Capsaicin is the chief capsaicinoid found in chilli peppers that belong to the group Capsicum. This phytochemical causes a burning sensation in any tissue that comes into contact. It is used in the preparation of varied topical ointments developed to alleviate the pain of peripheral neuropathy. The typical burning sensation is caused when capsaicin interact with the nerve cells. It is also believed that intake of capsaicin can cause a euphoric sensation due to the release of endorphins. As per studies, capsaicin can also alleviate symptoms associated with arthritis, improve flexibility of the joints, reduce psoriasis symptoms, and protect against gastric ulcers. And that's not all - research suggests that a combination of capsaicin and green tea can be effectively used in weight management too. This is because this combination promotes a feeling of fullness.

Guarana is a climbing plant of the Sapindaceae family native to the Amazon basin. Guarana is best known for its fruit and seeds. Guarana extracts contain naturally high amounts of caffeine which the plant uses in defense against pathogens. Its extracts are a natural and abundant source of caffeine in most parts of the world. It is added to soft drinks, herbal tea, energy shots and used in capsules. The extracts have a positive effect on cognition and they also increase memory retention and physical endurance. A 2007 study on human pilots showed its positive effects on memory, alertness and mood. It is also reported to have antioxidant and antibacterial effects.

Kola Nut, bitter brown seed that contains caffeine. Once used to make cola soft drinks, Kola Nut has been replaced by artificial flavourings in most beverages.

Yerba Matte, actually yerba maté, as it is called in Brazil, or Ilex paraguariensis in Latin, is a small tree or a shrub which can grow to fifteen meters. It is found naturally in South America, mainly in south of Brazil, Argentina, Paraguay, Uruguay and Chile. Foliage is evergreen, and the flowers are rather small, additionally there is a smallish fruit of red color. A tea like brewing in warm water, not boiling, is a popular drink in the native area, similar social gathering is common, akin to tea time practice in the United Kingdom. Yerba matte has several xanthines alkaloids which are related to caffeine, but although chemically identical to caffeine the mate xanthine cocktail provides different results, for instance it relaxes smooth muscle tissue and stimulates heart tissue. Yerba Matte is a potent ingredient in Yellow Hornet .

Yohimbe is a tree that grows in different parts of Western Africa. Active compounds called alkolids are present in its bark with Yohimbine being the principal alkaloid. Yohimbe bark extracts are available in health food outlets. You can also buy it online. These extracts are promoted as a product that increases sex drive and for the treatment of erectile dysfunction. However, there is proof of their effectiveness. Most studies are concerned with the drug Yohimbine and not herbal extract Yohimbe. The side effects of Yohimbe include anxiety and dangerous increase in blood pressure.