Abstract: This study aims to: a) obtain ethanolic (95% EtOH) and aqueous extracts of Selaginella elmeri, Christella dentata, Elatostema sinnatum, Curculigo capitulata, Euphorbia hirta, Murraya koenigii, Alpinia speciosa, Cymbopogon citratus, Eucalyptus globulus, Jatropha curcas, Psidium guajava, Gliricidia sepium, Ixora coccinea and Capsicum frutescens and screen them for larvicidal activities against Aedes aegypti (Linn.) and Aedes albopictus (Skuse) larvae; b) to fractionate the most active extract and determine the most active fraction; c) to determine the larvicidal properties of the most active extract and fraction against by computing their percentage mortality, LC50, and LC90 after 24 and 48 hours of exposure; and d) to determine the nature of the components of the active extracts and fractions using phytochemical screening. Ethanolic (95% EtOH) and aqueous extracts of the selected plants will be screened for potential larvicidal activity against Ae. aegypti and Ae. albopictus using standard procedures and 1% malathion and a Piper nigrum based ovicide-larvicide by the Department of Science and Technology as positive controls. The results were analyzed using One-Way ANOVA with Tukey’s and Dunnett’s test. The most active extract will be subjected to partial fractionation using normal-phase column chromatography, and the fractions subsequently screened to determine the most active fraction. The most active extract and fraction were subjected to dose-response assay and probit analysis to determine the LC50 and LC90 after 24 and 48 hours of exposure. The active extracts and fractions will be screened for phytochemical content. The ethanolic extracts of C. citratus, E. hirta, I. coccinea, G. sepium, M. koenigii, E globulus, J. curcas and C. frutescens exhibited significant larvicidal activity, with C. frutescens being the most active. After fractionation, the ethyl acetate fraction was found to be the most active. Phytochemical screening of the extracts revealed the presence of alkaloids, tannins, indoles and steroids. A formulation using talcum powder–300 mg fraction per 1 g talcum powder–was made and again tested for larvicidal activity. At 2 g/L, the formulation proved effective in killing all of the test larvae after 24 hours.
Abstract: Bacterial strains capable of degradation of malathion
from the domestic sewage were isolated by an enrichment culture
technique. Three bacterial strains were screened and identified as
Acinetobacter baumannii (AFA), Pseudomonas aeruginosa (PS1),
and Pseudomonas mendocina (PS2) based on morphological,
biochemical identification and 16S rRNA sequence analysis.
Acinetobacter baumannii AFA was the most efficient malathion
degrading bacterium, so used for further biodegradation study. AFA
was able to grow in mineral salt medium (MSM) supplemented with
malathion (100 mg/l) as a sole carbon source, and within 14 days,
84% of the initial dose was degraded by the isolate measured by high
performance liquid chromatography. Strain AFA could also degrade
other organophosphorus compounds including diazinon, chlorpyrifos
and fenitrothion. The effect of different culture conditions on the
degradation of malathion like inoculum density, other carbon or
nitrogen sources, temperature and shaking were examined.
Degradation of malathion and bacterial cell growth were accelerated
when culture media were supplemented with yeast extract, glucose
and citrate. The optimum conditions for malathion degradation by
strain AFA were; an inoculum density of 1.5x 10^12CFU/ml at 30°C
with shaking. A specific polymerase chain reaction primers were
designed manually using multiple sequence alignment of the
corresponding carboxylesterase enzymes of Acinetobacter species.
Sequencing result of amplified PCR product and phylogenetic
analysis showed low degree of homology with the other
carboxylesterase enzymes of Acinetobacter strains, so we suggested
that this enzyme is a novel esterase enzyme. Isolated bacterial strains
may have potential role for use in bioremediation of malathion
contaminated.
Abstract: Malathion (ML) is a well known pesticide commonly
used in many agricultural and non-agricultural processes. Its toxicity
has been attributed primarily to the accumulation of acetylcholine
(Ach) at nerve junctions, due to the inhibition of acetylcholinesterase
(AChE). The aim of the current research was to study the protective
effect of the melissa plant extract against reproductive impairment
induced by malathion in 32 male albino rats, and the biological
experiment was divided into four groups (8 in each) that given
malathion (27 mg/kg; 1/50 of the LD50 for an oral dose) and/or
Melissa officinalis (MO) extract (200mg/kg/day) by gavages
technique. The sperm counts, sperm motility, sperm morphology,
FSH, LH, and testosterone levels had been determined in testes
homogenate at the end of the experiment. It is worthy to report that,
rats treated with melissa extract did not show a significant difference
when compared with the control group, while rats given malathion
alone had significantly lower sperm count, sperm motility, and
significantly higher abnormal sperm numbers, than the untreated
control rats as well as having significantly lower serum FSH, LH, and
testosterone levels compared with the control group. Administrations
of melissa extract restore all mentioned histological parameters
towards the control group and the melissa extract had a strong
positive protective effect against malathion toxicity. Results the of
biological parameters were confirmed by the histological
examination of rat testes and indicated that, both control and melissa
groups showing normal seminiferous tubules, while malathion group
testicular tissues had necrosis, edema in the seminiferous tubules and
degeneration of spermatogonial cells lining the seminiferous tubules
with incomplete spermatogenesis. The use of melissa against
malathion improved the histological picture and showing normal
seminiferous tubules with complete spermatogenesis and almost there
was no histopathological changes could be noted.