Composition and stability of phytochemicals in five varieties of black soybeans (Glycine max)

Phytochemical compositions of five varieties of black soybeans (Glycine max) and their stabilities at room temperature, 4 and −80 °C over 14 months were determined by HPLC systems with electrochemical (ECD) and UV detectors. Polyphenol profiling was carried out by a liquid chromatography–electrospray ionisation-mass spectrometry (LC–ESI-MS) with orbitrap as a mass analyser in both positive and negative ion modes, and polyphenols in aglycone forms were quantified by HPLC–ECD. Five different varieties of black soybeans (G. max) contained 249–405 μg/g dry wt of γ-tocopherol and 6.76–14.98 μg/g dry wt of lutein. Major polyphenols in black soybeans (G. max) were daidzein (193–288 μg/g dry wt) and genistein (145–223 μg/g dry wt), mainly present as glucosides and acetyl glucosides. No significant decrease was found in total phenols of black soybeans (G. max) stored at room temperature, 4 or −80 °C for 14 months. On the other hand, lutein and γ-tocopherol degraded significantly within a month of storage at room temperature (p < 0.01), whereas they remained stable up to 6 months at 4 °C and up to 14 months at −80 °C. The current study indicates that black soybeans (G. max) are rich source of γ-tocopherol and phenols (isoflavones, flavonols, flavan-3-ols, proanthocyanidins and anthocyanin) and that the levels vary depending upon varieties. In addition, storage at low temperature is recommended to reduce the loss of fat-soluble phytochemicals in black soybeans (G. max) over an extended period of time.     

Nutrient contents of kale (Brassica oleraceae L. var. acephala DC.)

Fructose, glucose and sucrose, as the major soluble sugars and citric and malic acids, as the major organic acids, were identified and determined in kale (Brassica oleraceae L. var. acephala DC., black cabbage) leaves. Fructose was the predominant sugar (2011 mg 100 g⁻¹ dry wt) identified, followed by glucose (1056 mg 100 g⁻¹ dry wt) and sucrose (894 mg 100 g⁻¹ dry wt). The contents of citric and malic acids were at 2213 and 151 mg 100 g⁻¹ dry wt in the leaves. The 16:0, 18:2n − 6 and 18:3n − 3 fatty acids were the most abundant fatty acids in the leaves. Considering the level of these fatty acids, 18:3n − 3 was found to be the highest (85.3 μg g⁻¹ dry wt), contributing 54.0% of the total fatty acid content. Linoleic acid (18:2n − 6), being the second most abundant fatty acid was present at 18.6 μg g⁻¹ dry wt, contributing 11.8% of the total fatty acid content. In the seed oil of kale, 22:1n − 9 was the most abundant fatty acid (4198 μg g⁻¹ dry wt, 45.7%), with 18:2n − 6 (1199 μg g⁻¹ dry wt, 12.3%) and 18:1n − 9 (1408 μg g⁻¹ dry wt, 14.8%) being the second next most abundant fatty acids. The most abundant amino acid was glutamic acid (Glu) which was present at 33.2 mg g⁻¹ dry wt. Aspartic acid, which was the second most abundant amino acid, was present at 27.6 mg g⁻¹ dry wt and accounted for 10.2% of the total amino acid content of kale leaf. The amino acid content was assessed by comparing the percentages of the essential amino acids in kale leaf versus those of a World Health Organization (WHO) standard protein. The protein of kale leaf compares well with that of the WHO standard. Only one amino acid, lysine, had a score that fell below 100%; the lysine score of kale leaf was 95%. This study attempts to contribute to knowledge of the nutritional properties of the plant. These results may be useful for the evaluation of dietary information.     

Improved sample treatment and chromatographic method for the determination of isoflavones in supplemented foods

Isoflavones are a group of substances that belong to the family of phytoestrogens. These natural substances may offer several benefits to human health. One of the most important sources for human isoflavone intake is soy and soybean food derivatives. An improved sample treatment followed by a high performance liquid chromatographic method for the determination of isoflavones in supplemented milk and juices is proposed and compared to the AOAC official method. Detection limits found were between 0.2 and 0.3 mg L⁻¹ for daidzein and genistein respectively. Quantification limits found were between 0.7 mg L⁻¹ for daidzein to 1.0 mg L⁻¹ for genistin, while inter and intra-day variability was under 10% in all cases. Recoveries for spiked samples were over 90% and under 110%. The method was validated by comparison with the AOAC method and by recovery assay methodology.     

Enhanced technological and permeation properties of a microencapsulated soy isoflavones extract

Functional extracts from soybean have numerous health benefits deriving from their content in isoflavones, especially daidzein and genistein, natural antioxidant and estrogen-like (ES-like) molecules. However, soybeans denaturated dried extracts possess critical properties for industrial applications such as poor water-solubility and inadequate storage stability. The present research was aimed at developing a new sodium-carboxymethylcellulose (NaCMC) matrix by spray-drying to microencapsulate soy extracts obtaining enhanced technological and permeation properties. Microparticles (NaCMC-Iso) loaded with marketed soybeans extract (Iso), enriched in daidzein and genistein (about 90% w/w), were produced. Different liquid feeds, based on H₂O/EtOH/acetone co-solvent systems, and various process parameters were tested to obtain a free-flowing and manageable powder with satisfying yield. The engineered NaCMC-Iso powders showed satisfying loading efficiency, high flow properties, good stability and enhanced technological properties. Interestingly, the in vitro dissolution and permeation rates were dramatically improved suggesting a higher bioavailability after the oral administration. The made-up powder appears a newsworthy ingredient of easier manipulation for enclosing in dietary supplements and nutraceutical products.     

Supercritical fluid extraction of daidzein and genistein isoflavones from soybean hypocotyl after hydrolysis with endogenous β-glucosidases

An optimal condition of supercritical fluid extraction (SFE) for isoflavone aglycones (daidzein and genistein) in soybean hypocotyls previously subjected to thermohydration at pH 5.0 and a temperature of 50 °C for 6, 12 and 18 h was developed. Different temperatures, pressures and cosolvents (methanol, ethanol, and acetonitrile) was tested and compared with solid–liquid extraction using aqueous methanol solution (80% v v⁻¹) conducted in parallel for comparison. The extraction conditions were 50–70 °C, 176–380 bar, adding 0, 5, 10 mol% of cosolvents 80% in water as a modifier. The results from SC–CO₂ showed that the cosolvent and pressure have significant effects in the extraction efficiency. It was found that the extraction conditions promoting the highest extraction of daidzein and genistein were at the temperature of 60 °C, pressure of 380 bar and both static and dynamic extraction of 15 min with the addition of 10% acetonitrile (80% v v⁻¹). The maximum amounts of daidzein and genistein extracted by each method were solid–liquid extraction (70.07 mg 100 g⁻¹) and carbon dioxide–acetonitrile (17.97 mg 100 g⁻¹). The yield of daidzein and genistein achieved by a 30 min SC–CO₂ extraction on soybean hypocotyls after 12 h soaking time was markedly improved by the addition of a modifier (acetonitrile) to the CO₂ fluid. HPLC analysis of the obtained extracts revealed that extraction of isoflavone aglycones by SC–CO₂ was 4.78 and 13.19 mg 100 g⁻¹ for daidzein and genistein, respectively. The contents of daidzein and genistein obtained in the solid–liquid extraction were superior to 86% and 63%, respectively, compared to supercritical extraction.     

Antioxidant properties of aqueous and methanol soy extracts in minced trout muscle

Antioxidant capacity of freeze-dried aqueous and methanolic extracts of soy protein isolate (SPI) and soybean meal (SBM) were assessed by 2, 2′-Diphenyl-1-picrylhydrazyl (DPPH) assay and total phenolic content (TPC). Caffeic and chlorogenic acids in liquid aqueous extracts, and genistein and daidzein in liquid methanolic extracts were measured by HPLC. Freeze-dried extracts were applied (1000 and 4000 μg/g) to trout mince and TBARS formation monitored during 14 days refrigerated storage. SBM aqueous extracts-treated mince (4000 μg/g) had significantly lower (P < 0.05) TBARS than all other treatments. SPI methanolic extract had the highest TPC (100 mg chlorogenic acid equivalents/100 g extract) and genistein and daidzein contents. SPI aqueous extracts had the highest chlorogenic acid (280 μg/g) while SBM aqueous extracts had the highest caffeic acids content (484 μg/g). SPI had the best in vivo antioxidant profile. SBM extracts were most effective at retarding lipid oxidation in refrigerated trout mince.     

Spray-dried rosemary extracts: Physicochemical and antioxidant properties

In this work, spray-dried rosemary extracts were obtained. A 3³ Box-Behnken design was followed to evaluate the influence of drying conditions on the contents of chemical markers and “in vitro” antioxidant activity of the powder. Although the dry products lost some of their polyphenols, they still had antioxidant activities (IC₅₀) ranging from 17.6 to 24.8 μg · mL⁻¹. Analysis of variance proved that studied factors and some of their interactions significantly affected most of the quality indicators. The best combination of conditions to use for obtaining dry rosemary extracts with adequate physicochemical and functional properties involves an extract feed rate of 6 mL · min⁻¹, a drying air inlet temperature of 140 °C and a spray nozzle air flow rate of 50 L · min⁻¹.     

Polyphenolic content and antioxidant activity of Eugenia pollicina leaf extract in vitro and in model emulsion systems

The polyphenolic profile of a leaf extract of the Mauritian endemic plant, Eugenia pollicina, was assessed as a source of natural antioxidants. The amounts of flavan-3-ol derivatives determined by HPLC, were in the order of (−)-epicatechin (EC) > (−)-epigallocatechin gallate (EGCG) > (+)-catechin (C) > (−)-epicatechin gallate (ECG) with the levels of Procyanidin B2 and B1 dimers ranging from 1 to 3 mg g⁻¹ FW. The trolox equivalent antioxidant capacity and ferric reducing antioxidant power values were 796 ??mol g⁻¹ FW and 302 ??mol g⁻¹ FW respectively. E. pollicina extracts also strongly inhibited the FeCl₃ and ascorbate-dependent microsome lipid peroxidation, a function that is linked to their flavonoid contents. The extent of DNA damage induced by the extract under study in the copper-phenanthroline assay was lower than the effect of a reference of 240 ??M ascorbate. E. pollicina extracts also inhibited lipid autoxidation in the 30% (v/v) olive oil and soybean oil oil-in-water (O/W) emulsions and was effective in slowing down the formation of hydroperoxides in the emulsions during 13 days storage at 40 °C as determined by the peroxide, conjugated diene and para-anisidine values. The high levels of total phenolics, flavonoids and procyanidins measured indicate that E. pollicina is a potential source of antioxidants relevant to the maintenance of oxidative stability of the food matrix, cosmetics and/or pharmaceutical preparations.     

Profiling of in vitro neurobiological effects and phenolic acids of selected endemic Salvia species

The ethyl acetate and methanol extracts from 16 Salvia L. species were screened for their inhibitory activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase, and tyrosinase; the enzymes linked to neurodegeneration. Their antioxidant activity was also tested using DPPH radical scavenging, metal-chelation, and ferric-reducing antioxidant power (FRAP) assays. Total flavonoid content of the extracts was determined by AlCl₃ reagent, while HPLC technique was applied for analysis of various phenolic acids in the extracts. The extracts exerted weak cholinesterase and tyrosinase inhibition, and remarkable inhibition against lipoxygenase (13.07 ± 2.73-74.21 ± 5.61%) at 100 μg ml⁻¹. The methanol extracts showed higher antioxidant activity in DPPH radical scavenging and FRAP assays. The extracts were analyzed for their gallic, protocateuchic, p-hydroxy-benzoic, vanillic, caffeic, chlorogenic, syringic, o- and p-coumaric, ferulic, rosmarinic, and tr-cinnamic acid contents and the methanol extract of Salvia ekimiana (153.50 mg 100 g⁻¹) was revealed to be the richest in terms of rosmarinic acid.     

Antioxidant activities of mangrove Rhizophora apiculata bark extracts

Depolymerisation of mangrove Rhizophora apiculata bark extracts in the presence of phloroglucinol nucleophiles in ethanol was carried out. The flavan-3-ols and their phloroglucinol adducts were separated using reversed phase liquid chromatography (HPLC). The HPLC analysis of mangrove R. apiculata showed that catechin was the most common component of the flavanoid monomers. The antioxidant activities of these mangrove tannins were evaluated and compared with several commercial tannins by using reducing power, DPPH and ABTS assays with butylated hydroxytoluene, BHT and l-(+)-ascorbic acid as standards. All tannins had reducing power and percentage scavenging activities similar to the (+)-catechin and l-(+)-ascorbic acid standards. In the DPPH assay, >90% of the maximum scavenging activity was attained at 30 μg ml⁻¹. Mangrove tannins had stronger antioxidant activity than the BHT standard in the DPPH assay. The results of the ABTS assay were correlated with the DPPH assay. Scavenging activity in the ABTS assay increased as the tannin concentration increased, up to a plateau at 50 μg ml⁻¹.     

Antioxidant properties of hot water extracts from Agrocybe cylindracea

Agrocybe cylindracea (DC: Fr.) Mre. was available in the form of fruit bodies, mycelia and fermentation filtrate. From these three forms, hot-water extracts were prepared and their antioxidant properties were studied. Antioxidant activities of hot-water extracts from fruit bodies, mycelia and filtrate were 63.6%, 81.6% and 56.8% at 20 mg ml⁻¹, respectively. EC₅₀ values in reducing power were 2.72, 3.97 and 3.09 mg ml⁻¹ whereas those in scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl radicals were 0.62, 1.66 and 0.82 mg ml⁻¹ for fruit bodies, mycelia and filtrate, respectively. At 20 mg ml⁻¹, the scavenging abilities of hydroxyl radicals were 80.1%, 57.0% and 54.3% for fruit bodies, mycelia and filtrate, respectively. With regard to EC₅₀ values in chelating abilities on ferrous ions, the hot-water extract from filtrate was better than that from mycelia. Total phenols were the major naturally occurring antioxidant components found in hot-water extracts and in the range of 23.74–30.16 mg g⁻¹. From EC₅₀ values obtained, it can be concluded that hot-water extracts from three forms of A. cylindracea were good in antioxidant properties.     

Characterisation,extraction efficiency,stability and antioxidant activity of phytonutrients in Angelica keiskei

Phytonutrients in Angelica keiskei, a dark green leafy vegetable, were characterised and their extraction efficiency by different compositions of water/ethanol as well as stability at different temperatures was determined. A range in the content of lutein (205–265 mg/kg dry wt), trans-β-carotene (103–130 mg/kg dry wt), and total phenols (8.6–9.7 g/kg) was observed amongst Angelica keiskei grown in three different conditions. LC-ESI-MS/MS analysis identified chlorogenic acid, chalcones and the glucosides of luteolin and quercetin as the major phenolic compounds in Angelica keiskei. Only 46% of lutein was extracted by 70% of ethanol and no carotenoid was detected in 40% ethanol and 100% water extracts of Angelica keiskei. Major phytonutrients in Angelica keiskei were stable at −80 °C up to 12 months whilst β-carotene was significantly degraded at room temperature and 4 °C within 2 months and lutein at room temperature within 12 months.     

Red clover (Trifolium pratense L.) isoflavones: determination of concentrations by plant stage,flower colour,plant part and cultivar

BACKGROUND: Red clover (Trifolium pratense L.), a widely used fodder, has recently received considerable interest as a valuable source of isoflavones for many health‐related applications. The aim of this study was to analyse the concentrations of four isoflavones, daidzein, genistein, formononetin and biochanin A, in extracts of leaves, stems, roots and different coloured flowers from red clover by high‐performance liquid chromatography and to determine the antifungal activities of the extracts. RESULTS: Among greenhouse‐grown samples the highest amounts of daidzein and genistein were found in petioles (0.11–0.28 and 0.30–0.54 mg g^?1 respectively), while leaves were rich in formononetin and biochanin A (5.57–9.05 and 10.94–14.59 mg g^?1 respectively). High formononetin concentrations were found in roots, but very little biochanin A. Among field‐grown samples the highest concentrations of daidzein and genistein were detected in stems collected in August (0.24 and 0.55 mg g^?1 respectively), while the highest amounts of formononetin and biochanin A were found in young leaves collected in June (7.47 and 9.69 mg g^?1 respectively). Most of the extracts inhibited the growth of Drechslera teres, while the root extract showed the strongest effect against Microdochium nivale. CONCLUSION: High levels of bioactive compounds found not only in inflorescences but also in roots, leaves and stems suggest that red clover may be an inexpensive and valuable resource for many applications. Copyright © 2007 Society of Chemical Industry     

Changes of isoflavone in soybean cotyledons soaked in different volumes of water

Soybean cotyledons, recently dehulled, were soaked at 50 °C for 12 h as a pre treatment to obtain defatted soy flour enriched in aglycones. Grains of cultivar BRS 213 from the crop years 2004 and 2005 were used and initially had 1.4 and 1.2 mg g⁻¹ of total isoflavones, respectively. The molar mass of malonyl and β-glycosides decreased after soaking (33% and 56.5%, in grains from the crop years 2004 and 2005, respectively), while the aglycones daidzein and genistein, that were previously undetectable, increased to 0.5 and 0.8 μmol g⁻¹ in grains from the crop years 2004 and 2005, respectively. Cotyledons treated with the reduced volume of water had a reduction of 4% of the total isoflavone molar mass while, for the cotyledons treated with higher volume of water, there was a reduction of 14%, due to the leaching of isoflavones to the soaking water.     

Antioxidant potentials and rosmarinic acid levels of the methanolic extracts of Salvia verticillata (L.) subsp. verticillata and S. verticillata (L.) subsp. amasiaca (Freyn & Bornm.) Bornm

This study was designed to examine the in vitro antioxidant activities and rosmarinic acid levels of the methanol extracts of Salvia verticillata subsp. verticillata and S. verticillata subsp. amasiaca. The extracts were screened for their possible antioxidant activity by two complementary test systems, namely DPPH free radical-scavenging and β-carotene/linoleic acid systems. In the first case, S. verticillata subsp. verticillata was superior to the subsp. amasiaca with an IC₅₀ value of 14.5 ± 1.21 μg mg⁻¹. In the β-carotene/linoleic acid test system, inhibition capacity of S. verticillata subsp. verticillata was 74.4 ± 1.29%. Antioxidant activities of BHT, ascorbic acid, curcumin and α-tocopherol were determined in parallel experiments. Activity of rosmarinic acid was also screened for better establishing the relationship between rosmarinic acid level and antioxidant activity for the plant extracts. S. verticillata subsp. verticillata had the highest rosmarinic acid level with a value of 28.7 ± 0.89 μg mg⁻¹. There is a strong correlation between the rosmarinic acid level and antioxidant activity potential. Our results showed that rosmarinic acid and its derivatives are more likely to be responsible for most of the observed antioxidant activities of Salvia species.     

Estimation of neuroprotective effects of Laurocerasus officinalis Roem. (cherry laurel) by in vitro methods

Dichloromethane, ethyl acetate, acetone, methanol, and water extracts prepared from the fruits and leaves of Laurocerasus officinalis Roem. (LO) (Rosaceae) were screened for their cholinesterase inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in pathogenesis of Alzheimer's disease (AD), using ELISA microplate reader at 50, 100, and 200 ??g mL⁻¹. As AD is associated with oxidative stress, the antioxidant activity of the extracts was also tested by radical-forming methods against 2,2-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), and superoxide radicals as well as iron-related methods; iron-chelating capacity and ferric-reducing antioxidant power (FRAP) assays. Total phenol and flavonoid quantification was achieved using Folin-Ciocalteau and AlCl₃ reagents, respectively. The highest AChE (44.01 ± 1.75%) and BChE (19.91 ± 0.37%) inhibition was caused by the LO-leaf-methanol extract 200 ??g mL⁻¹, while it showed the best radical-scavenging activity against DPPH at 2000 ??g mL⁻¹. Only, the dichloromethane and water extracts of the fruits and the leaf water extract had an iron-chelating capacity, while the leaf methanol extract displayed the highest FRAP. The leaf methanol extract (113.45 ± 0.71 mg g⁻¹ extract) was found to be the richest in total phenols, while the leaf acetone extract (139.90 ± 4.64 mg g⁻¹ extract) had the most abundant amount of total flavonoids.     

Bioprospecting traditional Pakistani medicinal plants for potent antioxidants

Antioxidant potential of four methanol extracts from three selected plant species, namely Salvia nubicola (Lamiaceae), Acer oblongifolium (Aceraceae) and Hedera nepalensis (Araliaceae) was measured using assays in aqueous and lipid systems. Antioxidant activities were investigated in aqueous systems by using DPPH radical-scavenging assay, ABTS radical-scavenging assay and DNA protection assay, while antioxidant activity in a lipid system was determined by using the thiobarbituric acid-reactive substances (TBARS) assay. Additionally, the Folin-Ciocalteu method was used to measure total phenolic content. Methanol extracts of leaves and flowers of S. nubicola showed the highest Trolox equivalent (TE) values in the case of the DPPH assay, 2484 ± 4.9 mmol TE/g extract, as well as total phenolic content, 139 ± 0.2 mg gallic acid equivalents/g extract. Three fractions (A-C) of the methanol extract of S. nubicola leaves and flowers were produced by semi-preparative HPLC. Fraction B was found to be the most active in the DPPH radical-scavenging assay and had the highest total phenol content. HPLC-DAD and LC-MS revealed rosmarinic acid in S. nubicola extracts and chlorogenic acid and rutin in H. nepalensis extracts as the main phenolic antioxidants.     

Combination of low dose of genistein and daidzein has synergistic preventive effects on isogenic human prostate cancer cells when compared with individual soy isoflavone

The reduced incidence of prostate cancer (PCa) in Asia countries has been attributed to high soy diets, and major soy isoflavones, in particular daidzein and genistein, are thought to be the source of the beneficial and anti-cancer effects of soy foods. However, attention has been drawn to the safety of using high levels of soy isoflavones in humans, which is especially the concern for consumers taking regular soy isoflavone dietary supplements. The main objective of this study is thus to identify a soy isoflavone combination with lower levels of daidzein and genistein to be a more efficacious and safer chemo-preventive agent for PCa. The anticancer effects of daidzein and genistein, and their combinations on early-stage androgen-dependent PCa cells (LNCaP) and bone metastatic LNCaP-derivative PCa cells (C4-2B) were compared. Cells were treated with varying concentrations of daidzein, genistein (25–200 μM) or their combinations (25 or 50 μM) and cell proliferation, apoptosis, cell cycles and cellular uptakes of the isoflavones were measured after 48 h. Daidzein and genistein showed a synergistic effect on inhibiting cell proliferation and inducing apoptosis of both PCa cells. Twenty-five μM daidzein/50 μM genistein and 50 μM daidzein/50 μM genistein significantly increased the apoptotic effects on C4-2B cells although they did not show any effect when used individually. Except 50 μM daidzein/50 μM genistein, all other combinations had no impacts on cell cycles. For treatment with soy isoflavone combination, genistein was always better taken up than daidzein by both LNCaP and C4-2B cells.     

Antioxidant and antibacterial activities of Nephelium lappaceum L. extracts

Ether, methanolic and aqueous extracts of lyophilized rambutan (Nephelium lappaceum L.) peels and seeds were evaluated for phenolic contents, antioxidant and antibacterial activities. High amounts of phenolic compounds were found in the peel extracts and the highest content was in the methanolic fraction (542.2 mg/g dry extract). Several potential antioxidant activities, including reducing power, β-carotene bleaching, linoleic peroxidation and free radical scavenging activity, were evaluated. The peel extracts exhibited higher antioxidant activity than the seed extracts in all methods determined (P < 0.05). The methanolic fraction was found to be the most active antioxidant as shown by their 50% DPPH inhibition concentration, 4.94 μg/mL. The results indicated this fraction exhibited greater DPPH radical scavenging activity than BHT and ascorbic acid (0.32 g dry extract/g BHT or ascorbic acid). Antibacterial activity against eight bacterial strains was assessed by disc diffusion and broth macrodilution methods. All peel extracts exhibited antibacterial activity against five pathogenic bacteria. The most sensitive strain, Staphylococcus epidermidis, was inhibited by the methanolic extract (MIC 2.0 mg/mL).     

Antioxidant potential of solvent extracts of Kappaphycus alvarezii (Doty) Doty – An edible seaweed

Various solvent extracts of Kappaphycus alvarezii, an edible red seaweed (family Solieriaceae) were screened for total phenol content and antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferrous ion chelating activity, reducing power and antioxidant activity assays in a linoleic acid system with ferrothiocyanate reagent (FTC). The total phenol content of different extracts of K. alvarezii varied from 0.683 ± 0.040% to 2.05 ± 0.038%. The radical-scavenging activity of ethanol extract was, as IC₅₀ 3.03 mg ml⁻¹, whereas that of the water extract was IC₅₀ 4.76 mg ml⁻¹. Good chelating activity was recorded for methanol extract (IC₅₀ 3.08 mg ml⁻¹) wherein 67.0 ± 0.924% chelation was obtained using 5.0 mg ml⁻¹ of extract. The reducing power of the samples was in the following order: BHT > methanol > ethanol > ethyl acetate > water > hexane. But, in the linoleic acid system, the ethanol extract proved superior to the synthetic antioxidants butylated hydroxytoluene (BHT). Hence, these extracts could be considered as natural antioxidants and may be useful for curing diseases arising from oxidative deterioration.