Authentication of Euclea natalensis leaf by botanical identification

Microscopical characters are well established criteria in the identification and authentication of herbal drugs. Leaves of Euclea natalensis A. DC. (Ebenaceae) are commonly used in the treatment of headache and toothache, as well as for abdominal complaints and as purgative [1]. The purpose of this study was to determine the most relevant diagnostic characters to identify leaves of E. natalensis by light microscopy (LM) and scanning electronic microscopy (SEM). Used methodology includes the microscopic analysis of the whole, fragmentised and powdered dried leaves (minimum of 30 adult leaves). Results showed that among the most useful micro characters for leaf identification are the following: a thick cuticle on both epidermises; the dorsiventral organization of the mesophyll, with one to two cell layers of palisade parenchyma on the upper epidermis and spongy parenchyma with rounded cells on the lower epidermis; the midrib vascular bundle surrounded by a sclerenchymatous tissue; the xylem with numerous small vessels, radially arranged; the presence of calcium oxalate prism crystals; numerous paracytic and diacytic stomata frequent in lower epidermis with an irregular distribution and conical unicellular non-glandular trichomes, with thick walls, sometimes curved near the base and are also fairly abundant (Image 1).

Fig.1: Non-glandular trichomes and stoma random distribution on lower epidermis, by SEM (scale bar: 100µm)

A developed collenchyma is present under the lower epidermis of the midrib area and near the upper epidermis. The powdered material is characterized by the presence of fragments containing the above named structures. Obtained results can be useful on quality control protocols involving this medicinal plant.

References: 1. McGaw LJ. et al. (1997) Phytother Res 11:113–117.