ABSTRACT
Objective: To investigate the antibacterial activity of the extracts of Alternanthera philoxeroides (A. philoxeroides), Plumeria obtusa (P. obtusa), Polyalthia cerasoides (P. cerasoides) and Ixoraacuminate (I. acuminate) against human pathogens. Methods: Aqueous and chloroform: methanol (1:1) extracts of the dried leaf of A. philoxeroides, flowers of P. obtusa, fruits of P. cerasoides and flowers of I. acuminate were tested in vitro by the disk diffusion method against four bacterial strains, namely, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonasaeruginosa. Susceptibility of four reference bacterial strains to some antibiotics in nutrient agar was also tested. Minimal inhibitory concentration (MIC) values were determined and qualitative phytochemical analysis of the crude extract of the tested plant parts was done. Results: Both the aqueous and the chloroform: methanol (1:1) extracts of P. cerasoides showed the strongest activity, followed by flowers of P. obtusa, leaves of A. philoxeroides and flowers of I. acuminate. Aqueous extracts of all the plant parts appeared to have less antibacterial activity than the chloroform:methanol (1:1) extracts. The result of phytochemical analysis of the crude extract of the tested plants showed that flavonoid was absent from all plant parts whereas steroid was present in all tested plant parts. Conclusions: The results support that these plant extracts can be used for the treatment of bacterial diseases.
ABSTRACT
OBJECTIVE@#To analyze the larvicidal activity of two plant leaf powder and leaf-extracts, Dregea volubilis and Bombax malabaricum against Culex quinquefasciatus.@*METHODS@#The larvicidal bioassay was done for powdered leaves of Dregea volubilis and Bombax malabaricum individually and their methanol extracts against first-, second-, third- and fourth-instar larval forms of Culex quinquefasciatus. Mortality rate was recorded after 24, 48 and 72 h of post-exposure. LC(50) and LC(90) values were calculated at different time intervals for third instar larvae.@*RESULTS@#All the graded concentration (0.1%, 0.2%, 0.3%, 0.4%, 0.5%) of powdered leaves showed significant (P <0.05) larval mortality. The mortality rate was higher in 50 ppm doses of methanolic extracts of both the plants against Culex quinquefaciatus. The corresponding LC(50) values were 56.97 ppm and 48.85 ppm, respectively after 24 h of exposure. There is no mortality of non-target organism such as Chironomous circumdatus, Oreochromis niloticus niloticus and Diplonichus annulatum within 72 h of post exposure to 0.1%, 0.2%, 0.3% crude powdered leaves and methanolic extracts of both the two individual plants under the laboratory condition. The results of preliminary qualitative phytochemical analysis of both the plants revealed the presence of many bioactive principles such as steroids, tannins, flavonoids, triterpenoids, saponins, etc. that may be responsible for their bio-control potentiality.@*CONCLUSIONS@#The results have shown potential and eco-friendly use of both plant extracts against larva of Culex quinquefasciatus for the first time.