Identification of Frangula azorica bark a Portuguese Medicinal Drug

Frangula azorica V. Grubow is a medicinal plant of Macaronesia flora, endemic from Azores islands inscribed on IUCN Red List of Threatened Species [1]. Although belonging to Rhamnaceae family, known by two well known laxative herbal drugs present in Western Pharmacopoeia (Rhamnus frangula and Rhamnus purshiana) morphological and chemical studies are scarce about F. azorica.

In sequence of our work on medicinal plants from Azores hereby, we present results of chemical and botanical studies conducted in order to identify significant markers for diagnosis of this herbal drug. Methodology used includes macroscopic and microscopic analysis of whole, fragmentised and powdered bark. Additionally, scanning electron microscopy was used. TLC profile of the bark methanol extract was compared with a similar extract of alder buckthorn bark.

The most useful F. azorica macroscopic and microscopic characters observed include:

A channelled external surface with frequent lenticels and inner surface orange-reddish; transverse section show flattened cork cells with red content and a collenchymatous cortex; parenchyma with mucilaginous glands; groups of sclereids; frequent cluster crystals and scarce prisms crystals of calcium oxalate scattered in the parenchymatous tissues; uni or biseriate medullary rays; scarce fibres. Quantification of major features was performed.

Obtained results of the botanical study together with TLC profile permit the establishment of distinct characteristics for identification of F. azorica bark as herbal drug.

References: 1. http://www.iucn.org/en/news/archive/2006/05/02 pr red list en.htm