Alkaloids in Plant Chemistry

Basic, heterocyclic nitrogenous compounds of plant origin, possessing physiological activity

Grouping alkaloids based on plant family or genus without considering chemical structure

Grouping alkaloids based on their medical effect (e.g., analgesic, cardioactive)

Grouping alkaloids based on the original building blocks used to make them

A classification system of alkaloids; divides into true/typical and protoalkaloids, based on structure and properties

Basic, toxic, physiologically active compounds derived from amino acids; nitrogen in heterocyclic ring

Simple amines (basic) derived from amino acids; nitrogen not in heterocyclic ring

A ring structure containing carbon atoms and at least one other atom (like nitrogen) in organic chemistry

Alkaloids that are not derived from amino acids, but contain nitrogen in a heterocyclic ring.

Alkaloids come from various sources including plants, fungi, animals, bacteria, and can be synthetic.

All alkaloids have nitrogen, but not all compounds with nitrogen are alkaloids.

Alkaloids vary in their basicity, with some being very weak bases.

Alkaloids often have a protective role in plants due to their toxicity and bitter taste.

Alkaloids can be end products of detoxification processes in plants.

Some alkaloids contain sugars and provide energy for the plant.

Some alkaloids serve as a reserve source of nitrogen for the plant.

Some alkaloids affect plant growth by influencing metabolic processes.

The "Nor-" prefix in alkaloid names indicates N-demethylation or N-demethoxylation.

Lobeline HCl and Apoatropine HCl can dissolve in chloroform (CHCl3).

Alkaloids often have one or more chiral carbons, leading to optical isomers (different spatial arrangements). Levo-isomers often show higher biological activity than dextro-isomers.

Some alkaloids, like (+)Tubocurarine, (+)Quinidine, or a racemic mixture of Atropine, display activity in non-levo forms.

Alkaloids generally decompose when heated, and sublimation is possible for some, like caffeine. Solubility plays a role in stability, with soluble forms decomposing easier than dry salts.

The lone pair of electrons on the nitrogen atom makes alkaloids basic. Structure around the nitrogen affects basicity; electron-donating groups increase basicity, while electron-withdrawing groups decrease it.

These compounds (e.g., tubocurarine chloride) have four organic groups bonded to nitrogen, and are not affected by OH- ions because the nitrogen doesn't have a proton to lose.

Alkaloids have nitrogen atoms in heterocyclic rings or side chains, found as primary, secondary, tertiary, and quaternary amines (e.g., Norpseudoephedrine, Ephedrine, Nicotine, Tubocurarine).

Different forms of a molecule with the same chemical formula but different structures, like ephedrine and pseudoephedrine.

Indicates dehydration of a molecule, such as in apoatropine.

Indicates a molecule with a reduced or simpler structure, like nor-nicotine.

Alkaloid bases are generally insoluble in water but soluble in organic solvents; salts are soluble in water.

Indicates isomerism and used to differentiate related alkaloids, such as quinine and quinidine.

Indicates less active alkaloids from the isosergic acid series, like ergotaminine.

Most alkaloids are crystalline, definite melting point; some are amorphous or liquid (volatile or non-volatile).

Alkaloids are classified based on their physiological effects, like analgesic, stimulant, mydriatic, and anti-hypertensive.

Alkaloids are named by generic (source plant), specific (within a plant), common (name usage), physical property, discoverer, or physiological activity.

Most alkaloidal bases are insoluble in water but soluble in organic solvents. Exceptions apply for some alkaloids and salts.

Alkaloids react with dilute acids to form salts. Concentrated acids may cause significant changes. Alkaloids can undergo dehydration, hydrolysis, or demethoxylation under harsh conditions.

Some alkaloids lose water molecules to form anhydro or apoalkaloids. Examples include morphine to apomorphine and atropine to apoatropine.

Alkaloids with ester linkages or sugar moieties (glucoalkaloids) can be broken down (hydrolyzed) by acid/alkaline conditions into smaller components.

Removal of methoxy groups from some alkaloids. Examples include quinine, narcotine, codeine, and papaverine.

Weak alkalies liberate alkaloidal bases from salts. Weak alkalies can also form salts with alkaloids containing carboxylic acid groups (COOH). Strong alkalies form salts with alkaloids containing phenolic groups. Heated alkalies can hydrolyze ester alkaloids.

Detection of alkaloids generally uses two types of reagents. The first type creates precipitates with alkaloids, while others produce distinctive colors, aiding identification.

A reagent containing picric acid solution used to detect alkaloids, resulting in a yellow precipitate.

A reagent containing potassium bismuth iodide used to detect alkaloids which produce an orange-reddish precipitate.

A potassium cadmium iodide solution for alkaloid detection, producing a yellow precipitate.

An iodine solution in potassium iodide, producing a reddish-brown precipitate with alkaloids.

Potassium mercuric iodide solution for alkaloid detection with a creamy precipitate.

A positive result for an alkaloid test that is not actually due to an alkaloid, but another plant constituent (e.g., tannins, proteins).

Reagents that produce distinctive colors, reacted directly with alkaloids (not their solutions), often containing H2SO4.

A reagent made with sulfuric acid (H2SO4) and nitric acid (HNO3); used for alkaloid detection.

A reagent containing sulfuric acid (H2SO4) with formaldehyde, creating color reactions characteristic of alkaloids.

Reagents that give color reactions specific to various alkaloids, in contrast to general reagents.

Reagent producing blue color specifically with ergot alkaloids.

Reagent creating violet color reactions with Solanaceous alkaloids.