Lipophilic and hydrophilic antioxidants,lipid peroxidation inhibition and radical scavenging activity of two Lamiaceae food plants

Medicinal and aromatic plants are highly prized all over the world. According to local cuisine and pharmacopoeias, they used to be important as dietary supplements, providing bioactive compounds. Herein, we describe lipophilic (fatty acids, tocopherols and carotenoids) and hydrophilic (ascorbic acid, sugars and phenolic compounds) antioxidants, lipid peroxidation inhibition and free radical scavenging activity in aerial parts of two Lamiaceae species (Mentha pulegium and Thymus pulegioides). M. pulegium gave the highest antioxidant properties (EC₅₀<0.56 mg/mL), which is in agreement with its highest content in tocopherols, mainly α‐tocopherol (69.54 mg/100 g), ascorbic acid (7.90 mg/100 g), reducing sugars (7.99 g/100 g) and phenolics. The presence of these lipophilic and hydrophilic antioxidants could explain its use as antiseptic, anti‐inflammatory and as food preservative and special sauce. M. pulegium revealed the highest content of fat, α‐linolenic (ω‐3) and linoleic (ω‐6) fatty acids, while T. pulegioides revealed the highest content of carbohydrates (89.35 g/100 g). This could explain its use to improve the nutrition value of rye flour broth or potato based soups.     

Seed Oils of Five Black Tartary Buckwheat Cultivars with Biochemical Characterization and Antioxidant Properties

Black tartary buckwheat oils (BTBOs) were extracted from five major industrial tartary buckwheat cultivars grown under similar agronomical activities and environmental conditions. These oils were characterized for the bioactive compounds containing fatty acids, β‐carotene, lutein, α‐, β‐, δ‐ and γ‐tocopherol, and for their antioxidant properties. The total tocopherol contents that were obtained ranged from 704.66 to 1156.19 mg/kg, with γ‐tocopherol (588.98–977.91 mg/kg) as the main component. The concentration of lutein ranged from 253.14 to 429.63 mg/kg, which was almost ten times higher than that of β‐carotenoid (46.71–69.2 mg/kg), indicating that black tartary buckwheat seed oils were a good source of lutein. The predominant fatty acids were unsaturated oleic acid (C18:1) (35.27–40.61 %) and linoleic acid (C18:2) (38.25–42.90 %). Excellent values of 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH), diammonium salt (ABTS) radical scavenging activities were obtained and the highest oxygen radical absorbance capacity (ORAC) value of 13.89 mmol Trolox equiv/g oil was detected in the variety of Chuanqiao No. 1, which was clearly separated by principal component analysis (PCA) on the basis of the highest content of tocopherols and carotenoids. Moreover, the correlation analysis showed that tocopherols and carotenoids were the major contributors to the antioxidant activities of the BTBOs. This study demonstrates that lipophilic extraction in the tartary buckwheat seed contains many interesting bioactive compounds, which are beneficial for human health.     

The effect of temperature on the antioxidant activity of tocopherols

The effect of temperature on the antioxidant activity of α‐ and δ‐tocopherol (at 100 mg/kg level) was studied in pork lard, using the Oxipres apparatus, in the temperature range from 80 to 150 °C. The antioxidant activity of δ‐tocopherol decreased with increasing working temperature in the whole temperature range studied. The activity of α‐tocopherol was practically constant in the temperature range from 80 to 110 °C and decreased with increasing temperature at temperatures higher than 110 °C. Both tocopherols were ineffective at 150 °C (p <0.05). Due to different temperature effects on the antioxidant activities of α‐ and δ‐tocopherol, the δ‐tocopherol activity was approximately two times higher than the α‐tocopherol activity at 80 °C, but their activities were the same (p <0.05) at 130 °C.     

Determination of polyphenols,tocopherols, and antioxidant capacity in virgin argan oil (Argania spinosa,Skeels)

This study establishes data on polyphenols, tocopherols, and antioxidant capacity (AC) of virgin argan oil. A total of 22 samples from Morocco were analyzed. Total polyphenol content ranged between 6.07 and 152.04 mg GAE/kg. Total tocopherols varied between 427.0 and 654.0 mg/kg, being γ‐tocopherol the major fraction (84.68%); α‐, β‐, and δ‐tocopherols represent 7.75, 0.33, and 7.29%, respectively. No influence of oil extraction method on total tocopherols was observed. The AC of argan virgin oils determined by the ABTS method in n‐hexane oils dilution ranged between 14.16 and 28.02 mmol Trolox/kg, and by the ABTS, DPPH, and FRAP methods in methanolic oil extracts between 2.31–14.15, 0.19–0.87, and 0.62–2.32 mmol Trolox/kg, respectively. A high correlation was found between ABTS and DPPH methods applied to a methanolic oil extract. Virgin argan oil presents a higher polyphenol and tocopherol content, and total AC than other edible vegetable oils.     

Optimal tocopherol concentrations to inhibit soybean oil oxidation

The optimal concentration for tocopherols to inhibit soybean oil oxidation was determined for individual tocopherols (α-, γ-, and δ-tocopherol) and for the natural soybean oil tocopherol mixture (tocopherol ratio of 1∶13∶5 for α-, γ-, and δ-tocopherol, respectively). The concentration of the individual tocopherols influenced oil oxidation rates, and the optimal concentrations were unique for each tocopherol. For example, the optimal concentrations for α-tocopherol and γ-tocopherol were ∼100 and ∼300 ppm, respectively, whereas δ-tocopherol did not exhibit a distinct concentration optimum at the levels studied (P<0.05). The optimal concentration for the natural tocopherol mixture ranged between 340 and 660 ppm tocopherols (P<0.05). The antioxidant activity of the tocopherols diminished when the tocopherol levels exceeded their optimal concentrations. Above their optimal concentrations, the individual tocopherols and the tocopherol mixture exhibited prooxidation behavior that was more pronounced with increasing temperature from 40 to 60°C (P<0.05). A comparison of the antioxidant activity of the individual tocopherols at their optimal concentrations revealed that α-tocopherol (∼100 ppm) was 3–5 times more potent than γ-tocopherol (∼300 ppm) and 16–32 times more potent than δ-tocopherol (∼1900 ppm).     

Efficacy of myricetin as an antioxidant in methyl esters of soybean oil

The antioxidant activity of myricetin, a natural flavonol found in fruits and vegetables, was determined in soybean oil methyl esters (SME) and compared with α‐tocopherol and tert‐butylhydroquinone (TBHQ) over a 90‐day period employing EN 14112, acid value, and kinematic viscosity methods. Myricetin had greater antioxidant activity than α‐tocopherol, but was inferior to TBHQ. Synergism was observed between myricetin and TBHQ, but antagonism between α‐tocopherol and either myricetin or TBHQ was discovered. A binary mixture of myricetin and TBHQ at 1000 ppm (1:1) was the most effective treatment investigated at inhibiting oxidation of SME. Myricetin was not completely soluble in SME at 1000 ppm, suggesting that 500 ppm is a more appropriate treatment level. Pro‐oxidant activity of α‐tocopherol was observed when added to SME obtained from crude soybean oil, but antioxidant behavior was observed in distilled SME. Addition of α‐tocopherol to methyl esters initially free of antioxidants revealed that 600–700 ppm was the optimum concentration for antioxidant activity. Acid value and kinematic viscosity remained within prescribed specifications after 90 days, despite failure of a number of samples with regard to EN 14112, suggesting that these parameters are insufficient as sole indicators of oxidation stability.     

Effect of Agronomical Factors and Storage Conditions on the Tocopherol Content of Oblica and Leccino Virgin Olive Oils

The influence of agronomical factors (two growing areas and four harvest periods) and storage conditions of virgin olive oils (room temperature, +4 and ?20 °C) on tocopherols was investigated on two cultivars having significantly different tocopherol content (Oblica 269–443 mg/kg, Leccino 403–784 mg/kg). α‐Tocopherol accounted for 97 % of total tocopherols and its content decreased during ripening of both cultivars. In a warmer growing area both cultivars gained a higher γ‐tocopherol content while only Leccino showed a higher content of α‐tocopherol. After 12 months of storage α‐tocopherol content decreased by up to 27 %. Lower storage temperatures did not always contribute to the higher stability of α‐tocopherol compared to room temperature.     

Role of Water and Selected Minor Components on Association Colloid Formation and Lipid Oxidation in Bulk Oil

This study investigated the influence of water content in combination with selected minor components including oleic acid, stigmasterol, α‐tocopherol, and Trolox on their association colloid formation as well as their impact on lipid oxidation in bulk corn oil. First, surface activity of each minor component was evaluated by determining the ability of these components to lower the interfacial tension between bulk oil and water. All components but α‐tocopherol were able to decrease interfacial tension of stripped oil. Second, the critical micelle concentration (CMC) of each minor component was determined in bulk oil with no water added and in the presence of 1000 ppm of water. In the bulk oil without extraneous water, we could not determine the CMC of minor components in the range of concentrations studied. However, in the presence of 1000 ppm of water, only stigmasterol could form association colloids at the CMC of 20 mmol/kg oil. Last, the effect of water content (400 and 1000 ppm) and minor components on lipid oxidation in bulk oil was studied by following the lipid hydroperoxides and hexanal formation during storage at 55 °C. Different water content did not significantly impact the lag time of lipid oxidation compared with the control. Interestingly, water caused prooxidant by decreasing the lag time of lipid hydroperoxides and hexanal formation in bulk oil containing oleic acid, stigmasterol, and Trolox compared with the control of each system. On the other hand, there was not significant impact of water on the antioxidant activity of α‐tocopherol, a lipid soluble antioxidant in bulk oil. This study highlights the impact of water content on the surface activity of minor components as well as on the oxidative stability in bulk oil.     

3, 4‐Dihydroxymandelic acid amides of alkylamines as antioxidants for lipids

The antioxidative and radical scavenging activity of the 3, 4‐dihydroxymandelic acid (DHMA) amides of hexylamine, 2‐ethylhexylamine, octylamine, and cyclohexylamine was determined by several physicochemical test systems. The amides were synthesized by protecting group‐free coupling of in situ prepared N‐hydroxysuccinimidylester of DHMA and the amines. The radical scavenging activity was determined using the DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) method and by quenching superoxide anions generated using a horse radish peroxidase/H₂O₂ system. In the DPPH assay, all amides show higher radical scavenging activity (EC₅₀ 0.09‐0.12 mol/mol_DPPH) compared to the standard antioxidants ascorbic acid (EC₅₀ 0.27 mol/mol_DPPH) and tocopherol (EC₅₀ 0.25 mol/mol_DPPH). The amides are also more potent superoxide radical scavengers (IC₅₀ < 600 nm) than standard ascorbic acid (IC₅₀ 700 nm). Activity against lipid peroxidation was determined by accelerated autoxidation of highly unsaturated oils and squalene using the Rancimat. Again, the antioxidative potentials of the DHMA amides against lipid oxidation as determined by the Rancimat, are at least equal or higher compared to the standard lipid antioxidants tocopherol, BHT, BHA, and ascorbylpalmitate (concentration in soybean oil 0.05%, all other oils 0.025%, squalene 0.005%). In squalene, an equi‐amount mixture of DHMA octylamide and α‐tocopherol shows a synergistic effect. Last but not least, the amides are able to protect an emulsion of linoleic acid/β‐carotene against oxidation initiated by N, N‐azodiisobutyramidine dihydrochloride (IC₅₀ 0.19‐0.77 mmol/l, ascorbic acid > 0.9, tocopherol 0.08). The DHMA octylamide in combination with ascorbic acid shows a synergistic antioxidative effect in the emulsion model. In conclusion, the new alkylamides of DHMA are easy to synthesize, potent radical scavengers and protect lipids, in particular the highly unsaturated, both in bulk and in emulsions against autoxidation.     

Effects of Phosphatidylcholine on Interaction of α-Tocopherol and β-Carotene in Photosensitized Oxidation of Emulsions

The interaction between α‐tocopherol (500 mg/kg) and β‐carotene (10 mg/kg) during chlorophyll‐photosensitized oxidation of a sunflower oil emulsion was studied in the presence or absence of phosphatidylcholine (PC, 250 mg/kg) by determining peroxide (POV) and conjugated dienoic acid (CDA) values. Chlorophyll, α‐tocopherol, β‐carotene, and PC contents in the emulsion were also monitored. α‐Tocopherol and β‐carotene individually and interactively decreased the POV and CDA values of oil in the emulsion by singlet oxygen quenching. PC decreased the POV and CDA values of oil, however, the values of the emulsion with added α‐tocopherol, β‐carotene, and PC were not significantly different from those of the emulsion with added α‐tocopherol and β‐carotene without PC. Contents of α‐tocopherol did not change during 24‐h oxidation, whereas co‐present PC significantly caused α‐tocopherol and chlorophyll degradation. β‐Carotene and PC contents significantly decreased to 45.5 and 51.3 %, respectively, after 24 h, and α‐tocopherol protected β‐carotene from degradation. The results suggest that PC had no net effects on the interactive antioxidant activity of α‐tocopherol and β‐carotene during chlorophyll‐photosensitized oxidation of the emulsion through free radical generation, chlorophyll degradation, and lessening the potency of α‐tocopherol as a singlet oxygen quencher.     

The effect of antioxidants on butter in relation to storage temperature and duration

The effects of antioxidants on the oxidative stability of butter, under different storage time and temperature conditions, were evaluated. Natural (α‐tocopherol) and synthetic (BHA and BHT) antioxidants were added to the butter samples at two concentrations (50 and 100 ppm) immediately after the butter samples were produced from the pasteurised sweet cream, after which they were kept in the dark at 4 and ?20 °C for 6 months. Peroxide value (PV) and thiobarbituric acid (TBA) number and the residual antioxidants of the samples were examined at 30‐day intervals, starting on the second day until the end of the storage period. The measurements obtained by assaying PV and TBA number in butter samples showed that both the synthetic and natural antioxidants used were capable of protecting the butter samples against oxidation during storage at both temperatures. The butter samples with 50 ppm antioxidant could be stored for more than 180 days at 4 °C without spoilage. At ?20 °C, the addition of BHA, BHT and α‐tocopherol caused a reduction in the TBA number from 0.31 (control) to 0.21, 0.23 and 0.27 mg malonaldehyde/kg butter, respectively, and the PV decreased from 0.75 (control) to 0.46, 0.56 and 0.54 meq O₂/kg butter, respectively, after 6 months of storage. The highest residue values were determined in both the 100 and 50 ppm α‐tocopherol‐containing samples. These results indicate that α‐tocopherol exhibited a very strong antioxidant activity, which was almost equal to that of the synthetic antioxidants. Therefore, the use of α‐tocopherol is recommended as a natural antioxidant to suppress the development of rancidity in butter.     

Antioxidant effect of mono‐ and dihydroxyphenols in sunflower oil with different levels of naturally present tocopherols

Antioxidant properties of mono‐ and dihydroxyphenolic acids and their alkyl esters were examined, with emphasis on the relationship between their molecular structure and antioxidant activity. Test media with different tocopherol level were used for determining the oxidative stability: original refined sunflower oil (total tocopherols 149.0 mg/kg), partially tocopherol‐stripped sunflower oil (total tocopherols 8.7 mg/kg) and distilled fatty acid methyl esters (FAME) as a tocopherol‐free medium. The chemical reaction of tocopherols with diazomethane tested for the purpose to eliminate their antioxidant activity failed due to the negligible degree of methylation of hydroxyl group in the tocopherol molecule. Caffeic acid and protocatechuic acid (3,4‐dihydroxyphenolic acids) and their alkyl esters were found to be more active antioxidants than monohydroxyphenolic acid (p‐hydroxybenzoic acid), 2,5‐dihydroxyphenolic acid (gentisic acid), 3‐methoxy‐4‐hydroxyphenolic acids (vanillic and ferulic acids) and their corresponding alkyl esters. Naturally present tocopherols in refined sunflower oil proved to have a synergistic effect on gentisic acid but not on its alkyl esters. In contrast, tocopherols showed an antagonistic effect on alkyl esters of caffeic acid, because their protection factors decreased with increasing level of tocopherols in the test medium. Moreover, the antioxidant activity of these alkyl esters decreased with increasing length of their alkyl chain in conformity with the polar paradox hypothesis. Practical applications: Tocopherols as naturally present antioxidants influence considerably the antioxidant activity of other antioxidants added to plant oils used as a test medium. Distilled fatty acid methyl esters prepared from refined sunflower oil may serve as an optimal tocopherol‐free test medium. Some alkyl esters of phenolic acids were evaluated to be applicable as natural more lipophilic antioxidants in comparison with phenolic acids.     

Colorimetric determination of total tocopherols in palm oil,olein and stearin

By using a preliminary heat-bleach at 250 C the Emmerie-Engel method has been adapted for the determination of total tocopherols (including tocotrienols) in crude as well as refined palm oil, olein and stearin. Total tocopherol contents found were: Crude palm oil, 794 ppm (n=10); RBD palm oil, 563 ppm (n=13); RBD palm olein, 643 ppm (n=40); RBD palm stearin, 261 ppm (n=19), where n is the number of samples analyzed. During the detergent fractionation no tocopherols were lost, but the tocopherols were concentrated in the olein fraction. The fate of the tocopherols during degumming, bleaching and steam refining/deodorizing of Crude palm olein containing 978 ppm total tocopherol was studied. Over the whole refining process only 8% of the tocopherols were lost, 62% of the original tocopherols were retained in the RBD palm olein, while the remaining 30% were concentrated in the fatty acid distillate which contained 7,040 ppm tocopherol.     

Antioxidant activity of red wine phenolic extracts towards oxidation of corn oil

The antioxidant activity of Xinomavro red wine phenolic extracts in corn oil stripped of tocopherols was evaluated. One wine extract, at 100 mg/L total phenolics, rich in phenolic acids and flavonols, inhibited the oxidation of corn oil stripped of tocopherols to a greater extent than butylated hydroxyanisole, at 200 mg/L. Moreover, another extract, at 100 mg/L total phenolics, rich in flavanols, flavonols and tyrosol, also exhibited high inhibitory action. The present results indicate that some red wine phenolics – such as phenolic acids, flavonols or flavanols – may be strong antioxidants in corn oil.     

Effects of tocopherols and tocotrienols on the inhibition of autoxidation of conjugated linoleic acid

The effect of eight vitamin E homologues, i.e. α‐, β‐, γ‐, and δ‐tocopherol and α‐, β‐, γ, and δ‐tocotrienol, on the inhibition of autoxidation of conjugated linoleic acid (CLA) were investigated. The oxidation was carried out in the dark for 21 days at 50 °C and monitored by peroxide values (PV) and TBA values. The levels of the individual vitamin E homologues in CLA during storage were determined by HPLC. γ‐Tocopherol exhibited the highest antioxidant activity among the homologues tested in this study when the antioxidant activities of the individual homologues in CLA were compared by PV. The order of antioxidant activity of eight homologues was γ‐tocopherol > δ‐tocopherol = δ‐tocotrienol ≥ γ‐tocotrienol > β‐tocopherol = β‐tocotrienol > α‐tocopherol = α‐tocotrienol. The degradation rates of α‐tocopherol and α‐tocotrienol were faster than those of the other homologues, whereas δ‐tocopherol had the highest stability in CLA during storage. All homologues exhibited an antioxidant activity by inhibiting the formation of secondary oxidation products. It appears that α‐tocotrienol and β‐tocotrienol have significantly higher antioxidant activities for secondary oxidation in CLA than α‐tocopherol and β‐tocopherol. Meanwhile, the other homologues, namely γ‐tocopherol, γ‐tocotrienol, δ‐tocopherol, and δ‐tocotrienol, exhibited similar antioxidant activity for secondary oxidation in CLA.     

Biochemical Characterization of Arbequina Extra Virgin Olive Oil Produced in Turkey

Varieties of the olive cultivar Arbequina have recently been cultivated in Turkey. The objective of the study is to characterize and evaluate extra‐virgin olive oils (EVOO) produced from Arbequina grown in the Aegean and Mediterranean regions of Turkey. Major and minor components such as carotenoids, squalene, phenolics and tocopherols were studied to assess their effects on product quality and health benefits. The samples, identified as ArbqI and ArbqA, were from the Izmir and Adana provinces, respectively. Samples were analyzed by GC‐FID to determine fatty acid composition, sterol composition, TAG profile and squalene content. Individual phenolic fractions were analyzed by LC–MS/MS and tocopherol isomers were determined by HPLC. According to the results obtained from this study; Total phenolic content (TPC) of the samples were 454.68 and 50.86 mg Gallic acid/kg oil for ArbqI and ArbqA, respectively. Hydroxytyrosol and tyrosol were determined to be the main phenols. The major tocopherol isomer found in ArbqI and ArbqA was α‐tocopherol with levels of 179.55 and 202.5 mg/kg oil, respectively. β‐Carotene levels in both samples were similar at 0.2 mg/kg. Findings of this study were compared with the literature on Arbequina olive oil produced in different countries. It was determined that Arbequina olive oil of high quality can be produced in Turkey, especially in the Aegean region.     

Antioxidant activity of tea extracts in lipids and correlation with polyphenol content

The present study examined the antioxidative activity of water and ethanol extracts of green and black tea leaves against the oxidation of heated sunflower oil and lard. Oxidation was conducted at 110 °C in the Rancimat test. Total polyphenols and catechin contents in tea extracts were measured. The research showed that the total polyphenol content in green and black tea leaves was 205.2 and 148.7 mg/g, respectively. In tea leaves extracts, it ranged between 245.9 mg/g and 837.7 mg/g and depended on the extraction solvent and the kind of tea used (p <0.001). The highest polyphenol content was observed in samples extracted with 95% ethanol, lower contents were found with the use of water. Results showed that the highest antioxidant activity, measured as an induction period, with 1000 ppm green tea ethanol extract, was comparable to á‐tocopherol activity in sunflower oil. In lard, the longest induction period was measured with 500 and 1000 ppm of green tea ethanol extract. Other tea extract concentrations were significantly less active. Statistical analysis of the tea extract antioxidant activity in lipids in the Rancimat test showed an essential influence of the catechin contents. Further statistical analysis also showed an influence of (?)‐epicatechin gallate (ECG), (?)‐epicatechin (EC), and (+)‐catechin (C) contents in the tea extracts on the antioxidant activity in lipids. It was stated that the antioxidant activity was higher in tea extracts containing high levels of ECG, EC, and C.     

Contents of Carotenoids, Tocopherols and Sterols in Acacia cyanophylla Seed Oils

Seeds from 12 Acacia cyanophylla ecotypes, harvested in Tunisia, were examined for their seed oil contents of carotenoids, tocopherols and phytosterols. The average carotenoid content (lutein and zeaxanthin) was ca. 102 mg kg^?1 of total extracted lipids. Lutein (ca. 97 mg kg^?1 of total extracted lipids) was usually more abundant than zeaxanthin (ca. 5 mg kg^?1 of total extracted lipids). The mean total tocopherol content was ca. 704 mg kg^?1 of total extracted lipids. The main isomer was α‐tocopherol, with more than 75 % of total tocopherols (ca. 528 mg kg^?1 of total extracted lipids), followed by γ‐tocopherol (ca. 168 mg kg^?1 of total extracted lipids) and δ‐tocopherol (ca. 86 mg kg^?1 of total lipids). High levels of phytosterols (ca. 7.8 g kg^?1 of total extracted lipids) were detected, among which β‐sitosterol was the most abundant (47 %). All these results highlight the richness of carotenoids, tocopherols and sterols in A. cyanophylla seed oil, and imply that this species might constitute a potential resource for the development of functional foods.     

Tocopherol retention in physically refined rapeseed oil as a function of deodorization temperature

The effect of deodorization temperature (between 220 and 270 °C) on tocopherol retention in physically refined rapeseed oil during deodorization in a plant‐scale semi‐continuous tray‐type deodorizer was investigated. Among the three tocopherol homologues detected in the samples of rapeseed oils under study, the α‐ and γ‐tocopherol homologues, with the latter predominating, constituted the most abundant part of total tocopherols, accompanied by a small amount of δ‐tocopherol. The retention values calculated for both total and individual tocopherols decreased linearly with increasing deodorization temperature. The retention of total tocopherols decreased considerably from 91.5% at 220 °C to 54.7% at 270 °C, approaching a value of about 80% in the main area of concern between 230 and 240 °C. The retention values of individual tocopherols as well as the slopes resulting from the equations relating these retentions to deodorization temperature were observed to decrease in the same order as their molecular weights. Since the retention of α‐tocopherol is slightly higher than that of γ‐tocopherol, the average proportion of α‐tocopherol during deodorization slightly increases at the expense of γ‐tocopherol.     

Composition of Catalpa ovata Seed Oil and Flavonoids in Seed Meal as Well as Their Antioxidant Activities

In view of the growing demand for vegetable oil, currently exploration of some non‐conventional oils is of great concern. This study firstly analyzed the contents of fatty acids, phytosterols, and tocopherols in Catalpa ovata seed oil collected from four different Provinces in China. Then the composition of flavonoids as well as their antioxidant activities in defatted seed meal was determined. The results showed that the relative oil content in C. ovata seeds ranged from 24.0 to 36.0 % and seed oil was mainly composed of fatty acids linoleic acid (43.4–50.1 %), α‐linolenic acid (23.8–24.4 %), and oleic acid (13.1–16.2 %). The content of unsaturated fatty acids was up to 85.0 %. Sterol in seed oil mainly contained campesterol, stigmasterol, and β‐sitosterol. β‐sitosterol accounted for 74.0 % of the total sterol. The tocopherol content was 173.0–225.7 mg/100 g. Defatted seed meal from Hubei Province showed the highest content of total flavonoids (11 mg/g) and the strongest activities for DPPH radicals scavenging, ABTS radicals scavenging, and ferric reducing antioxidant power compared with other defatted seed meal in this study. Seven flavonoids were identified from C. ovata seed meal. These results suggest that C. ovata seeds may be developed as a new source of oil and can also be properly used in pharmaceuticals and cosmetics.