Alkaloids from Siparuna (Siparunaceae) are predicted as the inhibitors of proteolysis and plasma coagulation caused by snake venom and potentially counteract phospholipase A2 activity of Bothrops jararaca

ETHNOPHARMACOLOGICAL RELEVANCE

Snakebite envenomation (SBE) is the world's most lethal neglected tropical disease. Bothrops jararaca is the species that causes the greatest number of SBEs in the South and Southeastern of Brazil. The main symptoms are local (inflammation, edema, hemorrhage, and myonecrosis) and systemic (hemorrhage, hemostatic alterations with consumptive coagulopathy, and death) effects. Species of the genus Siparuna, Siparunaceae, are used in folk and traditional medicine to treat SBE. However, limited information is available concerning Brazilian Siparuna species against SBE.

AIM OF THE STUDY

To investigate the correlation between the compounds present in the extracts of five Siparuna species as potential agents against proteolytic activity, plasma coagulation, and phospholipase A2 (PLA2) activity caused by B. jararaca venom, using data obtained by UHPLC-MS/MS, biological activity, and multivariate statistics.

MATERIALS AND METHODS

The ethanol extracts from leaves of S. ficoides, S. decipiens, S. glycycarpa, S. reginae, and S. cymosa were fractionated by liquid-liquid extraction using different solvents of increasing polarity (hexane, dichloromethane, ethyl acetate, and n-butanol), affording their respective extracts, totaling 25 samples that were assayed through in vitro plasma coagulation and proteolytic activity assays. Moreover, the extracts were analyzed by UHPLC-MS/MS, using electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) in negative and positive ionization modes. The data was processed in MZmine v. 2.53 and evaluated by multivariate statistical tests (PLS) using the software UnscramblerX v. 10.4. These data were also used to build molecular networks (GNPS), and some ions of interest could be annotated using the library of molecules on the GNPS platform.

RESULTS

A total of 19 extracts inhibited B. jararaca-induced plasma coagulation, with emphasis on S. cymosa and S. reginae (800 s). The inhibition of the proteolytic activity was also promising, ranging from 16% (S. glycycarpa) to 99% (S. cymosa, S. decipiens, and S. reginae). In addition, most extracts from S. cymosa and S. reginae inhibited 70-90% of PLA2 activity. Based on data from positive mode APCI analyses, it was possible to obtain a statistic model with reliable predictive capacity which exhibited an average R2 of 0.95 and a Q2 of 0.88, indicating a robust fit. This process revealed five ions, identified as the alkaloids: coclaurine (1), stepholidine (2) O-methylisopiline (3), nornantenine (4) and laurolitsine (5). This is the first study to evidence the potential antivenom of alkaloids from Siparuna species.

CONCLUSIONS

Altogether, our results give support to the popular use of Siparuna extracts in SBE accidents, suggesting their potential as an alternative or complementary strategy against envenoming by B. jararaca venom. The predicted ions in the chemometric analysis for the assayed activities can also be correlated with the blocking activity and encourage the continuation of this study for possible isolation and testing of individual compounds on the used models.

Myrtucommulones and Related Acylphloroglucinols from Myrtaceae as a Promising Source of Multitarget SARS-CoV-2 Cycle Inhibitors

The LABEXTRACT plant extract bank, featuring diverse members of the Myrtaceae family from Brazilian hot spot regions, provides a promising avenue for bioprospection. Given the pivotal roles of the Spike protein and 3CLpro and PLpro proteases in SARS-CoV-2 infection, this study delves into the correlations between the Myrtaceae species from the Atlantic Forest and these targets, as well as an antiviral activity through both in vitro and in silico analyses. The results uncovered notable inhibitory effects, with Eugenia prasina and E. mosenii standing out, while E. mosenii proved to be multitarget, presenting inhibition values above 72% in the three targets analyzed. All extracts inhibited viral replication in Calu-3 cells (EC50 was lower than 8.3 µg·mL-1). Chemometric analyses, through LC-MS/MS, encompassing prediction models and molecular networking, identified potential active compounds, such as myrtucommulones, described in the literature for their antiviral activity. Docking analyses showed that one undescribed myrtucommulone (m/z 841 [M - H]-) had a higher fitness score when interacting with the targets of this study, including ACE2, Spike, PLpro and 3CLpro of SARS-CoV-2. Also, the study concludes that Myrtaceae extracts, particularly from E. mosenii and E. prasina, exhibit promising inhibitory effects against crucial stages in SARS-CoV-2 infection. Compounds like myrtucommulones emerge as potential anti-SARS-CoV-2 agents, warranting further exploration.

Antiviral, Cytoprotective, and Anti-Inflammatory Effect of Ampelozizyphus amazonicus Ducke Ethanolic Wood Extract on Chikungunya Virus Infection

Chikungunya fever, a debilitating disease caused by Chikungunya virus (CHIKV), is characterized by a high fever of sudden onset and an intense arthralgia that impairs individual regular activities. Although most symptoms are self-limited, long-term persistent arthralgia is observed in 30-40% of infected individuals. Currently, there is no vaccine or specific treatment against CHIKV infection, so there is an urgent need for the discovery of new therapeutic options for CHIKF chronic cases. This present study aims to test the antiviral, cytoprotective, and anti-inflammatory activities of an ethanol extract (FF72) from Ampelozizyphus amazonicus Ducke wood, chemically characterized using mass spectrometry, which indicated the major presence of dammarane-type triterpenoid saponins. The major saponin in the extract, with a deprotonated molecule ion m/z 897 [M-H]-, was tentatively assigned as a jujubogenin triglycoside, a dammarane-type triterpenoid saponin. Treatment with FF72 resulted in a significant reduction in both virus replication and the production of infective virions in BHK-21-infected cells. The viability of infected cells was assessed using an MTT, and the result indicated that FF72 treatment was able to revert the toxicity mediated by CHIKV infection. In addition, FF72 had a direct effect on CHIKV, since the infectivity was completely abolished in the presence of the extract. FF72 treatment also reduced the expression of the major pro-inflammatory mediators overexpressed during CHIKV infection, such as IL-1β, IL-6, IL-8, and MCP-1. Overall, the present study elucidates the potential of FF72 to become a promising candidate of herbal medicine for alphaviruses infections.

Anti-SARS-CoV-2 Activity of Ampelozizyphus amazonicus (Saracura-Mirá): Focus on the Modulation of the Spike-ACE2 Interaction by Chemically Characterized Bark Extracts by LC-DAD-APCI-MS/MS

Traditional medicine shows several treatment protocols for COVID-19 based on natural products, revealing its potential as a possible source of anti-SARS-CoV-2 agents. Ampelozizyphus amazonicus is popularly used in the Brazilian Amazon as a fortifier and tonic, and recently, it has been reported to relieve COVID-19 symptoms. This work aimed to investigate the antiviral potential of A. amazonicus, focusing on the inhibition of spike and ACE2 receptor interaction, a key step in successful infection. Although saponins are the major compounds of this plant and often reported as its active principles, a polyphenol-rich extract was the best inhibitor of the spike and ACE2 interaction. Chemical characterization of A. amazonicus bark extracts by LC-DAD-APCI-MS/MS before and after clean-up steps for polyphenol removal showed that the latter play an essential role in maintaining this activity. The effects of the extracts on viral replication were also assessed, and all samples (aqueous and ethanol extracts) demonstrated in vitro activity, inhibiting viral titers in the supernatant of Calu-3 cells after 24 hpi. By acting both in the SARS-CoV-2 cell entry process and its replication, A. amazonicus bark extracts stand out as a multitarget agent, highlighting the species as a promising candidate in the development of anti-SARS-CoV-2 drugs.

In silico screening of phenylethanoid glycosides, a class of pharmacologically active compounds as natural inhibitors of SARS-CoV-2 proteases

Since the advent of Covid-19, several natural products have been investigated regarding their in silico interactions with SARS-CoV-2 proteases - 3CL^pro and PL^pro, two of the most important pharmacological targets for antiviral development. Phenylethanoid glycosides (PG) are a class of natural products present in important medicinal plants and a drug containing this group of active ingredients has been successfully used in the treatment of Covid-19 in China. Thus, a dataset with 567 derivatives of this class was built from reviews published between 1994 and 2020, and their interaction against both SARS-CoV-2 proteases was investigated. The virtual screening was performed by filtering the PGs through the evaluation of scores based on the AutoDock Vina, GOLD/ChemPLP, and GOLD/GoldScore evaluation functions. The bRO5 pharmacokinetic parameters of the PGs ranked in the previous step were analyzed and their interaction with key amino acid residues of the 3CL^pro and PL^pro enzymes was evaluated. Ninety-eight compounds were identified by computational approaches against PL^pro and 80 PGs against 3CL^pro. Of these, four interacted with key catalytic residues of PL^pro, which is an indicative of inhibitory activity, and three compounds interacted with catalytic key residues of 3CL^pro. Of these, five PGs occur in plants of the Traditional Chinese Medicine (TCM), while two are components of plants/formulations currently used in the Covid-19 protocols in China. The data presented here show the potential of PGs as selective inhibitors of SARS-CoV-2 3CL^pro and PL^pro.

In vitro α-glucosidase inhibition by Brazilian medicinal plant extracts characterised by ultra-high performance liquid chromatography coupled to mass spectrometry

Aiming at finding natural sources of antidiabetics agents, 15 extracts from Brazilian medicinal plants of the Atlantic Forest and Amazon region were tested against α-glucosidase enzyme. Plants were selected based on the taxonomic relationships with genera including several species with antidiabetic activity. In this screening, the extracts obtained from the flowers of Hyptis monticola and the leaves of Lantana trifolia and Lippia origanoides resulted endowed with promising anti-α-glucosidase activity. The extracts from H. monticola and from L. origanoides collected in two different areas, were characterised by ultra-high performance liquid chromatography coupled to mass spectrometry. Bioassay-guided fractionation led to the identification of several enzyme inhibiting compounds, among them the mechanism of action of naringenin and pinocembrin was investigated. The two L. origanoides extracts showed differences in bioactivity and in the phytochemical profiles. The fractionation of the extract from H. monticola led to a partial loss of the inhibitory effect.

Saracura-Mirá, a Proposed Brazilian Amazonian Adaptogen from Ampelozizyphus amazonicus

The Amazon Forest is known all over the world for its diversity and exuberance, and for sheltering several indigenous groups and other traditional communities. There, as well as in several other countries, in traditional medical systems, weakness, fatigue and debility are seen as limiting health conditions where medicinal plants are often used in a non-specific way to improve body functions. This review brings together literature data on Ampelozizyphus amazonicus, commonly known in Brazil as "saracura-mirá" and/or "cerveja de índio", as an Amazonian adaptogen, including some contributions from the authors based on their ethnographic and laboratory experiences. Topics such as botany, chemistry, ethnopharmacological and pharmacological aspects that support the adaptogen character of this plant, as well as cultivation, market status and supply chain aspects are discussed, and the gaps to establish "saracura-mirá" as an ingredient for the pharmaceutical purposes identified. The revised data presented good scientific evidence supporting the use of this Amazonian plant as a new adaptogen. Literature data also reveal that a detailed survey on natural populations of this plant is needed, as well as agronomical studies that could furnish A. amazonicus bark as a raw material. Another important issue is the lack of developed quality control methods to assure its quality assessment.

Bioassay-Guided Fractionation of Siparuna glycycarpa n-Butanol Extract with Inhibitory Activity against Influenza A(H1N1)pdm09 Virus by Centrifugal Partition Chromatography (CPC)

Siparuna glycycarpa occurs in the Amazon region, and some species of this genus are used in Brazilian folk medicine. A recent study showed the inhibitory effect of this species against influenza A(H1N1)pdm09 virus, and in order to acquire active fractions, a polar solvent system n-butanol-methanol-water (9:1:10, v/v) was selected and used for bioassay-guided fractionation of n-butanol extract by centrifugal partition chromatography (CPC). The upper phase was used as stationary phase and the lower phase as mobile (descending mode). Among the collected fractions, the ones coded SGA, SGC, SGD, and SGO showed the highest antiviral inhibition levels (above 74%) at 100 µg·mL-1 after 24 h of infection. The bioactive fractions chemical profiles were investigated by LC-HRMS/MS data in positive and negative ionization modes exploring the Global Natural Products Social Molecular Networking (GNPS) platform to build a molecular network. Benzylisoquinoline alkaloids were annotated in the fractions coded SGA, SGC, and SGD collected during elution step. Aporphine alkaloids, O-glycosylated flavonoids, and dihydrochalcones in SGO were acquired with the change of mobile phase from lower aqueous to upper organic. Benzylisoquinolinic and aporphine alkaloids as well as glycosylated flavonoids were annotated in the most bioactive fractions suggesting this group of compounds as responsible for antiviral activity.

Flavonoids from Siparuna cristata as Potential Inhibitors of SARS-CoV-2 Replication

The novel coronavirus SARS-CoV-2 has been affecting the world, causing severe pneumonia and acute respiratory syndrome, leading people to death. Therefore, the search for anti-SARS-CoV-2 compounds is pivotal for public health. Natural products may present sources of bioactive compounds; among them, flavonoids are known in literature for their antiviral activity. Siparuna species are used in Brazilian folk medicine for the treatment of colds and flu. This work describes the isolation of 3,3',4'-tri-O-methyl-quercetin, 3,7,3',4'-tetra-O-methyl-quercetin (retusin), and 3,7-di-O-methyl-kaempferol (kumatakenin) from the dichloromethane extract of leaves of Siparuna cristata (Poepp. & Endl.) A.DC., Siparunaceae, using high-speed countercurrent chromatography in addition to the investigation of their inhibitory effect against SARS-CoV-2 viral replication. Retusin and kumatakenin inhibited SARS-CoV-2 replication in Vero E6 and Calu-3 cells, with a selective index greater than lopinavir/ritonavir and chloroquine, used as control. Flavonoids and their derivatives may stand for target compounds to be tested in future clinical trials to enrich the drug arsenal against coronavirus infections.

GRAPHICAL ABSTRACT

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43450-021-00162-5.

Distribution of 5,6-dihydro-α-pyrones by electrospray ionization ion trap mass spectrometry in different aerial parts of Hyptis monticola

Hyptis monticola Mart. ex Benth. (Lamiaceae) is an endemic species of altitude regions of Brazil. From the leaves of this plant, two 5,6-dihydro-α-pyrones, named monticolides A and B, have been reported as cytotoxic agents against different tumor cell lines. The isolation by high-speed countercurrent chromatography in combination with recycling preparative high-performance liquid chromatography of the undescribed monticolides C-F is presented. These compounds corresponded to a series of related monticolide derivatives differing from each other by the number of acyl substituents. Their characterization by mass spectrometry and nuclear magnetic resonance is also presented, in conjunction with an evidence by a simple chemical correlation for their absolute stereochemistry. The distribution of these chemical markers in extracts of flowers, leaves and branches collected in different seasons by electrospray ionization ion trap mass spectrometry in positive mode was analyzed. Multivariate data analyses indicated that seasonality affects monticolide concentrations in different organs of the aerial parts. Monticolides A-F seem to be present as the original markers of the analyzed plant. However, mono-, di- and triacetylated monticolides can undergo acid-catalyzed transesterifications and their natural yields estimated were affected during the isolation procedures.

Amazonian Siparuna extracts as potential anti-influenza agents: Metabolic fingerprinting

ETHNOPHARMACOLOGICAL RELEVANCE

Siparuna species are used in Brazilian Folk Medicine for the treatment and prophylaxis of colds, fever, headache, gastrointestinal disorders and rheumatic pain.

AIM OF THE STUDY

This study aimed to investigate a possible anti-influenza activity of 25 extracts from leaves of Amazonian S. cristata, S. decipiens, S. glycycarpa, S. reginae and S. sarmentosa based on their folk medicinal uses as well as to investigate their metabolic fingerprinting. The chemical composition of the active extracts was further dereplicated.

MATERIAL AND METHODS

The chemical composition of the crude EtOH extracts from five Siparuna species were investigated by ESI (±) LC-QTOF-MS². Organic extracts were obtained by liquid-liquid partition with solvents of increasing polarity, generating 25 extracts which were subjected to a quick DI-ESI (±) IT-MS fingerprint analysis. These extracts were tested against influenza virus replication and cellular toxicity using MDCK cells and influenza A/Michigan/45/2015 (H1N1)pdm09 virus. The compounds in the active BuOH extracts from S. glycycarpa and S. sarmentosa were annotated by ESI (±) LC-QTOF-MS².

RESULTS

Analysis of the EtOH extracts revealed the presence of alkaloids and flavonoids, in the positive and negative ionization modes. Out of the 25 organic extracts screened for their antiviral activity, the BuOH extracts from S. glycycarpa and S. sarmentosa were the most active, inhibiting 96.0 ± 1.3% and 89.5 ± 0.8% of influenza virus replication 24 h post-infection. These inhibitory effects were maintained until 72hpi. Alkaloids, O- and C-flavonoid glycosides, dihydrochalcones and a procyanidin dimer were annotated in these extracts.

CONCLUSIONS

The inhibitory effect against influenza A(H1N1)pdm09 virus replication shown by Amazonian Siparuna species corroborates the use of these plants in Brazilian Folk Medicine, showing their potential as anti-influenza agents. These promising results stimulate the continuation of this study with the aim of isolating the compound(s) responsible for this bioactivity, thus contributing to a better knowledge of those species and to the research of natural products with potential anti-influenza activity.

Antifungal Phenylpropanoid Glycosides from Lippia rubella

Lippia species share various pharmacological activities and are used in traditional cooking and medicine worldwide. Combined chromatographic techniques such as column chromatography, high-performance liquid chromatography, and countercurrent chromatography led to the purification of two new antifungal phenylpropanoid glycosides, lippiarubelloside A (1) and lippiarubelloside B (2), by bioactivity-directed fractionation of an ethanol-soluble extract from Lippia rubella, in addition to the known active related compounds forsythoside A (3), verbascoside (4), isoverbascoside (5), and poliumoside (6). The structures of compounds 1 and 2 were determined by comparison of their NMR spectroscopic data with the prototype active compound 4. Cryptococcus neoformans, which causes opportunistic lung infections, was sensitive to compounds 1-6 in the concentration range of 15-125 μg/mL. A synergistic effect (FIC_index = 0.5) between 3 and amphotericin B was demonstrated. The glycosylated flavonoids pectolinarin (7), linarin (8), and siparunoside (9) were also isolated.

Structure Elucidation, Conformation, and Configuration of Cytotoxic 6-Heptyl-5,6-dihydro-2 H-pyran-2-ones from Hyptis Species and Their Molecular Docking to α-Tubulin

Cytotoxic 6-heptyl-5,6-dihydro-2 H-pyran-2-ones are chemical markers of Hyptis (Lamiaceae) and are responsible for some of the therapeutic properties of species with relevance to traditional medicine. The present investigation describes the isolation of known pectinolides A-C (1-3), in addition to the new pectinolides I-M (4-8), from two Mexican collections of H. pectinata by HPLC. The novel biosynthetically related monticolides A (9) and B (10) were also isolated by high-speed countercurrent chromatography from H. monticola, an endemic species of the Brazilian southeastern high-altitude regions. A combination of chemical correlations, chiroptical measurements, and Mosher ester NMR analysis was used to confirm their absolute configuration. The utility of DFT-NMR chemical shifts and J_H-H calculations was assessed for epimer differentiation. Molecular docking studies indicated that 6-heptyl-5,6-dihydro-2 H-pyran-2-ones have a high affinity for the pironetin-binding site of α-tubulin, which may be a possible mechanism contributing to the cytotoxic potential of these small and flexible molecules.

Preparative mass-spectrometry profiling of minor concentrated metabolites in Salicornia gaudichaudiana Moq by high-speed countercurrent chromatography and off-line electrospray mass-spectrometry injection

Salicornia species have just been introduced to the European market as a vegetable named 'samphire', 'green asparagus', or 'sea asparagus'. Due to its increasing attention, and associated value, minor compounds of Salicornia gaudichaudiana Moq were investigated. The use of countercurrent chromatography and mass spectrometry enabled the search for known, as well as potentially novel natural products. Their identification was achieved based on molecular weights and mass-spectrometric fragmentation data. Low detection limits enabled the visualization of all compounds with their identification in almost real time close to the preparative countercurrent chromatography experiment. A list of known natural products from Salicornia genus guided the identification process of compounds occurring in Salicornia gaudichaudiana Moq by tandem mass spectrometry fragment comparison. The natural product classes were divided into four groups: chlorogenic acid derivatives; flavonoid derivatives; pentacyclic triterpenoid saponins; and other compounds.

Countercurrent chromatography separation of saponins by skeleton type from Ampelozizyphus amazonicus for off-line ultra-high-performance liquid chromatography/high resolution accurate mass spectrometry analysis and characterisation

Ampelozizyphus amazonicus Ducke (Rhamnaceae), a medicinal plant used to prevent malaria, is a climbing shrub, native to the Amazonian region, with jujubogenin glycoside saponins as main compounds. The crude extract of this plant is too complex for any kind of structural identification, and HPLC separation was not sufficient to resolve this issue. Therefore, the aim of this work was to obtain saponin enriched fractions from the bark ethanol extract by countercurrent chromatography (CCC) for further isolation and identification/characterisation of the major saponins by HPLC and MS. The butanol extract was fractionated by CCC with hexane - ethyl acetate - butanol - ethanol - water (1:6:1:1:6; v/v) solvent system yielding 4 group fractions. The collected fractions were analysed by UHPLC-HRMS (ultra-high-performance liquid chromatography/high resolution accurate mass spectrometry) and MSn. Group 1 presented mainly oleane type saponins, and group 3 showed mainly jujubogenin glycosides, keto-dammarane type triterpene saponins and saponins with C31 skeleton. Thus, CCC separated saponins from the butanol-rich extract by skeleton type. A further purification of group 3 by CCC (ethyl acetate - ethanol - water (1:0.2:1; v/v)) and HPLC-RI was performed in order to obtain these unusual aglycones in pure form.

A new tropane alkaloid from the leaves of Erythroxylum subsessile isolated by pH-zone-refining counter-current chromatography

Tropane alkaloids are bioactive metabolites with great importance in the pharmaceutical industry and the most important class of natural products found in the Erythroxylum genus. However, these compounds are usually separated by traditional chromatographic techniques, in which the sample is progressively purified in multiple chromatographic steps, resulting in a time- and solvent-consuming procedure. In this work we present the isolation of a novel alkaloid, 6β,7β-dibenzoyloxytropan-3α-ol, together with the two known 3α-benzoyloxynortropan-6β-ol and 3α,6β-dibenzoyloxytropane alkaloids, directly from the crude alkaloid fraction from the leaves of Erythroxylum subsessile, by using a single run pH-zone-refining counter-current chromatography method. The ethyl acetate/water (1:1, v/v) biphasic solvent system with triethylamine and HCl as retention and eluter agents, respectively, was used to isolate tropane alkaloids for the first time. The structures of the isolated alkaloids were elucidated by spectroscopic methods.

Gradient x Isocratic Elution CCC on the Isolation of Verbascoside and Other Phenylethanoids: Influence of the Complexity of the Matrix

Verbascoside is a phenylethanoid glycoside widely distributed in nature, especially among the order Lamiales, occurring in numerous plants that are constituents of folk medicine preparations. This natural compound, previously isolated by our group from the ethyl acetate extract of Lantana trifolia using the gradient approach in countercurrent chromatography, was now isolated from the butanol extract of the same plant and from Lippia alba f. intermedia (Verbenaceae) using countercurrent chromatography in either gradient or isocratic elution modes. The ethyl acetate extract of L. alba, rich in phenylethanoids and flavonoids, was fractionated using countercurrent chromatography in the step-gradient elution approach. The four-step solvent system was composed of n-hexane-ethyl acetate-n-butanol-water (4 : 10 : X : 10), where X = 1 (solvent system A), 3 (solvent system B), 5 (solvent system C), and 7 (solvent system D), and allowed for the isolation of verbascoside along with other phenylethanoids and flavonoids from both plants. Verbascoside and 2'-O-β-apiosylverbascoside were further isolated from the n-butanol extract of L. trifolia using the solvent system ethyl acetate-n-butanol-water 10 : 2 : 10 on an isocratic run. The difference in the complexity of the two plant extracts demanded different purification steps, which included a second high-speed countercurrent chromatography purification using the isocratic elution mode.

Gradient Elution in Countercurrent Chromatography

Countercurrent chromatography is a form of liquid-liquid partition chromatography in which the stationary liquid phase is retained in the apparatus without the use of a solid support. Gradient elution in countercurrent chromatography can be used in many different ways, such as linear gradients, stepwise elution gradients, pH gradients, etc. The main goal of using the gradient approach is to shorten the duration of the separation and improve resolution, especially when the retention range of the sample to be purified is broadening and, thus, the compounds cannot be purified by only one solvent system. The principle is based on modifying the mobile phase to increase the elution strength with no or minimum changes in the stationary phase, which can be a difficult task since both phases are in intimate contact all the time. The most common ways to perform gradients in countercurrent chromatography are changing the mobile's phase polarity, flow rate, and pH, what is called linear or step gradient, flow rate gradient, pH gradient, respectively.

Solvent system selectivities in countercurrent chromatography using Salicornia gaudichaudiana metabolites as practical example with off-line electrospray mass-spectrometry injection profiling

For the development of an efficient two-stage isolation process for high-speed countercurrent chromatography (HSCCC) with focus on principal metabolites from the ethyl acetate extract of the halophyte plant Salicornia gaudichaudiana, separation selectivities of two different biphasic solvent systems with similar polarities were evaluated using the elution and extrusion approach. Efficiency in isolation of target compounds is determined by the solvent system selectivity and their chronological use in multiple separation steps. The system n-hexane-ethyl acetate-methanol-water (0.5:6:0.5:6, v/v/v/v) resulted in a comprehensive separation of polyphenolic glycosides. The system n-hexane-n-butanol-water (1:1:2, v/v/v) was less universal but was highly efficient in the fractionation of positional isomers such as di-substituted cinnamic acid quinic acid derivatives. Multiple metabolite detection performed on recovered HSCCC tube fractions was done with rapid mass-spectrometry profiling by sequential off-line injections to electrospray mass-spectrometry (ESI-MS/MS). Selective ion traces of metabolites delivered reconstituted preparative HSCCC runs. Molecular weight distribution of target compounds in single HSCCC tube fractions and MS/MS fragment data were available. Chromatographic areas with strong co-elution effects and fractions of pure recoverable compounds were visualized. In total 11 metabolites have been identified and monitored. Result of this approach was a fast isolation protocol for S. gaudichaudiana metabolites using two solvent systems in a strategic sequence. The process could easily be scaled-up to larger lab-scale or industrial recovery.

Isolation of phenolics from Rhizophora mangle by combined counter-current chromatography and gel-filtration

Nine phenolic compounds, quercetin, epi-catechin, catechin, 4-hydroxybenzoic acid, kaempferol 3-O-β-glucopyranoside, quercetin 3-O-β-glucopyranoside, quercetin 3-O-6"-trans-coumaroyl-β-glucoside, kaempferol 3-O-β-rutinoside and quercetin 3-O-β-rutinoside, were isolated from the EtOAc leaf extract of Rhizophora mangle (Rhizophoraceae) combining counter-current chromatography (CCC) and gel-filtration. A solvent system of n-hexane-ethyl acetate-methanol-water (1.5:6:1.5:6) was employed at the preliminary stage of EtOAc extract fractionation as it was shown to contain compounds that differed highly in their hydrophobicity. The obtained fractions were further purified by either CCC or gel-filtration depending on their complexity. The isolated compounds were analyzed by NMR spectroscopy and the proposed structures were confirmed by HRES/ESI/TOF MS. Some of these compounds were isolated and/or identified for the first time in R. mangle.

Isolation of Phenolics from Rhizophora mangle by Combined Counter-current Chromatography and Gel-Filtration

Nine phenolic compounds, quercetin, epi-catechin, catechin, 4-hydroxybenzoic acid, kaempferol 3- O-β-glucopyranoside, quercetin 3- O-β-glucopyranoside, quercetin 3- O-6″- trans-coumaroyl-β-glucoside, kaempferol 3- O-β-rutinoside and quercetin 3- O-β-rutinoside, were isolated from the EtOAc leaf extract of Rhizophora mangle (Rhizophoraceae) combining counter-current chromatography (CCC) and gel-filtration. A solvent system of n-hexane-ethyl acetate-methanol-water (1.5:6:1.5:6) was employed at the preliminary stage of EtOAc extract fractionation as it was shown to contain compounds that differed highly in their hydrophobicity. The obtained fractions were further purified by either CCC or gel-filtration depending on their complexity. The isolated compounds were analyzed by NMR spectroscopy and the proposed structures were confirmed by HRES/ESI/TOF MS. Some of these compounds were isolated and/or identified for the first time in R. mangle.

Changes in the mobile phase composition on a stepwise counter-current chromatography elution for the isolation of flavonoids from Siparuna glycycarpa

This paper describes the isolation of flavonoids and other aromatic compounds from an ethyl acetate extract of leaves of Siparuna glycycarpa using stepwise elution counter-current chromatography (CCC). The elution profile yielded the following compounds: diglycosylated flavonoids, quercetin 3-O-rutinoside and quercetin 7-O-rutinoside, followed by monoglycosylated flavonoids, kaempferol-3-O-β-glucopyranoside, kaempferol-3-O-β-rhamnopiranoside, kaempferol-3-O-β-6''(p-coumaroyl) glucopyranoside, and quercetin-3-O-β-glucopyranoside, and then free phenolics, protocatechuic acid, and 2',6'-dihydroxy-4, 4'-dimethoxydihydrochalcone, which shows that this type of elution covers a broader range of polarity than the traditional isocratic mode. This makes it more suitable to perform separations of mixtures containing large differences in hydrophobicity. A GC analysis of a blank CCC run was performed to determine if changes in the mobile phase composition affect the chromatographic process. Results showed a gradual variation of the composition of the mobile phase emerging after the step gradient, favoring the selectivity of the solvent system.

Isolation of two bioactive diterpenic acids from Copaifera glycycarpa oleoresin by high-speed counter-current chromatography

INTRODUCTION

Phytochemical and biological studies carried out on Copaifera species showed that their oleoresins and isolated compounds have various biological activities.

OBJECTIVE

The aims of this work were (i) to analyse the Copaifera oleoresin by gas chromatography-mass spectrometry, (ii) to isolate the diterpenic acids from this oleoresin by high-speed countercurrent chromatography (HSCCC) and (iii) to determine the rhodamine 6G Pdr5p activity of these acids.

METHODOLOGY

HSCCC was used for the preparative separation of the diterpenes. Spectroscopic methods were used to establish their identity.

RESULTS

The gas chromatogram of the oleoresin showed approximately 30 compounds. The two major ones, kaur-16-en-18-oic and polyalthic acids, were isolated in high purity. Kaur-16-en-18-oic acid exhibited the highest rodomine 6G Pdr5p activity among the tested compounds.

CONCLUSION

HSCCC was shown to be a quick and effective tool in the isolation and purification of diterpenes from Copaifera oleoresin. This is the first report on the use of HSCCC for the fractionation of an oleoresin from Copaifera and the isolation of diterpenes therein.

Strategies of solvent system selection for the isolation of flavonoids by countercurrent chromatography

Flavonoids form a large class of important naturally occurring bioactive compounds. Their isolation and purification from natural sources can sometimes be very difficult and time-consuming when traditional phytochemical techniques are used. Countercurrent chromatography (CCC), a support-free liquid-liquid partition chromatography technique, is very useful for the isolation of polar compounds and its use is increasing in the natural products field. In this paper, we propose strategies of solvent system selection for the isolation of flavonoids by CCC, based on data from the literature, plus incorporation of own practical experiences. The selected references report the isolation of over 300 different flavonoid compounds from more than 100 plant species, using 40 different solvent systems, showing the versatility of this technique. The solvent system hexane-ethylacetate-methanol-water is proposed as a starting point for the separation of samples containing free flavonoids, as it was cited in more than 60% of the papers. A "fine tuning" step is proposed at each level of this solvent family. Other modifications include exchanging the alcohol in the system as well as introducing a fifth solvent. The solvent system ethyl-acetate-butanol-water is proposed as the starting point for glycosylated flavonoids. Other solvent systems are also discussed. The use of gradients is proposed for samples containing both free and glycosylated flavonoids, as the polarity window is larger in these cases. High-speed countercurrent chromatography was used in 89% of the reviewed data.

Flavones and phenylpropanoids from a sedative extract of Lantana trifolia L

The flavone glycosides, named scutellarein-7-O-beta-D-apiofuranoside and apigenin-7-O-beta-D-apiofuranosyl-(1-->2)-beta-D-apiofuranoside, and the flavone celtidifoline (5,6,4',5'-tetrahydroxy-7,3'-dimethoxyflavone), along with other 11 known compounds, were isolated from leaves of the ethyl acetate extract of Lantana trifolia L. using step gradient High Speed Countercurrent Chromatography (HSCCC) and High Performance Liquid Chromatography (HPLC), respectively. Their structures were elucidated by spectroscopic methods, including 2D NMR and mass spectrometry (ESI-MS) techniques. The ethanolic and ethyl acetate extracts produced an intense sedative effect in mice, one hour after oral administration of 1 mg/kg. This effect was neither due to a benzodiazepine-like effect of the three flavone derivatives neither of the phenylpropanoids, betonyoside F and verbascoside, that were tested for their affinity for the [3H] flunitrazepam binding sites.

Chemical Composition and Antimycobacterial Activity of the Essential Oil from Anemia tomentosa var. anthriscifolia

The essential oil from Anemia tomentosa var. anthriscifolia showed in vitro activity against Mycobacterium tuberculosis (MIC 100 μg/ml) and therefore was characterized by gas chromatography (GC) and by gas chromatography coupled with mass spectrometry (GC-MS). The major constituents of this essential oil were triquinane sesquiterpenes: silphiperfol-6-ene (14.7%), (–)-epi-presilphiperfolan-1-ol (30.6%), presilphiperfol-7-ene (3.9%), cameroonan-7α-ol (4.4%), prenopsan-8-ol (1.9%) and presilphiperfolan-8-ol (8.3%), suggesting the existence of different chemotypes for this species. The essential oil was fractionated by column chromatography and its major constituent and fractions were assayed against Mycobacterium tuberculosis and M. smegmatis. (–)-epi-Presilphiperfolan-1-ol exhibited an MIC of 120 μg/ml against M. tuberculosis H37Rv.

Chemical composition and antimycobacterial activity of the essential oil from Anemia tomentosa var. anthriscifolia

The essential oil from Anemia tomentosa var. anthriscifolia showed in vitro activity against Mycobacterium tuberculosis (MIC 100 microg/ml) and therefore was characterized by gas chromatography (GC) and by gas chromatography coupled with mass spectrometry (GC-MS). The major constituents of this essential oil were triquinane sesquiterpenes: silphiperfol-6-ene (14.7%), (-)-epi-presilphiperfolan-1-ol (30.6%), presilphiperfol-7-ene (3.9%), cameroonan-7 alpha-ol (4.4%), prenopsan-8-ol (1.9%) and presilphiperfolan-8-ol (8.3%), suggesting the existence of different chemotypes for this species. The essential oil was fractionated by column chromatography and its major constituent and fractions were assayed against Mycobacterium tuberculosis and M. smegmatis. (-)-epi-Presilphiperfolan-1-ol exhibited an MIC of 120 microg/ml against M. tuberculosis H37Rv.

Anatomical and chemical analyses of leaf secretory cavities of Rustia formosa (Rubiaceae)

Foliar secretory cavities, commonly called leaf pellucid glands, have been reported in many families of vascular plants. In the Rubiaceae, these structures have only been found in the sister genera Rustia and Tresanthera, which are also anomalous within the family because they have poricidal anthers, and in the distantly related Heterophyllaea. General leaf anatomy, with particular attention to secretory cavities, as well as the chemical analysis of the secreted substances of Rustia formosa, is presented here for the first time. The secretory structures have been found in the lamina between the palisade and spongy parenchymas and in the cortical region of the petiole. The chemical analysis showed that the essential oil secreted is a complex mixture of at least 75 components, mostly of sesquiterpenoid composition. Illustrations of the leaf anatomy, details of the secretory structures of Rustia formosa, a gas chromatogram, and a table of the principal components of the leaf essential oil are included.

Quantitative determination of liriodenine and moupinamide in five species of Mollinedia by high performance liquid chromatography

A simple method for the resolution and subsequent quantitative determination of liriodenine and moupinamide in Mollinedia species was developed using reversed-phase HPLC based on an octadecyl silane-packed column eluted with gradients of methanol and water.

3,4-seco-Lupanes and other constituents from Platypodium elegans

The isolation and NMR data of seco-lupane triterpenes and coumarins from Platypodium elegans are reported.

Screening of Brazilian plant extracts for antioxidant activity by the use of DPPH free radical method

Brazilian plant extracts belonging to 16 species of 5 different families (71 extracts) were tested against the stable DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free-radical. The ability to scavenge DPPH radical was measured in these experiments by the discoloration of the solution. Ginkgo biloba and rutin, commonly used as antioxidants for medical purposes, were used as standards. Based on our results, we can say that as a general rule the ethanol extracts of plants belonging to the Verbenaceae family showed lower EC(50) values than the other plant extracts. Among the partitions, the more polar ones (ethyl acetate and n-butanol) are those that generally have higher antioxidant activity (AA).

Chemical ecological characteristics of herbivory of Siparuna guianensis seeds by buffy-headed marmosets (Callithrix flaviceps) in the Atlantic Forest of southeastern Brazil

The buffy-headed marmoset (Callithrix flaviceps) is apparently the only predispersal herbivore of the seeds of Siparuna guianensis at the Caratinga Biological Station in southeastern Brazil. Both the fruit receptacles and the frutioles (seeds) of S. guianensis are relatively rich in nutrients such as carbohydrates, proteins, and lipids, but the receptacles contain high concentrations of benzylisoquinoline alkaloids. The latter presumably act as a qualitative chemical defense, impeding the access of potential predators to the alkaloid-poor frutioles. However, on ripening, the receptacle splits open, exposing the frutioles, which enables C. flaviceps to avoid the plant's chemical defenses effectively. Taking care to avoid contact with the receptacle, the marmosets pluck out the frutioles and ingest the seeds. Qualitative and quantitative changes (in particular a significant reduction in daily ranging) in the marmosets' behavior during the period when S. guianensis frutioles were accessible indicate that this was a preferred plant resource. This is the first record of the consumption of S. guianensis seeds by callitrichine monkeys (which are not known to be systematic seed eaters), despite the fact that both are widely distributed in the Neotropics. It is thus possible that the behavioral strategy observed here is a unique phenomenon resulting from a specific combination of factors, including the abundance of S. guianensis within the study area. The lack of other records may nevertheless be a result of insufficient sampling effort, in which case, the feeding strategies of callitrichines may have an important influence on the reproductive biology of S. guianensis in many areas.

Chemical constituents of two Mollinedia species

A butanolide, marliolide, was isolated from the hexane extract of leaves of Mollinedia marliae (Monimiacae) along with the long chain fatty alcohol hexacosanol. Phytol and a mixture of sitosterol and stigmasterol were also isolated from leaves of both M. marliae and M. gilgiana. trans-N-Feruloyltyramine, a ferulic acid derivative, is the major constituent of the stems of M. gilgiana.

Kaempferol glycosides from Siparuna apiosyce

The kaempferol derivative 3,7-di-O-methyl-4'-O-beta-[alpha rhamnosyl (1 --> 6)]-glucopyranoside (siparunoside) was isolated from the leaves of Sparuna apiosyce. Its structure was established by extensive NMR studies. The alkaloids reticuline and liriodenine were also isolated from the leaves along with the kaempferol derivative tiliroside. Benzylisoquinoline alkaloids were isolated from the wood (liriodenine) and wood bark (liriodenine, laurotetanine, N-methyl-laurotetanine, reticuline), together with a mixture of cis and trans-N-feruloyltyramines. 3,7,4'-tri-O-methylkaempferol was isolated from all organs.

Chemistry and pharmacology of Monimiaceae: a special focus on Siparuna and Mollinedia

The chemistry and pharmacology of species of the family Monimiaceae are reviewed, with special attention given to the genera Mollinedia and Siparuna, the two most important and representative in Brazil. The isolation of benzylisoquinoline alkaloids and kaempferol derivatives from Siparuna apiosyce is reported, as well as the isolation of aporphines from the fruits of Siparuna arianeae. Cinnamic acid derivatives and a gamma-lactone were isolated from Mollinedia gilgiana and Mollinedia marliae.