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.     

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.     

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.     

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.     

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.     

Rosmarinic acid,scutellarein 4′-methyl ether 7-O-glucuronide and (16S)-coleon E are the main compounds responsible for the antiacetylcholinesterase and antioxidant activity in herbal tea of Plectranthus barbatus (“falso boldo”)

Plectranthus barbatus, known as “falso boldo” in Brazil, is used in herbal tea or cooked as a vegetable. Infusions and decoctions of leaves from P. barbatus were analysed for their inhibition of acetylcholinesterase and their antioxidant activity. The decoction showed high inhibition activity (31% inhibition with 0.5 mg of extract/ml) and also high antioxidant activity (IC₅₀ = 45.8 ± 0.5 μg of dry extract/ml in the DPPH test; IC₅₀ = 69.8 ± 3.1 μg of dry extract/ml in the β-carotene–linoleic acid test). Rosmarinic acid, scutellarein 4′-methyl ether 7-O-glucuronide and (16S)-coleon E were the main constituents identified. These compounds have antiacetylcholinesterase activity. Rosmarinic acid and the scutellarein derivative have IC₅₀ = 440 μg/ml and 1 mg/ml, respectively. One milligram per millilitre of (16S)-coleon E showed 61% inhibition of the enzyme. Other Plectranthus species, P. ecklonii, P. fructicosus, P. lanuginosus and P. verticillatus, were also analysed and the results obtained correlated with the content in rosmarinic acid.     

Rapid isolation of geraniin from Nephelium lappaceum rind waste and its anti-hyperglycemic activity

Recently we confirmed the ability of ethanolic Nephelium lappaceum L. rind extract to act as anti-hyperglycemic agent. Geraniin, an ellagitannin, was identified as the major bioactive compound isolated from the ethanolic Nephelium lappaceum L. rind extract. In this study, we describe the rapid isolation of geraniin from the above plant. In addition to its extremely high anti-oxidant activity and low pro-oxidant capability, geraniin is seen to possess in vitro hypoglycemic activity (alpha-glucosidase inhibition: IC₅₀ = 0.92 μg/ml and alpha-amylase inhibition: IC₅₀ = 0.93 μg/ml), aldol reductase inhibition activity (IC₅₀ = 7 μg/ml) and has the ability to prevent the formation of advanced glycation end-products (AGE). Geraniin was observed to exhibit these properties at more significant levels compared to the positive controls acarbose (carbohydrate hydrolysis inhibitor), quercetin (aldol reductase inhibitor) and green tea (AGE inhibitor). Geraniin therefore, has the potential to be developed into an anti-hyperglycemic agent. Our findings also strongly support the use of a geraniin-standardised N. lappaceum extract in the management of hyperglycemia.     

Dioscin: A synergistic tyrosinase inhibitor from the roots of Smilax china

In our study, we investigated the inhibition of mushroom tyrosinase in Smilax china. A methanol (MeOH) extract of S. china was partitioned into hexane, ethyl acetate (EtOAc) and water. Of the three fractions, EtOAc extract showed the strongest inhibition of tyrosinase activity with l-tyrosine or l-DOPA as a substrate. Two compounds were isolated from a final active fraction by activity-guided column chromatography. These compounds were identified as dioscin and oxyresveratrol by comparing their mass, ¹H- and ¹³C-NMR spectral data with those reported in the literature. Dioscin showed little inhibition activity of tyrosinase, whereas oxyresveratrol, a known tyrosinase inhibitor, showed a strong tyrosinase inhibitory activity. We discovered that a mixture of oxyresveratrol and dioscin (IC₅₀ = 5.1 and 5.7 μg/ml) highly increased the inhibition of tyrosinase activity with l-tyrosine or l-DOPA as the substrate as compared to either oxyresveratrol (IC₅₀ = 7.8 and 10.9 μg/ml) or dioscin (IC₅₀ > 100 and 100 μg/ml) alone.     

Chemical and biological variability of hot pepper fruits (Capsicum annuum var. acuminatum L.) in relation to maturity stage

The aim of the present work was to evaluate the chemical composition and the radical-scavenging and antioxidant activities of hot pepper fruits (Capsicum annuum L. var. acuminatum) at three maturity stages (small green, green and red). GC–MS analysis of n-hexane and chloroform fractions showed a different composition between the three stages of ripening. The first stage of maturation (small green) showed the highest radical-scavenging activity (IC₅₀ of 129 μg/ml). Using the bovine brain peroxidation assay, the methanolic extract of green pepper showed significant antioxidant activity (IC₅₀ of 522 μg/ml). Addition of methanolic extract of red and green pepper inhibited oxidation of linoleic acid. Methanolic extract of red pepper showed greater antioxidative potency than the others (IC₅₀ of 3 μg/ml). The different composition of lipophilic compounds and the various amount of phenolics, showed in the three stage of ripening of C. annuum var. acuminatum fruits, modifies the antioxidant activity.     

The influence of fruit ripening on the phytochemical content and biological activity of Capsicum chinense Jacq. cv Habanero

During the past decade, it has been reported that the consumption of certain foods and spices such as pepper may have a positive effect on health. The present study evaluates the influence of fruit ripening on total phenols, flavonoids, carotenoids and capsaicinoids content and antioxidant, hypoglycaemic and anticholinesterase activities of Capsicum chinense Jacq. cv Habanero. The chemical investigation showed a different composition between the two stages of ripening (immature and mature). Generally, the concentration of carotenoids and capsaicinoids increased as the peppers reached maturity, whereas the concentration of phenols declined. The immature fruits showed the highest radical scavenging activity (IC₅₀ of 97.14 μg/ml). On the contrary, the antioxidant activity evaluated by the β-carotene bleaching test showed a significant activity for mature peppers (IC₅₀ value of 4.57 μg/ml after 30 min of incubation). Mature peppers inhibited α-amylase with an IC₅₀ of 130.67 μg/ml. The lipophilic fractions of both mature and immature peppers exhibited an interesting and selective inhibitory activity against α-amylase with IC₅₀ values of 29.58 and 9.88 μg/ml, respectively. Both total extracts of mature and immature peppers inhibited butyrylcholinesterase selectively. The obtained results underline the potential health benefits as a result of consuming C. chinense Habanero and suggest that it could be used as new valuable flavour with functional properties for food or nutriceutical products on the basis of the high content of phytochemicals and found biological properties.     

Antioxidant,anticholinesterase and antimicrobial constituents from the essential oil and ethanol extract of Salvia potentillifolia

The essential oil of Salvia potentillifolia was analysed by GC and GC–MS. Totally, 123 components were detected in both hydrodistilled and steam-distilled oils, α- and β-pinenes being major compounds. The antioxidant activities were determined by using complementary tests, namely, DPPH radical-scavenging, β-carotene-linoleic acid and reducing power assays. The ethanol extract also showed better activity (IC₅₀ = 69.4 ± 0.99 μg/ml) than that of BHT in the DPPH system, and showed great lipid peroxidation inhibition in the β-carotene-linoleic acid system (IC₅₀ = 30.4 ± 0.50 μg/ml). The essential oil showed meaningful butyrylcholinesterase activity (65.7 ± 0.21%), and α-pinene showed high acetylcholinesterase inhibitory activity (IC₅₀ = 86.2 ± 0.96 μM) while β-pinene was inactive. Antimicrobial activity was also investigated on several microorganisms, and the essential oil showed high activity against Bacillus subtilis and B. cereus. It also exhibited remarkable anticandidal activity against Candida albicans and C. tropicalis with MIC values of 18.5 and 15.5 μg/ml, respectively, while α- and β-pinenes showed moderate activity.     

Identification of polyphenols in tobacco leaf and their antioxidant and antimicrobial activities

Crude polyphenols were extracted from tobacco leaf by 80% ethanol solution with ultrasonic treatment and then purified by a macroporous resin. The polyphenols from tobacco leaf (PTL) were subjected to analyses by reverse-phase high-performance liquid chromatography (RP-HPLC) and electrospray ionization mass spectrometry (ESI-MS). The dominant polyphenols in tobacco leaf were identified as chlorogenic acid and rutin. Furthermore, the antioxidant activities of PTL were investigated, including scavenging activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals (5.02 μg/ml IC₅₀ value), hydroxyl radicals (49.6 μg/ml IC50 value) and superoxide anion radicals (44.0 μg/ml IC₅₀ value), inhibition activity of lipid peroxidation (132 μg/ml IC₅₀ value) and reducing power. The proliferation inhibition activities on Escherichia coli, Staphylococcus aureus and Bacillus subtilis were also measured for evaluating the antimicrobial activity of PTL. The diameters of inhibition zones were 20.23 ± 0.42, 17.66 ± 0.86 and 12.89 ± 0.29 mm, respectively. The results showed that PTL had great potential as antioxidant and antimicrobial agent.     

Antioxidant activity and cell toxicity of pressurised liquid extracts from 20 selected plant species in Jeju,Korea

Twenty plant species were selected from Jeju, Korea, and extracts made using a pressurised liquid extraction system. Integral antioxidative capacity (IAC), inhibitory activity of nitric oxide (NO) production, and cell toxicity were evaluated to identify new dietary antioxidants of natural origin with a low degree of cell toxicity. Geranium thunbergii and Pyrrosia lingua showed high IAC values of water-soluble substances (9.76 and 9.48 mmol ascorbic acid equivalents/g), with high IAC values of lipid-soluble substances of 5.20 and 1.97 mmol trolox equivalents/g, respectively. Prunus padus and Rhus javanica did not show any cytotoxicity on RAW 264.7 macrophages or HS-68 normal skin fibroblast cells and showed inhibitory activity of NO production (IC₅₀ = 327 and 337 μg/ml) with LPS-induced RAW 264.7 macrophages. Malus sieboldii did not exhibit cytotoxicity with either cell type and showed high inhibitory activity of NO production (IC₅₀ = 219 μg/ml) and high IAC values of water-soluble substances (4.93 mmol ascorbic acid equivalents/g).     

Flavonoids isolated from Syzygium aqueum leaf extract as potential antihyperglycaemic agents

Syzygium aqueum is a medicinal plant which is grown in tropical regions. In this study, the ethanolic extracts of S. aqueum leaf were investigated for its antihyperglycaemic activity. Our investigation revealed its effectiveness in inhibiting the carbohydrate hydrolysing enzymes, α-glucosidase (EC₅₀ = 11 μg/ml) and α-amylase (EC₅₀ = 8 μg/ml), at significant level than the commercial drug acarbose (EC₅₀ = 28 μg/ml, α-glucosidase; EC₅₀ = 12 μg/ml, α-amylase). In addition, the ethanolic leaf extracts were able to inhibit the key enzyme in the polyol pathway, aldose reductase (EC₅₀ = 0.03 μg/ml) and prevent the AGEs formation by 89%. Six flavonoid compounds, 4-hydroxybenzaldehyde (1), myricetin-3-O-rhamnoside (2), europetin-3-O-rhamnoside (3), phloretin (4), myrigalone-G (5) and myrigalone-B (6), were isolated from the ethanolic leaf extracts. Compounds (2) and (3) showed high inhibitory activities, with EC₅₀ values of 1.1 μM and 1.9 μM against α-glucosidase and EC₅₀ values of 1.9 μM and 2.3 μM against α-amylase, respectively. These findings provide a strong rationale to establish S. aqueum’s capability as an antihyperglycaemic agent.     

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.     

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.     

Composition,antimicrobial, antiradical and spasmolytic activity of Ferula heuffelii Griseb. ex Heuffel (Apiaceae) essential oil

The essential oil from underground parts of Ferula heuffelii from N.E. Serbia, was analysed using GC and GC–MS. The main compounds of the essential oil were elemicin (35.4%) and myristicin (20.6%). The essential oil exhibited the best antimicrobial activity against two strains of Candida albicans (MIC = 7.0 and 13.7 μg/ml), as well as against Micrococcus luteus (MIC = 13.7 μg/ml), Staphylococcus epidermidis (MIC = 17.6 μg/ml), Bacillus subtilis (MIC = 21.1 μg/ml) and Micrococcus flavus (MIC = 28.2 μg/ml). In the DPPH radical scavenging assay, essential oil showed substantial activity with SC₅₀ = 22.43 μl/ml. The essential oil was also tested for antispasmodic activity. It inhibited spontaneous contraction of isolated rat ileum dose-dependently, and at the concentration of 86.64 μg/ml exhibited 50% of the maximum effect of atropine. After incubation with 75.00 μg/ml of essential oil, acetylcholine did not induce contractions of ileum, and at 250.00 μg/ml, the essential oil almost completely abolished the spasmodic effect of potassium chloride (80 mM).     

Phytochemical composition,anti-inflammatory and antitumour activities of four Teucrium essential oils from Greece

The essential oils of four Teucrium species were studied and 150 components, in all, were identified. All oils were rich in sesquiterpenes (50.1–55.8%). Spathulenol and δ-cadinene were the main compounds of Teucrium brevifolium oil; caryophyllene and 4-vinyl guaiacol predominated in Teucrium flavum. Carvacrol and caryophyllene oxide predominated in Teucrium montbretii ssp. heliotropiifolium, while carvacrol and caryophyllene were the most abundant components in Teucrium polium ssp. capitatum. The oil which most effectively inhibited LPS-induced NO production in macrophage cell line RAW 264.7 was that from T. brevifolium (IC₅₀ = 7.1 μg/ml), followed by T. montbretii ssp. heliotropiifolium and T. polium ssp. capitatum (IC₅₀ = 16.5 and 29.4 μg/ml, respectively). The in vitro cytotoxic assay on three human cancer cell lines showed that the most antiproliferative oils were those from T. polium ssp. capitatum and T. montbretii ssp. heliotropiifolium on CACO-2 cell lines (IC₅₀ = 52.7 and 92.2 μg/ml, respectively). The T. brevifolium oil showed a selective cytotoxicity on COR-L23 while significant activity was exerted by T. polium oil on C32.     

The inhibitory effects of ethanol extracts from sorghum,foxtail millet and proso millet on α-glucosidase and α-amylase activities

Cereal crops have recently experienced increased interest due to their potential health benefits. It has been suggested that the intake of whole grain foods is beneficial to the prevention and management of diabetes mellitus. In this study, we investigated the inhibitory effect of 70% EtOH extracts from different cultivars of sorghum, foxtail millet and proso millet on α-glucosidase and α-amylase. Among the six sorghum cultivars, Mongdang-susu(SS-1), Me-susu(SS-2), Susongsaengi-susu(SS-3) and Sikyung-susu(SS-4) extracts exhibited higher inhibitory activities against α-glucosidase (IC₅₀ = 1.1–1.4 μg/ml) than acarbose, reference inhibitor (IC₅₀ = 2.1 μg/ml). In addition, these extracts strongly inhibited degradation of starch by pancreatic and salivary α-amylase, whereas extracts from foxtail and proso millets exhibited no visible or detectible inhibitory effect on α-amylase or on α-glucosidase activity. These in vitro studies indicate the potential of sorghum in the development of effective anti-diabetic agents.