Antioxidant and antimicrobial proprieties of chitin and chitosan extracted from Parapenaeus Longirostris shrimp shell waste.

INTRODUCTION: Chitosan, the linear polymer, is produced by alkali deacetylation of chitin (CHI). Recently chitin and chitosan were attracted marked interest due to their biocompatibility, biodegradability and non-toxicity. MATERIALS AND METHODS: In this study, chitin was extracted from shrimp shell (Parapenaeus longirostris) and chitosan was deacetylated by classical and ultrasound-assisted method. The identification of functional groups and the determination of degree of deacetylation of chitin (CHI), classical deacetylated chitosan (CDC) and ultrasound-assisted deacetylated chitosan (UDC) were carried through Fourier Transform-Infrared Spectroscopy. Their antimicrobial and antioxidant activity were also investigated. RESULTS: The degree of deacetylation of CHI, CDC and UDC is 33.64%, 73.68% and 83.55%, respectively. Results showed that CHI, CDC and UDC exhibited a good antimicrobial activity against (S. aureus, E. coli, P. aeruginosa, K. pneumonia) and (C. albicans and C. parapsilosis). The scavenging ability of CHI, CDC and UDC on 1,1-diphenyl-2-picrylhydrazyl radicals is ranging from 4.71% to 21.25%, 11.45% to 32.78% and 18.27% to 44.17%, respectively, at the concentrations of 0.25 to 1mg/mL. The inhibition of lipid peroxidation with thiobarbituric acid-reacting substances is ranging from 11.7% to 51.63%, 17.24% to 63.52% and 29.31% to 77.39%, respectively, at varying concentrations of 0.25 to 1mg/mL. CONCLUSION: The effectiveness of CHI, CDC and UDC is correlated with their degree of deacetylation. The results indicate the possibility of exploiting chitin and chitosan as antimicrobial agent.

Effects of sage extract on memory performance in mice and acetylcholinesterase activity.

INTRODUCTION: Salvia officinalis L. (sage) has been widely used in the Tunisian traditional medicine for the treatment of digestive system and memory disorders. OBJECTIVES: This work aims to investigate the anti-amnesiac and antioxidant activity of aqueous extract of S. officinalis (ASOE) in mice. MATERIALS AND METHODS: Evaluation of memory functions in rodents was assessed by Y-maze active test after an initial acquisition phase. RESULTS: Results showed that the S. officinalis aqueous extract had high total phenolic contents (6.2mg gallic E/g extract) and flavonoids (2.44mg catechin E/g extract). It exhibited an interesting scavenging activity (IC50=14.5µg/ml). The mice treated with 300mg/kg body weight for 7 days exhibited a significant decrease in avoidance and discrimination errors during a retention trial compared to control group (P<0.05). Acetylcholinesterase (AChE) activity significantly decreased in mice treated with the extract of sage. CONCLUSION: These findings suggested that aqueous extract of sage leaves possess a mnemonic effect on adult male mice, confirming their use in traditional medicine.

[Homocysteine, vitamin B-12, folic acid and the cognitive decline in the elderly]. / Homocystéine, vitamine B12 et acide folique dans le déclin cognitif chez les personnes âgées.

Hyperhomocysteinemia is a risk factor for neurological diseases, but the underlying pathophysiology has not been adequately explained. Mild hyperhomocysteinemia, which is sometimes associated with a low plasma level of vitamin B9, B12 and folic acid, is responsible in the toxicity in neural cell by activating NMDA receptor. Indeed, even if vitamin supplementation has clearly proven its efficiency on lowering plasma levels of homocysteine, recent studies do not show any positive effect of vitamin therapy on cognitive function. The hypothesis that this therapy is inefficient has been recently reinforced by two randomized trials on the effects of vitamin supplementation. Several hypotheses still need to be explored: Mechanisms of homocysteine toxicity and that of total uselessness of vitamin supplementation; the possible need to complete the actual data with further, more powerful studies in order to prove the role of homocysteine in the development of neurodegenerative diseases and a clinical effect of vitamin therapy.

[Interest of CSF beta-amyloid1-42 and t-tau protein level determinations for the diagnosis of Alzheimer's disease]. / Intérêt du dosage de la protéine amyloïde Abeta1-42 et de la protéine tau dans le LCR pour le diagnostic de la maladie d'Alzheimer : une étude tunisienne.

Early diagnosis of Alzheimer's disease remains a tactful poser. In order to clarify the importance of beta amyloid protein dosage (Abeta1-42) and protein tau (t-tau) in such pathology, we have rigorously studied three well recruited populations that match in age: healthy controls (n = 32), Alzheimer patients (n = 87) and non Alzheimer dementia (n = 31) patients. The combination of Abeta1-42 and t-tau at baseline yielded a sensitivity of 85.29 % for detection of Alzheimer's disease and the specificity was by 96.77 % to differentiate controls. So the combination of these tow markers helps in the diagnosis of Alzheimer because of the high specificity and sensibility of this method.

[Diagnostic value of serum and pleural fluid adenosine deaminase activity in tuberculous pleurisy]. / Valeur diagnostique de l'activité de l'adénosine désaminase pleurale et sérique dans la pleurésie tuberculeuse.

The biological diagnosis of tuberculous pleurisy poses the problem of the time required to obtain results and of the sensitivity of the usual diagnostic methods. The determination of adenosine deaminase (ADA) activity has been proposed for the diagnosis of tuberculous pleural effusion and for the follow-up. In the present study, ADA in pleural effusion (p-ADA) and in serum (s-ADA) has been measured in 2 groups of patients: tuberculosis (27) and non-tuberculosis (53) patients. The upper limit of the normal values was fixed at 37 U/L. Comparing these 2 groups, we observed a specificity of 81.2% and a sensitivity of 66.6%. The PPV and the NPV were respectively 64.3% and 82.7%. We used p-ADA/s-ADA ratio for diagnosis of tuberculous pleural effusion, a threshold value of 1.8 gave a sensitivity of 82.6% and a specificity of 84.8%. Within the tuberculosis patient group, the activity of ADA decreased after the appropriate treatment initiation. Thus, the determination of ADA activity and/ or the p-ADA/s-ADA ratio, can help to recognize the tuberculosis origin of pleural effusions.