Some analytical assays for the determination of bioactivity of exotic fruits.

INTRODUCTION: The consumption of new exotic fruits, with their high nutritional and sensory value, has significantly increased in the past few years. Among the tropical fruits durian (Durio zibethinus Murr.) is less known than mango (Mangifera indica L.) and avocado (Persea americana). It has been shown that durian, mango and avocado possessed high nutritional and bioactive properties, but these data were determined using different methods. In order to obtain reliable results we investigated samples of durian, mango and avocado of the same stage of ripeness and unified methods were used for determination of the antioxidant potential. As far as we know, no results of such comparative investigation of three tropical fruits (durian, mango and avocado) and the use of such tests for phytochemical control have been published. OBJECTIVE: Lyophilised durian, mango and avocado samples harvested in 2008 in Thailand and Israel were investigated. METHODOLOGY: The contents of crude protein, fat, carbohydrate, dietary fibre, total polyphenols, flavonoids, tannins and flavanols were determined by elemental analysis and UV spectroscopy. The presence of polyphenols (flavonoids and phenolic acids) in the investigated samples was studied by Fourier transform infrared (FT-IR) spectroscopy and three-dimensional fluorometry. Four complementary radical scavenging assays were used for antioxidant determination: ferric reducing antioxidant power (FRAP), 2, 2-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) diamonium salt (ABTS(*+)), 1-diphenyl-2-picrylhydrazyl method (DPPH) and cupric reducing antioxidant capacity (CUPRAC). Chemometrical processing was used for statistical comparison of the fruits. RESULTS: All spectrometric measurements were highly correlated. The contents of total fibre, proteins and fats were significantly higher (p < 0.05) in avocado, and carbohydrates were significantly lower in avocado (p > 0.05) than in the two other fruits. The wavelength numbers of FTIR spectra for three investigated fruits were in the same range (1700-600 cm(-1)) as for catechin and gallic acid, used as standards. One main peak could be easily observed at the approximate location of ex/em 275/305 nm and the other one at ex/em 350/430 nm in the methanol polyphenol extracts of investigated fruits in three-dimensional fluorescence, in contour and cross fluorescence maps. Similarity was found between durian, mango and avocado in polyphenols (9.88 +/- 1.0, 12.06 +/- 1.3 and 10.69 +/- 1.1, mg gallic acid equivalents/g dry weight, d.w.), and in antioxidant assays such as CUPRAC (27.46 +/- 2.7, 40.45 +/- 4.1 and 36.29 +/- 3.7, microM Trolox equivalent (TE)/g d.w.) and FRAP (23.22 +/- 2.0, 34.62 +/- 3.4 and 18.47 +/- 1.9, microM TE/g d.w.), respectively. The multisample median test between all possible pairs of groups is a Tukey-HSD type comparison and denotes the different groups in a case when a pair-wise test is significant and its q statistical value is greater than the table q parameter. The multisample median test of FRAP values were chosen from the compared fruits triplets as similar or homogenous subsets durian and avocado. CONCLUSION: Nutritional and bioactive values of durian are comparable with these indices in mango and avocado. These fruits contain high, comparable quantities of basic nutritional and antioxidant compounds, and possess high antioxidant potentials. All fruits show a high level of correlation between the contents of phenolic compounds and the antioxidant potential. The methods used (three-dimensional fluorescence, FTIR spectroscopy, radical scavenging assays) are suitable for bioactivity determination of these fruits. In order to receive best results, a combination of these fruits has to be included in the diet. The methods used are applicable for bioactivity determination in phytochemical analysis in general.

Glycolytic genes expression, proapoptotic potential in relation to the total content of bioactive compounds in durian fruits.

The properties of durian fruit at five stages of ripeness were evaluated and compared. The physicochemical parameters such as titratable acidity (TA) and total soluble solids (TSS) increased, whereas the pH slightly decreased during the ripening process. The highest contents of polyphenols, flavonoids, flavanols, tannins, vitamin C and the antioxidant capacities, measured by radical scavenging assays, were found in ripe and overripe fruits. The structural properties of extracted polyphenols were evaluated by Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. The interaction of polyphenols with the main drug carrier in blood human serum albumin (HSA) showed decrease in its fluorescence intensity. The binding properties of polyphenols were in direct correlation with the antioxidant capacities of the investigated fruits. HepG2 cells evaluated cytotoxic effect and the mechanism of cell death after treatment with durian. The metabolism of carbohydrates was examined on the expression of glycolysis-related genes (hexokinase 2 (HK2); 6-phosphofructo-2-kinase 4 (PFKFB4); facilitated glucose transporter member 1 (SLC2A1 (Glut1)) and lactate dehydrogenase A and utilization of glucose in the hepatocytes with durian treatment. Durian in immature stage had stronger cytotoxic effect and weak proapoptotic potential on HepG2 cells than the mature and overripe ones. The ripe and overripe fruits increased the expression of hepatic HK2 and PFKFB4 glycolytic genes and stimulated glucose utilization in HepG2 cells. The present results indicate that durians reveal different biological activity and may provide their broad and extensive use as medicinal or functional foods.

Durian (Durio zibethinus Murr.) cultivars as nutritional supplementation to rat's diets.

The properties of Mon Thong, Chani and Kan Yao durian (Durio zibethinus Murr.) cultivars were compared in vitro and in vivo studies in order to find the best one as a supplement to antiatherosclerotic diet. Total polyphenols (361.4+/-35.3 mgGAE/100g FW), flavonoids (93.9+/-8.9 mgCE/100g FW) and total antioxidant capacity determined by DPPH and beta-carotene-linoleic acid assays (261.3+/-25.3 microMTE/100g FW and 77.8+/-7.8% of inhibition) were maximal in Mon Thong in comparison with Chani and Kan Yao and showed a good correlation between these three variables (R(2)=0.9859). Five groups of rats were fed diets supplemented with cholesterol and different durian cultivars. Diets supplemented with Mon Thong and to a lesser degree with Chani and Kan Yao significantly hindered the rise in the plasma lipids (TC - 8.7%, 16.1% and 10.3% and (b) LDL-C - 20.1%, 31.3% and 23.5% for the Chol/Kan Yao, Chol/Mon Thong and Chol/Chani, respectively) and the decrease in plasma antioxidant activity (P<0.05). Nitrogen retention remained significantly higher in Chol/Mon Thong than in other diet groups. Diet supplemented with Mon Thong affected the composition of plasma fibrinogen in rats and showed more intensity in protein bands around 47 kDa. No lesions were found in the examined tissue of heart and brains. Mon Thong cultivar is preferable for the supplementation of the diet as positively influenced the lipid, antioxidant, protein and metabolic status. The durian fruit till now was not investigated extensively, therefore based on the results of this study durian cultivars can be used as a relatively new source of antioxidants.

Comparative study of health properties and nutritional value of durian, mangosteen, and snake fruit: experiments in vitro and in vivo.

In vitro and in vivo studies of the health and nutritional properties of durian (Durio zibethinus Murr.) were compared with snake fruit (Salacca edulis Reinw.) and mangosteen (Garcinia mangostana). Dietary fibers, minerals, and trace metals were comparable. Total polyphenols (mg of GAE/100 g of FW) and flavonoids (85.1+/-6.1) were significantly higher (p<0.05) than in snake fruit (217.1+/-13.2 (mg of CE/100 g of FW)), durian (309.7+/-19.3 and 61.2+/-4.9), and mangosteen (190.3+/-12.1 and 54.1+/-3.8). Antioxidant activity (microM TE/100 g of FW) of durian measured by DPPH and ABTS assays (228.2+/-13.4 and 2016.3+/-81.1) was significantly higher (p<0.05) than in snake fruit (110.4+/-7.9 and 1507.5+/-70.1) and mangosteen (79.1+/-5.9 and 1268.6+/-62.3). HPLC/DAD analysis of durian (microg/100 g of FW) showed that quercetin (1214.23+/-116.7) was present at levels three times that of caffeic acid, and twice as high as p-coumaric and cinnamic acids. The correlation coefficients between the bioactive compounds of fruits and their antioxidant activities were high (R2=0.99). Male Wistar rats (25) were divided into five dietary groups: the control group was fed the basal diet (BD); in addition to BD, the cholesterol (Chol) group was supplemented with 1% of Chol; the diets of the Chol/Durian, Chol/Snake, and Chol/Mangosteen groups were supplemanted with 5% of these fruits, respectively. It was found that diets supplemented with durian, and to a lesser degree with snake fruit and mangosteen, significantly hindered the rise in plasma lipids and the decrease in antioxidant activity. The nutritional values were comparably high. In conclusion, it could be suggested that inclusion of studied tropical fruits, especially durian, in known disease-preventing diets could be beneficial.

The nutritional and metabolic indices in rats fed cholesterol-containing diets supplemented with durian at different stages of ripening.

The aim of this investigation was to assess the nutritional and health properties of Mon Thong durian cultivar at different stages of ripening. The assessment was carried out in vitro and in vivo. The contents of dietary fibers, minerals and trace metals at different stages of ripening were comparable. Total polyphenols (mgGAE/100 g FW) and flavonoids (mg CE/100 gFW) in ripe durian (358.8 +/- 31.4 and 95.4 +/- 9.3) were significantly higher (p < 0.05) than in mature (216.1 +/- 1 and 39.9 +/- 3.8) and overripe (283.3 +/- 26.2 and 53.5 +/- 4.9). Antioxidant capacity (muMTE/100 g FW) in total polyphenol extracts of ripe durian measured by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and [2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) assays (259.4 +/- 23.6 and 2341.8 +/- 93.2) were significantly higher (p < 0.05) than that of mature (151.6 +/- 15.2 and 1394.6 +/- 41.5) and overripe (201.7 +/- 19.4 and 1812.2 +/- 61.4) samples. The correlation coefficients between the bioactive compounds in different stages of ripening and their antioxidant capacities were high (R;{2} = 0.99). Then 35 male Wistar rats were divided into 5 dietary groups each of 7 and named Control, Chol, Chol/Mature, Chol/Ripe and Chol/Overripe. During 30 days of the experiment the rats of all 5 groups were fed basal diet (BD), which included wheat starch, casein, soybean oil, vitamin and mineral mixtures. The rats of the Control group were fed a BD only. To the BD of the Chol group was added 1% of cholesterol. The BD of the Chol/Mature, Chol/Ripe and Chol/Overripe groups was supplemented with 1% of cholesterol and 5% of the mature, ripe and overripe durian as freeze-dried powder, respectively. Diets containing ripe and to a lesser degree mature and overripe durian significantly hindered the rise in plasma lipids and also hindered a decrease in plasma antioxidant activity. The nitrogen retention in rats of the Chol/Ripe group was significantly higher (63.6%, P < 0.05) than in other diet groups and the level of the plasma glucose remained normal. A decrease in fibrinogen fraction with ripe durian included in rat's diets was shown by electrophoretic separation. These changes were detected mostly in the low molecular weight proteins of rat's serum. Histological examination of aorta showed only slight differences in the tissue. In conclusion, ripe durian contains higher quantity of bioactive compounds, has higher antioxidant capacity and nutritional value. It positively affects the plasma lipid profile, the plasma glucose and the antioxidant activity in rats fed cholesterol enriched diets. Therefore, the ripe durian supplemented diet could be beneficial for patient suffering from hypercholesterolemia and diabetes mellitus. <

The comparative characteristics of snake and kiwi fruits.

In the time of globalization many of the tropical fruits can be find at the markets of Europe and North America. Most customers are not familiar with the nutritional and proliferative values of these fruits. Therefore, a less known snake fruit was compared with better known kiwi fruit, using fluorometry, FT-IR spectroscopy, several radical scavenging and proliferative assays and statistical evaluation. It was found similarity between snake fruit (cultivar Sumalee) and kiwi fruit (cultivar Hayward) in the contents of polyphenols (8.15-7.91, mg GAE g(-1) DW), antioxidant values by DPPH (11.28-10.24, microMTE g(-1) DW), and antiproliferative activities on both human cancer cell lines (Calu-6 for human pulmonary carcinoma, and SMU-601 for human gastric carcinoma, 90.5-87.6 and 89.3-87.1%, cell survival, respectively). In conclusion, snake fruit cultivar Sumalee is comparable with kiwi fruit cultivar Hayward. Two fruits can be used as supplements to the normal diet. Consumption of a combination of both fruits could be recommended in order to receive the best results.