Description

Solanum nigrum L., commonly known as black nightshade, blackberry nightshade, or African nightshade, is an annual or short-lived perennial flowering plant in the nightshade family Solanaceae (the same family as tomato, potato, eggplant, and pepper).

Morphology: The plant is an erect or widely spreading herb that typically grows from 25–70 cm (10–28 inches) tall, though it can reach up to 150 cm (5 feet) and form dense clumps up to 2 meters across. The stems are often angular to narrowly winged, sometimes flushed with purple, and are covered with curved, appressed simple hairs.

Leaves: The leaves are arranged alternately, measuring 2–14 cm long and 0.7–7.3 cm wide. They are ovate to ovate-lanceolate in shape, with bases that are sub-truncate, rounded, or cuneate, often decurrent into the petiole. The leaf margins range from entire to sinuate-dentate (wavy with blunt teeth), with juvenile leaves often entire and later leaves shallowly lobed. The leaves are pubescent (hairy) on both surfaces, with more numerous hairs along the veins and margins, and petioles are 0.3–6.5 cm long, flattened and narrowly winged in the upper portion.

Flowers: The inflorescences are lateral cymes (unbranched), lax, and typically bear 3–10 flowers. The flowers are small, star-shaped (stellate), with a white, cream, or yellowish corolla that may have a conspicuous yellow-green eye. The corolla measures 4–9 mm across. The flowers have yellow anthers (about 2 mm long) that form a prominent central cone, and a style that is straight or sigmoidal, with the stigma placed at or above the level of the anther pore openings.

Fruit: The fruit is a glossy, dull-black or purplish-black berry, measuring 6–10 mm in diameter. The berries typically form in trusses of 5–8, are broadly ovoid, smooth, and generally without sclerotic granules . Mature fruits are edible when fully ripe . The calyx (sepals) remains appressed or slightly reflexed, not enlarged, with bluntly triangular lobes.

Seeds: The seeds are light bone-colored (sometimes flushed with purple), measuring 1.7–2.4 mm long, and are obovate in outline with a minutely pitted surface.

Distribution: The plant is widely distributed globally, including throughout Africa and Nigeria, often growing as a weed in disturbed soils, gardens, farmlands, and roadsides. It is highly adaptable and fast-growing.

Taxonomic Note: Solanum nigrum is often confused with other nightshade species such as Solanum americanum (American black nightshade) and is sometimes wrongly called “deadly nightshade” – a common name better applied to Atropa belladonna .

Common Names

  • English: Black nightshade, Black-berry nightshade, African nightshade, Narrow-leaved nightshade
  • French: Morelle noire
  • German: Schwarzer Nachtschatten
  • Arabic: “Shirengeban شرنجبان” (UAE)
  • Hindi: Makoi
  • Yoruba: Odu (among other local names for edible nightshades)
  • Igbo: Anara (may be used for related Solanum vegetables)
  • Hausa: Gautan kaji (sometimes used for various nightshade species)
  • Kenya (Kikuyu): Managu
  • Kenya (Swahili): Mnavu
  • Uganda (Luganda): Nsugga
  • Cameroon (Nso): Nyuuseji

Health Benefits

Solanum nigrum contains bioactive compounds such as flavonoids, polyphenols, alkaloids (including solasodine and solanine), saponins, and antioxidants. Traditionally used in many cultures, including parts of Africa and Asia. Potential benefits (mostly from ethnobotanical use and preliminary studies) include:

  1. Nutritional Composition: African nightshade (Solanum nigrum) is a nutrient-dense leafy vegetable. Traditional preparation methods such as lactic acid fermentation have been shown to increase phenolic and flavonoid contents while maintaining antioxidant capacity.

Key nutritional highlights:

  • Rich in phenolic compounds and flavonoids
  • Contains carbohydrates, proteins, and dietary fiber
  • Fermented preparations show enhanced phytochemical content (228.8 mg/g GAE for phenols in starter-culture-inoculated samples)
  • Antitumor and Anticancer Properties: This is one of the most extensively studied health benefits of S. nigrum. Research has demonstrated multiple mechanisms:
    • Cervical carcinoma: Aqueous extract of S. nigrum inhibited growth of cervical carcinoma (U14) by modulating immune response and inducing tumor cell apoptosis, with little toxicity to the animals.
    • Cell cycle arrest: The extract induced tumor cell cycle arrest in G0/G1 phase .
    • Total alkaloids: Alkaloids isolated from S. nigrum interfere with tumor cell membrane structure and function, disturb DNA and RNA synthesis, and alter cell cycle distribution in tumor cells.
    • Alpha-solanine: This steroidal glycoalkaloid found in S. nigrum inhibits proliferation and induces apoptosis of tumor cells. It also inhibits PC-3 pancreatic cell invasion by blocking epithelial-mesenchymal transition and matrix metalloproteinases expression, and reduces ERK and PI3K/Akt signaling pathways.
    • Glycoprotein: A glycoprotein isolated from the plant exhibits anticancer abilities by blocking the NF-kappaB anti-apoptotic pathway, activating caspase cascades, and increasing nitric oxide production.
    • Hepatocellular carcinoma: Aqueous extract can potentially be used in novel integrated chemotherapy with cisplatin or doxorubicin for hepatocellular carcinoma patients .
  • Anti-inflammatory Properties: S. nigrum has demonstrated significant anti-inflammatory activity, supporting its traditional use for treating inflammatory conditions. In European traditional medicine, the plant has been used as a strong sudorific and analgesic. The whole plant is recognized for its anti-inflammatory, emollient, and soothing properties.
  • Antioxidant Activity: The plant exhibits potent antioxidant properties, neutralizing free radicals and reducing oxidative stress, which is implicated in aging, cancer, and various chronic diseases. Fermented preparations show antioxidant capacity with 60–80% radical scavenging activity.
  • Diabetes Management (Hypoglycemic Effects): S. nigrum has shown promising potential for managing diabetes mellitus through multiple mechanisms:
    • Enzyme inhibition: Leaf extract inhibits α-amylase and α-glucosidase, enzymes involved in glucose metabolism, helping to regulate blood sugar levels.
    • Glucose uptake: The extract increases glucose uptake by stimulating translocation of GLUT4 glucose transporter proteins to cell membranes in insulin-sensitive tissues.
    • Insulin sensitivity: It improves insulin sensitivity by stimulating signaling pathways such as AMPK and PI3K/Akt.
    • Lipid profile improvement: Studies demonstrate that S. nigrum extracts decreased serum triglycerides, cholesterol, and sugar levels, while inhibiting fat deposit, oxidative stress, and lipid peroxidation in high-fat diet-fed mice.
    • Insulin secretion: It appears to boost insulin secretion, further aiding blood sugar control.
  • Hepatoprotective (Liver-Protective) Effects: The plant is widely used in oriental medicine as a hepatoprotective agent. Studies have confirmed its ability to protect liver function.
  • Antimicrobial Activity: S. nigrum exhibits antimicrobial properties against various pathogens. It is used in Cameroon to treat pneumonia, tonsillitis, and other infections.
  • Antimalarial Effects: Research has documented antimalarial activities of the plant.
  • Analgesic (Pain-Relieving) Properties: Traditional medicine systems have used S. nigrum as an analgesic. In European traditional medicine, it was used as an analgesic with narcotic properties.
  • Diuretic and Cardiovascular Support: The herbal tea has diuretic properties and is recommended for the treatment of hypertension and atherosclerosis. The plant is considered a diuretic and antipyretic in oriental medicine.
  • Neuroprotective Effects: Emerging research suggests neuroprotective properties, indicating potential applications in neurodegenerative conditions.
  • Intestinal Flora Regulation: Studies have shown that S. nigrum may help regulate intestinal flora, contributing to gut health.
  • Immunological Effects: The plant exhibits immunomodulatory properties, helping to regulate immune system function.
  • Other Traditional Medicinal Uses:
    • Skin conditions: The juice of the plant is used on ulcers and other skin diseases; externally applied as a poultice for inflammation, lichens, pain, pruritus (itching), and bruises.
    • Digestive health: In traditional Indian medicine, infusions are used for dysentery, stomach complaints, and fever .
    • Respiratory conditions: The juice from its roots is used against asthma and whooping cough; the fruits are used for treating asthma .
    • Tuberculosis: Traditional Indian medicine uses infusions to treat tuberculosis .
    • Fever: The plant is used as an antipyretic (fever-reducing) agent .
    • Tonic and laxative: The fruits are used as a tonic and laxative .
    • Appetite stimulant: The fruits are used to stimulate appetite .
    • Epilepsy and nervous disorders: In homeopathy, the herbal infusion is used against nerve impulses, muscle contraction, and epilepsy .