Over 600 research papers have been published on variants of custard apples, yet few know about these amazing fruits. Most of the medicinal research conducted has concentrated on its anti-cancer properties due to a class of compounds called acetogenins which are specific to various plant organs of the Annonaceae family of custard apples.
Custard Apples are a sub-tropical deciduous tree belonging to the Annonaceae family. This family contains over 2000 members spread throughout the world. Of this family, it is the atemeoya, a hybrid of the Annona genus, that Australia’s commercial cultivars derive from.
The custard apple and its bizarre looking relatives (such as atemoya and sweetsop) are strictly tropical but the paw paw from can be grown in several U.S. states including California and Florida. If you live outside the tropics, rest assured that there’s a custard apple for you too!
The bioactive phytochemicals in custard apple are those that are related to its health and medicinal activity. The phytochemicals are mainly phenolic and flavonoid compounds, which are largely responsible for antioxidant activity. These bioactive compounds can vary widely within Annona hybrids.
Anti-Obese Effects
Several studies have examined why villagers on the island of Okinawa have extended longevity. These studies involved large scale screening of Okinawan plant foods to determine factors associated with the prevention of fat cell growth and promotion of fat digestion. Custard apple was listed as one of the foods with strong anti-obese activity. Custard apple is regularly consumed by the Okinawan population. The consumption of ethanol extracts of fresh custard apple fruit is associated with lowered plasma triglyceride concentrations by 65% of subjects fed a moderately high fat diet for four weeks and exhibited a potent inhibitory effect on reducing fat tissue by about 20%.
Anti-Diabetic and Haemoglobin Effects
Anti-diabetic properties of custard apples appear to be related to stimulation of insulin production and enhanced uptake of glucose by muscles leading to stabilisation of blood sugar concentrations. Studies in rabbits showed that 5g of semi-dried pulp of custard apple per kg of body weight was effective as an anti-diabetic treatment.
Rabbit studies that feeding custardsugar apple (Annona squamosa) pulp increased haemoglobin levels by up to 21% (Figure 8). This response, if translated to humans, could provide a significant boost to an athlete’s performance.
Anti-Cancer Properties
Difficulties with most of the chemotherapeutic drugs emanate from their concurrent eradication of normal healthy cells, including those responsible for immunity. Tumor cells grow and replicate more rapidly than normal cells. This is because they are better equipped to receive glucose, a good source of energy for fast replication. Also, cancer cells quickly develop a network of blood vessels (angiogenesis) to ensure an efficient supply of nutrients and oxygen. This is partly why cancer patients lose weight; the cancer cells rapidly take up nutrients meant for normal cells. Furthermore, with chemotherapy cancer cells develop resistance to the drugs, rendering chemotherapy useless and futile after a period of remission.
Cancer cells smartly find a way of protecting themselves from the damaging effects of drugs. They generate what is called the ABC transporter superfamily, which transports a variety of substrates including amino acids, sugars, inorganic ions, polysaccharides, peptides, and proteins into the cells. In cancer cells, a member of this superfamily, called the multidrug resistant (MDR) protein, is overexpressed and helps to pump drugs out of the cancer cells, making the cancer cells simultaneously resistant to a variety of drugs. Thus, the cancer cells are protected from the toxic effects of drug combinations.
The anti-cancer properties of custard apple appear to be mainly due to a class of compounds called acetogenins. T hroughout the 1990s, a team of researchers lead by Professor Jerry McLaughlin at Purdue University, in West Lafayette, Indiana, and another team at Kaohsiung Medical University, Kaoshiung Taiwan had evaluated the structure and anti-cancer properties of acetogenins.
To date, over 400 acetogenins have been identified and currently the Annonaceae remain a “hot’ family for the discovery of new anti-cancer therapeutic agents. Chinese and Taiwanese universities have successfully synthesized a range of these acetogenins.
Bullatacin, isolated from the fruit of custard apple, is one of the most potentially effective antitumor acetogenins. Bullatacin is 258 times more cytotoxic against breast cancer cells than adriamycin.
The Annonaceae family also shows excellent anti-microbial, anti-viral and anti-fungal activity from the essential oils of leaves, flowers and fruit.
Few fruits have the wide range of bioactivity exhibited by custard apple fruit even those that are already considered superfruits such as blueberry and pomegranate. Even though there have been limited animal and human studies, custard apple fruit appear to be have excellent health and medicinal benefits which deserve to be further explored. Compared with other fruits, custard apple could be classed as one of the new super fruits.
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