Ellagic acid rhamnosides from the stem bark of Eucalyptus globulus

Bioassay-guided isolation of anti-inflammatory and antinociceptive metabolites among three Moroccan Juniperus leaves extract supported with in vitro enzyme inhibitory assays

ETHNOPHARMACOLOGICAL RELEVANCE

Herbs of the genus Juniperus (family Cupressaceae) have been commonly used in ancestral folk medicine known as "Al'Araar" for treatment of rheumatism, diabetes, inflammation, pain, and fever. Bioassay-guided isolation of bioactives from medicinal plants is recognized as a potential approach for the discovery of novel drug candidates. In particular, non-addictive painkillers are of special interest among herbal phytochemicals.

AIM OF THE STUDY

The current study aimed to assess the safety of J. thurifera, J. phoenicea, and J. oxycedrus aqueous extracts in oral treatments; validating the traditionally reported anti-inflammatory and analgesic effects. Further phytochemical investigations, especially for the most bioactive species, may lead to isolation of bioactive metabolites responsible for such bioactivities supported with in vitro enzyme inhibition assays.

MATERIALS AND METHODS

Firstly, the acute toxicity study was investigated following the OECD Guidelines. Then, the antinociceptive, and anti-inflammatory bioactivities were evaluated based on chemical and mechanical trauma assays and investigated their underlying mechanisms. The most active J. thurifera n-butanol fraction was subjected to chromatographic studies for isolating the major anti-inflammatory metabolites. Moreover, several enzymatic inhibition assays (e.g., 5-lipoxygenase, protease, elastase, collagenase, and tyrosinase) were assessed for the crude extracts and isolated compounds.

RESULTS

The results showed that acute oral administration of the extracts (300-500 mg/kg, p. o.) inhibited both mechanically and chemically triggered inflammatory edema in mice (up to 70% in case of J. thurifera) with a dose-dependent antinociceptive (tail flick) and anti-inflammatory pain (formalin assay) activities. This effect was partially mediated by naloxone inhibition of the opioid receptor (2 mg/kg, i. p.). In addition, 3-methoxy gallic acid (1), quercetin (2), kaempferol (3), and ellagic acid (4) were successfully identified being involved most likely in J. thurifera extract bioactivities. Nevertheless, quercetin was found to be the most potent against 5-LOX, tyrosinase, and protease with IC50 of 1.52 ± 0.01, 192.90 ± 6.20, and 399 ± 9.05 μM, respectively.

CONCLUSION

J. thurifera extract with its major metabolites are prospective drug candidates for inflammatory pain supported with inhibition of inflammatory enzymes. Interestingly, antagonism of opioid and non-opioid receptors is potentially involved.

Phenolic Biotransformations in Wheatgrass Juice after Primary and Secondary Fermentation

Fermented wheatgrass juice was prepared using a two-stage fermentation process by employing Saccharomyces cerevisiae and recombinant Pediococcus acidilactici BD16 (alaD⁺). During fermentation, a reddish-brown hue appeared in wheatgrass juice due to production of different types of red pigments. The fermented wheatgrass juice has considerably higher content of anthocyanins, total phenols and beta-carotenes as compared to unfermented wheatgrass juice. It has low ethanol content, which might be ascribed to the presence of certain phytolignans in wheatgrass juice. Several yeast-mediated phenolic transformations (such as bioconversion of coumaric acid, hydroxybenzoic acid, hydroxycinnamic acid and quinic acid into respective derivatives; glycosylation and prenylation of flavonoids; glycosylation of lignans; sulphonation of phenols; synthesis of carotenoids, diarylnonanoids, flavanones, stilbenes, steroids, quinolones, di- and tri-terpenoids and tannin) were identified in fermented wheatgrass juice using an untargeted liquid chromatography (LC)-mass spectrometry (MS)-matrix-assisted laser desorption/ionization (MALDI)-time-of-flight (TOF)/time-of-flight (TOF) technique. The recombinant P. acidilactici BD16 (alaD⁺) also supported flavonoid and lignin glycosylation; benzoic acid, hydroxycoumaric acid and quinic acid derivatization; and synthesis of anthraquinones, sterols and triterpenes with therapeutic benefits. The information presented in this manuscript may be utilized to elucidate the importance of Saccharomyces cerevisiae and P. acidilactici BD16 (alaD⁺) mediated phenolic biotransformations in developing functional food supplements such as fermented wheatgrass juice.

Engineered production of bioactive polyphenolic O-glycosides

Polyphenolic compounds (such as quercetin and resveratrol) possess potential medicinal values due to their various bioactivities, but poor water solubility hinders their health benefits to humankind. Glycosylation is a well-known post-modification method to biosynthesize natural product glycosides with improved hydrophilicity. Glycosylation has profound effects on decreasing toxicity, increasing bioavailability and stability, together with changing bioactivity of polyphenolic compounds. Therefore, polyphenolic glycosides can be used as food additives, therapeutics, and nutraceuticals. Engineered biosynthesis provides an environmentally friendly and cost-effective approach to generate polyphenolic glycosides through the use of various glycosyltransferases (GTs) and sugar biosynthetic enzymes. GTs transfer the sugar moieties from nucleotide-activated diphosphate sugar (NDP-sugar) donors to sugar acceptors such as polyphenolic compounds. In this review, we systematically review and summarize the representative polyphenolic O-glycosides with various bioactivities and their engineered biosynthesis in microbes with different biotechnological strategies. We also review the major routes towards NDP-sugar formation in microbes, which is significant for producing unusual or novel glycosides. Finally, we discuss the trends in NDP-sugar based glycosylation research to promote the development of prodrugs that positively impact human health and wellness.

Hypoglycemic effect and toxicity of the dry extract of Eugenia biflora (L.) DC. leaves

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Eugenia biflora (Myrtaceae) are traditionally used by Amazonian populations for the control of diabetes. However, their chemical composition has not yet been described and pharmacological evidence has not been reported.

OBJECTIVE

This study aimed to identify the chemical constituents and evaluate the hypoglycemic and toxic effect of the dry extract of the E. biflora leaves (DEEB).

MATERIALS AND METHODS

DEEB, obtained by infusion, was analyzed using LC-HRMS and NMR, whose the catechin flavonoid was quantified using NMR. The antidiabetic effect of DEEB was evaluated according to its inhibition of the enzymes α-amylase and α-glucosidase, as well as the content of total phenols, free radical scavengingand antiglycation activities, and its in vitro cell viability. Oral maltose tolerance and chronic multiple dose tests (28 days) in streptozotocin-induced diabetic mice (STZ) were performed. The hypoglycemic effect and toxicity of this extract were evaluated in the multiple dose assay. Biochemical parameters, hemolysis, and levels of the thiobarbituric acid reactive species in the liver were investigated and histopathological analyses of the kidneys and liver were performed.

RESULTS

Eight phenolic compounds were identified, with catechin (15.5 ± 1.7 mg g-1) being the majority compound and a possible chemical marker of DEEB. The extract showed inhibition activity of the enzyme α-glucosidase. Chronic administration of DEEB (50 mg/kg of body weight) reduced glucose levels in diabetic animals, similar to acarbose; however, DEEB (100 and 200 mg/kg bw) caused premature death of mice by D22 of the treatment. Our data indicate that one of the mechanisms of toxicity in DEEB may be related to the aggravation of oxidative stress in the liver. This histopathological study indicated that DEEB failed to minimize the progression of the toxicity of diabetes caused by STZ.

CONCLUSIONS

This study demonstrated the hypoglycemic potential of E. biflora leaves. However, the prolonged use of this tea can be harmful to its users due to its considerable toxicity, which needs to be better investigated.

MicroRNA mediated therapeutic effects of natural agents in prostate cancer

BACKGROUND

Several natural products, extensively studied for their anticancer activities, have been found to play an efficient role in preventing prostate cancer (PCa). Recently many natural agents have been reported to modulate microRNAs (miRNAs), that are involved in cancer cell growth. The microRNAs are endogenous small noncoding ribonucleic acid molecules that regulate various biological processes through an elegant mechanism of post-transcriptional control of gene expression. Besides being involved in cancer initiation, progression, angiogenesis, inflammation, they have been reported to be responsible for chemoresistance, and radioresistance of tumors. The dysregulated miRNA expression has been associated with many cancers including PCa. Over the past several years, it has been found that natural agents are good regulators of miRNAs and have a role in PCa also. Understanding the molecular mechanisms involving miRNAs by natural agents could result in developing useful strategies to combat this deadly disease.

METHODS

In order to collect research articles, the PubMed search engine was used with keywords 'prostate cancer' and 'natural agents' and 2007 papers were retrieved, further refinement with keywords 'phytochemical' and 'prostate cancer' showed 503 papers. Data was collected from research articles, published from 2010 to 2021. From these, research articles showing miRNA-mediated mechanisms were selected.

RESULTS

In this review, we have summarized the information available on the modulation of miRNAs by natural agents, their derivatives, and various combinatorial strategies with chemo/radiation therapy for the mitigation of PCa.

CONCLUSIONS

Based on the current review of literature, it has been found that the use of natural agents is a novel approach for altering miRNA expression strongly associated with PCa development, recurrence and resistance.

Standardization of Eucalyptus globulus leaves and Cetraria islandica slan

The aim. The aim of this study was to propose methods of standardization of Eucalyptus globulus leaves and Cetraria islandica slan by the main group of biologically active substances (BAS). This was done for further development of complex medicines based on Eucalyptus globulus leaves and Cetraria islandica slan. These studies provide an opportunity for further development and standardization of extracts from these plants, and the main aim of this study is the development and standardization of a complex medicine. Materials and methods. Thin layer chromatography was used to determine the presence of these markers. Quantitative values of these biologically active substances were determined by spectrophotometric method according to the relevant methods of the State Pharmacopoeia of Ukraine. Results. Markers for the certification of Cetraria islandica and Eucalyptus globulus have been proposed in this study. Chlorophylls and 1,8-cineole were chosen as a marker for the study of Eucalyptus globulus, and polysaccharides were chosen as a marker for Cetraria islandica. The qualitative and quantitative content of these markers in the studied objects was studied. Further research in this direction will be aimed at developing methods for control and standardization of water and alcohol extracts from these plants. Conclusions. Biologically active substances in medicinal plant raw materials were studied. It is proposed to study extracts and finished products from Eucalyptus globulus leaves and Cetraria islandica slan using these methods. The method of qualitative and quantitative determination of polysaccharides in Cetraria islandica slan is easy to apply and easily reproducible. It is important to be able to standardize Eucalyptus globulus leaves for essential oils and chlorophylls. The biologically active substances-markers found in Eucalyptus globulus leaves and Cetraria islandica slan will be used for the development of herbal medicines, the standardization of which will be carried out for the same compounds.

Unravelling the Antibacterial Activity of Terminalia sericea Root Bark through a Metabolomic Approach

Terminalia sericea Burch. ex. DC. (Combretaceae) is a popular remedy for the treatment of infectious diseases. It is widely prescribed by traditional healers and sold at informal markets and may be a good candidate for commercialisation. For this to be realised, a thorough phytochemical and bioactivity profile is required to identify constituents that may be associated with the antibacterial activity and hence the quality of raw materials and consumer products. The aim of this study was to explore the phytochemistry and identify the antibacterial constituents of T. sericea root bark, using a metabolomic approach. The chemical profiles and antibacterial activities of 42 root bark samples collected from three districts in the Limpopo Province, South Africa, were evaluated. Dichloromethane:methanol (1:1) extracts were analysed using ultraperformance liquid chromatography (UPLC)-mass spectrometry (MS), and chemometric models were constructed from the aligned data. The extracts were tested against Bacillus cereus (ATCC 11778), Staphylococcus epidermidis (ATCC 12223), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 8739), Klebsiella pneumoniae (ATCC 13883), Pseudomonas aeruginosa (ATCC 27853), Shigella sonnei (ATCC 9292) and Salmonella typhimurium (ATCC 14028), using the minimum inhibition microdilution assay. Nine compounds; sericic acid, sericoside, resveratrol-3-O-β-rutinoside, ellagic acid, flavogallonic acid dilactone, methyl-flavogallonate, quercetin-3-(2′′-galloylrhamnoside), resveratrol-3-(6′′-galloyl)-O-β-d-glucopyranoside and arjunetin, were isolated from the root bark. All the compounds, with the exception of sericic acid, sericoside and resveratrol-3-O-β-rutinoside, were isolated for the first time from the root bark of T. sericea. Chemometric analysis revealed clustering that was not population specific, and the presence of three groupings within the samples, characterised by sericic acid, sericoside and an unidentified compound (m/z 682/4.66 min), respectively. The crude extracts from different populations displayed varied antibacterial activities against S. typhimurium (minimum inhibitory concentrations (MICs) 0.25–1.0 mg/mL), but similar activity towards Bacillus cereus (1.0 mg/mL). Several compounds present in the root bark were highly active towards all or most of the pathogens tested, but this activity was not reflected by the chemical profiles of extracts prepared from the individual samples. Among the pure compounds tested, only flavogallonic acid dilactone and methyl-flavogallonate exhibited broad-spectrum activity. A biochemometric analysis indicated that there was no consistent association between the levels of phytochemicals and the activity of the active or non-active extracts. Although it was deduced that the major constituents of T. sericea root bark contributed to the chemotypic variation, further investigation of the interactions of compounds present in the root bark may provide antibacterial efficacies not evident when examining compounds singularly. The data reported herein will provide information that is fundamentally important for the development of quality control protocols.

A Strategy Based on GC-MS/MS, UPLC-MS/MS and Virtual Molecular Docking for Analysis and Prediction of Bioactive Compounds in Eucalyptus Globulus Leaves

The discovery of medicinal plants is crucial for drug development. Eucalyptus globulus leaves are used as a traditional medicine in many areas of world due to herbicidal and insecticidal activity. While natural products are difficult to be separated and activity assayed, a new approach is needed to predict the active ingredients therein. In this study, a new method for screening active compounds extracted from E. globulus leaves was developed by GC-MS/MS and UPLC-MS/MS combined with molecular docking technology. Predicted compounds with high activity were proposed. Firstly, 35 volatile compounds and 34 aqueous extracted compounds were extracted from E. globulus leaves, and identified by GC-MS/MS and UPLC-MS/MS. The herbicidal receptor (1BX9) was then docked with the identified compounds by docking software, evaluated by docking models and seven scoring functions. The results showed that gallic acid had a strong inhibitory activity of 1BX9, which was speculated to be the main reason for the inhibitory effect of E. globulus leaves. Finally, allelopathic tests of gallic acid, citric acid, and isopulegol were carried out on grass seeds to verify its inhibitory activity against herbicide receptor 1BX9. The results show that the method can screen compounds with specific activity from a complex system of medicinal plants, which is very important for the screening of new active ingredients, confirmation of new medicinal ingredients, and the in-depth development of animal and plant medicines.

Identification of Ellagic Acid Derivatives from Stem Bark of Syzygium Guineense (Myrtaceae)

An LC-DAD-ESI-MSn technique was developed to investigate crude extracts of the stem bark of S. guineense for phenolic compounds. Ellagic acids were detected on the basis of their UV absorption spectra and ESI-MS fragmentation patterns. Six ellagic acid conjugates in the complex extract of S. guineense were identified. With the aim to confirm the structures, further purification of the extract afforded the known 3-O-ellagic acid-4′-O-α-rhampyranonosides (3), two new ellagic acid rhamnopyranosides, 3-O-methylellagic acid-4′-O-α-2″-O-acetylrhamnopyranoside (4) and 3-O-methylellagic acid-4′-O-α-3″-O-acetylrhamnopyranoside (6). The structures were identified on the basis of 1D- and 2D- NMR, IR, and UV spectroscopic and mass spectrometric data. The HMBC and NOESY data of these compounds were most useful for determination of their structures. Radical scavenging activities were evaluated in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Compounds 3, 4 and 6, with IC50 values of 6.1 ± 0.5, 5.8 ± 0.4, and 6.2 ± 0.4 μM, respectively were as active as ellagic acid (1) (IC50 = 4.9 ± 0.3 μM) and more active than catechin (IC50=10.8 ± 0.3 μM).

Ozone and Wounding Stresses Differently Alter the Temporal Variation in Formylated Phloroglucinols in Eucalyptus globulus Leaves

Formylated phloroglucinol compounds (FPCs) are a class of plant specialized metabolite present in the Myrtaceae family, especially in the genus Eucalyptus. FPCs are widely investigated due to their herbivore deterrence properties and various bioactivities of pharmaceutical relevance. Despite the increasing number of studies elucidating new FPCs structures and bioactivity, little is known about the role of those compounds in planta, and the effects of environmental stresses on FPC concentration. Ozone (O₃) and wounding are key stress factors regularly confronted by plants. In this study, we investigated how O₃, wounding, and their combination affected individual and total FPC foliar concentration of the economically important species Eucalyptus globulus. Six individual FPCs, including five macrocarpals and one sideroxylonal, showed different response patterns to the single and combined stresses. Total macrocarpals only increased under single O₃ treatment, whereas total sideroxylonals only increased in response to wounding treatment, suggesting different physiological roles played by the two groups of FPCs predominantly existing in E. globulus foliage. Total FPCs increased significantly under individual wounding and O₃ treatments but not under the combined treatment. A principal component analysis indicated that all different treatments had unique FPC fingerprints. Total phenolic contents increased in all O₃ and wounding treatments, and a marginally positive correlation was found between total FPCs and total phenolic contents. We suggest that, depending on the concentration and composition, FPCs play multiple physiological roles in planta, including serving as antioxidants to scavenge the reactive oxygen species brought about by O₃ and wounding stresses.

An Array of Bioactive Compounds From Australian Eucalypts and Their Relevance in Pancreatic Cancer Therapeutics

Pancreatic cancer (PC) is one of the most devastating human cancers, and despite the significant advances in the current therapeutic options, the overall survival rate for PC has remained static for the past 50 years. Plant-derived bioactive compounds play a vital role in cancer therapeutics by providing new lead compounds for future drug development. Therefore, the isolation, characterization, and identification of new bioactive compounds for the prevention and treatment of cancer continue to be an important aspect of natural product research. Many in vitro and in vivo studies published in the last few decades have established strong links between the phytochemical profile of eucalypts and anticancer activity. However, only a small number of these reports have attempted to demonstrate a relationship between the biological activity of eucalypt extracts and PC. This review focuses on potential anti-PC effects of an array of bioactive compounds present in various species of eucalypts. It also highlights the necessity for further in vitro and in vivo studies to develop a complete understanding of the potential this group of plants has for the development of potent and specific chemotherapeutic drugs for PC.

Antimicrobial and antioxidant potential of different solvent extracts of the medicinal plant Geum urbanum L

Many Geum species are known to be rich in biologically active compounds and therefore could be a source of new natural products with pharmacological potential. The medicinal plant Geum urbanum L. is widespread in Bulgaria and has been used in folk medicine. In the present study, the methanol extracts of the roots and aerial parts of G. urbanum and their fractions (petroleum ether, ethyl acetate and n-butanol) were investigated for antibacterial and radical scavenging activity. The ethyl acetate and n-butanol fractions inhibited the growth of Gram-positive pathogenic and opportunistic bacteria from the genus Staphylococcus (MIC EtOAc: 0.078 mg/ml aerial and 0.156 mg/ml roots; MIC n-BuOH: 0.156 mg/ml aerial and 1.25 mg/ml roots) and the species Bacillus cereus stronger than the other extracts and fractions tested (MIC EtOAc: 0.078 mg/ml aerial and 0.156 mg/ml roots; MIC n-BuOH: 0.156 mg/ml aerial and 0.078 mg/ml roots), and showed corresponding radical scavenging activity (EtOAc: EC50 1.5 µg/ml aerial, 0.8 µg/ml roots; n-BuOH: 4.5 µg/ml aerial; 3.7 µg/ml roots). Additionally, their total phenolic content was quantified (% of dry EtOAc fractions of roots 61%, of arial parts 32%; of dry n-BuOH fractions of roots 16%, of arial parts 13%). Seven compounds were isolated and identified spectroscopically from the ethyl acetate extract. Two acetylated ellagic acid rhamnosides were found for the first time in the genus Geum and three others, tormentic acid, niga-ichigoside F1, and 3,3'-di-O-methylellagic acid-4-O-β-D-glucopyranoside, were newly detected for the species G. urbanum. Our results reveal that G. urbanum L. is a perspective medicinal plant and deserves further, more detailed studies.

Hydrolyzable tannins from the fruits of Terminalia chebula Retz and their α-glucosidase inhibitory activities

Nine hydrolyzable tannins, including three previously unknown and six artifacts, were isolated, together with thirty-nine known ones, from the fruits of Terminalia chebula Retz. (Combretaceae). They were identified as 1,2,3-tri-O-galloyl-6-O-cinnamoyl-β-d-glucose, 1,2,3,6-tetra-O-galloyl-4-O-cinnamoyl-β-d-glucose, 4-O-(2″,4″-di-O-galloyl-α-l-rhamnosyl)ellagic acid, 1'-O-methyl neochebulanin, dimethyl neochebulinate, 6'-O-methyl neochebulagate, dimethyl neochebulagate, dimethyl 4'-epi-neochebulagate, and methyl chebulagate by the spectroscopic interpretation. After evaluation for α-glucosidase inhibition of all isolated compounds, 1,2,3,6-tetra-O-galloyl-4-O-cinnamoyl-β-d-glucose and 4-O-(2″,4″-di-O-galloyl-α-l-rhamnosyl)ellagic acid showed significant inhibitory activities with IC₅₀ values of 2.9 and 6.4 μM, respectively. In addition, inhibition kinetic studies showed that both compounds have mixed-type inhibitory activities with the inhibition constants (Ki) of 1.9 and 4.0 μM, respectively.

α-Amylase and α-Glucosidase Inhibitory Activities of Phenolic Extracts from Eucalyptus grandis × E. urophylla Bark

This study evaluated the inhibitory effects of different extracts and fractions from Eucalyptus. grandis × urophylla bark (EB) against α-glucosidase and α-amylase enzyme activities. The ethyl acetate extract (EB-E) showed the highest activity among others. Seven fractions were derived from EB-E; among them EB-E-7 showed the highest significant inhibition of both enzymes, with IC50 of 1.40±0.18 and 1.72±0.12 μg/mL, respectively. EB-E and its active fraction EB-E-7 showed highest contents of total phenolics: 178.79±4.68 and 920.4±5.46 mg GAEag−1, respectively. HPLC-MS analysis of EB-E-7 revealed the presence of ellagic acid, quercetin-glucuronide, quercetin-3-α-rhamnopyranoside, and ellagic acid rhamnoside as major compounds, together with smaller concentrations of myricetin-rhamnoside, isorhamnetin-hexoside, myricetin-3-α-arabinofuranoside, and isorhamnetin. Therefore, the phenolic compounds from Eucalyptus grandis × E. urograndis bark potently inhibited α-amylase and α-glucosidase activity, having potential in prevention of hyperglycemia.

Characterization and quantification of the compounds of the ethanolic extract from Caesalpinia ferrea stem bark and evaluation of their mutagenic activity

Caesalpinia ferrea Martius has traditionally been used in Brazil for many medicinal purposes, such as the treatment of bronchitis, diabetes and wounds. Despite its use as a medicinal plant, there is still no data regarding the genotoxic effect of the stem bark. This present work aims to assess the qualitative and quantitative profiles of the ethanolic extract from the stem bark of C. ferrea and to evaluate its mutagenic activity, using a Salmonella/microsome assay for this species. As a result, a total of twenty compounds were identified by Flow Injection Analysis Electrospray Ionization Ion Trap Mass Spectrometry (FIA-ESI-IT-MS/MSn) in the ethanolic extract from the stem bark of C. ferrea. Hydrolyzable tannins predominated, principally gallic acid derivatives. The HPLC-DAD method was developed for rapid quantification of six gallic acid compounds and ellagic acid derivatives. C. ferrea is widely used in Brazil, and the absence of any mutagenic effect in the Salmonella/microsome assay is important for pharmacological purposes and the safe use of this plant.

Evolution of ellagitannin content and profile during fruit ripening in Fragaria spp

Ellagitannins and ellagic acid conjugates are polyphenols present in the human diet, in particular strawberries (Fragaria spp.). The first aim of this study was isolation and structural characterization of casuarictin and 3-O-methyl ellagic acid 3'-O-α-rhamnopyranoside, which were found to be abundant in Fragaria spp., along with agrimoniin. The second aim was accurate profiling and quantification of 26 ellagitannins and ellagic acid conjugates in six Fragaria x ananassa cultivars and two Fragaria vesca species. The third aim was to describe the ellagitannins behavior during fruit ripening from the green stage to over-ripeness. It was shown that there are major qualitative and quantitative differences in the amount and profile of ellagitannins and ellagic acid conjugates between Fragaria spp. Genotype is a major factor in defining ellagitannin concentration and patterns between strawberries, and variable behavior of the genotypes was observed, in the context of a significant drop in ellagitannins during ripening.

Characterisation of Polyphenols in Terminalia arjuna Bark Extract

The bark of Terminalia arjuna is known for its heart-health benefits in ayurvedic literature. This has been further supported by in vivo studies on animal and human volunteers. But there is no detailed study on identification of the active ingredients such as polyphenols. Polyphenols possesses antioxidant properties and are well-known health actives, it is important to characterise polyphenols in Terminalia arjuna. Aqueous extract of Terminalia arjuna bark was analysed for its composition and molecular weight distribution by dialysis. Compositional analysis revealed that it has 44% polyphenols and dialysis study showed that 70% of the polyphenols have molecular weight greater than 3.5 kDa. High performance liquid chromatography and liquid chromatography-mass spectrometry analysis of Terminalia arjuna, confirmed that it contains flavon-3-ols such as (+)-catechin, (+)-gallocatechin and (-)-epigallocatechin. Phenolic acids such as gallic acid, ellagic acid and its derivatives were also found in Terminalia arjuna extract. Ellagic acid derivatives were isolated and their spectral studies indicated that isolated compounds were 3-O-methyl-ellagic acid 4-O-β-D-xylopyranoside, ellagic acid and 3-O-methyl ellagic acid 3-O-rhamnoside. Hydrolysis and thiolysis studies of high molecular weight polyphenols indicated that they are proanthocyanidins. Given these results, it may be possible to attribute the heart-health effects of Terminalia arjuna to these polyphenols which may be responsible for the endothelial benefit functions like tea.

Qualitative and semi-quantitative analysis of phenolics in Eucalyptus globulus leaves by high-performance liquid chromatography coupled with diode array detection and electrospray ionisation mass spectrometry

INTRODUCTION

Eucalyptus species are widely cultivated in Mediterranean regions. Moreover, plants of this family have been utilized for medicinal purposes. A number of studies have been devoted to the identification of eucalypt phenolics, all of them have focused on specific families of compounds, and no exhaustive profiling has been reported in leaves of this plant.

OBJECTIVE

To develop methods that allows the identification and quantification of different classes of phenolics in Eucalyptus globulus leaf.

METHODOLOGY

Acetonic extract was fractionated by chromatography on a Sephadex LH-20 column using consecutive elution with ethanol, methanol and aqueous acetone (60%). High-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS) were applied to determine the structure of different compounds. Quantities were evaluated from peak areas in the HPLC profile, using external calibration curves.

RESULTS

Fractionation of acetonic extract yielded three fractions: F1, F2 and F3. In total 39 phenolic compounds are detected. Among them: 16 hydrolyzable tannins, 3 terpenyl derivatives, 12 ellagic acid derivatives, 5 flavonols, 2 hydroxybenzoic acids and 1 formylated phloroglucinol. 26 compounds described in this study have not previously detected in leaves of this plant and this is the first report of quercetin 3-O-β-galactoside-6"-O-gallate and cypellogin A and B, in E. globulus plant. Quantitatively, ellagic acid derivatives and sideroxylonal A or B are largely predominant.

CONCLUSION

Fractionation of crude extract by chromatography on Sephadex LH-20 was efficient to separate different molecular weight compounds. HPLC-DAD-ESI/MS enabled detection of gallotannin, ellagitannin and flavonol derivatives, in leaves of E. globulus.

In vitro susceptibility of Mycobacterium tuberculosis to extracts of Eucalyptus camaldulensis and Eucalyptus torelliana and isolated compounds

CONTEXT

Eucalyptus camaldulensis Dehnh. (Myrtaceae) and Eucalyptus torelliana F. Muell are used in Nigerian traditional medicine for the treatment of cough associated with tuberculosis (TB) and other respiratory infections.

OBJECTIVE

Hexane, chloroform, methanol extracts, and isolated compounds of E. camaldulensis and E. torelliana were screened for activity against Mycobacterium tuberculosis H37Rv (MtbH37Rv) to authenticate the traditional use of these plants.

MATERIALS AND METHODS

The microplate alamar blue assay (MABA) method was used to investigate the anti-M. tuberculosis activities. Bioassay-guided fractionation of the hexane extract of E. torelliana leaf was performed, and isolated compounds were characterized by MS, 1D- and 2D-NMR.

RESULTS

The extracts inhibited the growth of MtbH37Rv [minimum inhibitory concentration (MIC) 4-64 µg/mL]. Spectroscopic characterization led to the identification of two compounds, hydroxymyristic acid methylester (1) and a substituted pyrenyl ester, a sterol (2). Compounds 1 and 2 had MIC of 49.45 and 46.99 µg/mL; IC(50) >100 and 38.21 µg/mL; selectivity index (SI) >2.02 and 0.81, respectively, and a minimum bactericidal concentration (MBC) of 62.50 µg/mL.

DISCUSSION AND CONCLUSIONS

The anti-TB activities of these plants on M. tuberculosis H37Rv support their use in traditional medicine for the treatment of coughs associated with TB and reveals the presence of anti-Mtb active compounds in the plants. These findings not only demonstrate a new potential area of therapeutic value of E. camaldulensis and E. torelliana, but also illustrate the role of esters as anti-Mtb active principles in ethnobotanical preparations and as lead compounds in the development of new and effective anti-Mtb drugs.

Characterization of phenolic components in polar extracts of Eucalyptus globulus Labill. bark by high-performance liquid chromatography-mass spectrometry

High-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) and tandem mass spectrometry (MS(n)) were used to investigate the phenolic constituents in methanol, water, and methanol/water extracts of Eucalyptus globulus Labill. bark. Twenty-nine phenolic compounds were identified, 16 of them referenced for the first time as constituents of E. globulus bark, namely, quinic, dihydroxyphenylacetic, and caffeic acids, bis(hexahydroxydiphenoyl (HHDP))-glucose, galloyl-bis(HHDP)-glucose, galloyl-HHDP-glucose, isorhamentin-hexoside, quercetin-hexoside, methylellagic acid (EA)-pentose conjugate, myricetin-rhamnoside, isorhamnetin-rhamnoside, mearnsetin, phloridzin, mearnsetin-hexoside, luteolin, and a proanthocyanidin B-type dimer. Digalloylglucose was identified as the major compound in the methanol and methanol/water extracts, followed by isorhamnetin-rhamnoside in the methanol extract and by catechin in the methanol/water extract, whereas in the water extract catechin and galloyl- HHDP-glucose were identified as the predominant components. The methanol/water extract was shown be the most efficient to isolate phenolic compounds identified in E. globulus bark.

Analysis by high-performance liquid chromatography diode array detection mass spectrometry of phenolic compounds in fruit of Eucalyptus globulus cultivated in Algeria

A method based on high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) following fractionation by chromatography on a Sephadex LH-20 column has been developed to determine the phenolic composition of fruit of Eucalyptus globulus growing in Algeria. The presence of 18 gallotannins, 26 ellagitannins, and 2 flavonols was established. Tentative identification is provided for these compounds on the basis of UV-visible spectra and mass spectrometry data. Most compounds described in this study have not previously detected in fruit of E. globulus. Moreover, this is the first report of methyl digalloyl diglucose, 3,3'-O-dimethylellagic acid 4-O-β-glucopyranoside, ellagic acid hexose, methyl ellagic acid pentose, methyltetragalloylglucose, and valoneic acid isomers (sanguisorbic, flavogallic acid dilactone) in the genus Eucalyptus. Quantitatively, ellagic acid and its derivatives, including ellagitannins, are largely predominant.

Nematicidal natural products from the aerial parts of Rubus niveus

Studies on the aerial parts of Rubus niveus yielded six known compounds, 3,5-dihydroxy benzoic acid C(7)H(6)O(4), (1), gallic acid C(7)H(6)O(5) (2), ethyl galactoside (3), oleanolic acid (4), beta-sitosterol (5) and 3-O-[beta-D-galactopyranosyl-(12)-D-glucopyranoside (6). Besides this, a gallic acid derivative with methyl substitution was synthesised as tetramethyl gallate (3). Together with this derivative, compounds 1, 2, the alcohol soluble, chloroform soluble and petroleum ether soluble extracts of the aerial parts of R. niveus were screened for its nematicidal activity against freshly hatched second stage juveniles of Meloidogyne incognita (root-knot nematode), exhibiting 100, 94, 100, 52, 45 and 14% mortality, respectively of M. incognita after 48 h at 0.5% concentration. Compounds 1, 2 and 3 were found to be more potent than the nematicide Azadirachta indica at the same concentration. Negative results were obtained for nematicidal activity of the petroleum ether extract of R. niveus leaf extract. This is the first report on the isolation of chemical constituents as well as the nematicidal activity of compounds and any part of R. niveus.

Phloroglucinol glycosides from the fresh fruits of Eucalyptus maideni

Five new phloroglucinol glycosides, eucalmainosides A-E (1-5), were isolated from the fresh fruits of Eucalyptus maideni, along with 15 flavonoids (6-20), seven (+)-oleuropeic acid derivatives (15, 16, and 22-26), three hydrolyzable tannins (32-34), and six simple phenolic compounds (21, 27-31). Their structures were determined on the basis of spectroscopic analyses, including HSQC, HMBC, and acidic hydrolysis. The in vitro anti-herpes simplex virus 1 (HSV-1) assay indicated that the flavonols, myricetin (6) and quercetin (7), and the ellagitannin isocoriariin F (33) showed weak anti-HSV-1 activity with TIC values of 0.31, 0.33, and 0.12 mM, respectively.

Ellagic Acid Derivatives from Syzygium cumini Stem Bark: Investigation of their Antiplasmodial Activity

Bioguided fractionation of Syzygium cumini (Myrtaceae) bark decoction for antiplasmodial activity was performed, leading to the isolation of three known ellagic acid derivatives (ellagic acid, ellagic acid 4-O-α-L-2″-acetylrhamnopyranoside, 3-O-methylellagic acid 3′-O-α-L-rhamnopyranoside), as well as the new derivative 3-O-methylellagic acid 3′-O-β-D-glucopyranoside. Activity investigation was based on the reduction of P. falciparum (PfK1) parasitaemia in vitro and the inhibition of β-hematin formation, a known mechanism of action of some antimalarial drugs. Among the investigated ellagic acid derivatives, only ellagic acid was able to reduce P. falciparum parasitaemia in vitro and inhibit β-hematin formation, suggesting that free hydroxyl groups are necessary for activity within this class of compounds.

Infusions of Portuguese medicinal plants: Dependence of final antioxidant capacity and phenol content on extraction features

BACKGROUND

Aqueous extracts of most medicinal plants traditionally employed in Portugal (at the ratio of 1 g plant: 110 mL water) have been assayed for total antioxidant capacity and phenol content, in order to elucidate their claimed medicinal features.

RESULTS

The antioxidant activity was assessed by the ABTS(•+) method; the ascorbic acid equivalent values ranged from 1.4280 ± 0.1261 g L(-1) for avocado (Persea americana (Lauraceae)) obtained by infusion of powder, down to 0.0027 ± 0.0012 g L(-1) for olive (Olea europaea (Oleaceae)) obtained by infusion of leaves. Total phenol content was determined by the Folin-Ciocalteu procedure; the gallic acid equivalent values ranged from 0.5541 ± 0.0289 g L(-1) for avocado obtained by infusion of powder, down to 0.0053 ± 0.0014 g L(-1) for olive obtained by boiling leaves. A good correlation between total antioxidant capacity and total phenol content was found.

CONCLUSION

The method of powder infusion should be chosen if high concentration of antioxidants are sought. On the other hand, a high antioxidant capacity and a high phenol content correlate well with the empirically established (and widely publicised) capacity to treat respiratory infections. Copyright © 2007 Society of Chemical Industry.

Ericifolin: an eugenol 5-O-galloylglucoside and other phenolics from Melaleuca ericifolia

Ericifolin, an eugenol 5-O-beta-(6'-O-galloylglucopyranoside) possessing the naturally unknown phenolic moiety, 5-hydroxyeugenol, together with the two new phenolics, 2-O-p-hydroxybenzoyl-6-O-galloyl-(alpha/beta)-4C1-glucopyranose and 3-methoxyellagic acid 4-O-rhamnopyranoside have been isolated from the antibacterial leaves extract of Melaleuca ericifolia. In addition, 19 known phenolics were also separated and characterized. All structures were elucidated on the basis of analysis of 1H, 13C NMR, HMQC, HMBC and FTMS spectral data.

Ellagic acid glycosides fromTurpinia ternata

Bioassay-guided fractionation of the methanolic extract of Turpinia ternata stems, has led to the isolation of the new ellagic acid derivative 3,4'-di-O-methylellagic acid-4-O-alpha-L-arabinofuranoside (1), and the known compounds ellagic acid (2), 3-O-methyl ellagic acid (3), 3-O-methylellagic acid-3'-O-alpha-L-rhamnopyranoside (4), and 3,3'-di-O-methylellagic acid-4'-O-alpha-D-glucopyranoside (5). Their structures were elucidated by extensive spectroscopic methods. Compounds 1, 3, and 4 showed moderate antioxidant activity against DPPH free radical, whereas compound 1 was found to be moderately cytotoxic against Artemia salina larvae.

Anti-babesial ellagic acid rhamnosides from the bark of Elaeocarpus parvifolius

Bioassay-guided investigation of the bark of Elaeocarpus parvifolius led to the isolation of three new ellagic acid derivatives, 4-O-methylellagic acid 3'-alpha-rhamnoside (2), 4-O-methylellagic acid 3'-(3''-O-acetyl)-alpha-rhamnoside (3), and 4-O-methylellagic acid 3'-(4''-O-acetyl)-alpha-rhamnoside (4) in addition to the known ellagic acid derivative, 4-O-methylellagic acid 3'-(2'',3''-di-O-acetyl)-alpha-rhamnoside (1). Their structures were elucidated on the basis of analysis of 1H NMR, 13C NMR, HMQC, HMBC and MS spectroscopic data. Compounds 1-4 were evaluated for their growth-inhibitory effect on Babesia gibsoni in vitro. Compounds 2 and 4 showed very weak activity, while compounds 1 and 3 showed moderate activity, with IC50 values of 28.5 and 52.1 microg/ml, respectively.

Cypellogins A, B and C, Acylated Flavonol Glycosides from Eucalyptus cypellocarpa

Three new acylated flavonol glycosides, cypellogins A (1), B (2) and C (3), along with eight known phenolic compounds, were isolated from the dried leaves of Eucalyptus cypellocarpa, and their structures were elucidated using spectroscopic methods, including 2D NMR experiments and chemical evidence.

Stages of activation of hepatic stellate cells: effects of ellagic acid, an inhibiter of liver fibrosis, on their differentiation in culture

To further explore that hepatic stellate cell (HSC) activation results in physiological protection against environmental insult, the profile of differentiation of HSC has been examined upon treatment with ellagic acid (EA), a plant-derived antioxidant that shows multiple protective effects during liver disease. Sparse rat liver cell cultures were grown in media containing EA (3, 6, 30 and 100 microg/ml) and, as controls, without EA, and inspected until day 7 in culture. The cells were double-labelled with antibodies against glial fibrillary acidic protein (GFAP) and smooth muscle alpha-actin (SMAA), marker proteins of quiescent and activated HSC, respectively. In EA-free culture conditions, the quiescent (SMAA-/GFAP+) HSC transiently acquired a semi-activated (SMAA+/GFAP+), phenotype and were further transformed into activated (SMAA+/GFAP-), pleomorphic HSC. Up to a concentration of 30 microg/ml, EA induced an early synthesis of SMAA in all HSC and inhibited their morphologic differentiation and individual growth throughout the culture period. At a concentration of 6 microg/ml, EA supported the semi-activated (SMAA+/GFAP+) phenotype of HSC throughout the culture period, whereas treatment with high EA concentrations (30 microg/ml) resulted in an early loss of GFAP expression.

IN CONCLUSION

(i) the uniform response of HSC to EA by mild activation adds functional significance to cellular features preceding the transformation of HSC to myofibroblasts; (ii) the high sensitivity of HSC to EA treatment suggests their involvement in any mechanisms of protection by this antioxidant; (iii) the maintenance of HSC morphology might be one of the factors playing a role in the prevention or slowing down of liver fibrosis; (iv) because the effects of EA are concentration- and time-dependent, an arbitrary usage of this antioxidant is a matter of potential concern; (v) the various patterns of HSC activation observed might correspond to distinct activities of these cells, which, in turn, might lead to different outcomes of liver fibrosis.

Novel detection of formylated phloroglucinol compounds (FPCs) in the wound wood of Eucalyptus globulus and E. nitens

This study characterized the chemical responses of Eucalyptus globulus and Eucalyptus nitens to artificial inoculation with a basidiomycete decay fungus. Nine-year-old trees responded to mechanical wounding or inoculation with the decay fungus by producing new wound wood characterized by the presence of dark extractives 17 months after wounding. Analysis of crude wound wood extracts by HPLC coupled to negative ion electrospray mass spectrometry revealed the presence of a complex mixture of many unidentified formylated phlorglucinol compounds (FPCs), in addition to a diverse range of other polyphenolic compounds (hydrolyzable tannins, proanthocyanidins, flavanone glycoside, stilbene glycosides). Prior to this study, FPCs have only been reported from leaves and buds of Eucalyptus spp. Unequivocal evidence for the presence of macrocarpal A and B, and sideroxylonal A and B in the crude extracts was obtained, as well as evidence for a wide range of as yet unreported FPCs. Subsequent preliminary in vitro fungal and bacterial bioassays did not support an antimicrobial role for FPCs in host-pathogen interactions in eucalypts.

Novel detection of formylated phloroglucinol compounds (FPCs) in the wound wood of Eucalyptus globulus and E. nitens

This study characterized the chemical responses of Eucalyptus globulus and Eucalyptus nitens to artificial inoculation with a basidiomycete decay fungus. Nine-year-old trees responded to mechanical wounding or inoculation with the decay fungus by producing new wound wood characterized by the presence of dark extractives 17 months after wounding. Analysis of crude wound wood extracts by HPLC coupled to negative ion electrospray mass spectrometry revealed the presence of a complex mixture of many unidentified formylated phlorglucinol compounds (FPCs), in addition to a diverse range of other polyphenolic compounds (hydrolyzable tannins, proanthocyanidins, flavanone glycoside, stilbene glycosides). Prior to this study, FPCs have only been reported from leaves and buds of Eucalyptus spp. Unequivocal evidence for the presence of macrocarpal A and B, and sideroxylonal A and B in the crude extracts was obtained, as well as evidence for a wide range of as yet unreported FPCs. Subsequent preliminary in vitro fungal and bacterial bioassays did not support an antimicrobial role for FPCs in host-pathogen interactions in eucalypts.