Posted by: Chris Maloney | July 7, 2011

Hogweed: Giant Member of a Toxic Family

A Giant Hogweed flower in close-up. Do not touch!

Image via Wikipedia

Well, the Huffington Post has announced the march of Giant Hogweed in NY state.  Terrible, just terrible, except it’s nothing new.  Giant Hogweed has been around for quite some time. 

And yes, Giant Hogweed is quite toxic.  It’s a member of the hemlock family, ala Socrates.  So it looks like the rest of its family, it acts like the rest of its family,  and the biggest problem is that we’ve gotten less careful about treating it with respect.  For a sight-seeing guide of the family in question, have a look here.

For those of us here in Maine, Heracleum mantegazzianum can be an issue.  The department of agriculture division of plant industry here in Maine would like your help in locating this rather hard-to-miss plant. 

Before you assume any contact with Giant Hogweed will eat off your face, the content of phototoxic compounds varies greatly from month to month and part to part. (see study below).

Anything that potent should be used as well as feared.  Sure enough, researchers  (below) are working on new chemotherapy drugs based on the same compound, furocoumarin, that is thought to cause the burns. 

It can also be useful for chronic skin diseases like Granuloma annulare.  (psoralen is a different name for a similar compound).  So before we make the plant extinct, maybe we should figure out how to harness its potential.  It could go from poisonous nuisance to cash crop. 

Bioorg Med Chem. 2011 Apr 1;19(7):2326-41. Epub 2011 Feb 18.

Pyrrolo[3,4-h]quinolinones a new class of photochemotherapeutic agents.


Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica Farmaceutica e Biologica, Università degli Studi di Palermo, Via Archirafi 32, Palermo 90123, Italy.


Pyrrolo[3,4-h]quinolin-2-ones were synthesized as nitrogen isosters of the angular furocoumarin angelicin, with the aim of obtaining new photochemotherapeutic agents with increased antiproliferative activity and lower undesired toxic effects. A versatile synthetic pathway was approached to allow the isolation of derivatives of the new ring system with a good substitution pattern on the pyrrole moiety. Photobiological screenings of the new compounds revealed a potent phototoxic effect and a great UVA dose dependence, reaching IC(50) values at submicromolar level. The induced cellular photocytotoxicity was related to apoptosis with the involvement of mitochondria and lysosomes, alteration of cell cycle profile and membrane lipid peroxidation.

Copyright © 2011 Elsevier Ltd. All rights reserved.

PMID:  21397509
Photodermatol Photoimmunol Photomed. 2011 Apr;27(2):81-4. doi: 10.1111/j.1600-0781.2011.00574.x.

Psoralen and ultraviolet A in the treatment of granuloma annulare.


Department of Dermatology, The General Infirmary at Leeds, Leeds, UK.



Granuloma annulare (GA) is a benign, usually self-limiting disease. Lesions may be localized or generalized with a tendency for generalized disease to follow a chronic course. There is evidence to support psoralen and ultraviolet A (PUVA) in the treatment of GA, but little data on long-term benefits. The purpose of this study was to investigate the effect of PUVA in the treatment of GA, and to establish clearance and remission rates.


We carried out a retrospective study of patients with generalized GA treated with PUVA over 13 years. Data were collected from case notes and a phototherapy database. On completion of treatment, outcome was assessed as clear, good improvement, moderate improvement and poor outcome. Follow-up data were obtained for patients who had cleared using a postal questionnaire in addition to clinic notes.


Fifty per cent of courses resulted in clearance of disease, 16% in good improvement, 25% had moderate benefit and 9% had a poor outcome. Of the patients that cleared, 79% remained in remission at 6 months but only 32% were still clear 12 months following treatment.


Our findings show clearance or good improvement of generalized GA in 66% of cases. Prolonged remission, however, occurred in less than a third of patients.

© 2011 John Wiley & Sons A/S.

Contact Dermatitis. 1983 Jul;9(4):281-4.

Seasonal variations in the content of phototoxic compounds in giant hogweed.


The Candida inhibition method of Daniels was used for monthly determinations of the relative amounts of phototoxic substances in giant hogweed from April to September. Significant seasonal variations were found in the highest content of active constituents in April and May, with a decrease in the following months. Except in May (where it was highest for the root), the highest content of phototoxic substances was found in the leaves. It was lower in the root and lowest in the stem and stalk.

PMID:  6352168




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