steroidal

Steroidal Alkaloids: Main Types

The two main types are: 1. Solanum alkaloids, and 2. Veratrum alkaloids.

Solanum Alkaloids: Definition and Source

Solanum alkaloids are glycosidal alkaloids (nitrogen-containing natural products) primarily found in Solanum species (Solanaceae family), such as potatoes.

Solanine: Chemical Composition

Solanine is a glycosidal alkaloid composed of an aglycone (Solanidine, a steroidal alkamine) and a glycone (Solanose, a trisaccharide).

Solanose: Monosaccharide Components

Solanose is composed of glucose, galactose, and rhamnose.

Solasodine: Analogue and Key Difference

Solasodine is an N-analogue of diosgenin (a steroidal sapogenin). It differs from diosgenin by having a nitrogen atom instead of an oxygen atom in its F ring.

Solanine in Potatoes: Purpose

Potatoes produce solanine as a natural defense mechanism against insects and pathogens.

Solanine in Potatoes: High Concentrations and Greening Indication

Glycoalkaloids like solanine are naturally high in potato leaves and stems. Greening on potato tubers, caused by light exposure, indicates a higher concentration of solanine, although the green pigment itself is harmless.

Solanine in Potatoes: Consumption Warning

Do not eat the green parts and roots of potatoes, as they are rich in solanine and potentially dangerous.

Solanine Toxicity: Taste and Location

Increased solanine levels make cooked potatoes taste bitter. Solanine is primarily concentrated on the skin surface, usually no deeper than 3 mm.

Solanine Poisoning: Main Symptoms

The main symptoms of solanine poisoning include gastrointestinal issues (nausea, diarrhea, dry sore throat) and neurological symptoms (headache, dizziness).

Solanine in Potatoes: Safe Consumption vs. Discarding

You can still eat potatoes with slight greening if you peel away all the green skin and surface layers. Discard the potato if the greening is very deep or if it tastes noticeably bitter, indicating high solanine levels.

Solanum Alkaloids: Commercial Value

Solanum alkaloids are valuable as precursors for the synthesis of steroidal sex hormones and corticoids.

Veratrum Alkaloids: Source and Types

Veratrum alkaloids are found in Veratrum species (Family Liliaceae) and are distinguished into two chemical types: 1. First type (Non-ester type), and 2. Second type (Ester type).

Veratrum Alkaloids (First Type): Characteristics

The first type includes simple typical or atypical steroidal alkamines with one or two non-esterified hydroxyl groups and a double bond between C5 and C6.

Veratrum Alkaloids (First Type): Examples

Examples include Rubijervine (typical) and Veratramine (atypical).

Veratrum Alkaloids (First Type): Occurrence in Plants

They are found in plant extracts partly as free alkamines and partly as glycosides (with one glucose molecule at C3-OH).

Rubijervine: Classification and Key Features

Rubijervine is a typical steroidal structure and a non-ester simple alkamine of the first type of Veratrum alkaloids, featuring an OH group at C11 and a C5-C6 double bond.

Veratramine: Classification and Key Features

Veratramine is an atypical steroidal alkaloid (C-nor, D-homo structure) and a non-ester simple alkamine of the first type of Veratrum alkaloids, characterized by a rearranged C and D ring system.

Veratrum Alkaloids (Second Type): Characteristics

The second type includes complex ester alkaloids, derived from highly hydroxylated atypical C-nor D-homo steroidal ring systems, with hydroxyl groups esterified by one to four organic acid molecules.

Veratrum Alkaloids (Second Type): Esterifying Acids

Organic acids that esterify hydroxyl groups in the second type include Acetic, alpha-methylbuteric, angelic, tiglic, vanillic, and veratric acids.

Protoverine and Protoveratrine A: Relationship and Type

Protoverine is the alkamine (non-esterified) precursor. Protoveratrine A is its 3,6,7,15 tetraester. Both are associated with the second type of Veratrum alkaloids.

Veratrum Alkaloids (Complex Esters): Medicinal Uses

These complex ester alkaloids are used as hypotensive agents (blood pressure lowering), often in combination with Rauwolfia alkaloids.

Veratrum Alkaloids: Forms of Administration

They are used as pure alkaloidal salts, purified extracts, or as the crude drug (rhizomes or roots).

Pyrrolizidine Alkaloids: Structure and Plant Sources

They contain a bicyclic pyrrolizidine nucleus with a bridgehead nitrogen. Found in Leguminosae (Crotalaria) and Compositae (Senecio) families.

Quinolizidine Alkaloids: Structure and Source

They contain a bicyclic quinolizidine nucleus with a nitrogen at the ring fusion. Primarily found in Lupinus species.

Quinolizidine Alkaloids: Bitter vs. Sweet Lupins

Bitter lupins are rich in toxic quinolizidine alkaloids; sweet lupins contain smaller, less toxic amounts.

Indolizidine Alkaloids: Structure and Source

They contain a bicyclic indolizidine nucleus (6-membered ring fused to a 5-membered ring with nitrogen at fusion). Found in the Erythrina genus (Fabaceae).

Erythrina Seeds: Poisonous Components

The seeds of many Erythrina species contain potent poisonous indolizidine and/or tetrahydroisoquinoline alkaloids