Everything about The Solanaceae totally explained
The
Solanaceae is a
family of
flowering plants, many of which are edible, while others are
poisonous (some have both edible and toxic parts). The name of the family comes from the
Latin Solanum "the nightshade plant", but the further etymology of that word is unclear; it has been suggested it originates from the Latin
verb solari, meaning "to soothe". This would presumably refer to alleged soothing
pharmacological properties of some of the
psychoactive species found in the family. It is more likely, however, that the name comes from the perceived resemblance that some of the flowers bear to the sun and its rays, and in fact a species of Solanum (
Solanum nigrum) is known as the
sunberry.
The family is also informally known as the nightshade or
potato family. The family includes the
Datura or
Jimson weed,
eggplant,
mandrake,
deadly nightshade or belladonna,
capsicum (
paprika,
chili pepper),
potato,
tobacco,
tomato, and
petunia.
The Solanaceae family is characteristically
ethnobotanical, that is, extensively utilized by humans. It is an important source of
food,
spice and
medicine. However, Solanaceae species are often rich in
alkaloids that can range in their
toxicity to humans and animals from mildly irritating to fatal in small quantities.
Flowers are typically conical or funnelform with five petals, usually fused. The leaves are alternate, often with a hairy or clammy surface. Solanaceous plants produce a
fruit that's either a
berry, as in the case of the
tomato or
wolfberry, or a dehiscent (breaks open upon drying, or dehiscing, releasing the seeds)
capsule as in the case of
Datura. The seeds are usually round and flat, being 2-4 millimeters in diameter. The
stamens are usually present in multiples of four (most commonly four or eight). The ovaries are inferior. The hypogynus gynoecium is a
syncarp located obliquely in relation to the median.
Alkaloids
The Solanaceae are known for possessing a diverse range of
alkaloids. As far as humans are concerned, these alkaloids can be desirable, toxic, or both, though they presumably evolved because they reduce the tendency of animals to eat the plants.
One of the most important groups of these compounds is called the
tropane alkaloids. The term "tropane" comes from a
genus in which they're found,
Atropa (the
belladonna genus). The belladonna genus is so named after the
Greek Fate,
Atropos, who cut the thread of life. This nomenclature betrays the toxicity and lethality that has long been known to be characteristic of these compounds.
Tropane alkaloids are also found in the
Datura,
Mandragora, and
Brugmansia genera, as well as many others in the Solanaceae family. Chemically, the molecules of these compounds have a characteristic bicyclic structure and include
atropine,
scopolamine, and
hyoscyamine. Pharmacologically, they're the most powerful known
anticholinergics in existence, meaning they inhibit the neurological signals transmitted by the endogenous
neurotransmitter,
acetylcholine.
Symptoms of overdose may include
mouth dryness,
dilated pupils,
ataxia,
urinary retention,
hallucinations,
convulsions,
coma, and death.
Despite the extreme toxicity of the tropanes, they're important drugs when administered in appropriate (and extremely small) dosages. They can reverse
cholinergic poisoning, which can be caused by overexposure to
pesticides and
chemical warfare agents such as
sarin and
VX. More commonly, they can halt many types of
allergic reactions.
Scopolamine, a commonly used
ophthamological agent, dilates the pupils and thus facilitates examination of the interior of the eye. They can also be used as
antiemetics in people prone to
motion sickness or receiving
chemotherapy. Atropine has a
stimulant effect on the
central nervous system and heart, whereas scopolamine has a
sedative effect.
Cocaine is also considered a tropane alkaloid due to its structural similarity to the aforementioned compounds. Its pharmacology, however, is radically different, and it doesn't occur in the Solanaceae family.
The most famous alkaloid from the Solanaceae family is
nicotine. Like the tropanes, its pharmacology acts on cholinergic neurons, but with the opposite effect (it is an
agonist as opposed to an
antagonist). It has a higher specificity for
nicotinic acetylcholine receptors than other ACh proteins. Its effects are well known.
Nicotine occurs naturally in the
Nicotiana or
Tobacco genus.
Capsaicin is structurally unrelated to nicotine or the tropanes, and is found in the genus
Capsicum, which includes
chili peppers such as
Tabasco peppers and
habaneros. The compound isn't appreciably toxic to animals. However, it stimulates specific pain receptors in most mammals, those which sense heat, in the oral
mucosa as well as many other
epithelial tissues. This causes a sensation of burning not unlike an actual heat or chemical burn. It is used in high concentration as a deterrent in pepper sprays, and sought after for many culinary dishes for its "spiciness".
It is thought that the reason one would deliberately induce pain while eating is the rewarding release of
endorphins it causes. The "hotness" of capsaicin products and foods is expressed in
Scoville units. A scoville unit is the factor by which the capsaicin-containing substance must be diluted to render the resulting solution imperceptible to a tester (for example, a teaspoon of a 5,000 Scoville unit
hot sauce would have to be diluted with 4,999 teaspoons of a sugar water solution to negate its potential to cause a sensation on the palate).
Nutritional importance
The most important species of this family for the global diet is the
potato or
Solanum tuberosum, whose
carbohydrate-rich
tubers have been a
staple food in many times and places, and which is one of the most grown crops today. In many genera, the fruits are the desirable item, for example,
tomatoes,
tomatillos,
eggplants,
uchuva, and
peppers.
While very popular, some people experience sensitivity or
allergy-like symptoms in response to nightshade plants.
Further Information
Get more info on 'Solanaceae'.
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