Introduction
Nightshade plants are evergreen plants that grow up to 75 centimeters and possess simple leaf morphological features like alternate margins, blunt teeth, and fine hair. These plants are cultivated through seeds. Their leaves taste like staple starch-based maize meal and tomatoes. These are fermented with milk as well. Such food preparations alter the effects of anti-nutrient compounds like solanaceous glycoalkaloids releasing a bitter taste. The nightshade vegetables mainly include tomatoes, potatoes, bell peppers, and eggplant.
Where Do the Nightshade Vegetables Found?
The plant known as nightshade in the regions of North America and the United Kingdom is Solanum dulcamara (woody nightshade or bittersweet). In the areas of sub-Saharan Africa, Solanum retroflexed is most commonly used under the local names of black nightshade or integral, umsobo, and muxe. In West, Central, and East Africa, various nightshade vegetables are consumed as Solanum villosum, Solanum scabrum Mill (mnavu), Solanum americanum, and Solanum nigrum.
What Are Their Properties?
The leaves and egg-shaped, red-colored berries of Solanum dulcamara are considered poisonous. These contain solanine, a substance that can lead to seizures and death if taken in large amounts. Solanum nigrum (known as black nightshade) also contains toxins. But completely ripened fruits, stems, and leaves of the black night are also cooked and consumed by the people of specific areas. Many nightshade plants contain certain compounds like alkaloids - nitrogen-containing solanine and lectins - carbohydrate-binding proteins.
What Is the Nutritional Content of Nightshade Plants?
The Mediterranean diet is regarded as one of the healthiest diets as it advises increasing the consumption of vegetables like -
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Tomato - This contains many anti-inflammatory and anti-aging compounds such as lycopene, and vitamin C. Lycopene is a potent antioxidant that helps in providing skin protection, improving cardiac functions, and lowering the risk of cancer cell growth. Vitamin C is a water-soluble vitamin useful in the formation of collagen and tissue repair and produces the enzymes for neurotransmitters.
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Bell Peppers - Vitamin C content is more in bell peppers as compared to tomatoes. Bell peppers are the richest source of many minerals and fiber.
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Potatoes - These contain antioxidants like flavonoids, carotenoids, and phenolic acids. Flavonoids have anti-inflammatory properties and protect the cells from oxidative damage responsible for causing diseases. Carotenoids help in boosting the immune response of the body. Phenolics also possess anti-inflammatory benefits and prevent the cellular damage that occurs as a result of free radical oxidation reactions. Potatoes also contain potassium and fiber. These help in keeping the stomach full and maintain general health.
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Eggplant - These are rich in nutrients such as potassium, magnesium, and vitamin K. Potassium and magnesium are responsible for the functions of nerves and muscles. The potassium-rich diet also diminishes the harmful effects of sodium and regulates blood pressure. Vitamin k is required for blood clotting and bone formation.
What Are the Micronutrients Presents in Nightshade Species?
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Iron- Iron is an essential trace element that performs the following bodily functions :
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Oxidation of macronutrients like carbohydrates, fats, and proteins.
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Biosynthesis of hemoglobin: It is the synthesis of two different components globin production and heme synthesis.
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The activity of the central nervous system with its essential role in oxidative metabolism and cofactor role in neurotransmitter synthesis.
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The recommended daily intake of iron is 8 mg/day. The iron content in African nightshade vegetables like Solanum retroflexum (7.2 mg /100 g of food weight), and Solanum villosum ( 12mg ) is more than other Southern African plants. The iron content in important Southern African vegetables is listed below :
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Corchorus tridens - 6.3 mg.
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Amaranthus cruentus - 5.1 mg.
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Corchorus olitorius - 3.6 mg.
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Bidens pilosa - 2.0 mg.
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Corchorus gynandra - 6.4 mg.
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Corchorus lanatus - 4.7 mg.
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Calcium - It is necessary for the maintenance of strong bones and teeth. The recommended daily intake is 1,200 mg for adults. Solanum villosum contains 199 mg per 100 gm of the dry weight of calcium which is in higher amounts than Bidens pilosa (162 mg) and Corchorus maxima (177 mg).
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Magnesium - It acts as a cofactor for many enzymatic reactions. The recommended daily intake of magnesium is 420 mg for adult males and 320 mg for adult females. Solanum retroflexum possesses 92 mg of magnesium content which is more than Corchorus tridens (80.9 mg).
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Copper - It is needed for the growth and development of the body. It participates in multiple functions as an essential role in antioxidant enzymes, including cardiovascular integrity, neovascularization, neuroendocrine activity, lung elasticity, and iron metabolism. Solanum retroflexum has 0.16 mg per 100 gm, higher than other species.
What Are the Macronutrients in Nightshade Species?
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Sugar Content: It is present in Solanum retroflexum 1.02 grams and in Solanum villosum 1.15 grams.
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Protein Content: It is present in Solanum retroflexum is 6 % higher than other traditional African vegetables like Corchorus maxima (4.24%), and Bidens pilosa (6 %).
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Fat Content: Solanum retroflexum contains,
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Monounsaturated fatty acids in the concentration of 2.51 g in a 100 g portion.
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Omega 3 fatty acids in the concentration of 0.33 g.
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Omega 6 fatty acids in the concentration of 0.63 g.
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Phytochemical Components - These are non-nutritive compounds that perform only biological activities. These are plant-based products and help in providing protection against non-communicable diseases.
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Phenols: They act as antioxidants because of their redox properties, carrying singlet and triplet oxygen, neutralizing free radicals, and decomposing peroxides. Solanum retroflexum contains rutin as the most important phenolic compound.
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Vitamin E: Solanum nigrum has the highest amount of vitamin E, around 229 mg per g, among all the nightshade species. Vitamin E helps maintain the health of the blood, brain, and skin. It prevents the breakdown of polyunsaturated fatty acids in membrane lipids and increases oxidative stress.
How Does Irrigation and Post Harvesting Impact the Mineral Content?
The amount of minerals in the night vegetables is greatly affected by the practices like methods of irrigation, late-season drought, and intercropping. Low irrigation contributes to the accumulation of carotenoids in Solanum scabrum. Irrigation simulated drought treatment in beta carotene and lutein.
Post-harvest drying and solar drying enhance the composition of functional substances present in the species of Solanum.
Conclusion
The nightshade vegetables are rich in minerals and phytochemicals, and post-harvesting reduces the loss of such compounds from the plants. Various food processing methods like fermentation and cooking at home affect the nutritional values of such foods. But due to the presence of some substances like solanine, they cause inflammation and even worse chronic conditions. These plant species are subjected to increase the feeling of fullness and keep humans hunger-free for quite a long period of time. It still remains a debatable topic when it comes to the benefits and disadvantages of such plants, but it is clear for sure that taken in large quantities will surely hamper the wellness of the body.
