The In Vitro Antioxidant Activity and Phytochemicals of Locally Consumed Plant Foods from Quezon Province, Philippines

Abstract

Background. Quezon province has been one of the primary agricultural sources of vegetables and crops in southern Luzon due to its diverse agricultural topography. Having increased dietary awareness, consumption of antioxidant-rich foods has become relevant. Objectives. Thirteen (13) methanolic extracts of endemic Quezon plant foods were evaluated for phytochemical constituents and antioxidant potential.Methods. The plant extracts were subjected to in vitro antioxidant assays, which include DPPH [2,2-diphenyl-1picrylhydrazyl], FRAP [Fluorescence recovery after photobleaching], metal chelation, superoxide, nitric oxide, hydroxyl radical scavenging activities and MTT [ (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)] reduction. Qualitative phytochemical analysis were also employed. Results. P. umbellatum, locally known as kamamba and C. longa, locally known as luyang dilaw showed high antioxidant activity using DPPH and MTT assays by 82.46±0.75% and 82.35±1.79% and 78.46±0.71% and 60.97±2.60% at 66.67 μg/mL, respectively. FRAP assay revealed a comparable reducing power with BHT (butylated hydroxytoluene) (93.61±0.56%) at 72.15 μg/mL in C. longa (92.49±1.32%), P. umbellatum (92.38±0.64%), and Z. officinale (90.33±2.06%) (luya), but found with low metal chelating activity. The highest activity against hydroxyl radical were observed in S. edule (sayote) (34.30±1.88%), P. edulis (pasyonaryo) (33.48±1.34%) and D. philippinensis (katmon) (34.71±0.85%) at 45.5 μg/mL. On the other hand, Z. officinale, C. esculenta (gabi), V. unguiculata (sitaw) fruit and D. philippinensis showed dual action, as antioxidant and as pro-oxidant, in Superoxide Scavenging and Nitric Oxide assays. Quezon province plant foods contain flavonoids, phenolic compounds, glycosides and coumarins and quinones which may explain their behavior as antioxidant.Conclusion. The study revealed that different plant foods showed different capacity to scavenge particular oxidants. However, P. umbellatum and C. longa may be considered promising sources of natural antioxidants.

Mechanism-based antioxidant activity of Rubiaceae species collected from Ilocos Norte, Philippines

“…The FRAP assay of the plant extracts (at 500 and 1000 μg/mL in MeOH) and the butylated hydroxytoluene (BHT) standard (at 500 and 1000 μg/mL in MeOH) were measured based on a previously described method (Yu et al, 2020). The working FRAP reagents were prepared by dissolving 0.2 M PBS (pH 7.4), 0.5 g K3Fe(CN)6, 5 g trichloroacetic acid (TCA), and 0.05 g FeCl3 in 50 mL distilled H2O.…”

“…The 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay is used to provide an initial assessment of the radical scavenging potential of the test compounds. Antioxidant activity is evaluated using colorimetric analysis, wherein a color change from purple to yellow indicates the conversion of the DPPH • radical to DPPH, a more stable product, by an antioxidant compound through hydrogen or electron donation (Cornago et al, 2011;Khatun et al, 2020;Yu et al, 2020). As shown in Figure 2, P. luzoniensis (96.40 % ± 0.44) demonstrated the highest radical scavenging activity and is statistically comparable to the standards (p > 0.05).…”

“…Antioxidants are substances that have become more significant in recent years because of their capacity to counteract some of the harmful effects of elevated ROS concentrations (Yu et al, 2020). Although many synthetic antioxidants have been developed, certain studies have reported that these may induce adverse effects on human health (Lourenço et al, 2019).…”

Correlation of total phenolic and flavonoid contents on the antioxidant activity of Psychotria gitingensis and Psychotria pilosella

“…The ferric reducing antioxidant power (FRAP) assay method described by Yu et al (2020) was used to measure the reducing power of the plant extracts, with slight modifications. The concentration of the plant extracts used in the assay was 500 ppm.…”

Phytochemical screening and antioxidant activity of methanol extract of Dillenia excelsa leaf

“…Liana and Murningsih 2019 reported that Dillenia auriculata bark extract has total phenolic content of 19.70±0.05 mg GAE/g extract and a total flavonoid of 19.53±0.08 mg RE/g extract, and potential as an antioxidant. Dillenia philippinensis contains flavonoids, phenolic compounds, glycosides, coumarins, and quinones, and potential as antioxidants (Yu et al 2020;Ansari et al 2021). While, the ethanolic extract of Dillenia pentagyna contains phenolics, flavonoids, tannins, saponins, alkaloids, and terpenoids (Patle et al 2020), and potentially as anticancer, antidiarrheal, antimicrobial, antioxidant (Ghandi and Mehta 2013).…”