Miracle fruit- a boon to sweet-toothed diabetics and dieters
Miracle fruit is the fruit of Synsepalum dulcificum, a member of Sapotaceae, having a sweet modifying protein, “Miraculin”, in the pulp which causes sour edibles to taste sweet after the mouth has been exposed to the fruits. The miracle plant was first discovered in 1725 by an explorer Chaveliar des Marchais who observed the natives chewed the fruit before meals to make stale food taste sweeter and better. This plant is reported in West and Central Africa, specifically in countries like Congo, Ghana and Nigeria. The plant is known as Agbayun and Uni respectively among the Yoruba and Igbo people of southern Nigeria. Miracle plant is a tall bush or a small tree growing to a height of about 3 m in cultivation, and 6.1 m in a native habitat. Leaves are 5–10 cm long and 2–3.7 cm wide. Flowers are cream-colored but turn dark-red or brown with maturity. The flowers are bisexual. The calyx is made up of four to five sepals, the corolla four to five petals, and the androecium five stamens. The gynoecium stands erect with an unspectacular stigma. The ripe fruit is red in color, clustered at the ends of the branches. The berry is about the size of a coffee bean, roughly 2 cm long and 1 cm wide. It has relatively large seed which is encapsulated by a translucent pulp that is covered by a thin skin. The sweetening principle, miraculin, is present in the pulp.
The pulp of the fruit contains 4.44% (fresh wt.) of Miraculin. Miraculin is a single polypeptide glycoprotein consisting of two sugars linked to two amino acid residues and with molecular weight ranging from 24,000 to 45,000 Da (Lim, 2012). The two amino acid residues are held together by intramolecular disulfide bonds and are composed of 191 amino acid residues.
The sweetening effect takes place when miraculin binds to taste cell membranes near the sweet receptor site. Consequently, a conformational change occurs in the receptor epithelial plasma membrane, allowing the carbohydrate portion of miraculin to bind to the sweet receptor site, and producing the sensation of sweetness. The presence of protons (H+) is required during the conformational change. That is, the property of miraculin to induce sweetness through conformational changes in the receptor membrane is pH-dependent. The duration of miraculin effect was established to be about 3 hrs and it vanishes gradually within 20 min. Miraculin binds to the membrane of the receptor taste receptor type 1 member 3 (T1R2-T1R3) and acts as antagonist in any sour solution. In addition to miraculin, the fruit contains potent Anthocyanins like delphinidin glucoside, cyanidin galactoside and malvidin galactoside, flavonoids like epicatechin, rutin, quercetin, myricetin, kaempferol and other antioxidantive phytochemicals like, gallic, ferulic, syringic acid, , a-tocotrienol, a- and c-tocopherol and lutein. Other constituents are vitamins A,C, E and K and both essential (lysine, leucine, isoleucine, phenylalanine, threonine etc) and non-essential (glycine, proline, serine, tyrosine) amino acids.
Miracle fruit is popular among patients with diabetes and obesity in Japan. A mixture of miracle fruit, carambola, pumpkin and papaya could boost the immune function of mice. It is also found effective in cancer, uric acid and high levels of cholesterol.
Leaves and roots
The vegetative parts of the plant also is a source of useful phytochemicals like dihydro-feruloyl-5-methoxytyramine; (+)-syringaresinol, (+)-epi-syringaresinol, N-cis-feruloyltyramine, N-trans-feruloyltyramine, and N-cis-caffeoyltyramine β-sitosterol, and stigmasterol.
Uses
All parts of S. dulcificum are reputed to cure or manage various human diseases and ailments and different herbal preparations from the plant are used in traditional medicine.
In Benin, the root is used to treat sexual weakness, cough and tuberculosis. Likewise, the leaves are involved in the treatment of diabetes, malaria, hyperthermia and enuresis while the bark is employed in the treatment of prostate ailments. In Nigeria, the root macerated in local gin or soda water is used for the cure of gonorrhoea (Ekpo et al., 2008). In Lagos (Nigeria), S. dulcificum leaves are used for the management of asthma, male infertility, diabetes, weight loss and cancer (Makinde et al., 2015). In other region of West Africa like Ghana, the fruit has been used to sweeten sour foods and beverages such as Koko and Kenkey made from fermented maize and millet, and palm wine.
In Congo, where it is known as bomonga, the bark is used as cure for erectile dysfunction. In Japan, miracle fruit is popularly used by diabetic and obese patients (Du et al., 2014). The use of S. dulcificum as a multipurpose traditional medicine has been translated into several commercial applications and it is a highly valued plant in the pharmaceutical, natural health and food industries (Akinmoladun, 2016).
In traditional medicine, the leaves are the most useful plant parts (90%), followed by the root (7%), bark (1.5%), stem (1%) and fruit (0.5%). Information on ethnomedicinal uses of S. dulcificum documented in this review was obtained from literature spanning seven countries. It is worthy of note that the region with the highest number of ethnomedicinal uses of S. dulcificum is West Africa. Literature records also show high degree of consensus for at least two major categories of diseases, notably diabetes and sexually-related diseases, for which this plant is used.
Cultivation
S. dulcificum is produced and cultivated in large quantities in Taiwan and Japan .The plant has now been known to be propagated by the United States Department of Agriculture, and Federal Experiment Station in Puerto Rico. It best adapts to Jamaica, the south of U.S. (best in Florida) or Hawaii. The fruit grows in a single season ranging from May to September, though berries are generated year-round.
References
Akinmoladun et al (2020) Nutritional benefits.......... Miracle fruit (Synsepalum dulcifolium Daniell) Heliyon 2020 Dec. 6(2):e05837. Published on line 2020 Dec. 29
Mammen Daniel
