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Phenolic compounds and antioxidant activity of Castanopsis phuthoensis and Castanopsis grandicicatricata

100%

Tuyen P. T., Khang D. T., Minh L. T., Minh T. N., Ha P. T. T., Elzaawely A. A., Xuan T. D.

International Letters of Natural Sciences

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2016

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tom 55

In this study, total phenolic and flavonoid contents, antioxidant capacity, and phenolic compositions of Castanopsis phuthoensis and Castanopsis grandicicatricata (Fagaceae family) were investigated. It was found that bark extracts were rich of phenolic contents, whereas leaf extracts were abundant of flavonoids. The total phenolics varied from 11.20 to 35.47 mg gallic acid equivalent g-1 dry weight (DW), and the total flavonoids were from 2.24 to 12.55 mg rutin equivalent g-1 DW. The results of antioxidant activity evaluation showed that the DPPH (1,1- diphenyl-2-picryl-hydrazyl) radical scavenging activity of the free phenolic extracts were higher than the bound phenolic extracts. Regarding the reducing power and β-carotene bleaching assays, the free phenolic extracts showed remarkably strong antioxidant capacity that were similar to the levels of the standard BHT (dibutyl hydroxytoluene) did. It could be concluded that free phenolic extracts were more effective in antioxidant activities than bound phenolic extracts. Highly significant correlations were observed between phenolic contents and antioxidant activities (0.813 for DPPH and 0.841 for reducing power). By HPLC analysis, seven phenolic acids were detected including gallic, p-hydroxybenzoic, vanillic, sinapic, p-coumaric, ellagic acids, and vanillin. Of which, gallic, ellagic, and sinapic acids were the most abundant compounds in the two species. The results suggest C. phuthoensis and C. grandicicatricata contain rich sources of natural antioxidants and phenolic compounds which are probably considered in pharmaceutical use.

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Effects of salinity stress on growth and phenolics of rice (Oryza sativa L.)

100%

Minh L. T., Khang D. T., Ha P. T. T., Tuyen P. T., Minh T. N., Quan N. V., Xuan T. D.

International Letters of Natural Sciences

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2016

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tom 57

This study was conducted to determine the correlation between of salinity stress on growth and phenolic compounds in rice. It was observed that salinity stress caused a significant decrease in shoot lengths, fresh and dry weights of all rice varieties. Under salinity stress, changes of chemical contents also differed among phenolic compounds and rice cultivars. Total phenolics and flavonoids, and contents of vanillin and protocatechuic acid in tolerant varieties were strongly increased, whereas in contrast, they were markedly reduced in the susceptible cultivar. Ferulic acid and p-coumaric acid were detected only in tolerance rice. Vanillin and protocatechuic acid may play a role, but ferulic acid and p-coumaric acid may be much involved in the tolerant mechanism against salinity stress. Ferulic acid and p-coumaric acid and their derivatives are potent to be exploited as promising agents to reduce detrimental effects of salinity stress on rice production.

3

Involvement of phenolic compounds in anaerobic flooding germination of rice (Oryza sativa L.)

84%

Khang D. T., Ha P. T. T., Lang N. T., Tuyen P. T., Minh L. T., Minh T. N., Bach D. T., Xuan T. D.

International Letters of Natural Sciences

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2016

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tom 56

By this study, thirty rice varieties were evaluated for anaerobic flooding tolerance using the direct sowing method. Phenolic profiles of strong and weak tolerant varieties were identified and compared based on HPLC chromatograms. The germination rates and shoot heights of rice were recorded for calculating the seedling vigor, which indicate the tolerant ability of rice in flooding condition. The results revealed a high variation of germination rate (10.01 to 100%), shoot height (0.35 to 78.17 mm) and seedling vigor (0.05 to 72.83). There was a high correlation between (r = 0.71) germination rate in 5 cm and 10 cm flood. Phenolic and flavonoid contents of the strong tolerant cultivar significantly and proportionally increased in the flooding levels (5 cm and 10 cm). There was a total difference in terms of number of phenolic acids found in the strong and weak tolerant varieties. In particular, six phenolic acids (gallic acid, catechol, caffeic acid, syringic acid, vanillin, and ellagic acid) were only identified with high concentration in the strong tolerant cultivar. The findings suggest that the phenolics presented in the strong tolerant varieties probably have a certain function in response and adaptation to anaerobic flooding condition. Further researches on exogenous application of these phenolic acids to increase the flooding tolerant level of rice should be continued at both green house and field treatments.

4

Correlation among agro-morphological variation and genetic diversity of rice (Oryza sativa L.) under drought stress

84%

Thu Ha P. T., Khang D. T., Tuyen P. T., Minh L. T., Minh T. N., Thi Lang N., Buu B. C., Xuan T. D.

International Letters of Natural Sciences

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2016

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tom 58

In this study, the correlation coefficients among agro-morphological variation, genetic diversity, and drought tolerance in 44 rice cultivars were analyzed. The drought tolerance at seeding stage (DTS) was significantly proportional to drought tolerance at vegetative stage (DTV) (r = 0.60). In addition, DTS and DTV had strong significant positive correlation to leaf roll (r = 0.87 and 0.54, respectively). Means of unfilled grains and tilling per panicle were proportionally correlated to DTS (r = 0.22 and 0.25, respectively), and DTV (r = 0.20 and 0.36, respectively). However, weight of 1000 grains and filled grains were recorded no correlation to DTS and DTV. At a homologous coefficient of 16.85 integrated from cluster analysis of agro-morphological, quantitative characteristics and drought tolerant scores, the rice cultivars were divided into five groups. Maximum polymorphic information content (PIC) values were detected in three markers including RM11125, RM21, and RM5629, which were from 0.78 to 0.79. Cluster analysis of microsatellite markers revealed that by a genetic distance of 0.63, the rice varieties were separated into three clusters. The results provide valuable information for rice breeders to select donors in breeding rice integrated with drought tolerance and good agronomic characteristics.

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Allelopathic activity of dehulled rice and its allelochemicals on weed germination

68%

Khang D. T., Anh L. H., Thu Ha P. T., Tuyen P. T., Quan N. V., Minh L. T., Quan N. T., Minh T. N., Xuan T. D., Khanh T. D., Trung K. H.

International Letters of Natural Sciences

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2016

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tom 58

In this study, the allelopathic potential of dehulled rice, rice, and hulls of rice on germination of weeds was evaluated in laboratory. Phenolic acids in growth media of these plants were also identified and quantified using HPLC. Identified allelochemicals were reversely tested for phytotoxic effects on germination and seedling growth of barnyardgrass, lettuce, radish and rice. The results showed that the inhibitory effects of dehulled rice were stronger than those of hulls and rice. Dehulled rice caused 66.7% and 50.6% reduction in radish root length and lettuce shoot height, respectively. Dehulled rice showed strong inhibitory effects on root length of lettuce and shoot height of radish while hulls and rice exhibited stimulation. Regarding phenolic identification, vanillin and vanillic acid were detected as allelochemicals in root exudates of rice and tested plants. The results revealed that most of the vanillin and vanillic acid treatments showed high inhibitory effects on germination rates and seedling growth of lettuce and radish, high stimulatory activity on root elongation of rice. Vanillic acid (100 ppm and 200 ppm), vanillin (100 ppm) and their mixture (200 ppm) completely inhibited survival of lettuce. The findings indicate the allelopathic potential of dehulled rice which can be used for identification of more phytotoxins to produce bioherbicides in agricultural practices.

Ograniczanie wyników

5 International Letters of Natural Sciences

5 Khang D. T.

5 Minh L. T.

5 Minh T. N.

5 Tuyen P. T.

5 Xuan T. D.

3 Ha P. T. T.

2 Quan N. V.

2 Thu Ha P. T.

1 Anh L. H.

1 Bach D. T.

1 Buu B. C.

1 Elzaawely A. A.

1 Khanh T. D.

1 Lang N. T.

1 Quan N. T.

1 Thi Lang N.

1 Trung K. H.

5 2016

Phenolic compounds and antioxidant activity of Castanopsis phuthoensis and Castanopsis grandicicatricata

Effects of salinity stress on growth and phenolics of rice (Oryza sativa L.)

Involvement of phenolic compounds in anaerobic flooding germination of rice (Oryza sativa L.)

Correlation among agro-morphological variation and genetic diversity of rice (Oryza sativa L.) under drought stress

Allelopathic activity of dehulled rice and its allelochemicals on weed germination