Evaluation of extracts and essential oil from Callistemon viminalis leaves: antibacterial and antioxidant activities, total phenolic and flavonoid contents

OBJECTIVE@#To investigate antioxidant and antibacterial activities of Callistemon viminalis (C. viminalis) leaves.@*METHODS@#The essential oil of C. viminalis leaves obtained by hydro-distillation was analyzed by GC/MS. Different extracts were tested for total phenolic and flavonoid contents and in vitro antioxidant (DPPH assay) and antibacterial (agar disc diffusion and 96-well micro-plates methods) actives.@*RESULTS@#Fourteen components were identified in the essential oil, representing 98.94% of the total oil. The major components were 1,8-cineole (64.53%) and α-pinene (9.69%). Leaf essential oil exhibited the highest antioxidant activity of (88.60±1.51)% comparable to gallic acid, a standard compound [(80.00±2.12)%]. Additionally, the biggest zone of inhibitions against the studied bacterial strains was observed by the essential oil when compared to the standard antibiotic (tetracycline). The crude methanol extract and ethyl acetate fraction had a significant antibacterial activity against the tested bacterial strains.@*CONCLUSIONS@#It can be suggested that C. viminalis is a great potential source of antibacterial and antioxidant compounds useful for new antimicrobial drugs from the natural basis. The present study revealed that the essential oil as well as the methanol extracts and ethyl acetate fraction of C. viminalis leaves exhibited highly significant antibacterial activity against the tested bacterial strains.

Effects of spinosad and emamectin benzoate on the blood picture and DNA structure of the cotton leaf worm spodoptera littoralis [boisd]

The physiological and genetical effects of spinosad and emamectin benzoate were studied on the cotton leaf worm Spodoptera littoralis [Boisduval] [Lepidoptera: Noctuidae]. The effect of these two insecticides, on the total and different haemocytes count of the 5[th] instar larvae of S. littoralis [Lepidoptera: Noctuidae] were evaluated. Results revealed that emamectin benzoate at LC[25] and LC[50] values decreased the total haemocytes counts [THCs] to 55.8% and 52%, respectively. In this respect, spinosad decreased the THCs to about 22.4% and 24.4%, respectively. The six haemocyte types identified as prohaemocytes [pr], granulocytes [gr], non-granulocytes [n-gr], plasmatocytes [pl], oenocytes [oe] and spherule [sph] cells were monitored. Generally, all the tested concentrations of emamectin benzoate decreased the counts of all the haemocyte types. However, the application of spinosad increased the pr, pl, oe and sph. While it dercreased both n-gr and gr. Spinosad and emamectin benzoate have had an effect on the larval DNA. Presence and absence of several bands were observed, as well as differences in the band intensity among the treatments. The toxicological profile of the tested pesticides described herein characterizes their effects on S. littoralis larval DNA. Results clearly proved that pesticides treatments induce DNA strand fragmentations at different sites when compared with the untreated check. In addition, the fluctuations occurred in THCs and translation systems represented in DNA were ongoing on the same direction. These results have drawn a new proposed mode of action to those friendly environmental promising compounds