Influence of drying treatments on antioxidant capacity of forage legume leaves

Parameters of antioxidant activity of Galega officinalis L. and Galega orientalis Lam. (Fabaceae Lindl.) plant raw material

The plant raw material of Galega officinalis L. (goat’s rue) and Galega orientalis Lam. (fodder galega) investigated in this study. These species are known as fodder crops with high productivity of green mass and as medicine plants. The current study was aimed to evaluate an accumulation in dry raw of selected plants the total content of phenolic acids (TPA) and flavonoids (TFC) as compounds with antioxidant activity (AA) by spectrophotometric method. AA by DPPH-method and phosphomolybdenum method (reducing power (RP)) was measured. Study of ethanolic extracts of G. officinalis showed accumulation of TPA in different organs in range from 3.65 to 15.17 mg.g-1 caffeic acid equivalent (CAE) and TFC from 10.08 to 65.75 mg.g-1 quercetin equivalent (QE), AA by DPPH-method from 6.02 to 8.45 mg.g-1 Trolox equivalent (TE) and RP of extracts by phosphomolybdenum method from 86.56 to 288.15 mg TE.g-1. In extracts of G. orientalis was identified TPA from 3.52 to 18.52 mg CAE.g-1 and TFC from 6.09 to 46.72 mg QE.g-1, antioxidant activity by DPPH-method from 6.80 to 8.48 mg TE.g-1 and antioxidant capacity by phosphomolybdenum method from 52.52 to 188.51 mg TE.g-1. It was established that less concentration of studied compounds found in the stems for both species. It should be noted that the content of phenolic acids in the leaves was decreased and flavonoids in stems increased during vegetation for both species. Content of phenolic acids in the generative organs and flavonoids in the leaves decreased in raw of G. orientalis during vegetation. Pearson’s correlation analysis demonstrated very strong relations between TFC and AA by DPPH, TPA and RP, TFC and RP for G. officinalis extracts. Very strong correlation in the extracts of G. orientalis found between TFC and RP, TPA and RP. Obtained results can be used in the further biochemical and pharmacological study.

A high correlation indicating for an evaluation of antioxidant activity and total phenolics content of various chilli varieties

Use of dimethyl sulfoxide (DMSO) as a suitable extraction solvent under the optimum conditions of microwave assisted extraction (MAE) prior to total phenolics determination and antioxidant activity assay was conducted. The MAE method was done with 0.05 g sample in 10 mL DMSO at 500 W within 5 min. The effects of DMSO on various antioxidant activities using DPPH(·+), DMPD(·+), ABTS(·+) and FRAP, and Folin-Ciocalteu reagent were investigated. From the results, it is clearly demonstrated that the DMSO itself shows no effect on any of those antioxidant assays including total phenolics content. The DMSO extracts of 14 local chilli varieties gave their antioxidant activities in the following ranges: DPPH, 3.07-20.0; DMPD, 1.52-6.61; ABTS, 20.4-56.0; FRAP, 8.98-42.1 mg GA/g DW. Their total phenolics contents were found in the range of 53.7-200 mg GA/g DW. This study demonstrates that DMSO was found as the most suitable extraction solvent for antioxidants and phenolics from chilli. In addition, analysis of the data obtained among four antioxidant activity assays with respect to total phenolics shows a highly significant and positive regression coefficient (r > 0.92), indicating the total phenolics are primarily responsible for their antioxidant activity of the chilli extract.

Antioxidant activities of lead (Leucaena leucocephala) seed as affected by extraction solvent, prior dechlorophyllisation and drying methods

Extracts of brown lead (Leucaena leucocephala) seed prepared using different extraction solvents were determined for antioxidative activities using different assays. The highest yield (3.4-4.0%) was obtained when water was used as an extraction solvent, compared with all ethanolic extracts used (1.2-2.0 %) (P < 0.05). Much lower chlorophyll content was found in the water extract. When hot water was used, the resulting extract contained lower total phenolic and mimosine contents (P < 0.05). In general, 60-80 % ethanolic extracts had higher 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, ferric reducing antioxidant power (FRAP) and metal chelating activity than water extracts (P < 0.05). When brown lead seed was dechlorophyllised prior to extraction, the water extract had slightly increased yield with lower chlorophyll content. Nevertheless, prior chlorophyll removal resulted in the increase in antioxidative activities but lower total phenolic and mimosine contents (P < 0.05). Generally, phenolic compounds and mimosine were more released when water was used as the extraction solvent, while the lower amount of chlorophyll was extracted. Oven-drying exhibited the negative effect on antioxidative activities and mimosine content. The higher antioxidative activities with concomitant higher total phenolic and mimosine contents were found in water extract dried by freeze drying. Thus, extraction solvent, dechlorophyllisation and drying methods directly influenced the yield and antioxidative activity of lead seed extract.