Antiprotozoal activity of natural products from Nigerien plants used in folk medicine.

In the course of the screening of plants from Niger for antiprotozoal activity, the methanol extract of Cassia sieberiana, and the dichloromethane extracts of Ziziphus mauritiana and Sesamun alatum were found to be active against protozoan parasites, namely Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and/or Plasmodium falciparum. Myricitrin (1), quercitrin (2) and 1-palmitoyl-lysolecithin (3) were isolated from C. sieberiana. From Z. mauritiana, the three triterpene derivatives 13, 15, and 16 are described here for the first time. Their chemical structures were determined by 1D and 2D NMR experiments, UV, IR and HRESIMS data. The absolute configurations were assigned via comparison of the experimental and calculated ECD spectra. In addition, eight known cyclopeptide alkaloids (4, 5, 7-12), and five known triterpenoids (6, 14, 17-19) were isolated. The antiprotozoal activity of the isolated compounds, as well as of eleven quinone derivatives (20-30) previously isolated from S. alatum was determined in vitro. The cytotoxicity in L6 rat myoblast cells was also evaluated. Compound 18 showed the highest antiplasmodial activity (IC50 = 0.2 µm) and compound 24 inhibited T. b. rhodesiense with an IC50 value of 0.007 µM. However, it also displayed significant cytotoxicity in L6 cells (IC50 = 0.4 µm).

Gastroprotective effect of Artemisia absinthium L.: A medicinal plant used in the treatment of digestive disorders.

ETHNOPHARMACOLOGICAL RELEVANCE: Wormwood (Artemisia absinthium L.) is traditionally used for stomach pain and gastric relief. However, its possible gastroprotective effect has not yet been experimentally evaluated. AIM OF THE STUDY: This study evaluated the gastroprotective effect of aqueous extracts obtained through hot and room temperature maceration of A. absinthium aerial parts in rats. MATERIALS AND METHODS: The gastroprotective effect of hot aqueous extract (HAE) and room temperature aqueous extract (RTAE) from A. absinthium aerial parts were evaluated in rats using a model of acute gastric ulcer induced by ethanol p.a. The stomachs were collected to measure the gastric lesion area and histological and biochemical analysis. UHPLC-HRMS/MS analysis was used to determine the chemical profile of the extracts. RESULTS: Eight main peaks in the UHPLC chromatogram were identified in both HAE and RTAE extracts: tuberonic acid glycoside (1), rupicolin (2), 2-hydroxyeupatolide (3), yangabin (4), sesartemin (5), artemetin (6), isoalantodiene (7), and dehydroartemorin (8). For RTAE, a higher diversity of sesquiterpene lactones was observed. The groups treated with RTAE at 3%, 10%, and 30% presented a gastroprotective effect, reducing the lesion area by 64.68%, 53.71%, and 90.04%, respectively, when compared with the vehicle (VEH)-treated group. On the other hand, the groups treated with HAE at 3%, 10%, and 30% presented values of lesion areas higher than those of the VEH group. Changes in the submucosa layer, inflammatory process with edema, cellular infiltration, and mucin depletion were detected in the gastric mucosa exposed to ethanol, which was fully prevented by RTAE treatment. Neither HAE nor RTAE could increase the reduced glutathione levels in the injured gastric tissue, but RTAE (30%) reduced the formation of lipid hydroperoxides. When the rats were pre-treated with NEM (a chelator of non-protein thiols) or L-NAME (non-selective nitric oxide synthase inhibitor), the RTAE lost the ability to protect the gastric mucosa. CONCLUSIONS: This study corroborates the ethnopharmacological use of this specie to treat gastric disorders revealing the gastroprotective effect of the room-temperature aqueous extract of A. absinthium aerial parts. Its mode of action may involve the ability of the infusion to maintain the gastric mucosal barrier integrity.

Isolation and Structure Elucidation of Compounds from Sesamum alatum and Their Antiproliferative Activity against Multiple Myeloma Cells.

The phytochemical investigation of the dichloromethane root extract of Sesamum alatum led to the isolation of 18 compounds. Among these, compounds 3-8, defined as 9-hydroxy-2,2-dimethyl-2H-benzo[g]chromene-5,10-dione 6-O-ß-d-glucopyranoside (3), (2S,3R)-3,4,7-trihydroxy-2-(3'-methylbut-2'-en-1'-yl)-2,3-dihydro-1H-inden-1-one (4), (Z)-2-(1',4'-dihydroxy-4'-methylpent-2'-en-1'-ylidene)-4,7-dihydroxy-1H-indene-1,3(2H)-dione (5), (S)-2,5,8-trihydroxy-3-(2'-hydroxy-3'-methylbut-3'-en-1'-yl)naphthalene-1,4-dione (6), 6-hydroxy-3-(3'-methylbut-2'-en-1'-yl)-4-oxo-4H-chromene-5-carboxylic acid (7), and (S)-2-(1'-hydroxy-4'-methylpent-3'-en-1'-yl)anthracene-9,10-dione (8), respectively, have not yet been described. Their structures were elucidated based on spectroscopic data analysis, including IR, NMR, HRESIMS and ECD measurements. Additional known compounds, namely, hydroxysesamone (1), anthrasesamone A (2), 2,6-dimethoxy-1,4-benzoquinone (9), syringic acid (10), syringaresinol (11), 2,3-epoxysesamone 8-O-ß-d-glucopyranoside (12), 2,3-diacetylmartinoside (13), 2,3-epoxy-4,5,8-trihydroxy-2-prenyl-1-tetralone (14), ursolic acid (15), chlorosesamone (16), 2,3-epoxysesamone (17), and 2-(4-methyl-3-pentenyl)anthraquinone (18) were isolated. The antiproliferative activity of the compounds was tested against the RPMI 8226 multiple myeloma cell line. When compounds presented an IC50 value <10 µM, they were tested against two other multiple myeloma cell lines, MM.1S and MM.1R. Compound 17 was found to be the most potent, with IC50 values of 0.6, 0.7, and 0.9 µM, respectively, for the three cell lines.

MEMO: Mass Spectrometry-Based Sample Vectorization to Explore Chemodiverse Datasets.

In natural products research, chemodiverse extracts coming from multiple organisms are explored for novel bioactive molecules, sometimes over extended periods. Samples are usually analyzed by liquid chromatography coupled with fragmentation mass spectrometry to acquire informative mass spectral ensembles. Such data is then exploited to establish relationships among analytes or samples (e.g., via molecular networking) and annotate metabolites. However, the comparison of samples profiled in different batches is challenging with current metabolomics methods since the experimental variation-changes in chromatographical or mass spectrometric conditions - hinders the direct comparison of the profiled samples. Here we introduce MEMO-MS2 BasEd SaMple VectOrization-a method allowing to cluster large amounts of chemodiverse samples based on their LC-MS/MS profiles in a retention time agnostic manner. This method is particularly suited for heterogeneous and chemodiverse sample sets. MEMO demonstrated similar clustering performance as state-of-the-art metrics considering fragmentation spectra. More importantly, such performance was achieved without the requirement of a prior feature alignment step and in a significantly shorter computational time. MEMO thus allows the comparison of vast ensembles of samples, even when analyzed over long periods of time, and on different chromatographic or mass spectrometry platforms. This new addition to the computational metabolomics toolbox should drastically expand the scope of large-scale comparative analysis.

Azepine-Indole Alkaloids From Psychotria nemorosa Modulate 5-HT2A Receptors and Prevent in vivo Protein Toxicity in Transgenic Caenorhabditis elegans.

Nemorosine A (1) and fargesine (2), the main azepine-indole alkaloids of Psychotria nemorosa, were explored for their pharmacological profile on neurodegenerative disorders (NDs) applying a combined in silico-in vitro-in vivo approach. By using 1 and 2 as queries for similarity-based searches of the ChEMBL database, structurally related compounds were identified to modulate the 5-HT2A receptor; in vitro experiments confirmed an agonistic effect for 1 and 2 (24 and 36% at 10 µM, respectively), which might be linked to cognition-enhancing properties. This and the previously reported target profile of 1 and 2, which also includes BuChE and MAO-A inhibition, prompted the evaluation of these compounds in several Caenorhabditis elegans models linked to 5-HT modulation and proteotoxicity. On C. elegans transgenic strain CL4659, which expresses amyloid beta (Aß) in muscle cells leading to a phenotypic paralysis, 1 and 2 reduced Aß proteotoxicity by reducing the percentage of paralyzed worms to 51%. Treatment of the NL5901 strain, in which α-synuclein is yellow fluorescent protein (YFP)-tagged, with 1 and 2 (10 µM) significantly reduced the α-synuclein expression. Both alkaloids were further able to significantly extend the time of metallothionein induction, which is associated with reduced neurodegeneration of aged brain tissue. These results add to the multitarget profiles of 1 and 2 and corroborate their potential in the treatment of NDs.

Isolation and Structural Elucidation of Compounds from Pleiocarpa bicarpellata and Their In Vitro Antiprotozoal Activity.

Species of the genus Pleiocarpa are used in traditional medicine against fever and malaria. The present study focuses on the isolation and identification of bioactive compounds from P. bicarpellata extracts, and the evaluation of their antiprotozoal activity. Fractionation and isolation combined to LC-HRMS/MS-based dereplication provided 16 compounds: seven indole alkaloids, four indoline alkaloids, two secoiridoid glycosides, two iridoid glycosides, and one phenolic glucoside. One of the quaternary indole alkaloids (7) and one indoline alkaloid (15) have never been reported before. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR experiments, UV, IR, and HRESIMS data. The absolute configurations were determined by comparison of the experimental and calculated ECD data. The extracts and isolated compounds were evaluated for their antiprotozoal activity towards Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum, as well as for their cytotoxicity against rat skeletal myoblast L6 cells. The dichloromethane/methanol (1:1) root extract showed strong activity against P. falciparum (IC50 value of 3.5 µg/mL). Among the compounds isolated, tubotaiwine (13) displayed the most significant antiplasmodial activity with an IC50 value of 8.5 µM and a selectivity index of 23.4. Therefore, P. bicarpallata extract can be considered as a source of indole alkaloids with antiplasmodial activity.

Hygroline derivatives from Schizanthus tricolor and their anti-trypanosomatid and antiplasmodial activities.

Chemical investigation of the alkaloid extract of the aerial parts of Schizanthus tricolor led to the targeted isolation of 26 hygroline derivatives of which 20 were fully characterized. They have not yet been described in the literature and their structures were established by 1D and 2D NMR, UV and IR spectroscopy, and HRESIMS. The configuration was determined by Gauge-Independent Atomic Orbital NMR chemical shift calculations supported by the advanced statistical method DP4 plus, vibrational circular dichroism, and measurement of optical rotation. Their anti-trypanosomatid, antiplasmodial and cytotoxic activities were measured. Several compounds exhibited low micromolar activity against Plasmodium falciparum. None of the identified molecules was cytotoxic.

Pyridine-4(1H)-one Alkaloids from Waltheria indica as Antitrypanosomatid Agents.

Twelve new pyridine-4(1H)-one derivatives, namely, 8-demethoxywaltherione F (1), waltheriones R-V (2, 6, 7, 10, and 11), 1-methoxywaltherione O (3), (S)-15-hydroxywaltherione G (4), (8R)-8-hydroxywaltherione M (5), (9S,13S)-2-hydroxymethylwaltherione C (8), (9S,10S,13S)-10-hydroxywaltherione C (9), and (S)-13-methoxywaltherione V (12), as well as melovinone (13) and 5'-methoxywaltherione A (14) were isolated from the CH2Cl2 extract of the aerial parts of Waltheria indica. Their chemical structures were determined by means of a comprehensive analysis including 1H NMR, DEPTQ, HSQC, HMBC, 1H-1H COSY, ROESY, and HRESIMS data. The absolute configurations were assigned via comparison of the experimental and calculated ECD data. In addition, the isolated constituents as well as the known waltheriones M-Q were evaluated for their in vitro antitrypanosomal activity. Compounds 2, 5, and 7 as well as waltheriones M, P, and Q showed potent growth inhibition toward Trypanosoma cruzi with IC50 values of 2.1, 0.8, 2.1, 1.3, 0.5, and 0.1 µM, respectively, and selectivity indices of >12, >33, >13, 5, 25, and 14. These findings further demonstrate that the waltheriones are a promising class of antichagasic compounds worthy of further investigations.

Bioactive Azepine-Indole Alkaloids from Psychotria nemorosa.

Phytochemical investigation of the alkaloid extract of the aerial parts of Psychotria nemorosa led to the isolation and characterization of 10 azepine-indole alkaloids, i.e., cimitrypazepine (1), fargesine (2), nemorosines A (3), and B (12), nemorosinosides A-F (4-9), as well as two ß-carboline derivatives, 10-hydroxyisodolichantoside (10) and 10-hydroxydolichantoside (11), an isoxazole alkaloid, nemorosinoside G (13), serotonin (14), bufotenine (15), and (S)-gentianol (16). Compounds 3-13 have not yet been described. These compounds were isolated by semipreparative HPLC, and their structures were determined by means of HRMS, NMR, and ECD measurements. In addition, the monoamine oxidase-A (MAO-A), MAO-B, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory activities were evaluated. Alkaloids 1-3 inhibited the MAO-A activity with IC50 values of 1.4, 1.4, and 0.9 µM, respectively.

Bioactive metabolites from the leaves of Withania adpressa.

CONTEXT: Withania (Solanaceae) species are known to be a rich source of withanolides, which have shown several biological properties. OBJECTIVE: To identify the compounds responsible for Withania adpressa Coss. antioxidant activity and further test them for their NF-κB inhibition and antiproliferative activity in multiple myeloma cells. MATERIALS AND METHODS: Compounds were obtained from the EtOAc extract of W. adpressa leaves. Structure elucidation was carried out mainly by 1D- and 2D-NMR, and mass spectrometry. Isolated compounds were tested in a dose-response for their in vitro NF-κB inhibition and antiproliferative activity in multiple myeloma cells after 5 and 72 h treatment, respectively. RESULTS: The fractionation resulted in the isolation of a new glycowithanolide named wadpressine (5) together with withanolide F, withaferin A, coagulin L, and nicotiflorin. The latter showed a moderate ability to scavenge free radicals in DPPH (IC50 = 35.3 µM) and NO (IC50 = 41.3 µM) assays. Withanolide F and withaferin A exhibited low µM antiproliferative activity against both multiple myeloma cancer stem cells and RPMI 8226 cells. Furthermore, they inhibited NF-κB activity with IC50 values of 1.2 and 0.047 µM, respectively. The other compounds showed a moderate inhibition of cell proliferation in RPMI 8226 cells, but were inactive against cancer stem cells and did not inhibit NF-κB activity. DISCUSSION AND CONCLUSIONS: One new glycowithanolide and four known compounds were isolated. Biological evaluation data gave further insight on the antitumor potential of withanolides for refractory cancers.

Anti-inflammatory and antiproliferative diterpenoids from Plectranthus scutellarioides.

Chemical investigation of the dichloromethane extract of the aerial parts of Plectranthus scutellarioides led to the isolation and characterization of 10 diterpenoids with an abietane skeleton and one cembrane-type diterpenoid. Among them, six have not yet been described in the literature. Their structures were established by 1D and 2D NMR, UV and IR spectroscopy, and HRESIMS. The relative configuration was determined by Gauge-Independent Atomic Orbital NMR chemical shift calculations supported by the advanced statistical method DP4 plus and further confirmed by electronic circular dichroism. The isolated constituents were evaluated for their in vitro NF-κB inhibitory activity, as well as for their cytotoxic effects in human multiple myeloma cancer stem cells and RPMI 8226 tumor cell line. Coleon O, coleon G, lanugone K and 6-acetylfredericone B showed the highest inhibitory effect against NF-κB, displaying IC50 of 11.2, 11.0, 4.5 and 9.7 µM, respectively. Coleon O exhibited also a significant activity towards human multiple myeloma cancer stem cells and RPMI 8226 cells with IC50 of 9.2 and 8.4 µM, respectively.

A new antifungal and antiprotozoal bibenzyl derivative from Gavilea lutea.

A new bibenzyl derivative (4), together with two glycosylated flavonoids (1 and 2), batatasin III (3) and the phenanthrene isohircinol (5) were isolated from the aerial parts of Gavilea lutea. Their structures were elucidated on the basis of spectroscopic studies including 1D and 2D NMR, UV, IR and HRESIMS. All isolated compounds were evaluated for their antifungal activity towards Candida albicans. The new compound 4 showed inhibitory activity with a MIQ of 50 µg. In addition, compound 4 exhibited a selective activity (IC50 = 2.3 µg/mL) against Leishmania donovani.

Targeted Isolation of Monoterpene Indole Alkaloids from Palicourea sessilis.

Phytochemical investigation of the alkaloid extract of Palicourea sessilis by LC-HRMS/MS using molecular networking and an in silico MS/MS fragmentation approach suggested the presence of several new monoterpene indole alkaloids. These compounds were isolated by semipreparative HPLC, and their structures confirmed by means of HRMS, NMR, and ECD measurements as 4-N-methyllyaloside (3), 4-N-methyl-3,4-dehydrostrictosidine (4), 4ß-hydroxyisodolichantoside (6), and 4α-hydroxyisodolichantoside (7), as well as the known alkaloids alline (1), N-methyltryptamine (2), isodolichantoside (5), and 5-oxodolichantoside (8). In addition, the acetylcholinesterase inhibitory activity of the compounds was evaluated up to 50 µM.

Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS.

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since the approval of romidepsin, a class I HDAC inhibitor for cancer therapy, and the clinical investigation of HDAC6-specific inhibitors for multiple myeloma. The present method is used to determine the inhibitory activity of test compounds on HDAC1 and HDAC6 in cells. The isoform activity is measured using the ultra-high-performance liquid chromatography - mass spectrometry (UHPLC-MS) analysis of specific substrates incubated with treated and untreated HeLa cells. The method has the advantage of reflecting the endogenous HDAC activity within the cell environment, in contrast to cell-free biochemical assays conducted on isolated isoforms. Moreover, because it is based on the quantification of synthetic substrates, the method does not require the antibody recognition of endogenous acetylated proteins. It is easily adaptable to several cell lines and an automated process. The method has already proved useful in finding HDAC6-selective compounds in neuroblasts. Representative results are shown here with the standard HDAC inhibitors trichostatin A (non-specific), MS275 (HDAC1-specific), and tubastatin A (HDAC6-specific) using HeLa cells.

Targeting Multiple Myeloma Cancer Stem Cells with Natural Products - Lessons from Other Hematological Malignancies.

Multiple myeloma is characterized by the accumulation of malignant plasma cells in the bone marrow. Multiple myeloma is the second most frequently diagnosed hematological malignancy, predominantly affecting the elderly. Despite recent advances in the development of novel therapies, multiple myeloma remains an incurable malignancy where the majority of patients relapse, develop resistance, and eventually die from the disease. This has been attributed to the fact that conventional therapy currently in use targets mainly the bulk of tumor cells, but not the tumor-initiating cancer stem cells. Cancer stem cells are a highly resistant subpopulation of cells believed to be responsible for the initiation, progression, metastasis, and relapse of cancer. Enormous efforts have been invested in the characterization of cancer stem cells. These efforts led to the characterization of key cellular signaling pathways responsible for conferring stem cell characteristics including self-renewal, differentiation, migratory, survival, and intracellular detoxification capabilities. Targeting these protective mechanisms offers a valuable strategy that may help combat a major driving force behind cancers. The use of natural products offers a promising therapeutic approach for targeting cancer stem cells. In this review, recent advances achieved in the characterization of cancer stem cells derived from hematological malignancies, with a particular focus on multiple myeloma, are discussed and major natural products that target cancer stem cells are presented. As natural products remain an essential source of novel chemical structures and medicinal leads, the exploitation of this immense reservoir is used to draw lessons in targeting multiple myeloma-cancer stem cells.

Cancer chemopreventive activity of compounds isolated from Waltheria indica.

ETHNOPHARMACOLOGICAL RELEVANCE: Waltheria indica L. is traditionally used in several countries against inflammatory related diseases and cancer, mainly as a decoction of the aerial parts. AIM OF THE STUDY: The transcription factor NF-κB is known to induce tumor promotion and progression and is considered a major player in inflammation-driven cancers. Therefore, inhibitors of this pathway possess cancer chemopreventive and chemotherapeutic activities. This study aimed first to confirm the use of Waltheria indica as a traditional anti-inflammatory remedy by assessing the NF-κB inhibitory activity and then to identify the major bioactive compounds. The isolated compounds were also tested for their QR inducing property, a complementary strategy in cancer chemoprevention able to target tumor initiation. Finally, the relevance of in vitro results was examined by investigating the occurrence of the active compounds in traditional preparations. MATERIALS AND METHODS: Compounds were isolated from the dichloromethane extract of the aerial parts using flash chromatography and semi-preparative HPLC. NF-κB inhibitory activity of pure compounds from Waltheria indica was assessed using a luciferase reporter assay in HEK293 cells. Their QR inducing activity was also assessed in Hepa1c1c7 cells. RESULTS: Twenty-nine compounds, of which 5 are new, were obtained from the dichloromethane extract and tested for their cancer chemoprevention activity. Eleven compounds inhibited NF-κB and/or induced QR in the low to mid µM range. Chrysosplenol E (20) was active in both tests. Two of the most potent NF-κB inhibitors, waltherione A (4) and waltherione C (5), as well as 20 were found in the traditional decoction, in which 4 and 5 were major compounds. CONCLUSION: The presence of potent NF-κB inhibitors and QR inducing compounds in the decoction of the aerial parts of Waltheria indica supports its traditional use in inflammatory-related diseases and cancer chemoprevention.

Passive Intestinal Absorption of Representative Plant Secondary Metabolites: A Physicochemical Study.

Natural products are generally ingested as part of traditional herbal decoctions or in the current diet. However, in natural product research, the bioavailability of secondary metabolites is often poorly investigated. In this work, a systematic study was carried out in order to highlight the physicochemical parameters that mainly influence the passive intestinal absorption of natural products. For this, a representative set of natural products including alkaloids, coumarins, flavonoid aglycones and glycosides, and carboxylic acids was selected and their physicochemical properties were predicted using relevant Volsurf+ descriptors. The chemical space obtained with this unbiased method was then correlated with experimental passive intestinal permeability data, which highlighted the main influence of lipophilicity, global hydrophilicity, size, and the ionisation state on passive intestinal absorption of natural products. Since the pH range encountered in the intestine is wide, the influence of the ionisation was investigated deeper experimentally. The ionisation state of weakly ionisable natural products, such as flavonoid aglycones, alkaloids, and carboxylic acids, was found to prevent the passive intestinal absorption of such natural products completely. In addition, the impact of solubility issues on passive permeability results was evaluated in cases of poorly water-soluble natural products, such as flavonoid aglycones and coumarins. The biomimetic fasted state simulated fluid-version 2 was found to improve the apparent solubility of such poorly soluble natural products without influencing their permeability behaviours. The use of such a solubilising buffer was found to be well adapted to the hexadecane membrane-parallel artificial membrane permeability assay and can circumvent the solubility issues encountered with poorly soluble natural products in such an assay.

Two New Hygroline and Tropane Alkaloids Isolated from Schizanthus hookeri and S. tricolor (Solanaceae).

Two new hygroline and tropane alkaloids, 4-hydroxybenzenepropanoylhygroline (1) and 3α,4ß-dihydroxy-6ß-angeloyoxytropane (2) have been isolated from the aerial parts of Schizanthus hookeri and S. tricolor, respectively, two plants indigenous from Chile. Their structures were elucidated by spectroscopic methods and high resolution mass spectrometry. Their antiparasitic activity and cytotoxicity were measured.

Antifungal Quinoline Alkaloids from Waltheria indica.

Chemical investigation of a dichloromethane extract of the aerial parts of Waltheria indica led to the isolation and characterization of five polyhydroxymethoxyflavonoids, namely, oxyanin A (1), vitexicarpin (3), chrysosplenol E (4), flindulatin (5), 5-hydroxy-3,7,4'-trimethoxyflavone (6), and six quinolone alkaloids, waltheriones M-Q (2, 7, 8, 10, 11) and 5(R)-vanessine (9). Among these, compounds 2, 7, 8, 10, and 11 have not yet been described in the literature. Their chemical structures were established by means of spectroscopic data interpretation including (1)H and (13)C, HSQC, HMBC, COSY, and NOESY NMR experiments and UV, IR, and HRESIMS. The absolute configurations of the compounds were established by ECD. The isolated constituents and 10 additional quinoline alkaloids previously isolated from the roots of the plant were evaluated for their in vitro antifungal activity against the human fungal pathogen Candida albicans, and 10 compounds (7, 9, 11-16, 18, 21) showed growth inhibitory activity on both planktonic cells and biofilms (MIC ≤ 32 µg/mL). Their spectrum of activity against other pathogenic Candida species and their cytotoxicity against human HeLa cells were also determined. In addition, the cytological effect of the antifungal isolated compounds on the ultrastructure of C. albicans was evaluated by transmission electron microscopy.

Prediction of the Passive Intestinal Absorption of Medicinal Plant Extract Constituents with the Parallel Artificial Membrane Permeability Assay (PAMPA).

At the early drug discovery stage, the high-throughput parallel artificial membrane permeability assay is one of the most frequently used in vitro models to predict transcellular passive absorption. While thousands of new chemical entities have been screened with the parallel artificial membrane permeability assay, in general, permeation properties of natural products have been scarcely evaluated. In this study, the parallel artificial membrane permeability assay through a hexadecane membrane was used to predict the passive intestinal absorption of a representative set of frequently occurring natural products. Since natural products are usually ingested for medicinal use as components of complex extracts in traditional herbal preparations or as phytopharmaceuticals, the applicability of such an assay to study the constituents directly in medicinal crude plant extracts was further investigated. Three representative crude plant extracts with different natural product compositions were chosen for this study. The first extract was composed of furanocoumarins (Angelica archangelica), the second extract included alkaloids (Waltheria indica), and the third extract contained flavonoid glycosides (Pueraria montana var. lobata). For each medicinal plant, the effective passive permeability values Pe (cm/s) of the main natural products of interest were rapidly calculated thanks to a generic ultrahigh-pressure liquid chromatography-UV detection method and because Pe calculations do not require knowing precisely the concentration of each natural product within the extracts. The original parallel artificial membrane permeability assay through a hexadecane membrane was found to keep its predictive power when applied to constituents directly in crude plant extracts provided that higher quantities of the extract were initially loaded in the assay in order to ensure suitable detection of the individual constituents of the extracts. Such an approach is thus valuable for the high-throughput, cost-effective, and early evaluation of passive intestinal absorption of active principles in medicinal plants. In phytochemical studies, obtaining effective passive permeability values of pharmacologically active natural products is important to predict if natural products showing interesting activities in vitro may have a chance to reach their target in vivo.