Friday, November 16, 2018

Article Index

7.0 Bioactive Phytochemicals

7.1 Phytochemicals

The bioactive phytochemicals in custard apple are those that are related to its health and medicinal activity.  These phytochemicals are mainly phenolic and flavonoid compounds, which are largely responsible for antioxidant activity.  These bioactive chemicals can vary widely within Annona spp. hybrids (Noichinda et al., 2009).  

The bioactive chemicals in custard apple and closely related species have been evaluated in many studies (Bhakuni, et al. 1972; Idstein et al.1985; Bartley, 1987; Wylie et al. 1997; Rios et al. 2003, Yu, et al. 2005, Pino et al. 2006; Noichinda et al., 2009).  

To date, the main bioactive phytochemicals found in Annona spp. fruit include:

  • Acetogenins - polyketide fatty acids (>300)
  • Aliphatic ketones e.g. palmitone
  • Alkaloids (>32)
    • aporphine
    • benzylisoquinolines
    • protoberberine
    • tetrahydroisoquinolines
  • Benzenoids (>19)
  • Cyclic peptides
  • Essential oils (>60)
  • Lignans (>15)
  • Long chain fatty acids (oleic, linoleic, palmitic, stearic found in seed)
  • Organic acids (47) hexanoic, and octanoic
  • Terpenoids,
    • monoterpenoids (>60%)
    • diterpenoids
    • kauranes (72)
    • sesquiterpenoids
  • Purines
  • Steroids
  • Tryptamine-derived amides
  • Volatiles (>180)

7.2 Volatiles and flavour components

Several studies (Bartley, 1987; Wong and Khoo, 1993; Wylie et al. 1997; Andrade et al., 2001; Rios et al. 2003; Yu, et al. 2005; Pino et al. 2006; Shashirekha, et al. 2008) have reported on the major volatiles found in custard apple fruit and closely related species.  These are presented below.

  • α-pinene
  • β-pinene
  • limonene
  • bornyl acetate
  • germacrene D

The volatile compound found in greatest concentration in custard apple fruit is pinene, a bicyclic terpene known as a monoterpene.  There are two structural isomers found in nature: α-pinene and β-pinene.  As the name suggests, both forms are important constituents of pine resin; they are also found in the resins of many other conifers, and more widely in other plants. 

7.3 Acetogenins

One class of chemicals which sets custard apple apart from other fruit species is the presence of acetogenins (McLaughlin, 2008).  The acetogenins are unique to the Annonaceous family and in in vitro and in vivo studies appear to have considerable anti-cancer properties (see later sections).  Many of the compounds appear to have multiple physiological activity e.g. some acetogenins have both anti-cancer and anti-hypertensive activity. 

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