Pyridine Alkaloids

Alkaloids that possess an aromatic pyridine ring often are called pyridine alkaloids. Traditionally, these compounds have been isolated from plants, such as piper (Piper nigrum), kava (Piper methysticum), areca nuts and Nicotiana tabacum, however, an increasing number of pyridine alkaloids are being isolated from insects, amphibians, and marine animals. They are widely distributed in nature. In addition, they perform many different functions in nature, such as training pheromones and defense mechanisms in insects.

Figure 1. The basic structure of the pyridine nucleus in pyridine alkaloids.

The sources of pyridine alkaloids

Pyridine alkaloids have been isolated from plant, marine and other sources, and some are present in a wide variety of life forms. Common sources of pyridine alkaloids are shown below.

• Plant-derived pyridine alkaloids

Some common plant-derived pyridine alkaloids are trigonelline, arecaidine, guvacine, and cytisine. These alkaloids are found in the botanical families Aizoaceae, Annonaceae, Araceae, Bignoniaceae, Dipsacaceae, Gramineae, Palmae, and Umbelliferae, among others.

• Marine-derived pyridine alkaloids

Anabaseine, isoanatabine, 2,3'-bipyridyl and nemertelline, agelongine and daminin are common pyridine alkaloids of marine origin. They have been isolated from marine worm Rhynchocoela, hoplonemertine Paranemertes peregrine, marine hoplonemertine worm A. angulatus and Indo-Pacific coral reefs.

• Multiple sources pyridine alkaloids

Some pyridine alkaloids are not of single origin. For example, trigonelline is a natural alkaloid mainly found in Trigonella Foenum Graecum (fenugreek) Fabaceae and other edible plants with a variety of medicinal applications. However, studies have shown that trigonelline is also widely distributed in various animal species, such as arthropods, marine poriferans and mammals.

Bioactivities of pyridine alkaloids

Structurally diverse pyridine alkaloids present a wide range of biological activities, which are attractive to the natural product chemistry and medicinal chemistry communities. Their main biological activities are described below.

• Analgesic activity

Pyridine alkaloids have a wide range of analgesic activity. For example, in a phytochemical study, cerpegin, a pyridine alkaloid consisting a 2-pyridone fused with a 2-furanone ring was isolated from the fleshy stem of C. juncea^[1]. Cerpegin has been shown to have an analgesic activity.

Figure 2. The structure of cerpegin.

• Antineoplastic activity

There are many types of alkaloids with antineoplastic activity, and pyridine alkaloids are one of them. For example, four pyridine alkaloids, Niphatesines A-D, were isolated from sponges of the genus Niphates obtained from the Kerama Islands near Okinawa, all of which showed potent antineoplastic activity^[2].

Figure 3. The structure of Niphatesines A-D.

• Antifungal activity

Pyridine alkaloids have good antimicrobial activity against a variety of pathogens. For example, two alkaloids, cribrochalinamine A and B, which bear the very rare azamethine-N-oxide function, have been obtained from the sponge Cribrochalina, collected off Hachiyo-jima Island. Both compounds exhibit antifungal activity.

Figure 4. The structure of cribrochalinamine A and cribrochalinamine B.

What we offer

As a supplier of alkaloids, Alfa Chemistry has always shown great interest in the latest developments in pyridine alkaloids. Alfa Chemistry is committed to providing a wide range of pyridine alkaloids. If you do not find what you need, please contact us. We also offer product customization according to customer's detailed requirements.

References

1. Adibatti, N.; et al. A pyridine alkaloid from ceropegia juncea. Phytochemistry. 1991, 30(7): 2449-2450.
2. Murayama, T.; et al. Niphatesines A-D, new antineoplastic pyridine alkaloids from the okinawan marine sponge Niphates sp. J. Chem. Soc., Perkin Trans. 1. 1990, 3301-3303.