Response of plant parts and age on the distribution of secondary metabolites on plants found in Quetta.

Abstract

Eight plant species belonging to 7 different families were collected from Botanical Garden, University of Balochistan, Quetta. Their leaves and stem was separately oven dried, powdered and analyzed for the arbitrary level of alkaloids, saponins, tannins and total phenolic contents in their young and old plant parts of leaves and stem. Results showed that leaves and stem of all plant species contained alkaloids. Their level in leaves was comparatively greater over the stem of the same plant species. Generally young plant parts contained greater level of alkaloids as compared to old parts. Results also showed that most of the plants are either lacking saponin, or if present are in a least quantity. However, it was noted that the level of saponin were comparatively found greater in stem over their respective leaves. Aged plant parts usually contained greater level of saponins. Results further revealed that except of Tamarex aphylla, all other remaining plant species are generally lacking tannins. The quantitative analysis of total phenolic contents also revealed that old leaves contained high level of phenolic contents as compared to old stem, while young leaves and stem showed mix trend towards the total phenolic contents. Minimum quantity of total phenolic contents (120 µg/g) was found in young leaves of Nerium oleander, while young leaves and stem of Rhododendron sp., contained maximum phenolic contents (340 µg/g) among all test plants. Whereas, all other remaining plant species produced 123-308 µg/g phenolic contents. These secondary metabolites (chemical defenses) are likely to have come about as a consequence of natural selection, as only that can protect themselves from predators are likely to survive to breed. The present findings might be useful to optimize the processing methodology of wild-harvested material to obtain increased concentration of these secondary metabolites. This then could be used as a natural source of pesticides.