Microbial load and stability of some phyto chemical compounds of selected Sudanese medicinal plant materials as affected by gamma irradiation

The aim of the present study was to evaluate the effect of gamma irradiation treatment on seeds of pepper cress (lepidium sativum L), seeds of black mustard (brassica nigra L.Koch), leaves of lemon grass (cymbopogon citratus), and calyces of roselle (hibiscus sabdariffa L), pods of senna (cassia senna L) and pods prickly acacia (Acacia nilotica L.). The radiation processing was carried out at dose levels of 0, 5, 10. 15 kGy. The irradiated and control samples were analyzed for microbial load, tannins and total phenol content as well as DPPH scavenging activity. The results indicated that gamma radiation treatment significantly reduced microbial load and showed that the total microbial load decreased linearly with absorbed radiation dose. They, also, indicated maximum reduction in tannin content in lemon grass, prickly acacia and roselle. On the other hand, irradiation with 15 kGy increased the tannin and phenol contents in black mustard, pepper cress and senna and reduced the phenol content of roselle and prickly acacia. The results also revealed that gamma irradiation resulted in significant decrease of DPPH radical scavenging activity of the different studied methanolic extracts with exception of pepper cress seeds.(Author)