Proximate composition, mineral content and in vitro antioxidant activity of leaf and stem of Costus afer (Ginger lily)

AIM

This study was designed to determine the proximate composition and mineral content of Costus afer leaf and stem, as well as to identify the most active antioxidant fraction.

MATERIALS AND METHODS

The proximate composition and mineral analysis of C. afer leaf and stem were performed using the standard methods described by Pearson and Association of Official Analytical Chemist while the 1,1 diphenyl 2 picryl hydrazyl (DPPH), thiobarbituric acid reactive species (TBARS), lipid peroxidation (LPO), and total antioxidant capacity (TAC) assays were used to determine the in vitro antioxidant activity of aqueous, n-butanol, ethyl acetate and hexane fractions of C. afer leaf and stem.

RESULTS

Proximate analysis revealed that the carbohydrate content was highest in the leaf (55.83 ± 3.71%) and stem (50.38 ± 1.27%) while crude fat content was lowest in the leaf (1.83 ± 0.43%) and stem (1.75 ± 0.48%). The minerals detected in appreciable quantity in both the leaf and stem samples were calcium, magnesium, potassium, sodium, chromium, lead, manganese, nickel, and copper. Further study showed that the aqueous leaf fraction exhibited a significantly (P < 0.05) high DPPH scavenging activity (IC50 = 259.07 µg/ml) and TAC (7.95 ± 0.37 mg ascorbic acid equivalent/g) compared with the other test fractions while the aqueous stem fraction had the highest TBARS scavenging activity (IC50 = 0.37 µg/ml) and inhibition of LPO (IC50 = 41.15 µg/ml) compared with the other test fractions.

CONCLUSION

The findings from this study indicate that C. afer could serve as a source of nutrient and minerals for animal nutrition and human metabolism. It also showed that the aqueous fractions of C. afer leaf and stem possess high antioxidant activity than the other fractions. In addition, this study may also explain the folkloric use of crude C. afer leaf or stem extracts in the treatment of oxidative stress associated diseases, including rheumatoid arthritis and hepatic disorder.

Fruits and vegetables diet improves some selected haemorheological parameters predisposing to cardiovascular disease in non insulin dependent diabetes mellitus NIDDM subjects

Fruits and vegetables have been shown to contain vital components that moderate disease conditions. However, there is dearth of information of these effects in Africans diabetic subjects. Thus, we investigated the relative effect of fruits and vegetables on some selected heamorological factors associated with cardiovascular disease in diabetic subjects. Thirty diabetic subjects were selected at the cardiovascular clinic of Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria. The subjects with mean Fasting Blood Glucose (FBG) level of 7.8 +/- 0.95 mmold L(-1) were placed on 300 g of fruits and vegetables per day, while they continued their normal medication and food intake. A significant difference (p < 0.05) was noticed between baseline and eight week values in all the parameters, Fibrinogen 262.75 +/- 2.64 to 250.57 +/- 3.98 mg dL(-1), Blood viscosity, 5.96 +/- 0.21 to 4.82 +/- 0.23 m Pas; erythrocyte sedimentation rate 49.40 +/- 2.34 to 32.8 +/- 1.26 min h(-1) and haematocrit 38.8 +/- 1.25 to 44.75 +/- 1.05%. At the eight week the fruits and vegetables were withdrawn for two weeks and the above parameters were reassessed (at the 10th week) which were compared with eight week values. Significant difference p < 0.05 was noticed in E.S.R. 32.8 +/- 1.26 to 38.8 +/- 1.23. However no significant difference (p > 0.05) was observed in haematocrit, 44.75 +/- 1.44 to 42.70 +/- 1.24, Fibrinogen, 254.5 +/- 3.98 to 250.57 +/- 3.16 mg dL(-1). The results showed that regular intake of fruits and vegetables by diabetic subjects may reduce cardiovascular risk factors.

The influence of a vegetarian diet on haemostatic risk factors for cardiovascular disease in Africans

Dietary habits have been implicated in the occurrence of cardiovascular diseases. Elevated plasma fibrinogen levels and decreased fibrinolytic activity have been identified as major independent cardiovascular risk factors. In this study, we compared the blood pressure, plasma fibrinogen concentration, and fibrinolytic activity of 40 nonvegetarians (NON-VEGs) with 36 vegetarians (8 VEGs and 28 SEMI-VEGs). The latter group consisted of students and lecturers of the Adventist Seminary Institute of West Africa, Ilishan Remo. All subjects had blood pressures below 140/90 mmHg, no underlying haemostatic disorders and were not on any medical treatment. The NON-VEGs had significantly decreased fibrinolytic activity (p<0.001) and increased plasma fibrinogen levels (p<0.001) compared with the SEMI-VEGs and VEGs. There were no significant differences between the blood pressure levels of the three groups, although the NON-VEGs had lower diastolic blood pressures. It is concluded that black African Seventh-Day Adventists who follow a vegetarian diet may be protected against premature cardiovascular disease because of beneficial dietary effects on plasma fibrinogen levels and fibrinolytic activity.

Blood pressure and blood lipid levels among vegetarian, semi-vegetarian, and non-vegetarian native Africans

BACKGROUND

Several epidemiological studies have implicated hypercholesterolemia and hypertriglyceridaemia as a dietary risk factor in the etiology of vascular disease. To date, there are virtually no blood lipid data available for Negroid Black African Seventh-Day Adventist vegetarians. This study was undertaken to gain a preliminary and better understanding of the relationships between BP, blood lipids, and diets in adults at the Seventh-Day Adventist Seminary of West Africa, Ilisan-Remo, Nigeria.

METHODS

Three randomly selected groups of the Nigerian populace with different dietary habits were investigated. The Seventh-Day Adventist Seminary of West Africa was the study area. Anthropometric measurements, blood pressure, serum cholesterol, triglycerides, and serum glucose were estimated using standard methods.

FINDINGS

The vegetarians (VEGs) had significantly lower body weight 75.0 +/- 1.9 kg than the semi-vegetarians (SEMI-VEGs) 77.3 +/- 1.8 kg (p < 0.05). There was no significant difference between the blood pressure (BP) of the three groups studied, although the VEGs exhibited lower systolic BP. The VEGs had significantly lower serum total cholesterol and triglycerides (p < 0.05), than non-vegetarians (NON-VEGs). The SEMI-VEGs had blood triglycerides values in between NON-VEGs and VEGs levels but these were not significant. There were no differences in blood glucose in the three groups.

CONCLUSIONS

The vegetarian diet as well as the African natural diet are associated with lower levels of important cardiovascular disease risk factors. The significantly lower cardiovascular disease risk factors in vegetarian African Adventists could be a protective measure against the development of premature IHD and CVD incidence.

Prediction of glycemic index for starchy foods

Associations between published values for glycemic index (GI) and chemical components were examined by regression analysis in 18 starchy foods. Independent variables were the amounts of protein, fat, phytic acid, and total dietary fiber (TDF) present in food portions containing 50 g available carbohydrate. GI was similarly and significantly correlated (P < 0.05) with TDF, protein, and phytate. When foods were considered as comprising two groups, legumes and others (grains and tubers), food category accounted for as large a fraction of variability in GI as did regression analysis with food components in the undivided sample. Most correlations between GI and components reverted toward zero when calculated only for the legumes or the "others" group. Evidence is cited that the method of preparing foods and the characteristics of starch and starch granules are more important in predicting GI among starchy food than is the content of any of these four food components.

Hepatic responses to edible gums during refeeding of starved rats

The ability of edible gums to depress total liver lipids and activities of two hepatic enzymes (glucose-6-phosphate dehydrogenase and NADP-linked malic enzyme) was examined during the refeeding of 2 d starved rats. Gums were fed as 4% of dry ingredients, occasionally with added water, in otherwise identical high glucose, nutritionally adequate diets. Feeding of xantham gum for 1 or 2 d decreased the rise in two enzyme activities and in total liver lipids, but after 4 or 7 d only total liver lipids were affected. Agar, which is insoluble at room temperature, was effective only when incorporated in the diet as a stiff gel. Guar, carrageenan, karaya and pectin reduced the change in at least one hepatic parameter, but acacia and gum ghatti, which impart little viscosity to water, were without effect. The ability of seven gums to form semisolid gels at low concentrations was measured and appeared to be associated with the variable effectiveness of those gums in influencing lipid contents and enzyme activities of the liver.

Effects of fructose feeding on lipid parameters in obese and lean, diabetic and nondiabetic Zucker rats

Effects of fructose feeding in moderate amounts on lipid metabolism of obese versus lean, and diabetic versus nondiabetic Zucker rats, were studied. Forty pairs of male lean and obese animals were assigned to two dietary groups, fructose and glucose. For each diet, one-half of lean and obese animals were injected with streptozotocin intraperitoneally (i.p.) to induce diabetes, and the other half were injected with buffer i.p. as a nondiabetic control group. After 9 wk of feeding, animals were fasted overnight, decapitated and exsanguinated. Organs were removed and weighed. Blood glucose, insulin, lactic acid, triglycerides, cholesterol, total liver lipids and urinary glucose were determined. Hyperphagia was observed in obese, non-diabetic and lean-diabetic animals. Streptozotocin injection drastically reduced insulin levels, and produced an impairment of growth, hyperglycemia, glucosuria, polydipsia and polyuria. Fructose feeding increased organ weights in kidney, liver and retroperitoneal adipose tissue, regardless of diabetic state. However, lactic acid levels were lower in fructose-fed groups than glucose-fed groups. In obese rats serum triglyceride levels were also lower in fructose-fed groups than in glucose-fed groups. Serum cholesterol was not affected by fructose feeding. The results indicated that fructose feeding did not produce hyperlipemia and lactic acidosis in the blood circulation in Zucker rats. However, fructose feeding did not improve glucose intolerance in diabetic animals, rather fructose feeding produced hyperinsulinemia in nondiabetic, obese animals.

Use of xanthan gum in dietary management of diabetes mellitus

Xanthan gum (12 g/day) was fed in muffins during either the first or second half of a 12-wk period of muffin feeding, to free-living subjects. Nine subjects were diabetic, having moderately elevated serum glucose but managing without insulin or hypoglycemic drugs, and four were nondiabetic controls. Before the study and at the end of the xanthan and xanthan-free periods, bloods were taken before and 2 h after an oral glucose load. The feeding of xanthan gum lowered fasting and postload serum glucose and reduced fasting levels of total plasma cholesterol in diabetic subjects. Xanthan gum also tended to lower fasting and postload levels of gastrin and gastric inhibitory polypeptide (GIP) and fasting levels of total and VLDL triglyceride and cholesterol in VLDL and LDL fractions. Subjects reported a sense of fullness after consuming xanthan muffins but no severe digestive symptoms.