Antioxidant and anti-glycation activities correlates with phenolic composition of tropical medicinal herbs.

OBJECTIVE: To determine the contribution of total phenolic content (TPC) in glycation inhibitory activity of common tropical medicinal food and spices with potential antioxidative properties. METHODS: In vitro glucose-bovine serum albumin (BSA) assay was used. Ethanolic extracts of ten common household condiments/herbs (Allium sativum, Zingiber officinale, Thymus vulgaris, Petroselinum crispum, Murraya koenigii Spreng, Mentha piperita L., Curcuma longa L., Allium cepa L., Allium fistulosum and Coriandrum sativum L.) were evaluated for antioxidative activity by 2,2-diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) and the TPC, flavonoid and tannins content were determined. RESULTS: Findings showed good correlation between TPC/DPPH (r = 0.8), TPC/FRAP (r = 0.8), TPC/anti-glycation (r = 0.9), DPPH/anti-glycation (r = 0.6), FRAP/anti-glycation (r = 0.9), Flavonoid/anti-glycation (r = 0.7) and Tannins/anti-glycation (r = 0.8) and relatively fair correlation for TPC/Flavonoids (r = 0.5) and TPC/Tannins (r = 0.5). Results imply that these plants are potential sources of natural antioxidants which have free radical scavenging activity and might be used for reducing oxidative stress. CONCLUSIONS: The positive glycation inhibitory and antioxidative activities of these tropical herbs suggest a possible role in targeting ageing, diabetic complications and oxidative stress related diseases.

Screening for alternative antibiotics: an investigation into the antimicrobial activities of medicinal food plants of Mauritius.

The present study was designed to evaluate the antimicrobial activities of 2 endemic medicinal plants; Faujasiopsis flexuosa (Asteraceae) (FF) and Pittosporum senacia (Pittosporaceae) (PS) and 2 exotic medicinal plants, Momordica charantia (Cucurbitaceae) (MC) and Ocimum tenuiflorum (Lamiaceae) (OT) that forms part of local pharmacopoeia of Mauritius and correlate any observed activity with its phytochemical profile. Aqueous and organic fractions of the leaves, fruits, and seeds of these plants were subjected to antimicrobial testing by the disc diffusion method against 8 clinical isolates of bacteria and 2 strains of fungus. It was found that MC, OT, and FF possessed antimicrobial properties against the test organisms. The MIC for MC ranged from 0.5 to 9 mg/mL and that of FF from 2 to 10 mg/mL and the lowest MIC value (0.5 mg/mL) was recorded for the unripe fruits of MC against E. coli. On the other hand, higher concentration of the unripe MC fruit extract of 9 mg/mL was needed to be effective against a resistant strain of Staphylococcus aureus (MRSA). The antimicrobial effect against MRSA was lost upon ripening of the fruits. The methanolic extract of both MC and FF showed highest MIC values compared to the corresponding aqueous extract, which indicates the low efficacy and the need of higher doses of the plant extract. Phytochemical screening of the plants showed the presence of at least tannins, phenols, flavonoids, and alkaloids, which are known antimicrobial phyto-compounds. In conclusion, the observed antimicrobial properties would tend to further validate the medicinal properties of these commonly used endemic medicinal and food plants of Mauritius.

Effect of exogenous ATP on Momordica charantia Linn. (Cucurbitaceae) induced inhibition of D-glucose, L-tyrosine and fluid transport across rat everted intestinal sacs in vitro.

Momordica charantia (MC) is a common oriental vegetable with known antidiabetic, laxative and antimicrobial properties. This study investigates the effects of aqueous fruit extract of MC on the transport of d-glucose, l-tyrosine and fluid across rat-everted intestine in vitro. Everted intestinal sacs from rats were mounted in an organ bath containing Krebs-Henseleit bicarbonate buffer. Graded concentrations (1.5-12mg/ml) of MC fruit extract were incubated in the mucosal solution with and without exogenous ATP in the mucosal bathing fluid. The serosal appearance and mucosal disappearance of d-glucose, l-tyrosine and the fluid absorptive capacity of the intestine were significantly inhibited (p<0.05) with increasing graded concentrations of MC. The concentration of d-glucose accumulated or metabolized by the enterocytes in the intestinal tissues were significantly higher (p<0.05) when incubated with MC. Increasing graded concentrations of exogenous ATP (25-200 microM) were incubated with 3.0mg/ml MC to confirm inhibition of the ATP-dependent active transport of d-glucose, l-tyrosine and fluid across rat enterocytes. It was found that increasing concentrations of mucosal ATP from 25 to 100 microM significantly (p<0.05) reverses the MC-depression of the d-glucose, l-tyrosine and fluid uptake across rat everted intestinal sacs. It is hypothesized that bioactive phytochemicals such as saponins in MC fruit extract inhibits the active transport of d-glucose, l-tyrosine and fluid across rat intestine by inhibiting the production of ATP responsible for the active transport of these molecules. It is likely that MC can be a potential alternative drug therapy of postprandial hyperglycaemia via inhibition of glucose uptake across the small intestine.

Stimulatory effects of Antidesma madagascariense on D-glucose, L-tyrosine, fluid and electrolyte transport across rat everted intestine, comparable to insulin action in vitro.

Medicinal plants are believed to be an important source of potential therapeutic agents. This study investigates the effects of Antidesma madagascariense (AM) extract on the transport of D-glucose, L-tyrosine, fluid and electrolytes (Na+ and K+) across rat everted intestinal sacs. These sacs were mounted in an organ bath containing Krebs-Henseleit bicarbonate (KHB) buffer. Experimental findings showed that incubation with graded aqueous AM extracts above 0.375 mg/mL significantly (P < 0.05) stimulated the mucosal disappearance and serosal appearance of glucose and fluid. The concentration of glucose accumulated in the intestinal tissues also increased significantly (P < 0.05) compared to that found in the controls. Transport of the amino acid L-tyrosine was not significantly enhanced (P > 0.05) when incubated with increasing concentrations of AM extract. Effects on electrolyte (K+ and Na+) transport were assessed. Na+ uptake and transport was significantly enhanced (P < 0.05) when incubated with 0.75 mg/mL AM extract; however, K+ transport was not significantly enhanced (P > 0.05). For comparison, insulin (1 and 2 units/mL) was incubated in the mucosal solution. Aqueous AM extract produced similar stimulatory effects on the transport of glucose, fluid and Na+ as were found with insulin. It is hypothesised that bioactive phytochemicals such as flavonoids, alkaloids, leucoanthocyanins, phenols and saponins from AM leaf extract might interfere with the Na+/glucose carrier, thereby enhancing the transport of glucose, Na+ and fluid across rat everted intestinal sacs. Thus, AM may represent a possible alternative dietary supplement for the treatment of type 2 diabetes.

Screening of traditional antidiabetic medicinal plants of Mauritius for possible alpha-amylase inhibitory effects in vitro.

In this study, seven exotic/indigenous medicinal plants of Mauritius, namely Coix lacryma-jobi (Poaceae), Aegle marmelos (Rutaceae), Artocarpus heterophyllus (Moraceae), Vangueria madagascariensis (Rubiaceae), Azadirachta indica (Meliaceae), Eriobotrya japonica (Rosaceae) and Syzigium cumini (Myrtaceae) were studied for possible effects on starch breakdown by alpha-amylase in vitro. The results showed that only Artocarpus heterophyllus significantly (p < 0.05) inhibited alpha-amylase activity in vitro. To confirm the observed effects, a further biochemical assay was undertaken to investigate the effects of Artocarpus heterophyllus on alpha-amylase activity using rat plasma in vitro. It was found that the aqueous leaf extract significantly (p < 0.05) inhibited alpha-amylase activity in rat plasma. The highest inhibitory activity (27.20 +/- 5.00%) was observed at a concentration of 1000 microg/mL. However, in both cases dose dependency was not observed. Enzyme kinetic studies using the Michaelis-Menten and Lineweaver-Burk equations were performed to establish the type of inhibition involved. In the presence of the plant extract the maximal velocity (Vmax) remained constant (1/150 g / L/s) whereas the Michaelis-Menten constant (Km) increased by 5.79 g / L, indicating that the aqueous leaf extract of Artocarpus heterophyllus behaved as a competitive inhibitor. Results from the present study tend to indicate that Artocarpus heterophyllus could act as a 'starch blocker' thereby reducing post-prandial glucose peaks.

A survey on home generated medical waste in Mauritius.

This study was carried out to evaluate home-generated medical waste in Mauritius. A questionnaire survey was undertaken among a random sample population in 250 houses in the nine districts of the island. Results of this study showed an overwhelmingly large proportion of medical waste arising from the domestic environment joins the common municipal solid waste stream and ends in landfills. This improper disposal process poses a serious health hazard to the general public, waste haulers and landfill personnel. It is therefore recommended that a national policy on medical waste management be urgently implemented, proper training of waste haulers be offered and education campaign be carried out to sensitize the general public on safe disposal of medical waste.

Multiple logistic regression modelling substantiates multifactor contributions associated with sick building syndrome in residential interiors in Mauritius.

This paper presents a mathematical model that depicts the relationship between the possibility of occurrence of common health problems and factors leading to Sick Building Syndrome symptoms in domestic interiors in Mauritius. The prevalence of upper respiratory symptoms (dry eyes, runny nose), central nervous system symptoms (headache, nervousness), and musculoskeletal symptoms (pain/stiffness in shoulders/neck) were found to be elevated when responses were statistically regressed to type of building and age of respondents. The model presented here will be useful in helping to identify and quantify the relative role of factors that contribute to Sick Building Syndrome. Thus it may be possible to evaluate the effectiveness of current building operation practices and to prioritise allocations of resources for reduction of risk associated with Indoor Environmental Air Quality.

Prevalence of HLA-B27 among donors and recipients for renal and bone marrow transplantation in Mauritius.

In this study, the frequency of the tissue antigen HLA-B27 is studied in 494 donors and recipients for renal and bone marrow transplantation on the multi-ethnic island of Mauritius, the majority of the population of which is of Indian descent. Although results showed a prevalence rate of 4.3%, inter-racial variation was not observed between the major ethnic groups (P>0.05). These findings are comparable with the results of studies on HLA-B27 prevalence rate in India, and lend support to the argument that the HLA-B27 test should not be used on a routine basis to diagnose HLA-B27-related rheumatic disorders in Mauritius.

Prevalence of HLA-B27 among donors and recipients for renal and bone marrow transplantation in Mauritius.

In this study, the frequency of the tissue antigen HLA-B27 is studied in 494 donors and recipients for renal and bone marrow transplantation on the multi-ethnic island of Mauritius, the majority of the population of which is of Indian descent. Although results showed a prevalence rate of 4.3%, inter-racial variation was not observed between the major ethnic groups (P>0.05). These findings are comparable with the results of studies on HLA-B27 prevalence rate in India, and lend support to the argument that the HLA-B27 test should not be used on a routine basis to diagnose HLA-B27-related rheumatic disorders in Mauritius.

Indoor biological contaminants and symptoms of sick building syndrome in office buildings in Mauritius.

This study was carried out to investigate possible relationship between bio-contaminants and symptoms of sick building syndrome among office workers in Mauritius. Viable microbial colonies were collected using a Casella slit sampler in 23 selected indoor office buildings. A questionnaire survey as well as a walk through investigation was undertaken. Physico-chemical measurements were also monitored in the selected offices. Results of this study showed that number of indoor bacterial bioaerosol concentrations ranged between 3 and 1110 CFU/m(3) while fungal counts were 0-196 CFU/m(3). However, most of the buildings showed absence of dust mites. In conclusions fungal contamination was found to be associated with the onset of sick building syndrome symptoms among workers in office buildings in Mauritius.

Effect of vitamin C on endothelial dysfunction during N-alpha-tosyl L-arginine methyl ester [TAME]-esterase induced contractions in rat aorta in vitro.

Contractions induced by TAME-esterase on rat aorta strips mounted in vitro were significantly inhibited in presence of Vitamin C. The work lends support to the role of ascorbic acid in preventing endothelial dysfunction through release of nitric oxide. It is suggested that conclusions TAME-esterase could be an important biological marker associated with onset of vascular discases such as hypertension.

Effect of genistein, a tyrosine kinase inhibitor, on TAME-esterase induced contractions in rat aorta in vitro.

Effect of genistein, a protein tyrosine kinase inhibitor, on TAME-esterase induced contractions were studied on rat aorta strips in vitro. Data showed that TAME-esterase induced contractions were concentration dependent and these contractions were significantly inhibited when rat aorta strips were pre-incubated with genistein. The present findings provide evidence for the possible contribution of tyrosine kinases during TAME-esterase induced contractions in aorta.

Plasma cardiolipin in postmenopausal women in mauritius.

Data concerning the relationship between anti-cardiolipin antibodies and several diseases including myocardial infarction are not readily available for Mauritius. Anticardiolipin antibodies were measured using commercially available ELISA kits. Haematological profiles were measured using a Coulter Counter in the study population. Our study revealed significantly higher IgG and IgA levels as well as a strong correlation between decreased platelet levels and increased anticardiolipin status in the women during postmenopause. It is concluded that abnormal cardiolipin level could be an important risk factor for cardiovascular accidents among postmenopausal women in Mauritius.

Experimental evidence for a non-renin mediated pathway during TAME-esterase induced contractions in rat aorta in vitro.

Possible pharmacological effects of N-alpha-tosyl L-arginine methyl ester [TAME] were studied on rat aorta strips in vitro. Results showed that [TAME]-esterase was an endothelium dependent component that involved a nitric oxide cyclic-GMP mediated pathway. Furthermore, during activation of Kinin-Kallikrein system, TAME-esterase induced contractions involve degradation of kinins by kininases.

[TAME]-esterase--a new cardiovascular risk factor in smokers.

A mathematical model has been proposed to study the effect of [TAME] esterase on blood clotting time. Using this model, clotting time was found to decrease by 30% with increasing plasma [TAME] esterase activity in a group of smokers. It is hypothesized that [TAME] esterase through its effect on Hageman factor could affect clotting time. However mechanism of clotting by [TAME] esterase remains to be elucidated. It is concluded that [TAME] esterase is involved in the cascade of reactions leading to blood coagulation and increased [TAME] esterase activity could be an additional risk factor for possible cerebro-vascular accidents in smokers.

Fatty acid composition of white adipose tissue and breast milk of Mauritian and French mothers and erythrocyte phospholipids of their full-term breast-fed infants.

The fatty acid compositions of white adipose tissue, colostrum and mature milk triacylglycerols from Mauritian (n 13) and French (n 15) women were analysed and compared in order to highlight cultural differences in dietary intakes and their influence on milk fatty acid composition. Erythrocyte phosphatidylethanolamine and phosphatidylcholine fatty acid compositions were also investigated in their term infants, breast-fed over a period of 6 weeks. Fatty acid composition (g/100 g) of all samples was determined by GLC and anthropometric measurements were assessed in the two populations at birth and on day 42. Comparisons of white adipose tissue fatty acid compositions demonstrated lower levels of saturated (23.64 (SE 1.54) v. 29.75 (SE 0.67), P < 0.01) and monounsaturated (39.44 (SE 1.27) v. 54.84 (SE 0.75), P < 0.001) fatty acids and higher levels of polyunsaturated fatty acids (n-6 series: 32.47 (SE 1.31) v. 14.32 (SE 0.47), P < 0.001 and n-3 series: 2.87 (SE 0.49) v. 0.80 (SE 0.07), P < 0.01) in Mauritian than in French samples respectively. Accordingly, milk fat of the Mauritian women contained higher levels of parent essential fatty acids and their longer-chain derivatives than did milk fat from French women. Higher levels of parent essential fatty acids but lower levels of long-chain polyunsaturated fatty acids were found in erythrocyte phospholipids of Mauritian infants compared with French infants. Infants' erythrocyte arachidonate and docosahexaenoate contents did not correlate with any anthropometric variables at birth or at day 42, neither did they correlate with anthropometric variation over the study period. Our results suggest the lack of a simple relationship between the amount of long-chain polyunsaturated fatty acids in human milk and their accretion in the erythrocyte phospholipids of breast-fed infants when provided concomitantly with high levels of both linoleic and alpha-linolenic acids in ratios which fall within recommended ranges.

Does TAME induced contraction involve an endothelium dependent nitric oxide-cyclic GMP mediated pathway?

Two enzyme inhibitors namely L-NAME, a nitric oxide synthase (NOS) inhibitor and methylene blue, a guanylate cyclase inhibitor, were used to elucidate whether N-alpha-tosyl L-arginine methyl ester (TAME)-induced contractions in toad intestinal rings in vitro are mediated through a nitric oxide (NO)- cyclic GMP (c-GMP) pathway. Moreover, a NO precursor, L-arginine was also used to investigate its effect on TAME-induced contractions. Our findings provide evidence that TAME-induced contractions have both an endothelium-dependent and an endothelium-independent component. Based on our findings we now propose that TAME induced contraction involves an endothelium-dependent component mediated through NO and c-GMP.

Role of circulating inflammatory cytokines in patients during an acute attack of bronchial asthma.

Experimental studies show the unique aspects of cytokines profiles in various inflammatory diseases of the lung lead to different clinical manifestations. To elucidate the potential role of cytokines in the pathogenesis of bronchial asthma, plasma interleukins-1 beta, interleukin-6, interferon-gamma and tumour necrosis factor-alpha were measured in 32 asthmatics during an onset of acute asthma. Nine healthy volunteers were included as controls. Cytokine levels were measured by using commercially available ELISA kits. Our results showed that except for interleukin-6, increased concentrations of cytokines were not detected in the controls. Detectable concentrations of IL-6 and TNF-alpha were more common in patients than in controls. However, Interferon-gamma concentrations were below the threshold of detection in both patient and control groups. In conclusions, our results suggest that IL-6 and TNF-alpha are involved during the onset of an acute attack of asthma once the threshold limit has been passed. Hence, these two cytokines are important markers of the inflammatory components of acute asthma.

Is TAME a potent constrictor of non-airway smooth muscles?

Under in vitro conditions N-alpha-tosyl L-arginine methyl ester (TAME) induced a concentration dependent contractile response on ileal strips with EC50 of 4.3 x 10(-5) M as compared to acetylcholine which induced sustainable contractions with EC50 of 3.2 x 10(-6) M. The present study is the first to demonstrate that TAME is a potent constrictor of non-airway smooth muscle.

Asthma mortality in Mauritius: 1982-1991.

BACKGROUND: Bronchial asthma is a common problem in the island of Mauritius and its prevalence seems to be increasing. OBJECTIVE: In order to appreciate the magnitude of the problem, patterns of asthma mortality were studied during a period of 10 years. METHOD: All death certificates issued in the island from 1982 to 1991 were reviewed and all cases of asthma deaths were selected. RESULTS: The global asthma mortality rate was found to be 20/100,000 in 1982, and it decreased to 12/100,000 in 1991. Similarly the asthma death rate for the 0 to 4 year age group decreased from 20/100,000 in 1982 to 5/100,000 in 1991. For the 5 to 34 year age group, it decreased from 2.6/100,000 in 1982 to 1.02/100,000 in 1991. There was no statistically significant difference between the various ethnic groups. CONCLUSION: Our study showed that in a developing country such as Mauritius asthma death rates may be high but may show decreasing trends. Nevertheless, it is generally perceived that the prevalence of the disease is increasing.