Ramit Singh1 and Dr. Noyingthung Kikon2
Annona muricata L., commonly known as soursop, prickly custard apple, graviola, guanabana, paw-paw and sirsak, is a member of the Annonaceae family comprising approximately 130 genera and 2300 species. The genus name ‘Annona’ is from the Latin word ‘anon’, meaning ‘yearly produce’, referring to the fruit production habits of the various species in this genus. Annona muricata is an evergreen plant native to the warmest tropical areas in South and North America and is now widely distributed throughout the world, including India, Malaysia and Nigeria.
It survives in the humid tropical and subtropical climate with mean annual temperature range of 25-30°C and mean annual rainfall above 1000 mm. It can tolerate both drought conditions and partial shade. This fruit crop grows in any kind of soil but prefers loose, fairly rich, deep loam and well-drained soil with pH ranging from 5.5 to 6.5. It thrives well from sea level up to 300 meters above sea level although it is known to grow up to 1000 m. It is commonly cultivated in home gardens, found in rural garden areas and is also grown as an ornamental plant. It is a sweet fruit with lots of health benefits associated with not only the fruit but also other parts of the plant such as the seeds, stem, roots and leaves.
The fruit is very rich in nutrients with high moisture content and are extensively used to prepare syrups, candies, beverages, ice creams and shakes. Different parts of the plant are used for a wide array of ethno medicinal activities and the indigenous communities in Africa and South America extensively use this plant in their folk medicine. Numerous investigations have substantiated these activities, including anticancer, anticonvulsant, anti-arthritic, anti-parasitic, anti-malarial, hepatoprotective and anti-diabetic activities. Phytochemical studies reveal that more than 100 annonaceous acetogenins have been isolated from leaves, barks, seeds, roots and fruits of Annona muricata.
Annona muricata is a slender, evergreen tree, 5-10 m in height and 15 cm in diameter; trunk is straight with dull grey or grey-brown smooth bark and brown or grey spreading branches. Young branchlets are rusty-hairy. Root system is extensive and superficial, spreading beyond the diameter of the crown although juvenile plants have a taproot that is eventually lost. Leaves are alternate, leathery, obovate to elliptic, glossy on top, glabrous on underside, simple with fine lateral nerves.
Solitary flowers emerge anywhere on the trunk, branches or twigs and are 4-5 cm long, and cone shaped, the 3 fleshy outer petals are yellow-green, the 3 inner petals are pale- yellow. Fruit is fairly variable in size, ranging from 10-30 cm long and up to 15 cm in width with an average weight of 1.2 to 1.5 kg per fruit, is covered with a leathery, inedible, bitter skin with flexible spikes and is segmented, with some segments containing a single oval, smooth, hard, black seed 2 cm long and 0.7 cm wide.
Skin of the immature fruit is dark green turning slightly yellowish before maturity. Inside of the skin is cream-colored and granular. Edible part of the flesh is white, fibrous and juicy which separates easily from the rind. Pulp has a sweet and acrid flavor.
Food: Annona muricata can be consumed fresh or made into beverages or dessert when fully ripe or mixed with ice cream or milk to make a delicious drink, as is done in Java and in Cuba and other parts of America. However, more often the puree is consumed after squeezing the pulp through a sieve. It can be made into fruit jelly, juice (with sugar added), nectar or syrup. Young fruits with seeds that are still soft are used as a vegetable. Mature but firm fruits may be made into candy of delicate flavour and aroma.
Timber: Sapwood is whitish and heartwood brown. Wood is soft, light (specific gravity of 0.4), not durable; it is rarely used as timber but has been used for ox yokes.
Ethnomedicinal uses: All portions of the Annona muricata tree, similar to other Annona species, including Annona squamosa and Annona reticulate are extensively used as traditional medicines against an array of human ailments and diseases, especially cancer and parasitic infections. Fruit is used as natural medicine for arthritic pain, neuralgia, arthritis, diarrhea, dysentery, fever, malaria, parasites, rheumatism, skin rushes and worms, it is also eaten to elevate a mother’s milk after childbirth and as remedies against catarrh.
Leaves are employed to treat cystitis, diabetes, headaches, insomnia, as an ethnomedicine against tumors and cancer. Moreover, internal administration of the leaf’s decoction is believed to exhibit anti-rheumatic and neuralgic effects. Crushed seeds are believed to have anthelmintic activities against external and internal worms and parasites. Plant is also used as an astringent, insecticide and piscicide agent and to treat coughs, pain and skin diseases. Root, bark and leaves are believed to have antiphlogistic or anti-inflammantory activities and are also attributed with hypoglycemic, sedative, smooth muscle relaxant, hypotensive and antispasmodic effects.
Potential anti-cancer and anti-proliferative properties: In the recent decades, the cross application of different cancer treatments by integrating natural substances into the established chemotherapy is steadily gaining interest. Plant-derived natural substances have long been targeted to possess capability in controlling cancer cells progression. In fact, majority of the chemo-drug used today are of plant origin. Annona muricata or Graviola has been vastly postulated to own valuable natural products that purportedly play a key role in promoting anticancer activity.
Annona muricata leaves have been subjected to investigation of numerous numbers of human diseases, including cancer. Studies have shown soursop extracts to be active against a range of cancer cell lines, including breast, lung, colon, prostate, liver and skin cancer, although no studies have yet been conducted with humans. The highly sought effects are most probably induced by its major bioactive components known as annonaceous acetogenins (ACGs).
These long chain fatty acids have been widely discussed for its potential in promoting anticancer and anti-proliferative activity towards numerous numbers of cancer cell lines. ACGs promotes cytotoxicity by affecting important process during cell metabolism, ATP generation and NADH oxidation. Traditionally, consuming brewed or crushed leaves and or roots and the fruits is supposed to help cure or prevent spread of cancer however, despite the numerous positive reviews from cancer patients regarding the therapeutic properties of Annona muricata, no human clinical trials have been performed as of yet.
- Ramit Singh is a Ph.D Research Scholar, SASRD, Medziphema.
- Dr. Noyingthung Kikon is JRA, ICAR, Medziphema.