Morphoanatomy and histochemistry of Maytenus heterophylla leaf, an African medicine

Leaves of Maytenus heterophylla (Eckl & Zeyh.) Robson (Celastraceae) are used in East Africa to treat different diseases such as infections, respiratory diseases and sores [1]. Despite some chemical studies have already been reported for this part of the plant, respective biological studies are scarce and there is a lack of studies aiming at its' botanical characterization. Alkaloids, triterpenes and tannins have previously been identified in the leaves [2].

Hereby we present results concerning the macroscopic and microscopic identification of M. heterophylla leaf as an herbal drug. Methodology includes the analysis of the whole, fragmentized and powdered plant material by light and scanning electron microscopy techniques. Some histochemistry and quantitative microscopy studies were also performed.

Among the identified characters the most useful for leaf identification includes the typical leaf bilateral organization; the presence of anomocytic stomata, more frequent in lower epidermis, and surrounded by a ring of four to six subsidiary cells appear with an irregular distribution; papillate cells on the surface of epidermal cells; multicelled uniseriate covering trichomes (rare). Calcium oxalate cluster crystals are present frequently in the palisade parenchyma, near the phloem cells of the midrib and occasionally occur on epidermis. Histochemical results confirm the presence of the major chemical classes previously reported, and allowed to know its' distribution: lipids on the surface epidermis and cuticle; alkaloids, tannins, terpenoids and starch in the mesophyll, and of some terpenoids on the collenchyma cells near the midribs.

Obtained results can be included in an herbal drug quality monograph of M. heterophylla.

References: [1] Kokwaro, J. O. (1976) Medicinal Plants of East Africa. East African Literature Bureau. Nairobi.

[2] Orabi, K. et al. (2001) Phytochemistry, 58:475–480.