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1

Allelopathic activity of dehulled rice and its allelochemicals on weed germination

100%

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.

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tom 58

EN

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.

2

Changes in phenolic acids of cherry laurel [Laurocerasus officinalis Oxygemmis] fruit during maturation

100%

Ayaz F. A.

Acta Biologica Cracoviensia. Series Botanica

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2001

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tom 43

EN

Changes in phenolic acid content during the maturation of cherry laurel (Laurocerasus officinalis ‘Oxygemmis’) fruits were studied. Samples were obtained starting 40 days after flowering between May and July. In the fruits, p-coumaric, caffeic and ferulic acids (as cinnamics) and benzoic, 4-hydroxybenzoic, vanillic and 3,4-dihydroxybenzoic acids (as benzoics) were identified. The content of benzoic, 4-hydroxybenzoic, vanillic and caffeic acids started to increase from 6 to 12 WAF (weeks after flowering). The content of p-coumaric and ferulic acids, highest at 6 WAF, declined gradually until 11 WAF and increased again at 12 WAF. All phenolic acids except vanillic and ferulic acids began to decrease in the fruits harvested at 16 WAF, that is, the normal harvesting season. Although an increase in vanillic and ferulic acid content was observed in post-ripening between 13 and 16 WAF, the values were not statistically significant (P = 0.05) between stages. The highest content of phenolic acid in the cultivar was found for benzoic, caffeic and vanillic acids: 2.53, 1.05 and 0.86 mg/100g dry weight, respectively.

3

Free and glucosylated phenolics, phenol beta-glucosyltransferase activity and membrane permeability in cucumber roots affected by derivatives of cinnamic and benzoic acids

80%

Politycka B.

Acta Physiologiae Plantarum

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1997

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tom 19

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nr 3

EN

Seven-day-old seedlings of cucumber (Cucumis sativus L.) cv. Wisconsin were treated with 0.01, 0.1 and 0.5 mM solutions of derivatives of cinnamic acid (ferulic and p-coumaric acids) and benzoic acid (p-hydroxybenzoic and vanillic acids) as stress factors. In cucumber roots phenolics (free and glucosylated), phenol β-glucosyltransferase (E.C. 2.4.1.35) activity as well as membrane permeability were examined. The most intensive glucosylation took place in the first hour of stress duration in roots treated with 0.01 mM ferulic and p-coumaric acids and with 0.01 and 0.1 mM p-hydroxybenzoic and vanillic acids. At these concentrations a high phenol β-glucosyltransferase activity was found. The deterioration of capacity for phenolic glucosylation as well as the decrease of the phenol β-glucosyltransferase was observed at the higher concentrations. It was associated with increased membrane permeability.

4

Aktywnosc mikrobiologiczna i cytotoksycznosc wybranych kwasow fenolowych w testach in vitro

70%

Czechowska S. K. , Markiewicz R. , Borawska M. H.

Bromatologia i Chemia Toksykologiczna

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2009

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tom 42

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nr 3

959-964

5

Sklad frakcji wolnych fenolokwasow w piwie

60%

Samotyja U. , Malecka M. , Klimczak I.

Przemysł Fermentacyjny i Owocowo-Warzywny

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2002

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tom 46

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nr 03

29-31

PL

W pracy przedstawiono warunki izolacji i chromatograficznego rozdziału wolnych fenolokwasów w piwie. W próbkach piwa pochodzących z różnych browarów zidentyfikowano i oznaczono ilościowo następujące kwasy: wanilinowy, kawowy, syringinowy, p-kumarowy, ferulowy i sinapinowy. Badane piwa charakteryzowały się zróżnicowanym profilem wolnych kwasów fenolowych. W największych ilościach występował kwas ferulowy; który stanowił 48-58% wszystkich wolnych fenolokwasów. Różnice między średnimi zawartościami w obrębie poszczególnych fenolokwasów były istotne statystycznie.

EN

The isolation and HPLC separation conditions of free phenolic acids of beer are presented. Five phenolic acids (vanillic, caffeic, syringinic, p-coumaric, ferulic and sinapic) were identified and quantified in the beer samples produced in different breweries. The differences in free phenolic acids profile of the analysed beers were observed. Ferulic acid was the main compound and covered 48 to 58 % of total free phenolic acids fraction. The differences in the average concentrations of particular phenolic acids were statistically significant.