A.A.L. Ordoñez

Bio: A.A.L. Ordoñez is an academic researcher from National University of Tucumán. The author has contributed to research in topics: Sechium & DPPH. The author has an hindex of 1, co-authored 1 publications receiving 817 citations.

Evaluation of Aluminium Complexation Reaction for Flavonoid Content Assay

Abstract: Two widely applied spectrophotometric assays based on aluminium complex formation used for determination of total flavonoid content in food or medicinal plant samples were examined for several compounds from different classes of flavonoid family. The method which involves the measurement at 410–430 nm after addition of AlCl3 solution is selective only for flavonols and flavones luteolin. The procedure in the presence of NaNO2 in alkaline medium seems to be specific for rutin, luteolin and catechins, but also phenolic acids exhibit considerable absorbance at 510 nm. Application of both procedures to natural samples gave different order in terms of their flavonoid content. Thus, the expression “total flavonoid” content is not adequate as the results of both methods are dependent on the structure of the individual flavonoids present.

In vitro models for antioxidant activity evaluation and some medicinal plants possessing antioxidant properties: An overview

Abstract: Reactive oxygen species (ROS) are a class of highly reactive molecules derived from the metabolism of oxygen. ROS, including superoxide radicals, hydroxyl radical and hydrogen peroxide molecules are often generated as by products of biological reactions or from exogenous factors. There is extensive evidence to involve ROS in the development of degenerative diseases. Evidence suggests that compounds especially from natural sources are capable of providing protection against free radicals. This has attracted a great deal of research interest in natural antioxidants. It is necessary to Screen out medicinal plants for their antioxidant potential. Therefore an attempt has been made to review different in vitro models for estimating antioxidant properties of natural products from medicinal plants. All the models are described along with the different standards that can be used for estimation. In the end, a large number of plants showing in vitro antioxidant activity are listed but in vivostudies are lacking. Key words: Antioxidant assay, in vitro models, antioxidant medicinal plants.

Antioxidant activities of extracts and main components of Pigeonpea [Cajanus cajan (L.) Millsp.] leaves.

Abstract: Antioxidant activities of the aqueous and ethanol extracts of pigeonpea [Cajanus cajan (L.) Millsp.] leaves, as well as petroleum ether, ethyl acetate, n-butanol and water fractions and the four main compounds separated from the ethanol extract, i.e. cajaninstilbene acid (3-hydroxy-4-prenylmethoxystilbene-2-carboxylic acid), pinostrobin, vitexin and orientin, were examined by a DPPH radical-scavenging assay and a beta-carotene-linoleic acid test. In the DPPH system, the antioxidant activity of the ethanol extracts was superior to that of the aqueous extracts, with IC(50) values were 242.01 and 404.91 microg/mL, respectively. Among the four fractions, the ethyl acetate one showed the highest scavenging activity, with an IC(50) value of 194.98 microg/mL. Cajaninstilbene acid (302.12 microg/mL) and orientin (316.21 microg/mL) showed more efficient radical-scavenging abilities than pinostrobin and vitexin. In the beta-carotene-linoleic acid test, the inhibition ratio (%) of the ethyl acetate fraction (94.13%+/-3.41%) was found to be the highest, being almost equal to the inhibition capacity of the positive control BHT (93.89%+/-1.45%) at 4 mg/mL. Pinostrobin (>500 microg/mL) and vitexin (>500 microg/mL) showed insignificant antioxidant activities compared with cajaninstilbene (321.53 microg/mL) and orientin (444.61 microg/mL). In general, the ethyl acetate fraction of the ethanol extract showed greater activity than the main compounds in both systems, such results might be attributed to the synergistic effects of the components. The antioxidant activities of all the tested samples were concentration-dependent. Based on the results obtained, we can conclude that the pigeonpea leaf extracts may be valuable natural antioxidant sources and are potentially applicable in both medicine and the healthy food industry.