Euphorbia pulcherrima L:
Common name: Poinsettia
The name pulcherrima means "most beautiful" and brilliant red floral display of E. pulcherrima, held against rich green foliage has made this unlikely species a holiday favorite. Its attractive appearance of the Christmas colors has so endeared the plant, that it is now second only to the Christmas tree as the most popular holiday plant. E. pulcherrima was named after Dr. J.R. Poinsett and was introduced to gardeners in the early 19th century.
The species is a tall, rangy shrub that grows to a height of 10 ft (3.1 m). It has large, dark green, oval leaves that are "toothed" on the sides and pointed at the tips. They emerge from smooth green erect stems. Flowers are born at the stem tips in winter season. The actual flowers are quite small and of yellow structures at the center of the brilliantly colored "bracts". The bracts are actually modified leaves, and usually there are 8 to 10 bracts in the species (Fig: 3.22 and 3.23).
Although many species in the genus Euphorbia are highly toxic, but E. pulcherrima is not among them. The effect of flowers of these plants as fungitoxicant on aflatoxin producing fungi A. flavus and A. parasiticus has not yet been studied. The present study was undertaken to assess the fungitoxic role of dry flower powder of E. milli and E. pulcherrima against aflatoxin producing strains of A. flavus and A. parasiticus. Aqueous flower extracts were also used for the bioassay of groundnut against these fungi (Abubacker and Ramanathan, 2003).
E. pulcherrima possesses various types of phytochemicals which shows antimicrobial activity (Table 3.6). E. pulcherrima has also been reported to inhibit the growth of isolated aflatoxin producing fungi A. flavus and A. parasiticus. Total inhibition (100%) was noticed in A. flavus when treated with dry flower powder. But in the case of A. parasiticus total inhibition was observed only at the high concentration of E. pulcherrima extract. The antimicrobial activity was possibly due to the presence of the simple phenols and phenolic acids, quinones, flavones, flavonoids and flavanols. This kind of interference may be at the biosynthetic level. (Murugan et al., 2007).
The level of inhibition between A. flavus and A. parasiticus differs a lot. Earlier studies have suggested that growth and aflatoxin production by A. flavus and A. parasiticus are independent phenomena (Singh, 1983; Bhatnagar and McCormick, 1987). The isolation and characterization of the compounds, capable of inhibiting aflatoxin-producing fungus A. flavus, would be useful since success in this aspect could provide a means for the elimination or control of aflatoxin contamination in food-stuffs (Mislivec et al., 1998).