compounds in the fruit and leaves of these pawpaw relatives may be responsible for the development of atypical Parkinsonism in later life (27, 28). The bioactivity for pawpaw was higher than that of the canned soursop used in this study; however, the canning process may have reduced the bioactivity of the soursop pulp, and fresh fruit was unavailable for comparison.

The consumption of North American pawpaw has not been reported to cause atypical Parkinsonism. Occasional consumption of acetogenin compounds may not induce atypical Parkinsonism in later life (32). Sensitivity to acetogenin compounds may be limited to those with a specific genetic predisposition, and some tau, microtubule-associated proteins, variants may be more vulnerable than others to mitochondrial dysfunction (29). Limited consumption of pawpaw, which is primarily a short-term seasonal event, may avoid increased risk of atypical Parkinsonism. Pawpaw fruit pulp may serve as a new large biomass source for the extraction of acetogenin compounds and points to the need for an assessment of bioavailability and degradation studies in mammals.