Introduction
Reactive oxygen (ROS) and nitrogen (RNS) species in biological media are responsible for the oxidative damage to biomolecules such as ADN, lipids and proteins, producing alterations in its structure and promoting tumoral, ulcer, and inflammatory processes and various degenerative diseases. A large group of secondary metabolites obtained from the plant kingdom includes: the flavonoids, are compounds characterized by containing numerous antioxidants agents.
Several species Dalea genus were studied, isolating different chemical compounds, which include flavonoids with antioxidant activity. There are four species described for Argentina, namely, Dalea elegans Gillies ex Hook. & Arn., D. boliviana Britton, D. leporina (Aiton) Bullock, and D. elegans var. onobrychioides (Griseb) Barneby (1). The first phytochemical and pharmacological advances on Argentinean Dalea species were conducted by our research group, starting with D. elegans (2-5) and D. boliviana (6). For further study of species in this genus related to the search for new antioxidant agents, in the present work we report the evaluation of the hydro-alcoholic extract obtained from roots of D. pazensis, a Bolivian species collected in Yotala, locality close to Sucre city. At first, the total content of phenols and flavonoids in the extract was analyzed. On the other hand, we evaluated the antioxidant properties of this extract by different in vitro tests: 1) Total antioxidant potential: phosphomolybdenum method (PM), 2) Radical scavenging capacity: methodology TEAC (Trolox Equivalent Antioxidant Capacity) and inhibition of the hemolysis induced by the radical AAPH on erythrocytes.
Thus this work is providing novel knowledge with impact in the search for new plant drugs that in the future can become sources of active compounds with antioxidant activity.
Materials and methods
Plant Material: 35 gr of D. pazensis roots were dried, powdered and extracted exhaustively with Ethanol:H20 (7:3 v/v).
Determination of total phenols content: Total phenols were determined by Folin-Ciocalteau method (7). Results were expressed as mg of gallic acid equivalents/g of extract (mgEqAG).
Determination of total flavonoids content: The quantitative determination of the flavonoid was performed by the AlCl3 method (8). Results were expressed as mg of quercetin equivalents/g of extract (mgEqQ).
Antioxidant activity "in vitro"assays
Determination of total antioxidant potential: Phospomolybdenum Method (PM) was used (9) and the antioxidant potential was expressed as µg of Ascorbic Acid equivalents in the analyzed plant extract.
Determination of the radical scavenging capacity by TEAC: Trolox equivalent antioxidant capacity (TEAC) methodology was used (10). The results were expressed as µg of Trolox equivalents/mg of analyzed extract.
Determination of the inhibitory activity of hemolysis: Hemolysis of erythrocytes induced by AAPH radical was used. Results were expressed as % inhibition of hemolysis in the analyzed extract.
Results
Results are shown in Tables 1 and 2
Conclusions
In the present work was quantified the total content of phenols and flavonoids of the hydroalcoholic extract of D. pazensis roots, also was evaluated its antioxidant activity through different in vitro methodologies. In previous studies we reported this evaluation in roots of other species of the genus: D. elegans and D. boliviana (11). In relation to the in vitro antioxidant evaluation the hydroalcoholic extract of D. pazensis showed an interesting antioxidant activity by radical scavenging capacity, when it was compared with the reference antioxidant quercetin. At the same time, this activity is similar to that observed in the other two mentioned species of Dalea (11). However, comparing the total content of flavonoids of the three species, it can be seen that the total content of flavonoid in D. pazensis extract (9.67 mg/gr of extract) is lower than D. boliviana and D. elegans (42.1 mg and 46.9/gr of extract, respectively) (11). These results allow us to infer that the phenolic compounds present in roots of D. pazensis could present a significant antioxidant activity. Therefore, D. pazensis is an interesting species for subsequent studies of isolation, separation, purification and structural elucidation of its active principles.
Table 1: Total content of phenols and flavonoids in extract of D. pazensis roots
|
Ethanol/H20 Extract |
Total phenols (a) |
Total flavonoids (b) |
|
Dalea pazensis |
33.73±0.02 |
9.67±0.2 |
|
a-Expressed as mg of gallic acid equivalents/g of extract (mgEqAG) | ||
|
b- Expressed as mg of quercetin equivalents/g of extract (mgEqQ). | ||
Table 2: Antioxidant activity of D. pazensis roots
|
Total Antioxidant Potential | ||||
|
Extract/Compound |
10 µg. |
25µg. |
50µg. |
90µg. |
|
Dalea pazensis |
4.49±0.04 (5.3%) |
5.73±0.08 (8.6%) |
9.8±0.1 (19.5%) |
17.9±0.2 (41.2%) |
|
Quercetin |
13.1±0.1 (19.4%) |
24.4±0.1 (43.7%)
|
33.6±0.1 (69.7%)
|
55.1±0.7 (100.0%)
|
|
Expressed as µg. Ac. Ascorbic equivalents. Expressed as % of antioxidant potential respect to ascorbic acid | ||||
|
Extract/Compound |
% inhibition of hemolysis (a) |
Radical scavenging capacity (b) | ||
|
Dalea pazensis |
Quercetin |
Dalea pazensis |
Quercetin | |
|
10µg. |
21.3±0.6 % |
5.97±1.64 % |
1.73±0.02 (26.6%) |
6.52±0.05 (97.4%) |
|
50µg. |
55.6±0.4 % |
97.74±3.2 % |
4.79±0.02 (69.7%) |
6.58±0.01 (98.3%) |
|
100µg. |
100±0.0 % |
97.39±2.21% |
6.49±0.04 (93.5%) |
6.56±0.03 (97.9%) |
|
a- Expressed as % inhibition of hemolysis | ||||
|
b- Expressed as µg. eq. de Trolox equivalents. Expressed as % of radical scavenging capacity with respect to Trolox
| ||||
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