Novel Source Of Natural Antioxidants Research Articles

Optimization of Plasma Activated Water Extraction of Pleurotus ostreatus Polysaccharides on Its Physiochemical and Biological Activity Using Response Surface Methodology.

This study focused on optimizing the extraction of P. ostreatus polysaccharides (POPs) using plasma-activated water (PAW). A single factor and response surface methodology were employed to optimize and evaluate the polysaccharide yield, physiochemical characteristics, and biological activities of POPs. The observed findings were compared to those obtained by the conventional hot water extraction method (100 °C, 3 h), as the control treatment. The optimal extraction conditions were obtained at 700 W PAW power, 58 s treatment time, 1:19 sample-to-water ratio, and 15 L/min gas flow rate. In these conditions, the PAW-treated samples experienced changes in surface morphology due to plasma etching, leading to a 288% increase in the polysaccharide yield (11.67%) compared to the control sample (3.01%). Furthermore, the PAW-treated sample exhibited superior performance in terms of biological activities, namely phenolic compounds (53.79 mg GAE/100 g), DPPH scavenging activity (72.77%), and OH scavenging activity (65.03%), which were 29%, 18%, and 38% higher than those of control sample, respectively. The results highlighted the importance of process optimization and provided new evidence for PAW as an alternative approach to enhance the extraction efficiency of POPs, a novel source of natural antioxidants which enables diverse applications in the food industry.

Antioxidant Activity and Phenolic Composition of Ethanol Extracts of Momordica charantia and Datura stramonium

Medicinal plants in the world are natural antioxidant sources as they contain some secondary metabolites such as phenolic acids and flavonoids. Therefore, they are used to prevent or treat many diseases in many parts of the world. However, the use of antioxidants in cancer treatment is still controversial. Accordingly, the phenolic composition and antioxidant potential of the ethanol extracts of Momordica charantia L. (Cucurbitaceae) and Datura stramonium L. (Solanaceae), which are used traditionally in Turkey and have cytotoxic potential on human cancer cells, were investigated. The antioxidant assays (DPPH, metal chelating, phosphomolybdenum, and ferric reducing power) were applied to the ethanol extracts of the fruits of M. charantia and the leaves of D. stramonium. The total phenolic and flavonoid contents were determined. The phenolic compounds contained in ethanolic extracts were identified using HPLC method. Fifteen phenolic compounds were identified in the extracts. Caffeic acid was the major constituent in both extracts. The amount of caffeic acid was detected to be 6282.51 and 15183.36 µg g-1 extract in M. charantia extract and the D. stramonium extracts, respectively. D. stramonium leaf extract showed higher antioxidant activity than M. charantia fruit extract and this activity may be associated with high phenolic compound concentrations. Hence, further studies about screening of bioactive compounds from various part of these plants will be a great importance for obtaining of source of novel natural antioxidants.

Extraction of phenolic compounds from Iraqi Coriandrum Sativum L. and loaded on copolymeric hydrogels and examine there as drug delivery system and antioxidant

The phenolic extracts for leaves and stems (L+S) parts and leaves (L) part of Iraqi Coriandrum Sativum L. and their total phenols, total tannins and total flavonoids are described. Three copolymeric hydrogels prepared and loaded with phenolic extract 4 (U1-U3). The HPLC results show three phenolic compounds, while the GC-Mass results show one phenolic compound and four non-phenolic compounds. Gained results showed that there are significant (P < 0.05) variations in total phenols (9.822 ± 0.634−4.015 ± 0.118 mg GAE/g DW), total flavonoids (8.112 ± 0.115−2.811 ± 0.371 mg QE/g DW) and total condensed tannin (4.245 ± 0.276−1.135 ± 0.091 mg QE/g DW) contents for all phenolic extracts. The swelling rate for (U1-U3) in distilled water, the SGF, and the SIF was estimated. The maximum swelling was observed in copolymeric hydrogels at pH 6.9 in distilled water. The IC50 values of radical scavenging activity of the phenolic extracts 4, 8 and phenolic extract 4 released from copolymeric hydrogels (U1-U3) show varied significantly (P < 0.05). Our results indicated that Iraqi Coriandrum Sativum L. could constitute a rich and novel source of natural antioxidants. When it loaded on, copolymeric hydrogels could be used as a drug delivery system.

Olive Oil Dregs as a Novel Source of Natural Antioxidants: Extraction Optimization towards a Sustainable Process

Olive oil dregs (OOD), which are an underutilized by-product from oil mills, were used for the extraction of antioxidant compounds. The residues from three oil mills located in Campania (Southern Italy) were extracted with acidified methanol, and hydroxytyrosol (HT) was the main phenolic compound detected. Total phenolic content (TPC) and HT amount were measured. EVO Campania oil mill provided the residue with the highest TPC and HT quantities: 6.801 ± 0.159 mg Gallic Acid Equivalents (GAE)/g OOD and 519.865 ± 9.082 μg/g OOD, respectively. Eco-friendly extractions at different temperatures and times were performed on EVO Campania OOD, obtaining 9.122 ± 0.104 mg GAE/g OOD and 541.330 ± 64.087 μg/g OOD for TPC and HT, respectively, at 121 °C for 60 min. Radical Scavenging Activity (RSA), Superoxide Scavenging Activity (SSA), and Ferric Reducing Antioxidant Power (FRAP) were measured in OOD aqueous extracts. Extract prepared at 37 °C for 60 min showed the greatest RSA and SSA values (44.12 ± 1.82 and 75.72 ± 1.78, respectively), whereas extract prepared at 121 °C for 60 min exhibited the highest FRAP value (129.10 ± 10.49 μg Ascorbic Acid Equivalents (AAE)/mg). OOD extracts were able to protect sunflower oil from oxidation for 4 weeks at 65 °C. The overall results suggest that this novel residue can be usefully valorized by providing HT-rich extracts to use as antioxidant agents.

Determination of phenolic compounds, antioxidant and anticancer activity of Chrozophora tinctoria accessions collected from different regions of Iran.

The present study was conducted to determine the total phenolics, flavonoids, flavonols, anthocyanin, and carotenoids as well as the antioxidant activity of 10 different Crozophora tinctoria accessions originated from Iran. The highest contents of total phenolics, flavonoids, flavonols, anthocyanin, and carotenoids were detected in C.t (2), C.t (10), C.t (10), C.t (9), and C.t (3) accessions, respectively. The highest antioxidant activities of the samples, evaluated using 1,1-diphenyl-2-picrylhydrazyl and phosphomolibdate assays, were detected in C.t (8) and C.t (3), respectively. The highest phenyl aminolyase activity was observed in C.t (4). Ten phenolic compounds, including quercetin, catechin, ellagic acid, rosmarinic acid, hesperetin, eugenol, hesperidin, carvacrol, thymol, and kaempferol were identified and quantified using high-performance liquid chromatography (HPLC) technique. The best anticancer activity against HeLa cell lines was observed at C.t (8) accession, originated from Qazvin Region. This study confirmed that the C. tinctoria accessions with rich phenolics compounds may be recommended as a novel source of natural antioxidants for future aims in medicinal fields. PRACTICAL APPLICATIONS: According to this findings there was high variation among phenolics compounds of C. tinctoria which is revealed by HPLC analysis. This study identified phenolic compounds with antioxidant and anticancer activity in Iranian accessions of C. tinctoria. With an increase in the rate of cancer disease, superior accessions of C. tinctoria may be recommended as a novel source of natural antioxidants for ethno pharmacological aims as cancer therapy, and also in nutraceutical fields.

Phytochemical profile, antioxidant and antimicrobial activities of Traganum nudatum Delile aerial parts organic extracts collected from Algerian Sahara’s flora

The aim of this study was to investigate for the first time the antioxidant and the antimicrobial activities of organic extracts from Traganum nudatum Delile using in vitro models. The extracts which exhibited the highest activities were then submitted to RP-HPLC–PDA analysis. The phytochemical screening revealed the presence of flavonoids, tannins, alkaloids, saponins and quinones. The highest amounts of polyphenols, flavonoids and flavonols were recorded in ethyl acetate fractions. The strongest DPPH scavenging ability was attributed to ethyl acetate fraction of crude extract prepared by maceration EAFM with IC50 value of 20 ± 0.11 µg/mL, ethyl acetate fraction of crude extract prepared by infusion EAFI was found to possess the highest ferric reducing power with EC50 of 35 ± 0.4 µg/mL. The highest antioxidant capacity 200.21 ± 0.2 mg AAE/g was exhibited by n-butanol fraction of crude extract prepared by maceration BFM. The antimicrobial activity was proven against all the tested microorganisms except on Candida albicans strains. The extracts were more active on Gram positive than Gram negative bacteria. The strongest inhibition was provided against Bacillus subtilis, Bacillus cereus and Listeria monocytogenes. The identification of phenolic compounds using RP-HPLC–PDA technique revealed the presence of sinapic, syringic, ferulic, p-coumaric acids, catechin, naringenin and vanillin that may be responsible for the bioactivities of the reported specie. Our results indicate that T. nudatum Delile may provide a rich and novel source of natural antioxidants for industrial utilization replacing synthetic ones.

Evaluation of antioxidant and neuroprotective activities of Cassia fistula (L.) using the Caenorhabditis elegans model.

BackgroundCassia fistula (L.) (Fabaceae) is a medicinal plant from tropical Asia. It is known for its marked antioxidant activity, which is attributed to its high phenolic content. The present study aims at testing both the antioxidant and neuroprotective effects of a hydroalcoholic extract from the aerial parts of Cassia fistula using the Caenorhabditis elegans model, which is widely used in this context.MethodsChemical profiling of secondary metabolites that seem to be responsible for both antioxidant and neuroprotective capacities was carried out by HPLC/PDA/ESI-MSn. Antioxidant activity was tested in vitro by CUPRAC and DPPH assays. In vivo antioxidant and neuroprotective activities were investigated using the C. elegans model.ResultsThe Cassia extract improved the survival rate of the nematodes and protected them against oxidative stress. In addition, a decrease in the accumulation of reactive oxygen species (ROS) was observed. The important role of DAF-16/FOXO pathway was confirmed through an increased nuclear localization of the DAF-16 transcription factor, increased expression of SOD-3 stress response gene and decreased expression of HSP-16.2. Furthermore, the putative involvement of SKN-1/NRF2 pathway was demonstrated by a decrease in GST-4 levels. A neuroprotective activity of the Cassia extract was shown by a decline in polyglutamine (polyQ40) aggregate formation and a delay in paralysis caused by amyloid beta (Aβ1–42) accumulation.DiscussionThe Cassia extract exhibits substantial antioxidant and neuroprotective activities in vivo, which might provide a rich and novel source of natural antioxidants and neuroprotective compounds to be further studied for the use in various food and cosmetic industrial fields.

Improvement of antioxidant activity of Morchella esculenta protein hydrolysate by optimized glycosylation reaction

ABSTRACTMorchella protein hydrolysate (MPH) is produced from an edible and medicinal fungus, Morchella esculenta (L.), and exhibits antioxidant activity. In order to further improve the antioxidant activity of MPH, glycosylation of MPH was conducted by applying response surface methodology via the Maillard reaction (MR). Optimum glycosylation conditions were confirmed as: xylose/MPH mass ratio of 3.7:1, pH 11.80, and reaction time 60 min. The glycosylation of MPH under these optimized conditions was characterized by Fourier transform infrared spectroscopy, fluorescence spectroscopy, and scanning electron microscopy. In vitro antioxidant activity tests showed that glycosylated MPH had significantly enhanced antioxidant activities compared to the native MPH, heat-treated MPH, or a MPH–xylose mixture. Collectively, these results indicate that glycosylation by the MR can improve the antioxidant activity of MPH, making it a novel source of natural antioxidants with excellent developmental prospects as a functional food.

Comparative assessment of phytochemical profiles and antioxidant properties of Tunisian and Egyptian anise (Pimpinella anisum L.) seeds

Anis (Pimpinella anisum L.) seeds obtained from two geographic origins Tunisia (TAS) and Egypt (EAS) were studied regarding their biochemical composition and the antioxidant potential of their extracts. The results showed that the highest value of oil was detected with TAS compared to that of EAS ones. Ten (10) fatty acids were identified for the two locations and petroselinic acid was the most prevalent in oil seeds and interestingly, TAS displayed a significantly higher level of this acid than EAS. Besides, TAS exhibited slightly higher essential oil yield than the Egyptian variety and that trans-anethole was the dominant for the two provenances. In both accessions, the highest total phenolic, flavonoid and tannin content was obtained with ethyl acetate fraction. Therefore, TAS exhibited higher chelating and reducing powers than EAS which may be due to a slightly different phenolic composition between the two accession seed extracts. The phenolic compositions of TAS and EAS revealed that ethyl acetate extracts showed higher proportions of naringin, chlorogenic acid and rosmarinic acid. However, ethanol extracts were richer in larcitrin, rosmarinic acid and cirsimartin. The overall results revealed that aniseeds might constitute a novel source of natural antioxidants and could be used as food additive.

Extraction optimization of medicinally important metabolites from Datura innoxia Mill.: an in vitro biological and phytochemical investigation.

BackgroundThe present study aims to probe the impact of polarity dependent extraction efficiency variation on pharmacological spectrum of Datura innoxia Mill. in order to reconnoiter its underexplored therapeutic potential.MethodsA range of solvent extracts was subjected to phytochemical and biological assays to find the most proficient solvent system and plant part for each type of bioactivity. Total phenolic and flavonoid contents were determined colorimetrically and specific polyphenols were quantified by HPLC-DAD analysis. The samples were biologically evaluated by employing multimode antioxidant, cytotoxic, protein kinase inhibition and antimicrobial assays.ResultsAmong all the solvents used, maximum percent extract recovery (33.28 %) was obtained in aqueous leaf extract. The highest amount of gallic acid equivalent phenolic and quercetin equivalent flavonoid content was obtained in the distilled water and ethyl acetate-ethanol extracts of leaf i.e., 29.91 ± 0.12 and 15.68 ± 0.18 mg/g dry weight (DW) respectively. Reverse phase HPLC-DAD based quantification revealed the presence of significant amounts of catechin, caffiec acid, apigenin and rutin ranging from 0.16 to 5.41 mg/g DW. Highest DPPH radical scavenging activity (IC50 = 16.14 μg/ml) was displayed by the ethyl acetate-acetone stem extract. Maximum total antioxidant capacity and reducing power potential were recorded in the aqueous leaf and ethyl acetate stem extracts i.e., 46.98 ± 0.24 and 15.35 ± 0.61 mg ascorbic acid equivalent/g DW respectively. Cytotoxicity against brine shrimps categorized 25 % of the leaf, 16 % of the stem and 8.3 % of the fruit extracts as highly potent (LC50 ≤ 100 μg/ml). Significant cytotoxicity against human leukemia (THP-1) cell line was exhibited by the chloroform and n-hexane fruit extracts with IC50 4.52 and 3.49 μg/ml respectively. Ethyl acetate and methanol-chloroform extracts of leaf and stem exhibited conspicuous protein kinase inhibitory activity against Streptomyces 85E strain with 22 mm bald phenotype. A noteworthy antimicrobial activity was exhibited by leaf extracts against Micrococcus luteus and n-hexane fruit extract against Aspergillus niger (MIC 3.70 and 12.5 μg/ml respectively).ConclusionMultiple solvent system is a crucial variable to retrieve pharmacological potential of medicinal plants and D. innoxia can be envisaged as a novel source of natural antioxidants, antimicrobials and anticancer compounds.

Phenolic profile, biological activities and fraction analysis of the medicinal halophyte Retama raetam

Retama raetam is a medicinal and aromatic plant present in the humid to the arid bioclimatic regions of Tunisia. In this work, we investigated R. raetam shoots antioxidant and antimicrobial activities and its natural antioxidant contents obtained from four fractions (petroleum ether, acetone 60%, ethyl acetate and water). Results showed that the ethyl acetate fraction exhibits the highest antioxidant activity as compared to the other ones. In fact, IC50 values of ethyl acetate extract were equal to 33.5, 500 and 1380μg/ml (DPPH and ABTS radicals scavenging activity and reducing power, respectively). Accordingly, this fraction presented the highest total polyphenol and flavonoid contents (401mgGAE/g DR and 33.21mgCE/g DR, respectively). Moreover, RP-HPLC analysis showed that syringic acid and coumarin were the major phenolic compounds. Furthermore, this moderately polar fraction showed considerable antibacterial properties against human pathogen strains especially against Escherichia coli and Bacillus cereus. Finally, fractionation allows the identification of R. raetam most active molecules and therefore the optimization of their utilization. Our findings pointed out the appropriate solvent for extracting R. raetam potent phenolics which might provide a rich and novel source of natural antioxidants as food additives replacing synthetic ones in food industry.

Anthocyanins, Phenolic Acids and Antioxidant Properties of Juçara Fruits (Euterpe edulis M.) Along the On-tree Ripening Process

Juçara (Euterpe edulis M.) fruits are an interesting source of phenolic compounds, mainly anthocyanins, making them valuable to the food and pharmaceutical industries. Juçara fruits were harvested along the on-tree ripening process between March and June as practiced in Paraná state, Brazil and examined for their total anthocyanin content (TAC), total phenolic content (TPC), total phenolic acid (TPA) and total antioxidant capacity (TAA). Overall, TAC increased (91.52-236.19mg cyanidin-3-glucoside equivalent/100gdm) whereas TPC (81.69-49.09mg GAE/gdm) and TPA (44.27-30.95mg/100gdm) decreased during ripening of juçara fruits. Use of tandem mass spectrometry allowed the identification of cyanidin-3,5-diglucoside, peonidin-3-glucoside and peonidin-3-rutinoside for the first time in juçara fruits. The analysis of the phenolic acids by HPLC-MS/MS indicated the presence of gallic, protocatechuic, p-hydroxybenzoic, vanillic, chlorogenic, caffeic, syringic, p-coumaric, sinapinic and ferulic acids. The high antioxidant capacity using DPPH radical scavenging capacity (655.89-745.32μmol TE/gdm) and ORAC assays (1088.10-2071.55μmol TE/gdm) showed that juçara fruits have potential as a source of novel natural antioxidants for disease prevention and health promotion, and also as natural food additives for developing new functional food products.

Antioxidant activity of methanolic extracts from three coriander (Coriandrum sativum L.) fruit varieties

In this study, fruit methanolic extract of three coriander (Coriandrum sativum L.) varieties (Tunisian, Syrian and Egyptian) was assayed for their antioxidant activities. Obtained results showed that there are significant (P<0.05) variations in total polyphenols (0.94±0.05–1.09±0.02mgGAE/gDW), total flavonoids (2.03±0.04–2.51±0.08mgEC/gDW) and total condensed tannin (0.09±0.01–0.17±0.01mgEC/gDW) contents. The RP-HPLC analysis revealed the identification of phenolics in coriander fruits with chlorogenic and gallic acids as main compounds in Tunisian, Syrian and Egyptian varieties, respectively. Moreover, fruit methanolic extracts exhibited remarkable DPPH radical scavenging activity with IC50 values ranged from 27.00±6.57 to 36.00±3.22μg/mL. EC50 values of reducing power activity varied significantly (P<0.05) from 54.20±6.22 to 122.01±13.25μg/mL. The IC50 values of β-carotene bleaching assay were between 160.00±18.63 and 240.00±26.35μg/mL. Our results indicated that coriander fruit might constitute a rich and novel source of natural antioxidants and may be suggested as a new potential source of natural antioxidant and could be used as food additive.

Effects of physiological stage and solvent on polyphenol composition, antioxidant and antimicrobial activities of Limonium densiflorum

Halophyte ability to withstand salt-triggered oxidative stress is governed by the synthesis of power antioxidant enzymes and substances. This might explain the utilization of some halophytes as traditional medicinal plants such as Limonium genus. In the present study ten extracts were used to examine the effects of solvent and physiological development stage on tissue phenolic contents, antioxidant and antimicrobial activities of Limonium densiflorum. Based on analysis of variance (ANOVA) test, results showed that solvent, physiological development stage and their interaction affected significantly phenolic composition and antioxidant activity. Moreover, solvent effect was much higher for flavonoid content, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene and Fe-reducing tests. While physiological stage effect was considerably larger than solvent effect for total antioxidant activity and tannin contents. Besides, shoot extracts exhibited high antiradical activity as compared to butylated hydroxytoluene (BHT). Furthermore, ethanol 95% extract showed the highest antibacterial activities mainly against gram positive germs. High-performance liquid chromatography (HPLC) analysis revealed several phenolic compounds including rutin hydrate and trihydrate as major phenolics. In conclusion, our findings identified the appropriate solvent and development stage for extracting phenolics which might provide a rich and novel source of natural antioxidants as additives replacing synthetic ones in industry. Key words: Limonium densiflorum, extracting solvent, physiological development stage, phenolics, antioxidant activity, antimicrobial capacity.

Effects of Extraction Solvents and Provenances on Phenolic Contents and Antioxidant Activities of Cumin (Cuminum cyminum L.) Seeds

Polyphenol contents and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity of cumin (Cuminum cyminum L.) seed extracts were compared depending on their geographical origin (Tunisia and India: TCS and ICS, respectively) and the extraction solvent polarity. The β-carotene bleaching assay, the chelating ability and the reducing power of the most promising solvent extracts were also assessed. In addition, TCS and ICS extracts were acid-hydrolyzed and the phenolics identified by reversed-phase high-performance liquid chromatography (HPLC). Seed phenolic contents and antioxidant activity appeared to be accession and solvent dependent. Extraction with 80% acetone led to the highest polyphenol (18.60 and 16.50 mg gallic acid equivalents (GAE)/g dry weight (DW)), flavonoid (5.91 and 4.99 mg catechin equivalents (CE)/g DW) and tannin (83.23 and 80.23 mg CE/g DW) contents, respectively for TCS and ICS. DPPH scavenging activity, β-carotene bleaching assay, chelating ability and reducing power were maximal in 80% acetone for both TCS and ICS. HPLC analysis revealed several phenolic compounds in C. cyminum seeds, with p-coumaric (4.83 and 2.33 mg/g DW), trans-2-dihydrocinnamic (1.09 and 1.20 mg/g DW) and rosmarinic (0.70 and 1.04 mg/g DW) acids as major phenolics in TCS and ICS, respectively. Thus, phenolic composition of cumin seeds is also origin dependent. Taken together, our findings indicate that cumin might constitute a rich and novel source of natural antioxidants as food additives in food industry and that acetone 80% would be the most appropriate solvent for seed extraction.

In vitro antioxidant activities of endophytic fungi isolated from the liverwort Scapania verrucosa

We investigated in vitro antioxidant activities of 49 endophytic fungi isolated from the liverwort Scapania verrucosa. Based on morphological and molecular identification, the endophytic fungi isolated were classified into seven genera (Hypocrea, Penicillium, Tolypocladium, Chaetomium, Xylaria, Nemania, and Creosphaeria), all belonging to one family (Xylariaceae). By screening with the 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) decolorization assay, the ethyl acetate extracts of five endophytic fungi (T7, T21, T24, T32, and T38 strains), which exhibited remarkable Trolox equivalent (TE) antioxidant capacity (ranging from 997.06 to 1248.10 μmol TE/g extract), were selected and their antioxidant capacity was further evaluated by assays for 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, hydroxyl radical scavenging, reducing power, and ferrous ion chelating. The ethyl acetate extracts of two endophytic fungi (T24 and T38) were found to have comparable scavenging abilities on both DPPH-free radicals (93.9 and 88.7%, respectively, at 50 μg/mL) and hydroxyl radicals (97.1 and 89.4%, respectively, at 2 mg/mL) when compared with those of the positive controls (ascorbic acid and butylated hydroxytoluene, respectively). Although their reducing powers were similar to that of butylated hydroxytoluene, as indicated by absorbance (0.35 and 0.30 at 50 μg/mL, respectively), only the T38 strain's ethyl acetate extract showed ferrous ion chelating ability (92.9% at 1 mg/mL) comparable to that of the EDTA-2Na control. These endophytic fungi in S. verrucosa are a potential novel source of natural antioxidants.

Solvent effects on phenolic contents and biological activities of the halophyte Limoniastrum monopetalum leaves

Limoniastrum monopetalum is a traditional medicinal species which leaf infusion exhibits antidysenteric properties against infectious diseases. In this study, ten kinds of leaf extracts were used to examine the effect of extraction solvent system with varying polarities on polyphenol contents and DPPH scavenging activity. Then the superoxide scavenging activity and the reducing power of the most promising solvent extracts were evaluated too. Moreover, the efficiency of the best leaf extract has been investigated against pathogenic bacteria and yeast. Eventually leaf extract was hydrolyzed by acid and the phenolics identified by RP-HPLC. Results showed that phenolic contents and antioxidant activities varied considerably as function of solvent polarity. Leaf extract using pure methanol showed the highest polyphenol content (15.85 mg GAE/g DW). Moreover, antiradical capacities against DPPH and superoxide, and reducing power were maxima in acetone/water (8:2) of leaf extract. However, the latter showed a slight antimicrobial activity against human pathogen strains such as Staphylococcus aureus, Micrococcus luteus and Candida holmii. The HPLC analysis revealed several phenolic compounds in L. monopetalum leaf including vanillic and gallic acids as major phenolics. Our findings identified the appropriate solvent for extracting halophyte phenolics which might provide a rich and novel source of natural antioxidants as food additives replacing synthetic ones in food industry.

A Potential Antioxidant Resource: Endophytic Fungi from Medicinal Plants

Medicinal plants and their endophytes are important resources for discovery of natural products. Several previous studies have found a positive correlation between total antioxidant capacity (TAC) and total phenolic content (TPC) of many medicinal plant extracts. However, no information is available on whether such a relationship also exists in their endophytic fungal metabolites. We investigated the relationship between TAC and TPC for 292 morphologically distinct endophytic fungi isolated from 29 traditional Chinese medicinal plants. The antioxidant capacities of the endophytic fungal cultures were significantly correlated with their total phenolic contents, suggesting that phenolics were also the major antioxidant constituents of the endophytes. Some of the endophytes were found to produce metabolites possessing strong antioxidant activities. Several bioactive constituents from the fungal cultures and host plant extracts were identified. This investigation reveals that the metabolites produced by a wide diversity of endophytic fungi in culture can be a potential source of novel natural antioxidants.