Cytoprotective and antioxidant activity of free,conjugated and insoluble-bound phenolic acids from swallow root (Decalepis hamiltonii)

Swallow root (Decalepis hamiltonii) was extracted for free (SRFP), conjugated (SRCP) and insoluble-bound phenolic acids (SRIBP), and evaluated for cytoprotectivity, 1,1,diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, reducing power and protection to DNA damage. In addition, the constituent phenolic acids in the extracts were also analysed. Results indicated a total phenol content of 20.72, 7.97 and 11.52 mg gallic acid equivalents (GAE)/g for SRFP, SRCP and SRIBP extracts, respectively. At 0.12 μg/mL concentration SRCP showed 87% cytoprotection (on NIH 3T3 cells) compared to SRFP (47%) and SRIBP (65%). DPPH radical scavenging activity indicated an IC₅₀ of 0.046, 0.06 and 0.128 μg/mL for SRCP, SRIBP and SRFP, respectively. Also, SRCP showed higher reducing power and DNA protectivity (80%). HPLC analysis of phenolic acid extracts showed the presence of hydroxybenzoate and cinnamate derivatives. Among the phenolics identified gallic, gentisic, protocatechuic and p-coumaric acids were the major contributors to antioxidant activity.     

Flavonoid content and antioxidant activity of vegetables from Indonesia

Extracts from 11 vegetables of Indonesian origin were screened for flavonoid content, total phenolics, and antioxidant activity. The flavonols myricetin, quercetin, and kaempferol and flavones luteolin and apigenin were quantified by HPLC. Flavonoid content in mg/100 g fresh weight (fw) was apparently initially reported for Cosmos caudatus H.B.K. (52.19), Polyscias pinnata (52.19), Pluchea indica Less. (6.39), Nothopanax scutellarius (Burm.f.) Merr (5.43), Talinum triangulare (Jacq.) Willd. (3.93), Pilea melastomoides (Poir.) Bl. (2.27), and Etlingera elatior (Jack) R.M.Sm (1.18). The flavonoid content of the vegetables studied were mainly quercetin and kaempferol and ranged from 0.3 to 143 mg/100 g fw, with the highest level found in Sauropus androgynus (L) Merr. C. caudatus H.B.K. had the greatest total phenols among the vegetables analysed, with 1.52 mg GAE/100 g fw. P. indica Less. and C. caudatus H.B.K. had the highest antioxidant activity as measured by ferric cyanide reducing power, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) scavenging, and inhibition of linoleic acid oxidation. Therefore, S. androgynus (L) Merr, C. caudatus H.B.K., and P. pinnata were identified as potentially rich sources of dietary flavonoids and antioxidants.     

Development and validation of an HPLC-method for determination of free and bound phenolic acids in cereals after solid-phase extraction

Whole cereal grains are a good source of phenolic acids associated with reduced risk of chronic diseases. This paper reports the development and validation of a high-performance liquid chromatography–diode array detection (HPLC–DAD) method for the determination of phenolic acids in cereals in either free or bound form. Extraction of free phenolic acids and clean-up was performed by an optimised solid-phase extraction (SPE) protocol on Oasis HLB cartridges using aqueous methanol as eluant. The mean recovery of analytes ranged between 84% and 106%. Bound phenolic acids were extracted using alkaline hydrolysis with mean recoveries of 80–95%, except for gallic acid, caffeic acid and protocatechuic acid. Both free and bound phenolic extracts were separated on a Nucleosil 100 C₁₈ column, 5 μm (250 mm × 4.6 mm) thermostated at 30 °C, using a linear gradient elution system consisting of 1% (v/v) acetic acid in methanol. Method validation was performed by means of linearity, accuracy, intra-day and inter-day precision and sensitivity. Detection limits ranged between 0.13 and 0.18 μg/g. The method was applied to the analysis of free and bound phenolic acids contents in durum wheat, bread wheat, barley, oat, rice, rye, corn and triticale.     

Inhibition of fish oil oxidation and the radical scavenging activity of New Zealand seaweed extracts

This study describes the potential use of New Zealand seaweed extracts as antioxidants in fish oils. The extracts from two brown seaweeds (Ecklonia radiata, Macrocystis pyrifera) and two red species (Champia sp. and Porphyra sp.), were added to hoki (Macruronus novaezelandiae) oil and assessed by production of oxidation products in an elevated temperature (60 °C) storage trial. Antioxidant assays ORAC and DPPH were conducted to elucidate the radical scavenging activity of the seaweed extracts. The results showed that all the lipid-soluble seaweed extracts had some antioxidative capacity, with brown algae generally outperforming red algae species. Extracts from E. radiata performed best with significantly lower primary, secondary and total oxidation products, and higher DPPH radical scavenging ability than the commercial antioxidant, BHT. This study demonstrated the potential of brown algae seaweed extracts, in particular E. radiata, for use as antioxidants in fish oil products.     

Essential oils,kava pyrones and phenolic compounds from leaves and rhizomes of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm. and their antioxidant activity

During essential oil production from Alpinia zerumbet, large volumes of water and solid wastes are produced and subsequently discarded. An extraction protocol to obtain essential oil, dihydro-5,6-dehydrokawain (DDK) and enriched antioxidant phenolic extracts from fresh leaves or rhizomes of A. zerumbet and their wastes was developed. The main components determined in leaf oil were 1,8-cineol, camphor and methyl cinnamate, whereas rhizome oil mainly contained DDK and methyl cinnamate. The highest DDK content was found in the hexane extract of fresh rhizomes. Ethyl acetate extracts from leaves showed higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities than those from rhizomes. Ethyl acetate extract from wastewater of leaves possessed the strongest inhibition to β-carotene oxidation. Ferulic and p-hydroxybenzoic acids were the major phenolics present in these extracts. The results indicate that disposed wastes produced during essential oil production from A. zerumbet leaves or rhizomes may be utilized in foodstuffs as a cheap source of natural antioxidants.     

Thymus lotocephalus wild plants and in vitro cultures produce different profiles of phenolic compounds with antioxidant activity

We compared the phenolic metabolites and antioxidant activities of Thymus lotocephalus G. López & R. Morales wild plants and in vitro cultures using different extraction solvents. HPLC-DAD analysis allowed the identification and quantification of phenolic (caffeic and rosmarinic) acids and flavones (luteolin and apigenin) in extracts from both sources. The in vitro cultures accumulated large amounts of rosmarinic acid. However, extracts from both sources were able to neutralise free radicals in different test systems (TEAC and ORAC assays), to form complexes with Fe(2+) and to protect mouse brains against Fe(2+)-induced lipid peroxidation. The solvent significantly influenced the phenolic content and antioxidant activity of the extracts, water/ethanol being the most efficient for the extraction of antioxidant phytochemicals. We conclude that in vitro cultures of T. lotocephalus represent a promising alternative for the production of valuable natural antioxidants and an efficient tool for the in vitro biosynthesis of rosmarinic acid, therefore avoiding the need to exploit populations of wild plants.