Mexican Petunia (Ruellia simplex C.Wright)

Ruellia simplex, the Mexican petunia, Mexican bluebell or Britton's wild petunia, is a species of flowering plant in the family Acanthaceae. Ruellia simplex C.Wright is the oldest and accepted name for this species, which has been variously called Ruellia angustifolia (Nees) Lindau, Ruellia brittoniana Leonard, and Cryphiacanthus angustifolius Nees, among several synonyms.

Ruellia simplex is an evergreen perennial growing 0.91 m tall, forming colonies of stalks with lance-shaped leaves that are 15 to 30 cm and 1.3 to 1.9 cm wide. Trumpet shaped flowers are metallic blue to purple, with five petals, and 7.6 cm wide. There is a dwarf variety that is only 0.30 m tall.

Mexican Petunia (Ruellia simplex C.Wright) is a plant with a diverse range of medicinal uses, including cardiovascular, antihyperglycaemic, antioxidant, antimicrobial, antibacterial, anticancer, antinociceptive, and anti-inflammatory properties. It is primarily used for diabetes in phytotherapy and is even consumed as tea by Taiwanese people.

The chemical composition varies depending on the extraction method but typically includes abundant amounts of tannins, flavonoids, steroids, triterpenoids, and phenolic compounds. 

Additionally, the purple-coloured flowers contain a high concentration of anthocyanins.

The ethyl acetate and methanolic extracts are comprised of eight primary components, namely: isobargaptol 5-O-β-D-glucopyranoside, syringaresinol, catechin, pulmatin, verbascoside, hydroxymethylfurfural, rutin, and homoplantaginin.

In addition to the aforementioned active constituents, there are approximately 100 active ingredients present.

The flowers feature essential oils that provide an intense flavour, with terpenoid and phenolic components being particularly prominent. Hexadecanoic acid is present in high concentration, accounting for 15% of the essential oil.