[cheryl j (OP)]

In an explanation of taste in the sensory system it says that the receptors for bitterness detect alkaloids and other compounds. The explanation was a lot less clear cut than for other receptors that detect sugars or sodium ions or H+ ions in acid.

[CliffordK]

Alkaloids are a group of naturally occurring nitrogen containing compounds.  Most have the nitrogen incorporated in a cyclic structure, and most are basic due to the nitrogen. 

According to the notes, most are bitter, and many are toxic, and are produced by plants to discourage animals from eating them.

Apparently there is quite a diversity between different alkaloids.

[chiralSPO]

Alkaloids are a huge class of bioactive compounds. Many find use as pharmaceuticals, recreational drugs and poisons. Well known plant-derived alkaloids include morphine, cocaine, mescaline, atropine, quinine, strychnine, caffeine, etc.

[cheryl j (OP)]

Thanks, that helps.

[alancalverd]

IIRC the "bitter" receptors detect electron donors, which will include OH- ions from dissolved alkalis and organic donors such as alkaloids. Seems odd for a textbook to mention alkaloids before alkalis. Maybe the authors are more familiar with cocaine than Drano. O tempora, o mores.

(Off to the evil laboratory to develop sweet cocaine. I shall rule the world. Sneering laugh.)

[RD]

... Off to the evil laboratory ...

While you're in the evil laboratory the "redneck deathray" needs tweaking []

Two men, including a member of the KKK, have been arrested after trying to build a portable X-ray machine to allegedly kill President Obama ...

http://www.dailymail.co.uk/news/article-2344657/KKK-member-friend-built-truck-mounted-death-ray-wanted-kill-President-Obama-Muslims-revenge-Boston-bombings.html

[cheryl j (OP)]

IIRC the "bitter" receptors detect electron donors, which will include OH- ions from dissolved alkalis and organic donors such as alkaloids. Seems odd for a textbook to mention alkaloids before alkalis. Maybe the authors are more familiar with cocaine than Drano. O tempora, o mores.

(Off to the evil laboratory to develop sweet cocaine. I shall rule the world. Sneering laugh.)

The theory was that these receptors make humans averse to poisonous plants. They also make kids dislike some green vegetables, because those receptors are more sensitive when you're young. So you should also make some better tasting brussel sprouts in the evil lab.

[lucas2]

Alkaloids are present in organisms (mainly plants) in a class of basic nitrogen compounds,
most complex ring structure, and more nitrogen contained in the ring,
there are significant biological activity, are herbal in one important active ingredients.