Antioxidant activities and phytochemical characteristics of extracts from Acacia confusa bark

Chemical composition, antioxidant and anti-tyrosinase potentials of Acacia cyclops trunk bark using in vitro and in silico approaches

The purpose of this paper was to evaluate the phytochemical profile of Acacia cyclops trunk bark methanol extract using LC-MS/MS, as well as to assess its antioxidant and anti-tyrosinase activities. Thus, total phenolic and flavonoid contents of the studied extract were established and 19 compounds were detected and quantified. In addition of their antioxidant potential against DPPH and ABTS assays, in vitro and in silico studies were adopted to evaluate tyrosinase inhibitory property of A. cyclops extract. Methanol trunk bark extract showed significant total phenolic content, antioxidant potential in terms of free radical scavenging, as well as an interesting tyrosinase inhibitory action (IC50= 05.12 ± 0.41 μg/mL). The molecular docking analysis and the drug-likeness prediction of the major selected compounds supported the significant anti-tyrosinase activity of the studied extract. The obtained results suggest that A. cyclops extract could be a promising candidate in the treatment of skin hyperpigmentation disorders.

Xylan, Xylooligosaccharides, and Aromatic Structures With Antioxidant Activity Released by Xylanase Treatment of Alkaline-Sulfite–Pretreated Sugarcane Bagasse

Xylanase enzymes are useful to fractionate plant biomass, producing xylan, xylooligosaccharides (XOS), and antioxidant-derived XOS. In a biorefinery, pretreated biomass can be digested with xylanase prior to cellulose saccharification, enhancing the product portfolio in the process. With this vision, this study highlighted a wide range of new products attainable from alkaline-sulfite–pretreated sugarcane bagasse by treatments with endo-xylanase under controlled conditions. The developed process provided a crude extract corresponding to 29.7% (w/w) of pretreated sugarcane bagasse. The crude extract included a relatively polymeric glucuronoarabinoxylan fraction, DP2-DP6 xylooligosaccharides, and aromatic compounds. The enzymatically produced extract was fractionated with increasing ethanol concentrations [up to 90% (v/v)], providing precipitation of varied polymeric xylan fractions (48% (w/w) of the crude extract) with average molar masses ranging from 28 kDa to 3.6 kDa. The fraction soluble in 90% ethanol was subjected to adsorption on 4% (w/v) activated charcoal and eluted with an ethanol gradient from 10% to 70% (v/v), thus providing xylooligosaccharides and aromatic fractions. Most of the xylooligosaccharides (74% of the eluted sugars) were washed out in 10%–30% ethanol. DP2 and DP3 structures predominated in the 10% ethanol fraction, while DP5 structures were significantly enriched in the 30% ethanol fraction. Higher ethanol concentrations desorbed xylooligosaccharides associated with higher amounts of aromatic compounds. Total aromatics, phenolic structures, and p-hydroxycinnamates predominated in the fractions desorbed with 60% and 70% ethanol. The antioxidant activity of produced fractions correlated with their phenolic contents. Compiled results indicate that a wide variety of products can be prepared from pretreated biomass using xylanase-aided extraction procedures. Recovered fractions presented different features and specific application prospects. Beyond polymeric xylan with low lignin contamination, xylooligosaccharides or even lignin-carbohydrate complexes with antioxidant activity can be included in the biorefinery portfolio based on the currently developed fractionation studies.

Recent Developments in Effective Antioxidants: The Structure and Antioxidant Properties

Since the last few years, the growing interest in the use of natural and synthetic antioxidants as functional food ingredients and dietary supplements, is observed. The imbalance between the number of antioxidants and free radicals is the cause of oxidative damages of proteins, lipids, and DNA. The aim of the study was the review of recent developments in antioxidants. One of the crucial issues in food technology, medicine, and biotechnology is the excess free radicals reduction to obtain healthy food. The major problem is receiving more effective antioxidants. The study aimed to analyze the properties of efficient antioxidants and a better understanding of the molecular mechanism of antioxidant processes. Our researches and sparing literature data prove that the ligand antioxidant properties complexed by selected metals may significantly affect the free radical neutralization. According to our preliminary observation, this efficiency is improved mainly by the metals of high ion potential, e.g., Fe(III), Cr(III), Ln(III), Y(III). The complexes of delocalized electronic charge are better antioxidants. Experimental literature results of antioxidant assays, such as diphenylpicrylhydrazyl (DPPH) and ferric reducing activity power assay (FRAP), were compared to thermodynamic parameters obtained with computational methods. The mechanisms of free radicals creation were described based on the experimental literature data. Changes in HOMO energy distribution in phenolic acids with an increasing number of hydroxyl groups were observed. The antioxidant properties of flavonoids are strongly dependent on the hydroxyl group position and the catechol moiety. The number of methoxy groups in the phenolic acid molecules influences antioxidant activity. The use of synchrotron techniques in the antioxidants electronic structure analysis was proposed.

Greek Sage Exhibits Neuroprotective Activity against Amyloid Beta-Induced Toxicity

Alzheimer's disease (AD) is the most common neurodegenerative disease, affecting the elderly at a high incidence. AD is of unknown etiology and currently, no cure is available. Present medication is restricted to treating symptoms; thus, a need exists for the development of effective remedies. Medicinal plants constitute a large pool, from which active compounds of great pharmaceutical potential can be derived. Various Salvia spp. are considered as neuroprotective, and here, the ability of Salvia fruticosa (SF) to protect against toxic effects induced in an AD cell model was partly assessed. Two of AD's characteristic hallmarks are the presence of elevated oxidative stress levels and the cytotoxic aggregation of amyloid beta (Aβ) peptides. Thus, we obtained SF extracts in three different solvents of increasing polarity, consecutively, to evaluate (a) their antioxidant capacity with the employment of the free radical scavenging assay (DPPH^•), of the ferric reducing ability of plasma assay (FRAP), and of the cellular reactive oxygen species assay (DCFDA) and (b) their neuroprotective properties against Aβ_25–35-induced cell death with the use of an MTT assay. All three SF extracts showed a considerable antioxidant capacity, with the methanol (SFM) extract being the strongest. The results of the total phenolic and flavonoid contents (TPC and TFC) of the extracts and of the FRAP and the DCFDA assays showed a similar pattern. In addition, and most importantly, the dichloromethane (SFD) and the petroleum ether (SFP) extracts had an effect on Aβ toxicity, exhibiting a significant neuroprotective potential. To our knowledge, this is the first report of SF extracts demonstrating neuroprotective potential against Aβ toxicity. In combination with their antioxidant capacity, SF extracts may be beneficial in combating AD and other neurodegenerative diseases.

Anti-Inflammatory Principles from Tamarix aphylla L.: A Bioassay-Guided Fractionation Study

Natural products have served as primary remedies since ancient times due to their cultural acceptance and outstanding biodiversity. To investigate whether Tamarix aphylla L. modulates an inflammatory process, we carried out bioassay-guided isolation where the extracts and isolated compounds were tested for their modulatory effects on several inflammatory indicators, such as nitric oxide (NO), reactive oxygen species (ROS), proinflammatory cytokine; tumour necrosis factor (TNF-α), as well as the proliferation of the lymphocyte T-cells. The aqueous ethanolic extract of the plant inhibited the intracellular ROS production, NO generation, and T-cell proliferation. The aqueous ethanolic crude extract was partitioned by liquid-liquid fractionation using n-hexane (n-C₆H₆), dichloromethane (DCM), ethyl acetate (EtOAc), n-butanol (n-BuOH), and water (H₂O). The DCM and n-BuOH extracts showed the highest activity against most inflammatory indicators and were further purified to obtain compounds 1-4. The structures of 3,5-dihydroxy-4',7-dimethoxyflavone (1) and 3,5-dihydroxy-4-methoxybenzoic acid methyl ester (2) from the DCM extracts; and kaempferol (3), and 3-hydroxy-4-methoxy-(E)-cinnamic acid (4) from the n-BuOH extract were elucidated by different spectroscopic tools, including MS, NMR, UV, and IR. Compound 2 inhibited the production of ROS and TNF-α, whereas compound 3 showed inhibitory activity against all the tested mediators. A better understanding of the potential aspect of Tamarix aphylla L. derivatives as anti-inflammatory agents could open the door for the development of advanced anti-inflammatory entities.

Evaluation of Antioxidant and Antibacterial Activities, Cytotoxicity of Acacia seyal Del Bark Extracts and Isolated Compounds

Water extract of Acacia seyal bark is used traditionally by the population in Djibouti for its anti-infectious activity. The evaluation of in vitro antibacterial, antioxidant activities and cytotoxicity as well as chemical characterization of Acacia seyal bark water and methanolic extracts were presented. The water extract has a toxicity against the MRC-5 cells at 256 μg/mL while the methanolic extract has a weak toxicity at the same concentration. The methanolic extract has a strong antioxidant activity with half maximal inhibitory concentration (IC50) of 150 ± 2.2 μg/mL using 1-diphenyl-2-picrylhydrazyl (DPPH) and IC50 of 27 ± 1.3 μg/mL using 2,2'-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical methods. For ferric reducing/antioxidant power (FRAP) assay, the result is 45.74 ± 5.96 μg Vitamin C Equivalent (VCE)/g of dry weight (DW). The precipitation of tannins from methanol crude extract decreases the MIC from 64 µg/mL to 32 µg/mL against Staphylococcus aureus and Corynebacterium urealyticum. However, the antioxidant activity is higher before tannins precipitation than after (IC50 = 150 µg/mL for methanolic crude extract and 250 µg/mL after tannins precipitation determined by DPPH method). By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, the results showed that the condensed tannins consist of two types of catechin and gallocatechin-based oligomers. The fractionation led to the identification of three pure compounds: two flavanols catechin and epicatechin; one triterpene as lupeol; and a mixture of three steroids and one fatty acid: campesterol, stigmasterol, clionasterol, and oleamide.

A review of antioxidant and pharmacological properties of phenolic compounds in Acacia confusa

In the present review article, the phytochemical, antioxidant and pharmacological studies are congregated and summarized concerning the current knowledge of the phenolic compounds of a traditional medical plant Acacia confusa in Taiwan. This plant is native to Taiwan and South-East Asia. It possesses major pharmacological activities, including antioxidant and radical scavenging activity, hepatoprotective effect, xanthine oxidase inhibition, semicarbazide-sensitive amine oxidase inhibition, angiotensin I converting enzyme inhibition, antihyperuricemic effect and anti-inflammatory activity. Phenolic compounds, especially flavonoids, flavonol glycoside and phenolic acid derivatives, are the main phytochemical compounds isolated from different plant parts of A. confusa. Recent interest in this species has focused on pharmacological investigations of the phytochemicals which exhibit potent antioxidant activity based on the multiple phenolic functionalities. The consequence of this review will further extend the potential applications of this plant and offer persuasive support to its future use in the fields of clinical medicine and health functional food.

Valorisation of softwood bark through extraction of utilizable chemicals. A review

Softwood bark is an important source for producing chemicals and materials as well as bioenergy. Extraction is regarded as a key technology for obtaining chemicals in general, and valorizing bark as a source of such chemicals in particular. In this paper, properties of 237 compounds identified in various studies dealing with extraction of softwood bark were described. Finally, some challenges and perspectives on the production of chemicals from bark are discussed.

Antioxidant and antigenotoxic potential of Ramaria largentii Marr & D. E. Stuntz, a wild edible mushroom collected from Northeast Romania

Ramaria largentii Marr & D. E. Stuntz (orange coral mushroom) is a wild edible mushroom whose chemical composition and bioactivity have not been investigated. Herein, we present a study on the phenolic constituents, antioxidant and antigenotoxic effects of a hydromethanolic extract of the fruiting bodies. Total phenolic content, estimated by Folin-Ciocalteu assay, was found to be 42.33 ± 0.18 mg GAE/g. Protocatechuic and vanillic acids were detected by HPLC-DAD-ESI-MS. The extract showed good free radical scavenging and reducing capacities (EC₅₀ = 64.3 ± 0.2 and 61.54 ± 0.46 μg/mL, respectively). In normal Vero cells, the extract (100, 200 and 300 μg/mL) showed no genotoxic potential and moreover, almost completely protected DNA against H₂O₂-induced damage (2.09-7.91% tail DNA) (24 and 48 h pre-treatment). Taken together, the results of our study show that Ramaria largentii extract is devoid of genotoxicity and has a remarkable DNA protective activity against H₂O₂-induced damage.

Evaluation of antioxidant, anti-hemolytic and anticancer activity of various solvent extracts of Acacia hydaspica R. Parker aerial parts

BACKGROUND

Acacia hydaspica R. Parker, family leguminosae, is a medicinally important plant. Different plant parts are used in various ailments in folk medicine. The current study aimed at investigating the in vitro antioxidant, anti-hemolytic and anticancer activity of A. hydaspica.

METHODS

Antioxidant potential was assessed using DPPH, ABTS and •OH, scavenging of H2O2, inhibition of lipid peroxidation and β-carotene bleaching inhibition assays. Anti-hemolytic activity was assessed using H2O2 induced hemolysis of RBCs. Anticancer potential was assessed using MTT assay. Spectrometric methods and HPLC-DAD analysis was performed for phytochemical screening.

RESULTS

EC50 values based on reduction of DPPH, ABTS and •OH, scavenging of H2O2, inhibition of lipid peroxidation and β-carotene bleaching for AHB, AHE and AHM were generally lower manifesting potential antiradical capacities. The fractions also exhibited significant (P <0.001) anti-hemolytic potential. Regarding IC50 values for anticancer activity against HCC-38 and MDA-MB-361 cancer cell lines; AHB, AHE and AHM exhibited significant (P <0.001) cyto-selection indices. Plant extracts showed no cytotoxicity against normal Vero cells (IC50 > 250 μg/ml). While significant (P <0.001) cytotoxicity was elicited by these extract/fractions against cancer cell lines. AHE was the most effective and IC50 was found to be 29.9 ± 0.909 μg/ml (SI = 9.83) and 39.5 ± 0.872 μg/ml (SI = 7.44) against MDA-MB-361 and HCC-38 cancer cells respectively. Higher amounts of TPC and TFC were exhibited by AHE and AHB as compared to other fractions. Gallic acid, catechin and myricetin were identified in AHE whereas gallic acid and catechin were identified in AHB by HPLC.

CONCLUSION

The presence of bioactive constituents in AHE and AHB might be responsible for antioxidant, anti-hemolytic and anticancer activities.

Vernonia kotschyana roots: therapeutic potential via antioxidant activity

The roots of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae) are used in Malian traditional medicine in the treatment of gastroduodenal ulcers and gastritis. Since oxidative stress is involved in gastric ulceration, the aim of this study was to screen the root extracts for their in vitro antioxidant activity and phenolic content. The roots were extracted successively with chloroform, ethyl acetate, ethanol and water. The antioxidant activity of root extracts was evaluated in both cell-free and cell-based assays. Their chemical characterization was performed by Fourier transform infrared spectroscopy (FT-IR) whereas the total phenolic content was determined by the Folin-Ciocalteu method. The ethyl acetate extract displayed the highest phenolic content and was found to be the most active in the free radical scavenging and lipid peroxidation inhibition assays; it also showed a high antioxidant activity in MCF-12F cells. This study suggests a potential use of the ethyl acetate extract of Vernonia kotschyana not only as an antioxidant agent in gastroduodenal ulcers and gastritis, but also in other disorders characterized by high levels of oxidative stress.

Antioxidant activities and phytochemicals of leaf extracts from 10 native rhododendron species in taiwan

Rhododendron, one of the most famous ornamental plants in the world, is traditionally a medicinal plant. However, the potential bioactivities of native Rhododendron in Taiwan have not been completely studied. In this study, the results revealed that Rhododendron pseudochrysanthum exhibited the best antioxidant activities among 10 native Rhododendron species in Taiwan. Furthermore, based on a bioactivity-guided isolation principle, nine specific phytochemicals were isolated and identified as (2R,3S)-catechin (1), (2R,3R)-epicatechin (1′), (2R,3R)-dihydromyricetin 3-O-β-l-arabinopyranoside (2), (2S,3S)-taxifolin 3-O-β-l-arabinopyranoside (2′), (2R,3R)-taxifolin 3-O-β-l-arabinopyranoside (3), myricetin 3-O-β-d-glucopyranoside (3′), rutin (4), hyperoside (5), and quercitrin (6). Of these compounds, 2 and 3 were found to be major bioactive compounds, and their concentrations in the n-butanol (BuOH) fraction were determined to be 52.0 and 67.3 mg per gram, respectively. These results demonstrated that methanolic extracts of Rhododendron pseudochrysanthum leaves have excellent antioxidant activities and great potential as a source for natural health products.

In vitro antioxidant activity of hydro alcoholic extract from the fruit pulp of Cassia fistula Linn

The present study is aimed to investigate antioxidant activity of the extracts of Cassia fistula Linn. (Leguminosae) fruit pulp. Cassia fistula Linn., a Indian Laburnum, is widely cultivated in various countries and different continents including Asia, Mauritius, South Africa, Mexico, China, West Indies, East Africa and Brazil as an ornamental tree for its beautiful bunches of yellow flowers and also used in traditional medicine for several indications. The primary phytochemical study and in vitro antioxidant study was performed on hydro alcoholic extract of fruit pulp. Phytochemical screening of the plant has shown the presence of phenolic compounds, fatty acids, flavonoids, tannins and glycosides. Phenolic content was measured using Folin-Ciocalteu reagent and was calculated as gallic acid equivalents. Antiradical activity of hydro alcoholic extract was measured by DPPH (2,2-diphenyl-1- picrylhydrazyl) assay and was compared to ascorbic acid. Ferric reducing power of the extract was also evaluated by Oyaizu method. In the present study, three methods were used for evaluation of antioxidant activity. First two methods were for direct measurement of radical scavenging activity and third method to evaluate the reducing power. Results indicate that hydro alcoholic fruit pulp extracts have marked amount of total phenols which could be responsible for the antioxidant activity. These in vitro assays indicate that this plant extract is a significant source of natural antioxidant, Cassia fistula fruit pulp extract shows lower activity in DPPH and total phenol content as compared with standard which might be helpful in preventing the progress of various oxidative stresses.

HPLC analysis of phenolics compounds and antioxidant capacity of leaves of Vitex megapotamica (Sprengel) Moldenke

Vitex megapotamica (Sprengel) Moldenke belongs to the Verbenaceae family and is popularly known as "tarumã". The antioxidant capacity of fractions and crude extract from the leaves of V. megapotamica were determined in this study through the capacity to remove reactive species and phenolic compounds were quantified in the various fractions. The IC50 (DPPH) ranged from 14.17 ± 0.76 to 37.63 ± 0.98 µg/mL. The ethyl acetate fraction might contain the strongest lipid peroxidation inhibitory compounds with an IC50 of 16.36 ± 5.09 µg/mL, being also the one with the highest content of polyphenols (522.4 ± 1.12 mg/g), flavonoids (220.48 ± 0.30 mg/g) and condensed tannins (3.86 ± 0.53 mg/g). Compounds quantified by HPLC/DAD in the crude extract and fractions were chlorogenic and rosmarinic acids. Higher dosages of the extracts were more effective in reducing levels of plasma protein carbonyls and were also shown to be able to remove reactive species by a 2',7'-dichlorofluorescein diacetate assay, reducing oxidative stress in all tested fractions. Results obtained indicated that V. megapotamica exhibits good potential to prevent diseases caused by the overproduction of free radicals and it might also be used as a potential source of natural antioxidant agents.

Protective effect of ethyl acetate fraction of Acacia ferruginea DC. against ethanol-induced gastric ulcer in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional systems of medicine, stem bark of Acacia ferruginea DC. is used for the treatment of itching, leucoderma, ulcers, stomatitis and diseases of the blood. In the present study, we determined antioxidant and anti-ulcerogenic activities of Acacia ferruginea stem bark.

MATERIALS AND METHODS

Acetone extract and its sub-fractions of Acacia ferruginea stem bark were subjected to assess their antioxidant potential using various in vitro systems such as DPPH(•), ABTS(•+) scavenging, FRAP and phosphomolybdenum reduction activities. Based on the antioxidant potential, the ethyl acetate fraction was used to evaluate the protective effect of ethanol-induced gastric damage in rat model. Enzyme activities such as superoxide dismutase, glutathione, catalase and lipid peroxidation were also determined in the stomach tissues.

RESULTS

Ethyl acetate fraction (AFE) of Acacia ferruginea stem bark registered higher antioxidant and free radical scavenging activities than the crude acetone extract and other fractions. In addition, AFE exhibited that the IC50 values of DPPH (2.5µg/ml) and ABTS (1.8µg/ml) were lower when compared to the standard quercetin (12.4µg/ml and 4.7µg/ml, respectively). In ethanol induced gastric ulcer, administration of AFE at doses of 10mg/kg, 50mg/kg and 100mg/kg body weight prior to ethanol ingestion significantly protected the stomach ulceration. Consequently significant changes were observed in enzyme activities such as SOD, CAT, GSH and LPO in the stomach tissues when compared with ethanol control group.

CONCLUSION

It is concluded that the ethyl acetate fraction of Acacia ferruginea stem bark possessed higher antioxidant and anti-ulcerogenic activities. Based on the results, we suggest that Acacia ferruginea stem bark has potential to provide a therapeutic approach to ethanol mediated ulcer as an effective anti-ulcer agent.

Antioxidant and antiproliferative activities of Abrus precatorius leaf extracts--an in vitro study

BACKGROUND

The use of traditional medicine at the primary health care level is widespread and plant-based treatments are being recommended for curing various diseases by traditional medical practitioners all over the world. The phytochemicals present in the fruits, vegetables and medicinal plants are getting attention day-by-day for their active role in the prevention of several human diseases. Abrus precatorius is a widely distributed tropical medicinal plant with several therapeutic properties. Therefore in the present study, A. precatorius leaf extracts were examined for their antioxidant and cytotoxic properties in vitro in order to discover resources for new lead structures or to improve the traditional medicine.

METHODS

In this study, antioxidant and antiproliferative properties of the different leaf extracts (hexane, ethyl acetate, ethanol and water) from A. precatorius were investigated along with the quantification of the polyphenol and flavonoid contents. The ability of deactivating free radicals was extensively investigated with in vitro biochemical methods like DPPH(∙), (∙)OH, NO, SO(2-) scavenging assays and inhibition capability of Fe(II)-induced lipid peroxidation. Furthermore, antiproliferative activities using different human cancer cell lines and primary cell line was carried out by MTT method.

RESULTS

Total phenolic content and total flavonoid content of the extracts were found in the range of 1.65 ± 0.22 to 25.48 ± 0.62 GAE mg/g dw and 6.20 ± 0.41 to 17.16 ± 1.04 QE mg/g dw respectively. The experimental results further revealed that A. precatorius extracts showed strong antiradical properties, capable to chelate Fe(2+) and possess good inhibition ability of lipid peroxidation. In addition, as a first step towards the identification of phytoconstituents endowed with potent chemopreventive activities, we evaluated the inhibitory effects of A. precatorius extracts on the proliferation of four different human tumour cell lines such as human colon adenocarcinoma cells (Colo-205), human retinoblastoma cancer cells (Y79), human hepatocellular carcinoma cells (HepG2) and Leukemia cells (SupT1). Ethanol extract (APA) and ethyl acetate extract (APE) of A. precatorius had apparent capabilities of inhibiting the survival of tested human cancer cell lines. Moreover, it was observed that the A. precatorius extracts did not inhibit the growth of mice peritoneal macrophages, thus confirming that plants extracts are selective against the cancer cell lines.

CONCLUSION

This work provides a scientific support for the high antioxidant and antiproliferative activity of this plant and thus it may find potential applications in the treatment of the diseases caused by ROS. Further studies are needed to confirm in vivo anti-tumorgenicity and subsequent chemical characterization of the active molecule(s).

Antioxidant and cytotoxic activity of polyphenolic compounds isolated from the leaves of Leucenia leucocephala

CONTEXT

Cancer is a serious clinical problem to the health care system. Anticancer drugs have been extracted from plants containing phenolic compounds. Leucenia species (Fabaceae) contain a variety of bioactive components of numerous biological and pharmacological properties.

OBJECTIVE

This study explored the constitutive polyphenols of Leucenia leucocephala Lam. growing in Egypt and evaluated the antioxidant and cytotoxic activity.

MATERIALS AND METHODS

Chemical structures of the isolated compounds from the leaves of L. leucocephala were established by spectral techniques (UV, (1)H, and (13)C NMR, MS).

RESULTS

Chromatographic separation of 80% MeOH extract of the leaves of L. leucocephala have resulted in a novel flavonoid-galloyl glycoside [myricetin 3-O-(2',3'4'-tri-O-galloyl)-α-L-rhamnopyranoside] with three known polyphenolic compounds isolated for the first time from this species (apigenin 7-O-β-D-glucuronopyranoside methyl ester, luteolin 7-O-β-D-glucuronopyranoside methyl ester, and 1,3,6-tri-O-galloyl-β-D-glucopyranose) and seven known previously isolated compounds. Also, 80% methanol extract exhibited high antioxidant activity (SC(50) = 3.94 µg/ml), which is correlated with its phenolic content. The extract also showed cytotoxic activity against Hep G2 (IC(50) value 1.41 µg/ml) confirming its anticancer activity against hepatocellular carcinoma. Among the tested compounds (4-8) for antioxidant property, compound 7 was the most active compound (SC(50) = 2.49 µg/ml). Also compounds 7 and 8 exhibited high cytotoxic activity (IC(50) = 2.41 and 2.81 µg/ml, respectively).

DISCUSSION AND CONCLUSION

These findings demonstrate that the leaves of L. leucocephala contain a considerable amount of polyphenolic compounds with high antioxidant properties, thus it has great potential as a source for natural health products.

Chemical, antioxidant and antimicrobial investigations of Pinus cembra L. bark and needles

The chemical constituents and biological activity of Pinus cembra L. (Pinaceae), native to the Central European Alps and the Carpathian Mountains, are not well known. The aim of the present work was to examine the phenolic content, antioxidant and antimicrobial effects of hydromethanolic extracts of Pinus cembra L. bark and needles. Bark extract had higher concentrations of total phenolics (299.3 vs. 78.22 mg gallic acid equivalents/g extract), flavonoids (125.3 vs. 19.84 mg catechin equivalents/g extract) and proanthocyanidins (74.3 vs. 12.7 mg cyanidin equivalents/g extract) than needle extract and was more active as a free radical scavenger, reducing agent and antimicrobial agent. The EC₅₀ values in the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) and reducing power assays were 71.1, 6.3 and 26 μg/mL for bark extract and 186.1, 24 and 104 μg/mL for needle extract, respectively. In addition, needle extract showed ferrous ions chelating effects (EC₅₀ = 1,755 μg/mL). The antimicrobial effects against Staphylococcus aureus, Sarcina lutea, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans were assessed by the agar diffusion method. Both extracts (4 mg/well) were active against all the microorganisms tested; bark extract showed higher inhibition on all strains. These results indicate that Pinus cembra L. bark and needles are good sources of phytochemicals with antioxidant and antimicrobial activities.

Antioxidant activities of extracts and fractions from Eupatorium lindleyanum DC

The antioxidant activities of water extract (WE), ethanol extract (EE), residue water extract (RWE) and petroleum ether (PF), ethyl acetate (EF), n-BuOH (BF) and water (WF) fractions of the ethanol extract from Eupatorium Lindley DC were investigated for the first time. Total phenolics content, DPPH radical scavenging activities, superoxide radical scavenging activities, total reduction capability, and ferrous ions chelating activities were determined for all the extracts and fractions. The results showed that all the extracts and fractions exhibited antioxidant activities with different magnitudes of potency. Among all the samples, WE and RWE exhibited the best antioxidant capacities, the BF also exhibited high antioxidant abilities in all tests except for the metal chelating activity, while the other extracts and fractions were relatively weak antioxidants. The BF had the highest total phenolics contents in all extracts and fractions, and the WE and RWE were found to be rich in tannins. Furthermore, the content of total phenolics showed good correlation with DPPH radical scavenging activity, superoxide anion radical scavenging activity, and the reducing power. Phenolic composition of all the extracts and fractions was identified and quantified by HPLC. The results indicate that the extracts of E. Lindley DC might be a useful potential source of natural antioxidant ingredients.

Anti-hepatitis C virus activity of Acacia confusa extract via suppressing cyclooxygenase-2

Chronic hepatitis C virus (HCV) infection continues to be an important cause of morbidity and mortality by chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) throughout the world. It is of tremendous importance to discover more effective and safer agents to improve the clinical treatment on HCV carriers. Here we report that the n-butanol-methanol extract obtained from Acacia confusa plant, referred as ACSB-M4, exhibited the inhibition of HCV RNA replication in the HCV replicon assay system, with an EC(50) value and CC(50)/EC(50) selective index (SI) of 5 ± 0.3 μg/ml and >100, respectively. Besides, ACSB-M4 showed antiviral synergy in combination with IFN-α and as HCV protease inhibitor (Telaprevir; VX-950) and polymerase inhibitor (2'-C-methylcytidine; NM-107) by a multiple linear logistic model and isobologram analysis. A complementary approach involving the overexpression of COX-2 protein in ACSB-M4-treated HCV replicon cells was used to evaluate the antiviral action at the molecular level. ACSB-M4 significantly suppressed COX-2 expression in HCV replicon cells. Viral replication was gradually restored if COX-2 was added simultaneously with ACSB-M4, suggesting that the anti-HCV activity of ACSB-M4 was associated with down-regulation of COX-2, which was correlated with the suppression of nuclear factor-kappaB (NF-κB) activation. ACSB-M4 may serve as a potential protective agent for use in the management of patients with chronic HCV infection.

A dimeric high-molecular-weight chymotrypsin inhibitor with antitumor and HIV-1 reverse transcriptase inhibitory activities from seeds of Acacia confusa

A dimeric 70-kDa chymotrypsin inhibitor with substantial N-terminal sequence homology to serine protease inhibitors was isolated from Acacia confusa seeds. The chymotrypsin inhibitor was purified using a protocol that entailed ion exchange chromatography on Q-Sepharose, SP-Sepharose and fast protein liquid chromatography-gel filtration on Superdex 75. The chymotrypsin inhibitor was unadsorbed on both Q-Sepharose and SP-Sepharose. Its chymotrypsin inhibitory activity was stable from pH 3 to 10 and from 0 to 50 degrees C. It exerted antiproliferative activity toward breast cancer MCF-7 cells with an IC(50) of 10.7+/-4.2 microM. It inhibited HIV-1 reverse transcriptase with an IC(50) of 8+/-1.5 microM. It was devoid of antifungal activity toward a variety of fungal species. The distinctive features of the chymotrypsin inhibitor included dimeric nature, a high molecular mass, lack of trypsin inhibitory activity, highly potent HIV-1 reverse transcriptase inhibitory activity, specific antitumor activity and relatively high pH-stability.

MALDI-TOF MS analysis of condensed tannins with potent antioxidant activity from the leaf, stem bark and root bark of Acacia confusa

The structures of the condensed tannins from leaf, stem bark and root bark of Acacia confusa were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, and their antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that the condensed tannins from stem bark and root bark include propelargonidin and procyanidin, and the leaf condensed tannins include propelargonidin, procyanidin and prodelphinidin, all with the procyanidin dominating. The condensed tannins had different polymer chain lengths, varying from trimers to undecamers for leaf and root bark and to dodecamers for stem bark. The condensed tannins extracted from the leaf, stem bark and root bark all showed a very good DPPH radical scavenging activity and ferric reducing power.

Antioxidant activities and xanthine oxidase inhibitory effects of phenolic phytochemicals from Acacia confusa twigs and branches

This study investigates bioactivities and active phytochemicals of the extracts of twigs and branches from the indigenous Taiwanese tree Acacia confusa Merr. The bioassay-guided fractionation yielded 8 potent antioxidative phytochemicals. Catechins are the major components in the extract of 5 cm branch bark, including catechin, catechin-3-O-rhamnopyranoside, epi-catechin, and quercetin-3-O-rhamnopyranoside, while flavonol glycosides are the major components in twig extract, namely, myricetin-3-O-glucopyranoside, myricetin-3-O-rhamnopyranoside, quercetin-3-O-rhamnopyranoside, myricetin-3-O-(2''-O-galloyl)-alpha-rhamnopyranoside, and luteolin. Of the test compounds, myricetin-3-O-(2''-O-galloyl)-alpha-rhamnopyranoside exhibited the highest antioxidant activity against DPPH radicals, showing a 2.8-fold lower IC(50) value of 5.3 microM related to that of quercetin. On the other hand, catechins apparently had no XOD inhibitory effect apart from their good antioxidant activities, while luteolin exhibited excellent activity against XOD with an IC(50) value of 11.6 microM. These results may provide useful information for future studies on the applications of A. confusa to be used as a source for natural health products.

Variation in Antioxidant Activity of Extracts of Acacia confusa of Different Ages

The antioxidant activity of extracts of Acacia confusa of different ages has been evaluated. Ethanolic extracts of bark, twigs, branches (2- and 5 cm-diameter branch-bark, 2- and 5 cm-diameter branch-wood), and leaves of 15-, 25-, and 35-year-old A. confusa were examined. Results indicate that the ethanolic extracts of 5 cm-diameter branch-bark and bark of A. confusa exhibited stronger antioxidant activities, and higher phenolic and proanthocyanidin contents than the other plant parts. Furthermore, twig, 2 cm-diameter branch-wood, 2 cm-diameter branch-bark, and 5 cm-diameter branch-wood extracts of 35-year-old specimens showed better antioxidant activities and higher phenolic contents, followed by the 25- and 15-year-old specimens tested. This reveals that the composition of extracts and their differential antioxidant activities are dependent on the age of A. confusa. In addition, the total phenolic content of A. confusa ethanolic extracts has a high positive correlation with the DPPH free-radical scavenging activity (R2 = 0.83), superoxide radical-scavenging activity (R2 = 0.66), ferrous ion-chelating effect (R2 = 0.67), and reducing power (R2 = 0.92).

Antioxidant activities of flavonol derivatives from the leaves and stem bark of Scutia buxifolia Reiss

This study evaluated the antioxidant activities in the leaves and stem bark fractions of Scutia buxifolia. Cerebral lipid peroxidation (TBARS) was induced by Fe(II) and radical-scavenging activity was determined by DPPH method. Folin-Ciocalteu was used to determine phenolic contents. Quercetin, quercitrin, isoquercitrin and rutin were isolated from leaf ethyl acetate fraction and their levels were measured by high performance liquid chromatography-photodiode array detector. IC(50) (DPPH) varied from 4.35+/-1.30 to 29.55+/-0.54 microg/mL for stem bark and from 6.50+/-0.40 to 30.54+/-1.14 in the leaves. Ethyl acetate and butanolic fractions caused a sharp fall in TBARS production with IC(50) from 2.93+/-2.17 to 40.46+/-2.51 microg/mL for the leaves and 0.66+/-0.17 to 27.3+/-1.23 for the stem bark. Results obtained indicated that S. buxifolia has a great potential to prevent disease caused by the overproduction of free radicals and also it might be used as a potential source of natural antioxidant agents.