Subclass of Terpenoids

Sesquiterpene Lactones

Bitter sesquiterpenes of the daisy family — anti-inflammatory, but the main cause of Asteraceae contact allergy.

Overview

About Sesquiterpene Lactones

Sesquiterpene lactones are fifteen-carbon terpenes carrying a lactone ring — an ester closed into the structure. They are the bitter principle of the daisy family, and the reason a chamomile flower or a dandelion leaf tastes the way it does.

Most of the group shares one reactive feature: an α-methylene-γ-lactone group that behaves as a Michael acceptor, latching onto the thiol groups of proteins. Nearly everything this class does — the anti-inflammatory activity and the allergy alike — traces back to that single piece of chemistry.

Where They Occur

Overwhelmingly a daisy-family (Asteraceae) group, with scattered occurrences elsewhere:

Feverfew

parthenolide

Arnica

helenalin and its esters

Wormwood and mugwort

absinthin, artemisinin's relatives

Chicory, dandelion and lettuce

lactucin, lactucopicrin, taraxinic acid

Artichoke

cynaropicrin

Sweet wormwood

artemisinin, the antimalarial

Content is highest in flowers and latex, which is why the milky sap of a broken dandelion stem is the bitterest part of the plant.

Pharmacological Importance

The Michael-acceptor chemistry lets these compounds alkylate cysteine residues on NF-κB, shutting down a master switch of inflammatory gene expression. That is the accepted mechanism behind parthenolide's use in migraine prophylaxis and helenalin's anti-inflammatory potency.

As bitters they stimulate salivary, gastric and biliary secretion on contact with the tongue — the basis of the digestive-bitter herbs. And artemisinin, whose endoperoxide bridge is a different reactive motif again, remains the backbone of frontline malaria treatment worldwide.

Toxicity & Safety

This is the terpene subgroup that genuinely demands care. The same thiol reactivity that dampens inflammation also haptenizes skin proteins, making sesquiterpene lactones the principal cause of contact allergy to the daisy family — a well-documented occupational dermatitis in florists and gardeners, and the reason cross-reactivity between Asteraceae herbs is common.

Potency varies widely by member. Helenalin is markedly toxic, which is why arnica is a topical-only herb in ordinary practice. Anyone with a known Asteraceae allergy should treat the whole family with caution rather than trialling members one at a time.

Constituents

All Sesquiterpene Lactones

54 total Filter sesquiterpene lactones

10-Epicanin 1 herb 11-beta,13-Dihydrolactucin 2 herbs 13-O-Acetylsolstitialin A 1 herb 8-Deoxylactucin

Absinthin 1 herb Achillicin 1 herb Achillin 2 herbs Achillolide A 1 herb Arnicin 1 herb Arteannuin B 1 herb Artecanin 1 herb Artemisinin 1 herb Artemorin 1 herb Artemvulactone E 1 herb

Balchanin 1 herb Bilobalide 1 herb

Calein A 1 herb Calein B 1 herb Calein C 1 herb Canin 1 herb Cnicin 1 herb Costunolide 2 herbs Cynaratriol 1 herb Cynarolide 1 herb

Open in filterable index

Source Plants

Herbs Containing Sesquiterpene Lactones

15 herbs

Plants in the materia medica documented to carry sesquiterpene lactones, with the compounds each one is listed for. The bar counts how many DISTINCT sesquiterpene lactones 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.