Antimicrobial and antioxidant properties of the essential oils and methanol extract from Mentha longifolia L. ssp. longifolia

This study was designed to evaluate antimicrobial and antioxidant activities of the essential oil and methanol extract from Mentha longifolia ssp. longifolia. The essential oil showed strong antimicrobial activity against all 30 microorganisms tested whereas the methanol extract almost remained inactive. In contrast, the extract showed much better activity than the essential oil in antioxidant activity assays employed, e.g. in the inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene/linoleic acid systems. In the former, the extract was able to reduce the stable free radical DPPH with an IC₅₀ of 57.4 μg/ml while that of the oils was 10 700 μg/ml. When compared to BHT, a synthetic antioxidant, both showed weaker antioxidative potential. Similarly, in β-carotene/linoleic acid assay, these samples were not effectively able to inhibit the linoleic acid oxidation; exhibiting only 24% and 36% inhibitions at 2 mg/ml, respectively; both were far below than that of BHT. Total phenolic constituent of the extract was 4.5 g/100 g as gallic acid equivalent. GC–MS analysis of the oil resulted in the identification of 45 constituents, cis-piperitone epoxide, pulegone and piperitenone oxide being the main components.     

Antioxidant activity of microwave-assisted extract of Buddleia officinalis and its major active component

Buddleia officinalis Maxim, commonly used as rice dye for festivals, was extracted with ethanol using microwave-assisted extraction and Soxhlet extraction. The antioxidant activities of microwave-assisted extract of B. officialis (MEB) and Soxhlet extract of B. officianils (SEB) at the optimum extraction conditions were evaluated and compared with synthetic antioxidant butylated hydroxytoluene (BHT) employing DPPH free radical assay, ABTS assay, total antioxidant activity and reducing power. MEB and SEB had stronger antioxidant activities than BHT in all assays except reducing power, and the effects decreased as follows: MEB > SEB > BHT. The total phenolic contents of MEB and SEB reached 113.56 mg/g and 100.94 mg/g dry weight of extract, respectively, expressed as pyrocatechol equivalents, while the total flavonoids contents were 75.33 mg/g and 62.56 mg/g dry weight of extract, respectively, expressed as catechin equivalents (P < 0.05). Higher phenolic and flavonoids compounds may be major contributors to their higher antioxidant activities. Following activity-oriented separation, luteolin was isolated as an active principle, which exhibited excellent free radical scavenging activities with DPPH IC₅₀ 3.09 μg/ml and ABTS IC₅₀ 2.20 μg/ml.     

Antioxidative and ACE inhibitory activities in enzymatic hydrolysates of the cotton leafworm, Spodoptera littoralis

The larvae of the cotton leafworm, Spodoptera littoralis, were used as a source of food proteins exerting possible biological activities. A simulated gastrointestinal digestion (IC₅₀ = 320 μg/ml) and digestion by mucosal enzymes (IC₅₀ = 211 μg/ml) reveals a significantly higher in vitro ACE inhibitory activity compared to hydrolysis using thermolysin (IC₅₀ = 1392 μg/ml) and alcalase (IC₅₀ = 827 μg/ml) as pretreatment. This indicates that the choice of enzymes to generate ACE inhibitory peptides is important. All hydrolysates were also tested for antioxidant activity using two tests: a radical scavenging test using DPPH and the ferric reducing antioxidant power (FRAP) assay, and they showed a similar antioxidant activity which was relatively low compared to the standard antioxidants BHT and vitamin C. As a conclusion, the data obtained suggest that insect protein can be used to generate hydrolysates, exerting both ACE inhibitory and antioxidant activity, which might be incorporated as multifunctional ingredient into functional foods.     

Standardised Mangifera indica extract is an ideal antioxidant

The standardised ethanolic and aqueous extracts of Mangifera indica leaf were prepared and analysed for their free radicals scavenging activity. The IC₅₀ values using the DPPH assay were 0.17 ± 0.02 and 0.49 ± 0.4 mg/ml, respectively. Standardised ethanolic extracts of the M. indica leaf had a solid content of 9.1 ± 0.7%, mangiferin concentration of 73 ± 0.17 mg/g of dry weight of the extract, free radical scavenging activity (IC₅₀) of 0.17 ± 0.02 mg/ml and total phenolic content of 590 ± 48 mg/g of extract. The protection exhibited by these extracts against lipid peroxidation was superior to butylated hydroxytoluene (BHT) and commercial grape seed extract. These extracts at higher concentration did not exhibit pro-oxidant activities when compared to vitamin C. Our findings also show that the aqueous and ethanolic extracts of M. indica leaf protect NIH/3T3 cells from oxidant-induced cell death.     

GC/MS analysis and in vitro antioxidant activity of essential oil and methanol extracts of Thymus caramanicus Jalas and its main constituent carvacrol

Chemical composition of the essential oil, antioxidant activity (DPPH and β-carotene/linoleic acid assays), and total phenolic content (Folin–Ciocalteu assay) of aerial parts of Thymus caramanicus were determined. The highest radical-scavenging activity (DPPH test) was shown by the polar subfraction of the methanol extract (IC₅₀ = 43.0 μg/ml) which was also higher than that of butylated hydroxytoluene (BHT, IC₅₀ = 19.7 μg/ml). However, it was the nonpolar subfraction of the methanol extract that showed the highest inhibition (84.4%), as assessed by the β-carotene/linoleic acid assay, which was only slightly lower than that shown by BHT (93.3%). The antioxidant activities of the essential oil main component (carvacrol) were also evaluated for comparison. Total phenolic content of the polar subfraction, as gallic acid equivalents, was 124.3 μg/mg. Essential oil extracted from the aerial parts by hydrodistillation was analysed by GC and GC/MS. Fifteen constituents, representing 99.3% of the oil, were identified, of which the major ones, carvacrol (85.9%), thymol (3.3%), p-cymene (3.2%), γ-terpinene (1.8%) and borneol (1.3%), accounted for 95.6% of the oil.     

Antioxidant activities of barley seeds extracts

The antioxidant activities of different polarity solvents extracts from barley were evaluated by various antioxidant assays, including reducing power, free radical scavenging and lipid oxidation inhibition. Those various antioxidant activities were compared to standard antioxidants, butylated hydroxyluene (BHT) and ascorbic acid (Vit. C). The properties of the extracting solvents significantly affected the total phenolics, proanthocyanidins and antioxidant activities of barley extract. The highest contents of total phenolics and proanthocyanidins were obtained from extraction with 70% acetone. For three different solvent extracts, the antioxidant activities were in this order: 70% acetone extract > 70% ethanol extract ? 70% methanol extract. Reducing powers of three extracts and their scavenging effects on 2, 2-diphenyl-1-picrylhydrazyl radicals were effective at amount of 200 μg. The 70% acetone extract of barley exhibited high antioxidant activity in linoleic acid system, which was not significantly (P < 0.05) different from BHT during the incubation time.     

Antioxidant and hepatoprotective activity of ethanolic extract of leaves of Solidago microglossa containing polyphenolic compounds

The antioxidative and hepatoprotective potential of Solidago microglossa D.C, a widely used medicinal plant from Brazil was investigated. The leaf extract showed inhibition against thiobarbituric acid reactive species (TBARS) induced by different prooxidants (10 μM FeSO₄ and 5 μM sodium nitroprusside SNP) in rat liver, brain and phospholipid homogenates from egg yolk. Moreover, the free radical scavenging activities of the extract was evaluated by the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC_50, 3.8 ± 0.5 μg/ml) and hydroxyl radical on benzoic acid hydroxylation (IC_50, 32.3 ± 1.3 μg/ml) and deoxyribose (IC_50, 39.1 ± 2.4 μg/ml) assays. The ethanolic extract showed significant hepatoprotective activity against paracetamol (250 mg/kg) induced liver damage in mice in a dose dependent manner. The phenolic composition and their quantification by high performance liquid chromatography (HPLC) resulted in the identification of gallic acid and flavonoids: quercetrin (quercetin-3-O-rhamnoside), rutin (quercetin-3-O-rutinoside) and quercetin.     

6,7,4′-Trihydroxyisoflavone from Doenjang inhibits lipid accumulation

Doenjang is a unique traditional Korean fermented soybean paste. 6,7,4′-Trihydroxyisoflavone was identified from traditional Korean fermented Doenjang. The four products isolated from 100 g Korean Doenjang using acetonitrile and methanol (70/30, v/v) was identified as daidzein, genistein, glycitein and 6,7,4′-trihydroxyisoflavone. The products were structurally elucidated by GC–MS and ¹H NMR analysis. 6,7,4′-Trihydroxyisoflavone was evaluated for antioxidant activity against the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging and superoxide radical scavenging activity. Among four products isolated, 6,7,4′-trihydroxyisoflavone had remarkable antioxidant activity with IC₅₀ values of 31.5 μM, 50.0 μM, respectively. Furthermore, 6,7,4′-trihydroxyisoflavone was found to inhibit fat droplet formation triglyceride accumulation in 3T3-L1 adipocytes. Accordingly, 6,7,4′-trihydroxyisoflavone compound is of growing scientific interest due to its attractive biological properties.     

In vitro activity of the essential oils of Origanum vulgare, Satureja montana and their main constituents in peroxynitrite-induced oxidative processes

The essential oil obtained from aerial parts of Satureja montana L. and Origanum vulgare L. (Labiatae) along with four of its main components, p-cymene, carvacrol, thymol and γ-terpinene were tested in models of in vitro peroxynitrite-induced formation of both 3-nitrotyrosine and malondialdehyde, two biomarkers of the oxidative stress of recognised pathological and toxicological significance. The essential oils showed a significant activity, thus decreasing 3-nitrotyrosine formation (IC₅₀ values of 43.9 μg/ml for S. montana and 19.2 μg/ml for O. vulgare), and also inhibited the peroxynitrite induced malondialdehyde formation (IC₅₀ values of 27.2 μg/ml and 17.0 μg/ml respectively). Thymol and carvacrol inhibited 3-nitrotyrosine formation (IC₅₀ values of 81.3 μM and 106.3 μM; ascorbic acid IC₅₀ = 400 μM) and reduced malondialdehyde formation (IC₅₀ values of 43.9 μM and 70.1 μM respectively; trolox IC₅₀ = 240 μM). On the contrary, p-cymene and γ-terpinene were completely inactive in both assays under the concentration of 300 μg/ml. These results support, in particular for origanum, the nutraceutical value of these spices and the potential of thymol and carvacrol in preventing the formation of toxic products by the action of reactive nitrogen species.     

Antioxidant and free radical scavenging activities of wild bitter melon (Momordica charantia Linn. var. abbreviata Ser.) in Taiwan

Momordica charantia Linn. var. abbreviata Ser. (Cucurbitaceae), also known as “Shan Ku Gua”, is a wild variety of bitter melon (BM) in Taiwan. The size of its fruits is only about one-fifth of the commonly seen BM. It is commonly consumed as vegetable and also used as a popular folk medicine. In this study, the antioxidant and free radical scavenging activities of BM aqueous (BM-H₂O) and ethanol (BM-EtOH) extracts were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), metal chelation, cytochrome c and xanthine oxidase inhibition (XOI) assays, as well as FeCl₂-ascorbic acid induced lipid peroxidation (thiobarbituric acid reactive substances, TBARS) assay in rat liver homogenates in vitro. Total flavonoid and phenol contents of BM extracts were also analyzed. Results showed that both BM-H₂O (IC₅₀=129.94 μg/ml) and BM-EtOH (IC₅₀=156.78 μg/ml) possess potent DPPH radical scavenging activity, which was better than vitamin E (IC₅₀=172.21 μg/ml). These extracts also showed better iron chelating activity than vitamin E. However, they were weaker than vitamin E in free radical scavenging, xanthine oxidase inhibitory and anti-lipid peroxidation activities. With the exception of XOI activity [IC₅₀=7.90 μg/ml (BM-H₂O) vs. 7.69 μg/ml (BM-EtOH)], BM-H₂O showed a lower IC₅₀ value in free radical scavenging [IC₅₀=6.15 μg/ml (BM-H₂O) vs. 7.08 μg/ml (BM-EtOH)] and anti-lipid peroxidation [IC₅₀=53.72 μg/ml (BM-H₂O) vs. 88.51 μg/ml (BM-EtOH) for liver; 82.53 μg/ml (BM-H₂O) vs. 91.83 μg/ml (BM-EtOH) for brain] activities than BM-EtOH. Both BM extracts showed a weak anti-lipid peroxidation activity in plasma. BM-H₂O (62.0 mg/g) possessed a significant higher concentration of total flavonoids than BM-EtOH (44.0 mg/g), but was lower in the total phenol content (BM-H₂O: 51.6 mg/g vs. BM-EtOH: 68.8 mg/g). In conclusion, BM extracts possess potent antioxidant and free radical scavenging activities. These antioxidant activities could have contributed, at least partly, to the therapeutic benefits of the certain traditional claims of wild BM.     

Novel angiotensin I-converting enzyme inhibitory peptides derived from soya milk

Inhibitors of angiotensin I-converting enzyme (ACE) are useful in treating hypertension, and many have been derived from food products, including soybeans. Using the industrial protease PROTIN SD-NY10, we developed a processed soya milk (PSM) with enhanced ACE inhibitory activity. The ACE inhibitory activity of PSM (IC₅₀ = 0.26 μg/ml) was greater than that of regular soya milk (IC₅₀ = 8.75 μg/ml). Eight novel ACE inhibitory peptides were purified from PSM by reversed-phase chromatography: FFYY (IC₅₀,1.9 μM), WHP (4.8 μM), FVP (10.1 μM), LHPGDAQR (10.3 μM), IAV (27.0 μM), VNP (32.5 μM), LEPP (100.1 μM), and WNPR (880.0 μM). The IC₅₀ values of these peptides are comparable to those reported for other ACE inhibitory peptides derived from wheat, chicken, bonito, wine, etc. Due to the relatively low IC₅₀ values of several peptides identified in this study, they may serve as ideal base components of food supplements for patients with hypertension.     

Antioxidant and cytotoxic flavonoids from the flowers of Melastoma malabathricum L.

Phytochemical and bioactivity studies of the flowers of Melastoma malabathricum L. (Melastomataceae) have been carried out. The ethyl acetate extract yielded three compounds, identified as naringenin, kaempferol and kaempferol-3-O-d-glucoside, and methanol extract gave kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl)glucoside and kaempferol-3-O-d-glucoside. The crude extracts and isolated compounds were screened for their antioxidant and cytotoxic activities. The antioxidant assay was carried out by the DPPH radical-scavenging electron spin resonance (ESR) spectroscopic method. The cytotoxicity was measured by the MTT assay against a MCF7 cell line. Naringenin, kaempferol, kaempferol-3-O-d-glucoside, kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl) glucoside, ethyl acetate and methanol extracts were found to be active as radical-scavengers with IC₅₀ values of 0.52 mM, 81.5 μM, 1.07 mM, 35.8 μM, 7.21 μg/ml and 6.59 μg/ml, respectively. Naringenin and kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl)glucoside were also found to be active in inhibiting cell proliferation of MCF7 with IC₅₀ values of 0.28 μM and 1.3 μM, respectively.     

Antioxidant and radical scavenging activities of the pyroligneous acid from a mangrove plant, Rhizophora apiculata

Total phenolics content, free radical scavenging activity, reducing power, and antioxidant activity of the pyroligenous acid from a mangrove plant, Rhizophora apiculata were evaluated. Dichloromethane extraction of the raw pyroligneous acid successfully yield 2 extracts, i.e. concentrated pyroligneous acid (CPA) and concentrated pyroligneous acid extract (CPAE). Phenolic contents in CPAE and CPA, expressed as (±)-catechin equivalents/g of the sample were 5465 ± 367 mg and 2502 ± 152 mg, and expressed as gallic acid equivalents/g of the sample were 2919 ± 209 mg and 1348 ± 90 mg, respectively. CPAE exhibited superior free radical scavenging activity with EC₅₀ value = 0.1235 mg/ml, or 80.96% of free radical scavenging capability. The ferric reducing power of CPAE was approximately 3.7, 5.1, 6.1, and 21.3 times higher than that of ascorbic acid, BHA, BHT and alpha-tocopherol. In phosphomolybdenum assay, CPAE showed the greatest antioxidant efficacy (A₆₉₅ = 1.278) compared to those of CPA and different standards. In addition, the free radical scavenging activity, ferric reducing power and total antioxidative activity of CPAE and CPA showed positive correlation with their total phenolic content with R² values ranging from 0.9624 to 0.9979.     

Anti-oxidant,anti-proliferative and anti-inflammatory activities of the extracts from black raspberry fruits and wine

The purpose of the study was to determine polyphenols, anthocyanins and ascorbic acid in the extracts of black raspberry fruits and wine, along with their anti-oxidant, anti-proliferative and anti-inflammatory activities. Black raspberry fruits without or with seeds crushed were blended in 60% ethanol (FE and FES, respectively) or in water (FW and FWS, respectively). Black raspberry wine without or with seeds crushed (W and WS, respectively) were prepared. Polyphenol content was the highest in the FES (8.25 mg/g fruit). Generally the ethanol extracts with seeds crushed showed higher anti-oxidant activities with the lowest DPPH IC₅₀ (130 μg/ml (freeze-dried extract/reaction solution)) for the FES and the lowest ABTS IC₅₀ (198 μg/ml) for the WS. Cell viabilities were reduced by 13–70% when treated with 100 μg/ml (freeze-dried extract/medium) for HT-29 cells and 1000 μg/ml for LNCaP cells. The FES most actively suppressed nitric oxide production in LPS-stimulated RAW264.7 cells (p < 0.05). Superoxide dismutase and glutathione peroxidase activities treated with the extracts were higher than the control (p < 0.05).     

Residue levels of food-grade antioxidants in postharvest treated in-pod peanuts during five months of storage

In order to investigate residue levels of butylated hydroxyanisole (BHA), propyl paraben (PP) and butylated hydroxytoluene (BHT) during storage, eight-hundred kilograms of bulk peanuts were treated with the following antioxidant emulsions: BHA (1802 μg g⁻¹), BHA–PP (1802 μg g⁻¹ + 1802 μg g⁻¹) M1 and BHA–PP–BHT mixtures (1802 μg g⁻¹ + 901 μg g⁻¹ + 2204 μg g⁻¹) M2 and (1802 μg g⁻¹ + 1802 μg g⁻¹ + 2204 μg g⁻¹) M3. Residues were determined in peanut pod and seed tissues at 1-month intervals during the storage. While the reduction levels of BHA and PP in pods at the end of the storage period ranged from 66% to 76%, BHT levels were decreased extensively (86%). Twenty-four hours after peanuts were treated, antioxidant emulsions effectively seeped into the seeds and low levels of these chemicals were detected during the assay. Residues of PP in seeds were lower (62%) than the other antioxidants. Although the doses used were higher than those approved for food-grade antioxidants in stored peanuts, the residue levels in seeds (32.8–0.02 μg g⁻¹) did not exceed the maximum residue limits during the storage period.     

Substituted imino and amino derivatives of 4-hydroxycoumarins as novel antioxidant,antibacterial and antifungal agents: Synthesis and in vitro assessments

A series of imino and amino derivatives of 4-hydroxycoumarins were synthesised and evaluated for antioxidant potential, through different in vitro models such as (DPPH) free radical-scavenging activity, linoleic acid emulsion model system, reducing power assay and phosphomolybdenum method. Also, antimicrobial activity of obtained coumarins was evaluated against 13 bacteria and eight fungi. All prepared compounds possessed good antioxidant activity and among them a p-nitrophenol derivative with IC₅₀ at 25.9 μM possessed radical-scavenging activity which was comparable to BHT. Observed data for antibacterial activity indicated strong activity of all tested amino derivatives, while imines showed better antifungal properties.     

Antioxidant and antiacetylcholinesterase activities of five plants used as Portuguese food spices

In the present work, we report the results of a study aimed at evaluating the antiradical activity, the antioxidant activity and the acetylcholinesterase (E.C. 3.1.1.7.) inhibitory capacity of essential oils, ethanol and boiling water extracts from five aromatic herbs growing wild in Portugal and used in traditional food preparations: fennel (Foeniculum vulgare), mint (Mentha spicata), pennyroyal (Mentha pulegium), rosemary (Rosmarinus officinalis) and wild thyme (Thymus serpyllum). The water extracts of M. spicata and M. pulegium showed the highest radical-scavenging activity (DPPH test) values (IC₅₀ = 5.7 ± 0.4 and 8.9 ± 0.2 μg ml⁻¹ respectively). This activity was higher than that found with the standard antioxidant BHT. The ethanol extracts of M. spicata, T. serpyllum and F. vulgare showed the highest antioxidant activities measured by the β-carotene/linoleic acid assay, IC₅₀ = 36.9 ± 0.1, 41.2 ± 0.1 and 68.7 ± 0.1 μg ml⁻¹, respectively. The inhibition of AChE was higher in the essential oil fraction. The highest activity was found for R. officinalis with an IC₅₀ = 69.8 ± 0.1 μg ml⁻¹.     

Chemical composition and antioxidant activity of the essential oil of Clinopodium vulgare L.

This study was designed to examine the chemical composition and in vitro antioxidant activity of the essential oil of Clinopodium vulgare. GC–MS analysis of the oil resulted in the identification of 40 compounds, representing 99.4% of the oil; thymol (38.9%), γ-terpinene (29.6%) and p-cymene (9.1%) were the main components. The samples were subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, IC₅₀ value of the C. vulgare essential oil was determined as 63.0 ± 2.71 μg/ml. IC₅₀ value of thymol and γ-terpinene, the major compounds of the oil, was determined as 161 ± 1.3 μg/ml and 122 ± 2.5 μg/ml, respectively, whereas p-cymene did not show antioxidant activity. In β-carotene-linoleic acid system, C. vulgare essential oil exhibited 52.3 ± 1.19% inhibition against linoleic acid oxidation. In both systems, antioxidant capacities of BHT, curcumine and ascorbic acid were also determined in parallel experiments.     

Iron-chelating ability and antioxidant properties of phycocyanin isolated from a protean extract of Spirulinaplatensis

The invitro scavenger activities of different reactive oxygen species (superoxide radical, hydroxyl radical, hydrogen peroxide, hypochlorous acid and peroxyl radical), the effects on lipid peroxidation and the iron-chelating ability of a Spirulinaplatensis protean extract and the biliprotein, phycocyanin, isolated from this microalga were studied. S. platensis protean extract inhibited the generation of hydroxyl radical (IC₅₀ = 537 μg/ml for the system with EDTA and 1500 μg/ml without EDTA), the production of peroxyl radical (IC₅₀ = 230 μg/ml), and the lipid peroxidation process (IC₅₀ = 2320 μg/ml for the enzymatic system and 2180 μg/ml for the non-enzymatic system). Besides, phycocyanin inhibited hydroxyl and peroxyl radicals and the lipid peroxidation process. The iron ions decreased the maximum fluorescence emission spectra of S. platensis protean extract and phycocyanin and it was an indicator of the metal-chelating activity. The antioxidant properties of S. platensis and phycocyanin may arise from both radical-scavenging and metal chelation. Our results suggest that S. platensis could be used as a dietary supplement to prevent some diseases where free radicals are involved.