Do Tan Khang

Phenolic Profiles and Antioxidant Activity of Germinated Legumes

Bioactive compounds, which are naturally produced in plants, have been concerned with the food and pharmaceutical industries because of the pharmacological effects on humans. In this study, the individual phenolics of six legumes during germination and antioxidant capacity from sprout extracts were determined. It was found that the phenolic content significantly increased during germination in all legumes. Peanuts showed the strongest antioxidant capacity in both the DPPH• (1,1-diphenyl-2-picrylhydrazyl) method and the reducing power assay (32.51% and 84.48%, respectively). A total of 13 phenolic acids were detected and quantified. There were 11 phenolic constituents identified in adzuki beans; 10 in soybeans; 9 in black beans, mung beans, and white cowpeas; and 7 compounds in peanuts. Sinapic acid and cinnamic acid were detected in all six legume sprouts, and their quantities in germinated peanuts were the highest (247.9 µg·g−1 and 62.9 µg·g−1, respectively). The study reveals that, among the investigated legumes, germinated peanuts and soybeans obtained maximum phenolics and antioxidant capacity.

Phenolic Compositions and Antioxidant Properties in Bark, Flower, Inner Skin, Kernel and Leaf Extracts of Castanea crenata Sieb. et Zucc

In this study, different plant parts (barks, flowers, inner skins, kernels and leaves) of Castanea crenata (Japanese chestnut) were analyzed for total phenolic, flavonoid, and tannin contents. Antioxidant properties were evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), reducing power, and β-carotene bleaching methods. The highest total phenolic and tannin contents were found in the inner skins (1034 ± 7.21 mg gallic acid equivalent/g extract and 253.89 ± 5.59 mg catechin equivalent/g extract, respectively). The maximum total flavonoid content was observed in the flowers (147.41 ± 1.61 mg rutin equivalent/g extract). The inner skins showed the strongest antioxidant activities in all evaluated assays. Thirteen phenolic acids and eight flavonoids were detected and quantified for the first time. Major phenolic acids were gallic, ellagic, sinapic, and p-coumaric acids, while the principal flavonoids were myricetin and isoquercitrin. The inner skin extract was further fractionated by column chromatography to yield four fractions, of which fraction F3 exhibited the most remarkable DPPH scavenging capacity. These results suggest that C. crenata provides promising antioxidant capacities, and is a potential natural preservative agent in food and pharmaceutical industries.

Effects of Exogenous Application of Protocatechuic Acid and Vanillic Acid to Chlorophylls, Phenolics and Antioxidant Enzymes of Rice (Oryza sativa L.) in Submergence

In this study, effects from application of protocatechuic acid (PA) and vanillic acid (VA) and their mixture on the submergence tolerance of rice were examined. The treatment of 0.01 mM PA and VA did not show significant increase of rice growth as compared to the controls. However, at higher concentrations (0.1–1.0 mM), rice shoot was elevated in submergence by 20.8–22.4%. The survival percentage of rice seedlings at any dose of PA, VA and their mixture was significantly higher than the controls. In general, the mixture of PA and VA was more active to promote shoot elongation and survival in submergence than sole treatment of either PA or VA. The amount of chlorophyll b by PA was significantly increased, while no change in chlorophyll a content was observed. VA remarkably reduced malondialdehyde quantity at three days of submergence, while no significant difference among treatment was observed in PA, the mixture, and respective controls. The two phenolic acids promoted contents of phenolics and flavonoids in rice leaves and roots, however the quantities of endogenous PA and VA in rice were not markedly differed after PA and VA treated on roots of rice seedlings. The ascorbate peroxidase and superoxide dismutase activities were enhanced, while the expression of genes encoding antioxidant enzymes was favored. VA increased the expression level of ascorbate peroxidase genes in higher levels than PA and their mixture, while no significant difference was observed in the other genes including superoxide dismutase, catalase, glutathione reductase, and peroxidase. Findings of this study showed that PA and VA increased the submergence tolerance of rice by promoting the photosynthetic and anti-oxidative processes in rice seedlings. The treatment of PA and VA mixture on seedling roots was potent to promote the submergence tolerance in rice.

Potential Use of Plant Waste from the Moth Orchid (Phalaenopsis Sogo Yukidian “V3”) as an Antioxidant Source

This research was conducted to exploit the waste of used plant parts from the widely marketed moth orchid cultivar (Phalaenopsis Sogo Yukidian “V3”). Various extracts of roots, stems, and leaves were evaluated for total phenolics, total flavonoids, and antioxidant capacity. The bound extract from stems contained the highest total phenolics (5.092 ± 0.739 mg GAE (gallic acid equivalent)/g DW (dry weight)). The maximum total flavonoids (2.218 ± 0.021 mg RE (rutin equivalent)/g DW) were found in the hexane extract of leaves. Ethyl acetate extract from roots showed the greatest antioxidant activity compared to other extracts. Of these extracts, the IC50 values of these samples were 0.070 mg/mL, and 0.450 mg/mL in a free radical 1,-diphenyl-picryl-hydrazyl (DPPH) assay and reducing power method, respectively. The lipid peroxidation inhibition (LPI) was found to be 94.2% using the β-carotene bleaching method. Five phenolic compounds including caffeic acid, syringic acid, vanillin, ellagic acid, and cinnamic acid were quantified by high performance liquid chromatography (HPLC). It is suggested that the roots of the hybrid Phalaenopsis Sogo Yukidian “V3” cultivar may be exploited as an effective source of antioxidants.

Phenolic Compounds and Antioxidant Activity of Phalaenopsis Orchid Hybrids

Phalaenopsis spp. is the most commercially and economically important orchid, but their plant parts are often left unused, which has caused environmental problems. To date, reports on phytochemical analyses were most available on endangered and medicinal orchids. The present study was conducted to determine the total phenolics, total flavonoids, and antioxidant activity of ethanol extracts prepared from leaves and roots of six commercial hybrid Phalaenopsis spp. Leaf extracts of “Chian Xen Queen” contained the highest total phenolics with a value of 11.52 ± 0.43 mg gallic acid equivalent per g dry weight and the highest total flavonoids (4.98 ± 0.27 mg rutin equivalent per g dry weight). The antioxidant activity of root extracts evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging assay and β-carotene bleaching method was higher than those of the leaf extracts. Eleven phenolic compounds were identified, namely, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, vanillin, ferulic acid, sinapic acid, p-coumaric acid, benzoic acid, and ellagic acid. Ferulic, p-coumaric and sinapic acids were concentrated largely in the roots. The results suggested that the root extracts from hybrid Phalaenopsis spp. could be a potential source of natural antioxidants. This study also helps to reduce the amount of this orchid waste in industrial production, as its roots can be exploited for pharmaceutical purposes.