The Half Decent Pharmaceutical Chemistry Blog

Last Sunday I went to Venice to complete this year’s visit to the Biennale, before its closing day (which is tomorrow). The weather was…predictable and not bad: a cloudy and chilly day in Venice is, in my opinion, the best you can get in this period. What’s more, I really enjoyed the trip from the railway station to the exhibition site on a so-called water bus: the see was not too rough but I nevertheless liked staying on the deck very much. That’s because I like the see very much and so far, I’ve never been sick on a boat, whatever the conditions.
The Biennale itself, this year, was pretty good too. On this very occasion, I visited the Old Arsenal building only, where you generally have less stuff and therefore, much more time to see every installation. I also met two guys form Basel, Switzerland: one had Italian origins and told me he was a member of a hip-hop group called Tre Cani (Three Dogs). Briefly, he was there not only as an art student, but also to shoot a scene for his band’s next video clip. I’ll admit that Switzerland and hip-hop music seems a weird combination, but the guy looked very motivated and wasn’t the gansta kind of rapper. Mind you, check out their website on myspace.

Anyhow, as I’m sure you know, most of the exhibitions of the Biennale are located at the Giardini, which I visited, back in September. There, you have the national pavilions, surrounded by a peaceful garden: so, you can go there only in the summer.

I was pretty impressed by a 1991, untitled (as usual) installation at the American pavilion. The floor of a room was pretty much entirely covered by liquorice rods, each of them neatly wrapped in cellophane. The light in the room created an strange and evocative atmosphere. And I have to say I quite proud of the picture I took there.
Still, when it comes to picture of liquorice, nothing can’t beat this one, which seems to be taken straight from a 1300s book, where some monk kept record of his poisons and drugs.
Poisonous as liquorice can be. Yes: you look at a rod of liquorice and think that it doesn’t look that dangerous. I mean, it often kill your hunger, if eaten before supper. That’s something your mother or granny has always told you, hasn’t she?
Besides, the roots of Glycyrrhiza Glabra are very good-looking and no wonder an artist thought of this legume for one of its works of art: dark on the outside, with a bright yellow fibre inside.
Its active principle is an awesome triterpenoid glycosidic saponin called glycyrrhizin, with plenty of useful activities. Once the glycosidic bond is hydrolysed, glycyrrhetic acid is freed and this substance is an emollient, an expectorant, an aromatiser, a mild laxative and even milder spasmolytic More recently, it’s reported to be increasingly tested as an indirect-acting anti-ulcer medication. Glycyrrhetic acid inhibits the local, catabolic metabolism of prostaglandins, which act on primary gastric cells, through binding to their receptors, enhancing the secretion of protective mucous and reducing that of hydrochloric acid.
This new function has lead to a synthetic analogue of glycyrrhetic acid called carbenoxolone, launched on the British market as a treatment for oesophageal ulceration and inflammation.

That’s all very appealing and reassuring, but not that fast on that. Glycyrrhizin not only impairs the catabolism of prostaglandins, but it also affect aldosterone. An excessive use of liquorice, therefore, can cause edema, hypokalemia, sodium retention and hypertension. That’s why there’s even a toxic dose for people suffering from hypertension and it’s actually rather low: 150 mg. This explains all those glycyrrhizin-free liquorice preparations available.