## 3 Results and Discussion
### Biologically Active Compounds and Secondary Metabolites in Investigated Fruits  
The contents of total phenolics (TPs), flavonoids (TFAs), flavanols (TFLs), tannins (TNs) and vitamin C (VC) are presented in Table 1. The main active compounds in the fruits were polyphenols and vitamin C and their values were ranging from 32.37 \(\pm\) 1.34 to 4.31 \(\pm\) 0.21 mg GAE/g DW and from 36.51 \(\pm\) 1.65 to 2.31 \(\pm\) 0.23 mg AA/g DW, respectively (Table 1), showing the highest values for kiwifruit cultivar 'Bidan'. The obtained results differ from previously presented data [1,5,32,39], because of different conditions of extraction, including various solvents, temperature and time of the process. In the present research, as mentioned above, the extraction of bioactive substances was performed in water (pH 3), because for polyphenols most extractions are carried out under acidic conditions. The polyphenols are more stable in low pH, and the acidic condition helps polyphenols to stay neutral [25,26]. The aqueous extracts are important for the further use in the interaction of polyphenols with HSA, because such reactions appeared in human metabolism under similar conditions [40]. The present results (Table 1) are in line with other reports [20], evaluating that among various ripe kiwifruit grown in South Korea, 'Bidan' had the highest total phenolics and antioxidant capacity, and the lowest total flavonoids; whereas, another cultivar 'Chiak' had the highest level of total flavonoids, but the lowest antioxidant capacity. It was reported that the raw 'Hayward' kiwifruit had a VC content of 0.55 mg/g fresh weight (FW) [11]. _A. arguta_[20,41] showed lower results of VC of about 1.5-2.0 mg AA/g FW and TPs of 656-1400 mg GAE/kg FW than the obtained values in Table 1, but the present data well agreed with similar characterizations of the same fruits by other investigators [42]. The evaluation of 62 consumed fruits [18] showed that persimmon with 112.09 mg GAE/100 g FW was the seventh most beneficial fruit in terms of antioxidant and phenolic properties, a result that agrees well with the present results. The secondary metabolites were determined by MS and presented below. The ethanolic extracts for ADH [M-H]- (% in MS) showed the following results: catechol (_m/z_ 110 (6)), caffe acid (_m/z_ 179 (8)), quintic acid (_m/z_ 191 (85)), synergic acid (_m/z_ 198 (20)), kaempfer (_m/z_ 286 (9)), quercetin (_m/z_ 301 (10)), rutin (_m/z_ 609 (12)) and hesperidin (_m/z_ 610 (8)). AEB ([M-H]-(% in MS) samples were characterized by the following peaks: catechol (_m/z_ 110 (8)), protocatechic acid (_m/z_ 154 (12)), caffe acid (_m/z_ 179 (6)), quintic acid (_m/z_ 191 (100)), synergic acid (_m/z_ 198 (14)), kaempfer (_m/z_ 286 (12)), quercetin (_m/z_ 301 (18)), rutin (_m/z_ 609 (12)) and hesperidin (_m/z_ 610 (11)). The main peaks for AAC [M-H]-(% in MS) were identified as follows: catechol (_m/z_ 110 (8)), caffe acid (_m/z_ 179 (7)), quintic acid (_m/z_ 191 (87)), sygnergic acid (_m/z_ 198 (19)), quercetin (_m/z_ 301 (20)), and hesperidin (_m/z_ 610 (10)). DKF spectra recorded six main peaks in the extracts: vanillic acid (m/z 168 (29)), gallic acid (_m/z_ 169 (80)), caffe acid (_m/z_ 179 (18)), kaempfer (_m/z_ 286 (7)), epicatechin (_m/z_ 288(11)), and quercetin (_m/z_ 301 (8)). As can be seen, ethanol extracts of kiwifruit cultivars characterized by chlorogenic acid of the [M-H]-deprotonated molecule and the ion corresponding to the deprotonated quintic acid (_m/z_ 191), as the most abundant compound, in accordance with other reports [6,43]. Caffeic, quintic, and sygnergic acids, catechol, quercetin and hesperidin were identified in different amounts in all kiwifruit extracts with the highest in AEB. Although there is a difference in the profile of compounds identified in the samples, but the majority of compounds such as caffeic acid, quercetin and kaempfer were present in investigated extracts, except AAC.