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Eugenol, a member of the phenylpropanoids class of chemical compounds, is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, and bay leaf. The antibacterial activity of eugenol and its mechanism of bactericidal action against Proteus mirabilis were evaluated. Treatment with eugenol at their minimum inhibitory concentration [0.125 % (v/v)] and minimum bactericidal concentration [0.25 % (v/v)] reduced the viability and resulted in complete inhibition of P. mirabilis. A strong bactericidal effect on P. mirabilis was also evident, as eugenol inactivated the bacterial population within 30 min exposure. Chemo-attractant property and the observance of highest antibacterial activity at alkaline pH suggest that eugenol can work more effectively when given in vivo. Eugenol inhibits the virulence factors produced by P. mirabilis as observed by swimming motility, swarming behavior and urease activity. It interacts with cellular membrane of P. mirabilis and makes it highly permeable, forming nonspecific pores on plasma membrane, which in turn directs the release of 260 nm absorbing materials and uptake of more crystal violet from the medium into the cells. SDS-polyacrylamide gel, scanning electron microscopy and Fourier transform infrared analysis further proves the disruptive action of eugenol on the plasma membrane of P. mirabilis. The findings reveal that eugenol shows an excellent bactericidal activity against P. mirabilis by altering the integrity of cell membrane.

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Context: Alzheimer’s disease (AD) is believed to develop due to deposition of β-amyloid (Aβ) peptide. Hence, efforts are being made to develop potent drug that target amyloid hypothesis.Objective: The present study explores the effect of the seaweed Gelidiella acerosa (Forsskål) Feldmann & Hamel (Gelidiellaceae) against Aβ 25–35 peptide in Swiss albino mice.Materials and methods: The animals were administered through intracerebroventricular (ICV) injection with the Aβ 25–35 peptide (10 μg/10 μL/ICV site) on 21st day of the pretreatment of G. acerosa (whole plant) benzene extract (200 and 400 mg/kg bw). On day 30, animals were sacrificed and brain tissue homogenate was prepared. The activities of AChE, BuChE, b-secretase, MAO-B, and caspase-3 were determined, and Bax expression was assessed by Western blotting.Results:Gelidiella acerosa benzene extract restored the level of antioxidant enzymes and prevented lipid and protein oxidation significantly (p < 0.05). The extract protected the mice from cholinergic deficit significantly (p < 0.05) by inhibiting the activities of AChE and BuChE, which was about 0.116 ± 0.0088 U/mg of protein and 0.011 ± 0.0014 U/mg of protein respectively, which was otherwise increased in peptide-treated group (0.155 ± 0.007 U/mg of protein and 0.015 ± 0.0012 U/mg of protein respectively). Interestingly, G. acerosa benzene extract inhibited β-secretase and MAO-B activity. Reduction (p < 0.05) in level of caspase-3 activity and Bax expression suggests that G. acerosa protects the cells from apoptosis.Discussion and conclusion: The results suggest that G. acerosa possesses excellent neuroprotective potential against peptide mediated toxicity under in vivo conditions.

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2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental toxin formed as an unintentional by-product of incomplete combustion. Several therapeutic approaches have evolved to combat its toxicity since it elicits immunotoxicity, neurotoxicity, hepatotoxicity, carcinogenicity and lethality. Search for drugs from natural resources especially from seaweeds has become intense due to their enormous pharmacological potential. Hence, the present study aims at revealing the protective effect of methanolic extract of G. acerosa (MEGA) in Peripheral Blood Mononuclear Cells (PBMC) against TCDD induced toxicity, by assessing the antioxidant, anti-apoptotic and cytoprotective activities. The results of antioxidant assays suggests that MEGA reverted TCDD induced toxicity by causing an alteration in the levels of antioxidant enzymes (Catalase [CAT], Superoxide dismutase [SOD], Glutathione peroxidase [GPx], Glutathione-S-transferase [GST]) and Glutathione [GSH]. The results of lipid peroxidation assay and protein carbonyl content reveal that MEGA protects PBMC from TCDD induced macromolecular damage. MEGA was found to exhibit significant (p < 0.05) anti-apoptotic activity as verified by evaluation of mitochondrial membrane potential and AO-EtBr dual staining. In addition, PBMC co-treated with MEGA prevented TCDD induced oxidative DNA damage. Levels of phase-I detoxification enzymes determined by EROD assay and semi-quantitative RT-PCR showed that TCDD up-regulates the expression of CYP1A1 and upon co-treatment with MEGA, the expression got slightly decreased suggesting its protective role. Preliminary phytochemical analysis demonstrates that the extract is rich in cardiac glycosides and terpenoids. LC-MS analysis revealed the presence of antioxidants including caffeic acid, phytol and mannoheptulose in MEGA, which could be attributed for the observed protective effect against TCDD induced toxicity.

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