Study of the Biological Activity of Aqueous Extract of Cuminum cyminum L. and Hibiscus sabdariffa L. and Detection of Some Active Groups in them.


The studies about the effect of plant extract against different types of bacteria are still one of the most important fields of researches because they are available, cheep, safe, and easy to use by not professional populations. In this work, two plant extracts (Hibiscus sabdariffa) and Cuminum cyminum) were tested for there possible biological activity against bacteria. Boiled aqueous extract of both plants at the following concentrations (1, 5, 10, and 20%) were used after cooling. Agar well diffusion was used to examine the biological activity of each extract and the results expressed as zone of inhibition in (mm). The bacteria used in this study are (Gram positive: Streptococcus faecalis and Staphylococcus aureus) and (Gram negative: Pseudomonas pyogens, Escherichia coli, and Klebsiella pneumoniae).The tests for functional groups that can be extracted by water were carried out. Hence Alkaloids, Saponines, Tannins, Glycosides were screened using a suitable method while oils noticed as upper layer (if present). At 1% concentration, there are no detectable inhibition zones of both aqueous extracts. The inhibition zones appeared at 5% and further inhibition showed as concentration increased. In general, the aqueous extract of Hibiscus sabdariffa has shown more biological activity than the corresponding concentration of Cuminum cyminum. The lowest activity was shown against Escherichia coli bacteria while the other bacteria showed different zone diameters as a response for the same concentration. In Cuminum cyminum there are detectable amounts of essential oils, glycosides and high amounts of tannins while alkaloids and saponines are not detectable using the described methods. In Hibiscus sabdariffa, there is a detectable amount of saponines, glycosides, and high amounts of tannins while there are no positive results for essential oils and alkaloids.In conclusion, the aqueous extracts of H. sabdariffa and Cuminum cyminum have antibacterial activity at concentrations ≥5%. Hibiscus sabdariffa has shown more biological activity than the corresponding concentration of Cuminum cyminum. This fact may be due, in part, to the presence of saponines in Hibiscus sabdariffa. The results can be explained through the presence of different active substances in the aqueous extract of both plants.