Subclass of Alkaloids

Isoquinoline Alkaloids

A large alkaloid family including berberine, sanguinarine, and the bisbenzylisoquinolines.

Overview

About Isoquinoline Alkaloids

Isoquinoline alkaloids are built on a benzene ring fused to a pyridine — the isoquinoline nucleus — and derive from tyrosine by way of dopamine. They are the second great alkaloid class after the indoles, and between them the two account for most of the plant kingdom's potent nitrogen chemistry.

Because dopamine is the starting material, several members retain enough of its shape to act at dopamine and opioid receptors — which is how a poppy came to produce the most important analgesic in medical history.

The Main Structural Groups

The isoquinoline core is elaborated in several distinct directions, and the subgroup usually predicts the pharmacology:

Benzylisoquinolines: papaverine, laudanosine
Morphinans: morphine, codeine, thebaine
Protoberberines: berberine, palmatine, canadine
Benzophenanthridines: sanguinarine, chelerythrine, chelidonine
Bisbenzylisoquinolines: tubocurarine, berbamine, tetrandrine
Aporphines: boldine, apomorphine, magnoflorine

Where They Occur

Three families dominate — the poppies, the barberries and the moonseeds:

Papaveraceae

opium poppy, greater celandine, bloodroot, California poppy

Berberidaceae and Ranunculaceae

barberry, Oregon grape, goldenseal

Menispermaceae

the curare vines, pareira

Magnoliaceae and Lauraceae

the aporphines

Ephedra's relatives and various tropical barks

Pharmacological Importance

Morphine remains the reference standard against which every analgesic is measured, and the opioid receptors were named for it rather than the reverse. Tubocurarine, from South American arrow poison, gave surgery its first controllable muscle relaxant and founded modern anaesthesia.

On the herbal side berberine is the most-studied member, with credible randomized-trial evidence in type 2 diabetes and dyslipidaemia through AMPK activation, alongside its long antimicrobial and antidiarrhoeal use. Sanguinarine and chelerythrine are potent antimicrobials with a much narrower safety window.

Toxicity & Safety

Potency and hazard are the norm here, not the exception. Sanguinarine is cytotoxic and DNA-intercalating and was implicated in the epidemic dropsy episodes caused by adulterated mustard oil; greater celandine has an established idiosyncratic hepatotoxicity signal serious enough to have prompted regulatory action.

Berberine, the most consumed member, is relatively well tolerated but is a meaningful CYP3A4 and P-glycoprotein inhibitor, is contraindicated in pregnancy and in neonates through kernicterus risk, and should not be treated as a benign supplement.

Constituents

All Isoquinoline Alkaloids

81 total Filter isoquinoline alkaloids

(S)-scoulerine 2 herbs 4-methylcurine 1 herb

Allocryptopine 3 herbs Anhalinine Anhalonidine 1 herb Anhalonine Anomurine 1 herb Apomorphine 1 herb Aporphine 1 herb

Bebeerine 1 herb Berbamine 1 herb Berberastine 1 herb Berberine 6 herbs Boldine 1 herb Bulbocapnine 2 herbs

Californidine 1 herb Canadaline 2 herbs Canadine 2 herbs Chelerythrine Care 2 herbs Chelidonine Care 1 herb Chondocurine 1 herb Cissamine 1 herb Cissampareine 1 herb Cissampeline 1 herb

Open in filterable index

Source Plants

Herbs Containing Isoquinoline Alkaloids

16 herbs

Plants in the materia medica documented to carry isoquinoline alkaloids, with the compounds each one is listed for. The bar counts how many DISTINCT isoquinoline alkaloids are on record for a plant, relative to the best-documented — it measures breadth of record, not potency, so a plant with one well-studied compound can outrank a richer source that has simply been analysed less. Where a measured concentration is on record it is quoted inline; most entries have none yet.