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We investigated the content of phenolic compounds and antioxidant capacity of two batches of non-heated and heated leaves of the yacon cultivar “Andes no yuki”, grown in Japan. Lyophilized yacon leaves heated at 160°C for 20 min and 100°C for 60 min had a 1.96 to 9.69-times higher total phenolic content than that of the non-heated leaves. Heated leaves exhibited a 1.98 to 4.07-times higher antioxidant capacity than that of the non-heated leaves in three different free radical scavenging assays. Heated leaves were more efficient at attenuating the superoxide anion radical production in human granulocytic cells than the non-heated leaves. High-performance liquid chromatography analysis revealed that, in the heated leaves, the caffeic acid content was 2.13 to 3.64-times higher and the chlorogenic acid content was slightly lower than those in the non-heated leaves. Hence, heat processing may affect the active constituent contents in yacon leaves, potentiating its antioxidant capacity. Abbreviations: ABTS+: 2,2′-azinobis(2-ethylbenzothiazoline-6-sulfonic acid) cation; DPPH: 1,1-diphenyl-2-picrylhydrazyl, HPLC: high-performance liquid chromatography; NBT: nitroblue tetrazolium; O2−: superoxide anion; PMA: phorbol 12-myristate 13-acetate; PMS: phenazine methosulfate; TEAC: Trolox equivalent antioxidant capacity

UNLABELLED Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot-water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot-water extract was similarly demonstrated among these extracts. Varying concentrations of the hot-water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC50 28.1 μg/mL), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical (EC50 23.7 μg/mL), galvinoxyl radical (EC50 3.06 μg/mL), and chlorpromazine cation radical (EC50 475 μg/mL). The yacon tea-leaf extract further demonstrated superoxide anion (O2(-)) radical scavenging effects in the phenazine methosulfate-NADH-nitroblue tetrazolium (EC50 64.5 μg/mL) and xanthine oxidase assay systems (EC50 20.7 μg/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea-leaf extract could suppress the cellular O2(-) radical generation (IC50 65.7 μg/mL) in a phorbol 12-myristate 13-acetate-activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders. PRACTICAL APPLICATION Yacon has been considered to be a potent alternative food source for patients who require a dietary cure in regional area, while the leaf part has been provided and consumed as an herbal tea in local markets. We demonstrated here potent antioxidative effects of the tea leaves from yacon in different free radical assays, reducing power assay, and cellular superoxide anion radical generation assay. Results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders.

Yacon (Smallanthus sonchifolius) is known as a root crop rich in fructans and polyphenol. In the present study, the effects of yacon silage (YS) on body weight change, digestibility of feed, blood characteristics and level of urinary 8-hydroxydeoxyguanosine (8-OHdG) in ewes were evaluated. Ewes were fed basal diets (40% of soybean curd residue silage (SS) on a dry matter [DM] basis) supplemented with 60% of YS (YS group) or bermudagrass (Cynodon dactylon) hay (BH; BH group) on a DM basis for 36 days. YS did not influence the ewes’ body weight or digestibility of feed. The serum concentrations of total protein, glucose and total cholesterol of the YS group were significantly lower than those of the BH group (P

Yacon (Smallanthus sonchifolius [Poepp. & Endl.] H. Robinson) plant cultivation has extended rapidly throughout Japan since 1985 because of its utility as a tuberous root crop. In this study, strains with high yields of both above-ground and underground parts were identified to investigate the use of above-ground parts for animal feed silage. In addition, we measured the anti-oxidative activity of the silage as a functional characteristic. Data from 5 years of the cultivation of 17 yacon strains suggest that the most suitable strain for planting in the Aso region of Japan is SY217, which has a high yield of both above-ground parts and tuberous roots. The root tuber parts of yacon are used almost entirely as food; actually, most foliage parts are hardly used, except for some above-ground parts, which are used as tea. The fermentation qualities of the silage using all above-ground parts and harvest residue tuberous roots (harvest residues) are high and their dry matter digestibility, investigated using pigs, is 66.7%. Fresh above-ground parts had very strong anti-oxidative activity as compared with butylated hydroxyanisole and α-tocopherol. In addition, that activity is retained during ensiling for 4 weeks. These results suggest that the entire yacon plant can be used effectively as a feedstuff resource with the added bonus of anti-oxidant activity.

To resolve the discrepancy among previous karyotype descriptions, chromosome comparative study between two closely related cucumber cultivars, C. sativus L. cv. Borszczagowski and cv. Monastyrski, was performed by chromosome preparation technique with enzymatic maceration, and fluorescent banding method with chromomycin A3 (CMA) and 4′,6-diamidino-2-phenylindole (DAPI). Heterochromatic band polymorphisms were detected in chromosomes 2, 3, 5 and 7, whereas no chromosomal polymorphism was found in chromosomes 1, 4 and 6. In cv. Borszczagowski chromosome 2, CMA+DAPI+ heterochromatic band at terminal region of the long arm was smaller than that of cv. Monastyrski. Chromosome 3 of cv. Monastyrski was characterized by CMA+DAPI+ bands on the terminal regions of both arms, whereas that of cv. Borszczagowski displayed only on the terminal region of long arm. Distinct CMA+DAPI+ band located at terminal region of the long arm in cv. Borszczagowski was larger than that of cv. Monastyrski. In chromosome 7, terminal CMA+DAPI+ band at the short arm was only observed in cv. Monastyrski. This result suggested that inconsistency of karyotypes among previous reports was due to chromosomal polymorphism.

Zoysiagrass displays good adaptability to its environment, and is utilized for golf courses and athletic fields. Immature inflorescences were obtained from 5 varieties of zoysiagrass, ‘Miyako’, ‘Misato’, ‘Meyer’, ‘Yamato’ and ‘B14’. However, regenerated plants were only obtained in ‘Miyako’. A relationship between the size of the inoculated inflorescences and the callus induction frequency was observed. A high frequency of callus formation was shown in earlier developmental stages shorter than 20 mm in the length of inflorescences in ‘Miyako’. Plant regeneration was observed efficiently when the compact calli, which were formed in the callus induction medium (Linsmaier and Skoog 4 mg l−1 thiamine–HCl, 100 mg l−1 α-ketoglutaric acid, 2 mg l−1 2,4-D, 0.1 mg l−1 BA, 3% sucrose, 0.2% gelrite), were transferred to the regeneration medium (Linsmaier and Skoog 1 mg l−1 BA, 3% maltose, 0.5% gelrite ) in ‘Miyako’.

To determine the direct cause of the low seed set in sweet potato, 14 cross-compatible combinations among 11 varieties were histologically examined for the process from fertilization to embryogenesis at 4, 7 and 48 hours after pollination. Pollen fertility on the flowering day exceeded 80 % in most of the varieties examined and pollen germination 4 hours after pollination reached 10~20 % in most of the crosses. These results show that neither the fertility of mature pollen nor the pollen germination on stigma is the principal cause of the low seed set. The mean number of pollen tubes passing through the conducting tissue of the ovary 7 hours after pollination largely differed among the cross combinations. However, it did not show a close relationship with the number of seeds per capsule. Among the embryosacs examined 48 hours after pollination, those that had not been penetrated by pollen tubes were mostly abnormal, in which the development of the egg apparatus had been interrupted halfway. On the other hand, the number of normal young embryos was closely correlated with the number of seeds per capsule. These results suggest that a large number of such abnormal embryosacs is the principal cause of the low seed set of sweet potato.