Solanine

Solanine (exactly: alpha-Solanine) is a bitter tasting, glycosidic steroid alkaloid (see below Solanum alkaloids) which can be found in many Solanum plants, especially in Solanum species, e.g. Solanum dulcamara, Solanum tuberosum (potato) and Solanum lycopersicum(tomato).
Alpha-solanine is heat resistant, poorly soluble in water, highly soluble in hot ethanol and ether.

Solanine is a strong local irritant and protoplasmic toxin. Solanine has a saponin-like effect (see saponins below) and thus has a haemolytic effect; furthermore, the substance has a toxic effect on mitochondrial membranes and leads to cell apoptosis. Alpha-solanine has a neurotoxic effect when applied systemically; it first causes excitation, then paralysis of the CNS with central respiratory paralysis. Solanine is excreted unchanged; this causes degenerative damage to the kidneys.

Potatoes (Solanum tuberosum) contain large amounts of solanine, especially in their herbaceous part. Furthermore in the green parts of the tubers and in the germination plants. In tomatoes, the solanine content decreases with increasing ripeness. Tomatoes (Solanum lycopersicum) also contain solanine (also incorrectly called tomatoine). In green tomatoes the solanine content is between 9 - 32 mg/100 g). In red ripe tomatoes, the solanine content of 0 to 0.7 mg/100 g is clearly minimized and outside the toxic range.

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