# Properties of Different Varieties of Durian
## 1 Introduction  
Fruits are one of the important parts of human consumption. All fruits have a rich composition as natural antioxidants. Durian has been recognized as an important fruit, especially for the underlying nutritional attributes of the fruit [1]. Durian belongs to the category of exotic fruits, having specific taste as a mixture of mango and avocado [2]. Durian is also rich in polyphenols such as flavolons (flavamones, flavonols, flavones, flavonols, flavonols, anthocyanins), phenolic acids (cinamic and hydroxybenzoic acids), tannins, and other bioactive components, such as carotenoids and ascorbic acid [3, 4, 5, 6, 7]. Durian fruit possessed an acute effect on the blood pressure of hypertensive rats, but heart rate was unaffected [8]. The present studies showed that polyphenols decrease the risk of chronic diseases, such as heart diseases, diabetes, and others [9, 10]. Potential health benefits with special regards to cholesterol-lowering effects were described in durian and its products [11]. The ripe and overripe fruits increased the expression of hepatic HK2 and PFKFB4 glycolytic genes and stimulated glucose utilization in HepG2 cells [12]. Althoughin our previous studies different durian cultivars were used [13], mostly the research was concentrated on the main Monthong cultivar [14]. Metabolic variations in the pulps of two durian cultivars (Thai Chanee and Monthong) identified cultivar-dependent metabolite markers [15], related to durian fruit quality traits, such as nutritional value (pyridoxamine), odor (cysteine, leucine), and ripening process (aminocyclopropane carboxylic acid). As discussed above, durian in vitro studies by antioxidant assays [3], in vivo on the animal model [9; 10] and cells experiments [12; 14] contained relatively high amounts of potential antioxidants, improved the lipid and serum antioxidant status in diets high in cholesterol and possessed antiproliferative activities and proapoptotic potential in relation to the total content of bioactive compounds. Our findings for the first time indicated that one of the positive benefits of fruit consumption in patients with coronary artery disease (CAD) was diminishing the production of plasma circulation fibrinogen and its stability, which reduced the potential risk exerted by this protein [16], decreasing the triglycerides, total and low-density cholesterol. Phenolic compounds in general, under non-oxidative conditions, form reversible complexes with plasma proteins, involving hydrogen bonds, electrostatic interactions, hydrophobic effects and van der Waals forces. The distribution of drugs and dietary phenolic compounds in the human metabolism depends also on binding to plasma proteins, because of their biological activity, forming phenol-human serum protein complexes [16; 17; 18]. Despite the significant progress in the investigation of this special fruit, there is a lack of the comparison of durian cultivars, their properties, especially in relation to Monthong, which is the most popular and commonly consumed. The research area of the bioactivity of extracted polyphenols with the main human serum proteins such as albumin, globulin, and fibrinogen, which are the biomarkers of health properties, has not been exhausted yet. In this research, local Thai durian cultivars will be compared on the basis of their physicochemical and antioxidant characterization. The binding properties of the main serum proteins with the extracted polyphenols will be determined by fluorescence studies and antioxidant assays. In addition, the Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) measurements will be employed in order to characterize the bioactivity of durian cultivars.