Pharmacognostical studies of Hymenodictyon orixence (Roxb.) Mabb. leaf

Hymenodictyon orixence is medicinally important plant found in India, Malaysia and Africa. Due to overexploitation the population of this species has decreased very rapidly. The present study includes pharmacognostical examination of this species. It includes morphological, anatomical, chemical and chromo- ﬁ ngerprinting characters of Hymenodictyon orixence leaf.


INTRODUCTION
Standardization of natural products is a complex task due to their heterogeneous composition, which is in the form of whole plant, plant part/extracts obtained thereof. To ensure reproducible quality of herbal products, proper identifi cation of starting material is essential.
Hymenodictyon orixence is a Rubiaceae member commonly known as 'Bhorsal' and is mainly known for its wound healing property. It has been reported to have antimicrobial, [1,2] anticoagulant, antiinfl ammatory and sun screening activity. [3] The present study was carried out to establish methods to facilitate proper identifi cation of Hymenodictyon orixence leaf and its powdered form on the basis of morphological, anatomical, chemical and chromo-fi ngerprinting characters.

Pharmacognostical studies
Morphological studies including size, shape, apex, margin, surface and colour were carried out. Other important microscopic characters like epidermal cell number, stomatal index, vein termination, vein islet number and trichomes of both the surfaces was carried out by using standard procedures. [7] Transverse sections taken by razor were dehydrated, double stained and observed. [8] Some basic chemical reactions were carried with powdered material. Chromo-fi ngerprints were developed by slight modifi cation of methodology of fl uorescence analysis of powdered drugs. [9]

RESULTS AND DISCUSSION
The leaves of Hymenodictyon orixence are simple, opposite decussate, stipulate and petiolate. The leaf measures about 12-30 cm in length and 8-15 cm in width, elliptic in shape, with an abruptly acute apex. The margin is entire, with the base narrowed into a petiole, which is about 2.5-7 cm long and hairy. Dark green above and pale below, the young leaves are silvery and clustered at the end of branches. The stipule is interpetiolar, triangular or broadly ovate, obtuse recurved and deciduous.
The midrib is elevated on both the surfaces, with the upper being conical and lower semicircular in outline. Inner to the epidermis there is a few layered collenchyma followed by large parenchyma. Vascular bundle shallow is 'U' shaped with incurved margins. The xylem strands are few and embedded in phloem [ Figure 1].
Upper epidermal cells are larger than the lower ones. Both the      [Table 1].
Behavior of leaf powder with different chemical reagents was studied to detect the presence of phytoconstituents with colour changes under day light and the results were presented in the table [ Table 2].
The colour of the plant extract is mainly due to its chemical composition. The same extract may appear different in different wavelength of light. Kokashi et al, [9] studied the behavior of different vegetable drugs under UV radiation and found that different drugs exhibit different colours and those colours were characteristic for the particular drug. In our study we found a specifi c colour pattern which is characteristic for Hymenodictyon orixence, and hence can be used as a fi nger print for crude drug identifi cation [ Figure 4].