Medicinal plants of northern Angola and their anti-inflammatory properties

Ethnobotany in Angola: The contribution of late 19th century christian missionaries to the knowledge of medicinal wild plants

ETHNOPHARMACOLOGICAL RELEVANCE

Angola has an extraordinary plant diversity and a great ethnobotanical potential. However, there is a general lack of information about the first botanical explorations in the country and their contribution to the knowledge of the medicinal flora.

AIM OF THE STUDY

The main aim of this study was to unveil the ethnobotanical legacy of José Maria Antunes and Eugène Dekindt, priests of the first Catholic mission in Huíla (Angola) and shed light on their contribution to the knowledge of medicinal wild plants of the country, including information on the uses, plant parts used, and preparation methods documented in the late 19th century. The findings are discussed considering recent ethnobotanical studies to offer a more comprehensive understanding of the historical and traditional uses of plants in Angola over the last two centuries.

MATERIALS AND METHODS

Based on the information available in manuscripts and on the study of botanical collections preserved in herbaria of Portugal and Angola, we extracted relevant information about the species used in traditional medicine by the rural population of Huíla, the health conditions treated, and the mode of preparation and application.

RESULTS

Our results revealed that Antunes and Dekindt conducted the first ethnobotanical study in Huíla, and documented a large number of medicinal wild plants. From these, we report 191 medicinal species, including 25 endemic and four introduced species, belonging to 56 plant families and 146 genera. Fabaceae family presents the highest richness of medicinal plants (39 taxa), followed by Rubiaceae (13), Asteraceae (10), and Apocynaceae (9). The illnesses reported were classified into 15 different categories, with the highest number of species (49) corresponding to unspecific conditions, such as general pains, chills, and fever. Thirty-seven species were reported for respiratory diseases, 31 for musculoskeletal problems, and 30 for digestive issues. Leaves were the most used plant part for medicinal purposes (84 species). Infusion was the most frequently described preparation method (40 species), followed by maceration (24 species), and powdering (36 species).

CONCLUSIONS

The legacy of Antunes and Dekindt's work improves our understanding of Angola's botanical richness and traditional uses of plant resources. Our findings highlight the presence of unique medicinal resources in Angola, especially among endemic species, which hold the potential to improve the quality of life of rural communities. Moreover, our research underscores the lack of knowledge of medicinal species, emphasizing the risk of losing valuable historical information.

An imprecise probability approach-based determination of over-represented southern African plant genera and families used in ethnopharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The analyses of patterns of over-representation of southern African traditional medicinal plants at the genus and family level provide information about the differences in plant use among southern African countries and disease categories. 'Over-representation' refers to the phenomenon whereby the proportion of plants belonging to a taxonomic group is higher in ethnobotanical pharmacopoeia than in the total flora.

AIM OF THE STUDY

This study aimed to use the Imprecise Dirichlet Model (IDM) to analyse data from ten southern African countries to establish how over-represented medicinal plant families compare with over-represented genera, how over-represented medicinal taxa differ among countries in this region of Africa, and how over-represented taxa differ among six major disease categories.

MATERIALS AND METHODS

Floral data for the total species composition of each country were obtained from online databases. Medicinal plant species lists were generated from published surveys, inventories, and books. IDM calculations were executed using the inverse of the cumulative beta probability density function in Microsoft Excel™. Python programming language source code was used to calculate Pearson correlation (r) values and Jaccard coefficients (J).

RESULTS

Nine of forty-two over-represented medicinal plant families in southern Africa (group 1) do not have over-represented genera. Seven of the forty genera with the highest margins of over-representation belong to under-represented families. Nineteen of the forty-two over-represented families have margins of over-representation smaller than the cumulative margins of their over-represented genera. Groups of countries with similar overall flora (J ≥ 0.333) are Botswana and Namibia (group 2), Malawi, Mozambique, Zambia and Zimbabwe (group 3). The families and genera with the highest margins of over-representation are Loganiaceae and Albizia in group 1, Combretaceae and Vachellia in group 2, Dioscoreaceae and Senna in group 3, and Sapotaceae and Solanum in group 4 (South Africa). The families and genera with the highest margins of over-representation across disease categories are Ebenaceae and Albizia, Canellaceae and Dicoma, Combretaceae and Pterocelastrus, Ebenaceae and Bersama, Francoaceae and Erythrina, and Aristolochiaceae and Strychnos for plants used in the treatment of STIs, febrile and mosquito-vector diseases, microbial infections, pain, skin conditions, and female sexual/reproductive problems, respectively.

CONCLUSIONS

Genus-level calculations are more efficient in generating taxonomic lists that can be used for ethnopharmacological investigations due to the exclusion of under-represented genera. Limiting the size of geographical areas from which medicinal plant lists are sampled and targeting plants used to treat specific types of disease prevents the underestimation of niche over-represented taxa.

Mechanism of Smilax china L. in the treatment of intrauterine adhesions based on network pharmacology, molecular docking and experimental validation

BACKGROUND

Smilax china L. (SCL) is a traditional herbal medicine for the potential treatment of intrauterine adhesion (IUA). However, the mechanisms of action have not yet been determined. In this study, we explored the effects and mechanisms of SCL in IUA by network pharmacology, molecular docking and molecular biology experiments.

METHODS

Active ingredients and targets of SCL were acquired from TCMSP and SwissTargetPrediction. IUA-related targets were collected from the GeneCards, DisGeNET, OMIM and TTD databases. A protein‒protein interaction (PPI) network was constructed by Cytoscape 3.9.1 and analysed with CytoHubba and CytoNCA to identify the core targets. The DAVID tool was used for GO and KEGG enrichment analyses. Furthermore, molecular docking was employed to assess the interaction between the compounds and key targets. Finally, the mechanisms and targets of SCL in IUA were verified by cellular experiments and western blot.

RESULTS

A total of 196 targets of SCL were identified, among which 93 were related to IUA. Topological and KEGG analyses results identified 15 core targets that were involved in multiple pathways, such as inflammation, apoptosis, and PI3K/AKT signalling pathways. Molecular docking results showed that the active compounds had good binding to the core targets. In vitro experiments showed that astilbin (AST), a major component of SCL, significantly reduced TGF-β-induced overexpression of fibronectin (FN), activation of the PI3K/AKT signalling pathway and the expression of downstream factors (NF-κB and BCL2) in human endometrial stromal cells, suggesting that AST ameliorates IUA by mediating the PI3K/AKT/NF-κB and BCL2 proteins.

CONCLUSIONS

AST, a major component of SCL, may be a potential therapeutic agent for IUA. Moreover, its mechanism is strongly associated with regulation of the PI3K/AKT signalling pathway and the downstream NF-κB and BCL2 proteins. This study will provide new strategies that utilize AST for the treatment of IUA.

Bioassay-Guided Isolation of Anti-Inflammatory Constituents of the Subaerial Parts of Cyperus articulatus (Cyperaceae)

Based on data from a previous ethnobotanical study in northern Angola, phytochemical investigations into the methanolic rhizomes and roots extract of Cyperus articulatus, monitored by in vitro assays, resulted in the recovery of 12 sesquiterpenes, 3 stilbenes, 2 phenolic acids, 1 monoterpene, and 1 flavonoid. Among them, 14 compounds were isolated for the first time from this species. Their inhibitory potential against nitric oxide (NO) production, as well as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, was evaluated in LPS-treated J774A.1 murine macrophages. Especially, both stilbene dimer trans-scirpusin B and trimer cyperusphenol B showed promising inhibitory activity against the production of the inflammatory mediator, NO, in a concentration-dependent manner (10−1 µM). The obtained data are the first results confirming the anti-inflammatory potential of C. articulatus and support its indigenous use as a traditional remedy against inflammation-related disorders.

A review of the ethnomedicinal uses, chemistry, and pharmacological properties of the genus Acanthus (Acanthaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The Acanthus genus belongs to the Acanthaceae family, and its species are distributed in all continents, mainly in tropical and subtropical regions. Several traditional applications are referred to, but few scientific studies validate them. Despite this, studies in animal models corroborate some of its uses in folk medicine, such as anticancer, antidiabetic, anti-inflammatory, and antinociceptive, which encourages the research on plants of this genus.

AIM OF THE REVIEW

To our knowledge, this document is the first comprehensive review study that provides information on the geographic distribution, botanical characteristics, ethnomedicinal uses, phytochemicals, and pharmacological activities of some Acanthus species to understand the correlation between traditional uses, phytochemical, and pharmacological activities, providing perspectives for future studies.

RESULTS

In traditional medicine, Acanthus species are mainly used for diseases of respiratory, nervous and reproductive system, gastrointestinal and urinary tract, and skin illness. The most used species are A. montanus, A. ilicifolius, and A. ebracteatus. Chemical compounds (125) from different chemical classes were isolated and identified in seven species, mainly from A. ilicifolius, about 80, followed by A. ebracteatus and A. montanus, appearing with a slightly lower number with fewer phytochemical profile studies. Isolated phytoconstituents have been mainly alkaloids, phenylpropanoid glycosides, and phenylethanoids. In addition, aliphatic glycosides, flavonoids, lignan glycosides, megastigmane derivatives, triterpenoids, steroids, fatty acids, alcohols, hydroxybenzoic acids, simple phenols were also cited. Scientific studies from Acanthus species extracts and their phytoconstituents support their ethnomedical uses. Antimicrobial activity that is the most studied, followed by the antioxidant, anti-inflammatory, and anticancer properties, underlie many Acanthus species activities. A. dioscoridis, A. ebracteatus, A. hirsutus, A. ilicifolius, A. mollis, A. montanus, and A. polystachyus have studies on these activities, A. ilicifolius being the one with the most publications. Most studies were essentially performed in vitro. However, the anticancer, antidiabetic, anti-inflammatory and antinociceptive properties have been studied in vivo.

CONCLUSION

Acanthus species have remarkable phytoconstituents with different biological activities, such as antioxidant, antimicrobial, anti-inflammatory, antinociceptive, hepatoprotective, and leishmanicidal, supporting traditional uses of some species. However, many others remain unexplored. Future studies should focus on these species, especially pharmacological properties, toxicity, and action mechanisms. This review provides a comprehensive report on Acanthus genus plants, evidencing their therapeutic potential and prospects for discovering new safe and effective drugs from Acanthus species.

The relevance of quantitative ethnobotanical indices for ethnopharmacology and ethnobotany

ETHNOPHARMACOLOGICAL RELEVANCE

As an interdisciplinary field of research ethnopharmacology draws on methodologies and methods from a variety of disciplines. A range of ethnobotanical indices are frequently used to transform primary data obtained through field studies into statistical measures. These indices are claimed to serve as a proxy for efficacy or drug discovery (Fidelity Level 'FL') and to show the importance of botanical drugs and plants used as medicines (Relative Importance 'RI', Use Value 'UV' or Cultural Importance Index 'CI', Cultural Value Index 'CV', Relative Frequency of Citation 'RFC'). This is, however, doubtful, as these indices have not been developed by statisticians, nor by pharmacologists while a proof of concept is lacking. Moreover, the question whether a simple number can summarize the cultural value or importance of plants is not only mathematical but also epistemological.

MATERIAL AND METHODS

The FL, RI, UV/CI, CV and the RFC are shortly reviewed. Their statistical rigour is explained and the relevance for ethnobotany, ethnopharmacology and drug discovery discussed.

RESULTS

The effect of the sample size on the dispersal of data and the differential probability of botanical drugs being used for the different categories of use are not being considered by these indices. They lack statistical rigour and are simple percentage calculations. Moreover, important factors influencing plant use, such as the availability of pharmaceutical drugs, or the severity of diseases covered by the use-categories, are not accounted for.

CONCLUSION

Especially unexperienced and young researchers may be ensnared by using ethnobotanical indices to describe their field data. However, the cultural value and importance of plants in general, and more specifically, of medicinal plants and botanical drugs cannot be summed up by numbers. The discussed indices encrypt parts of the primary data but fail to show the value or importance of plant use because the reasons for which plants are valued or important to people are far more complex than what the formulations of these indices suggest. The indices also lack the power to pinpoint plant species or botanical drugs for drug discovery that contextualized primary data has. Botanical drugs may be useful for a range of disorders or only for specific indications, according to their pharmacologic properties. Therefore, the exclusiveness of therapeutical applications (FL) does not serve as a proxy for effectiveness. The solution is to use and understand the contextualized primary data.

Thonningia sanguinea Extract: Antioxidant and Cytotoxic Activities Supported by Chemical Composition and Molecular Docking Simulations

The current study was designed to investigate the antioxidant and cytotoxic activities of Thonningia sanguinea whole-plant extract. The total phenolic content was determined using Folin-Ciocalteu reagent and found to be 980.1 mg/g, calculated as gallic acid equivalents. The antioxidant capacity was estimated for the crude extract and the phenolic portion of T. sanguinea, whereupon both revealed a dose-dependent scavenging rate of DPPH• with EC50 values of 36.33 and 11.14 µg/mL, respectively. Chemical profiling of the plant extract was achieved by LC-ESI-TOF-MS/MS analysis, where 17 compounds were assigned, including ten compounds detected in the negative mode and seven detected in the positive mode. The phenolic portion exhibited promising cytotoxic activity against MCF-7 and HepG2 cells, with IC50 values of 16.67 and 13.51 μg/mL, respectively. Phenolic extract treatment caused apoptosis in MCF-7 cells, with total apoptotic cell death 18.45-fold higher compared to untreated controls, arresting the cell cycle at G2/M by increasing the G2 population by 39.7%, compared to 19.35% for the control. The apoptotic investigation was further validated by the upregulation of proapoptotic genes of P53, Bax, and caspases-3,8 9, and the downregulation of Bcl-2 as the anti-apoptotic gene. Bcl-2 inhibition was also virtualized by good binding interactions through a molecular docking study. Taken together, phenolic extract exhibited promising cytotoxic activity in MCF-7 cells through apoptosis induction and antioxidant activation, so further fractionation studies are recommended for the phenolic extract for specifying the most active compound to be developed as a novel anti-cancer agent.

Promising Antioxidant Activity of Erythrina Genus: An Alternative Treatment for Inflammatory Pain?

The negative impact that oxidative stress has on health is currently known. The complex mechanism of free radicals initiates a series of chain reactions that contribute to the evolution or development of different degenerative disorders. Likewise, these disorders are usually accompanied by inflammatory processes and, therefore, pain. In this sense, reactive oxygen species (ROS) have been shown to promote the nociceptive process, but effective treatment of pain and inflammation still represents a challenge. Over time, it has been learned that there is no single way to relieve pain, and as long as there are no other alternatives, the trend will continue to apply multidisciplinary management, such as promote the traditional use of the Erythrina genus to manage pain and inflammation. In this sense, the Erythrina genus produces a wide range of secondary metabolites, including flavanones, isoflavones, isoflavones, and pterocarpans; these compounds are characterized by their antioxidant activity. Phenolic compounds have demonstrated their ability to suppress pro-oxidants and inhibit inflammatory signaling pathways such as MAPK, AP1, and NFκB. Although there is preclinical evidence supporting its use, the pharmacological effect mechanisms are not entirely clear. Nowadays, there is a fast advancement in knowledge of the disciplines related to drug discovery, but most of nature's medicinal potential has not yet been harnessed. This review analyzes the decisive role that the Erythrina genus could play in managing inflammatory pain mediated by its compounds and its uses as an antioxidant.

Effect of Non-Volatile Constituents of Elsholtzia ciliata (Thunb.) Hyl. from Southern Vietnam on Reactive Oxygen Species and Nitric Oxide Release in Macrophages

The extract of Elsholtzia ciliata aerial parts was subjected to bio-guided isolation using the intercellular ROS reduction in J774A.1 macrophages to monitor the anti-oxidative activity. Fifteen compounds were isolated from the active fractions including eleven flavonoids (vitexin, pedalin, luteolin-7-O-β-d-glucopyranoside, apigenin-5-O-β-d-glucopyranoside, apigenin-7-O-β-d-glucopyranoside, chrysoeriol-7-O-β-d-glucopyranoside, 7,3'-dimethoxyluteolin-6-O-β-d-glucopyranoside, luteolin, 5,6,4'-trihydroxy-7,3'-dimethoxyflavone, 5-hydroxy-6,7-dimethoxyflavone (compound 13), 5-hydroxy-7,8-dimethoxyflavone); three hydroxycinnamic acid derivatives (caffeic acid, 4-(E)-caffeoyl-l-threonic acid, 4-O-(E)-p-coumaroyl-l-threonic acid) and one fatty acid (α-linolenic acid). The biological evaluation of these compounds (10-2.5 μm) indicated that all of them exerted good antioxidant and anti-inflammatory activities, in particular compound 13.

Use of herbal remedies in the management of sleeping sickness in four northern provinces of Angola

ETHNOPHARMACOLOGICAL RELEVANCE

This study reports for the first time on the use of folk medicine to treat sleeping sickness and its symptoms in four endemic provinces in northern Angola. By interviewing both traditional practitioners and confirmed patients, it highlights reasons to recourse to folk medicine, the plant species used for this affection as well as arises awareness about the use of particular plants showing potential risks.

AIM OF THE STUDY

The aims of this explorative study were three-fold. Firstly, it informed on access to, and use of plant-based medicine as first-choice treatment by infected persons. Secondly, it aimed at collecting comprehensive data from patients and traditional healers on herbal remedies in order to identify plant species used in the management of the disease. Thirdly, it served as contribution for primary indication of potential risk of use associated with the studied plants and their preparation.

MATERIALS AND METHODS

The study was conducted in 4 endemic provinces of Angola, namely Bengo, Zaire, Kwanza Norte and Uíge. We explored the use of herbal remedies by conducting structured and semi-structured interviews within two distinct study populations. The first group comprises 30 patients who had been diagnosed for trypanosomiasis and treated by the reference treatment. The second group included 9 traditional practitioners who had already treated sleeping sickness. The plants that were cited during the interviews were collected during field walks under supervision of a traditional healer, then authenticated and deposited at the National Herbarium in Luanda.

RESULTS

Of the 30 included patients, 12 (40%) had turned to folk medicine in the management of trypanosomiasis and related symptoms. 7 medicinal plants were reported by this group. Considering the key motivation to consult a traditional practitioner, two main factors accounted for half of the cases: "past experience with folk medicine" and "family habit". Out of 9 traditional practitioners' interviewees, 26 medicinal plants were cited. Roots and leaves were the most used plant parts, and decoction was the common mode of preparation. Evidence for antitrypanosomal activity in the scientific literature was found for 56% (17 of 30) of the identified plant species. The most cited plant was Crossopteryx febrifuga (UR = 6). Some of the cited plants, as for example Aristolochia gigantea, raised concern about potential toxicity.

CONCLUSIONS

With 40% of infected persons having turned first to folk medicine before consulting a medical doctor, this explorative study points out that plant-based medicines play an important role in local dynamics of health care. It highlights the need for primary assessment of potential risk of use related to the herbal recipes, and for reporting it to the concerned population. This first ethnobotanical study on trypanosomiasis in endemic provinces of Angola provides information on 30 plants, of which some had been identified as promising for further pharmacological research. Our results provide a first step towards the validation and valorization of Angolan herbal remedies for sleeping sickness.

Medicinal Plants for Treating Musculoskeletal Disorders among Karen in Thailand

Millions of people suffer from Musculoskeletal System Disorders (MSDs), including Karen people who work hard in the fields for their subsistence and have done so for generations. This has forced the Karen to use many medicinal plants to treat MSDs. We gathered data from 15 original references covering 27 Karen communities and we document 461 reports of the use of 175 species for treating MSDs among the Karen people in Thailand. The data were analyzed by calculating use values (UV), relative frequency of citation (RFC) and informant consensus factor (ICF). Many use reports and species were from Leguminosae and Zingiberaceae. Roots and leaves were the most used parts, while the preferred preparation methods were decoction and burning. Oral ingestion was the most common form of administration. The most common ailment was muscle pain. Sambucus javanica and Plantago major were the most important species because they had the highest and second-highest values for both UV and RFC, respectively. This study revealed that the Karen people in Thailand use various medicinal plants to treat MSDs. These are the main resources for the further development of inexpensive treatments of MSDs that would benefit not only the Karen, but all people who suffer from MSD.

Virtual Screening Identifies Chebulagic Acid as an Inhibitor of the M2(S31N) Viral Ion Channel and Influenza A Virus

The increasing prevalence of drug-resistant influenza viruses emphasizes the need for new antiviral countermeasures. The M2 protein of influenza A is a proton-gated, proton-selective ion channel, which is essential for influenza replication and an established antiviral target. However, all currently circulating influenza A virus strains are now resistant to licensed M2-targeting adamantane drugs, primarily due to the widespread prevalence of an M2 variant encoding a serine to asparagine 31 mutation (S31N). To identify new chemical leads that may target M2(S31N), we performed a virtual screen of molecules from two natural product libraries and identified chebulagic acid as a candidate M2(S31N) inhibitor and influenza antiviral. Chebulagic acid selectively restores growth of M2(S31N)-expressing yeast. Molecular modeling also suggests that chebulagic acid hydrolysis fragments preferentially interact with the highly-conserved histidine residue within the pore of M2(S31N) but not adamantane-sensitive M2(S31). In contrast, chebulagic acid inhibits in vitro influenza A replication regardless of M2 sequence, suggesting that it also acts on other influenza targets. Taken together, results implicate chebulagic acid and/or its hydrolysis fragments as new chemical leads for M2(S31N) and influenza-directed antiviral development.

Anti-inflammatory properties of the ethanol extract from Clerodendrum cyrtophyllum Turcz based on in vitro and in vivo studies

ETHNOPHARMACOLOGICAL RELEVANCE

Clerodendrum cyrtophyllum Turcz, a plant belonging to the Verbenaceae family, has been used in traditional medicine for the treatment of various inflammatory diseases in many Asian countries.

AIM OF THE STUDY

The study aimed to evaluate anti-inflammatory properties of the ethanol extract from Clerodendrum cyrthophyllum Turcz leaves (EE-CC) through in vitro and in vivo models.

MATERIAL AND METHODS

Total phenolic and flavonoid contents in the extract were determined using colorimetric methods and HPTLC. In red blood cell membrane stabilization model, rat erythrocyte suspension was treated with crude ethanol extract at different concentrations, the hemoglobin content of the supernatant solution released by red blood hemolysis was estimated. We also evaluated the effects of the ethanol extract from this plant on the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-α) in stimulated RAW 264.7 cells. In order to elucidate its anti-inflammatory molecular mechanisms, we further evaluated the effects of the EE-CC on the expression of the inflammatory genes in inflammation-induced zebrafish model by tail-cutting using qPCR analysis.

RESULTS

Colorimetric methods and HPTLC revealed high phenolic and flavonoid contents in the extract. In the red blood cell membrane stabilization model, the amount of hemoglobin released by red blood hemolysis significantly decreased in the presence of EE-CC, demonstrating a strong membrane stabilizing activity. EE-CC did not cause any toxic effect on cell viability but strongly inhibited NO and TNF-ɑ release due to LPS induction. The association with EE-CC significantly reduced the expression of cox-2, pla2, c3a, il-1(il1fma), il-8 (cxcl8b.1), tnf-α, and nf-ƙb, while increased the expression of the anti-inflammatory cytokine il-10 gene in cut-tail induced inflammation of zebrafish model.

CONCLUSIONS

Taken together, the results suggest that the raw ethanol extract from C. cyrtophyllum Turcz leaves presents potent anti-inflammatory activities and may be useful for the treatment of various inflammatory diseases.

Chemical Profiling of Embelia ribes by Ultra-High-Performance Liquid Chromatography Quadrupole Time-of-Flight Tandem Mass Spectrometry and Its Antioxidant and Anti-inflammatory Activities In Vitro

Embelia ribes is a traditional Chinese medicine compound used as a remedy for various diseases. Nevertheless, detailed information regarding its chemical composition is unavailable. Herein, ultra-high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry was used to characterize the components of E. ribes. A total of 56 compounds, including 16 phenolics, 16 flavonoids, 4 coumarins, 5 fatty acids and 15 other compounds were identified. Furthermore, the total phenolic and total flavonoid content was also assessed; the acetic ether extract of E. ribes was an ideal source of phenolics (308.16 ± 0.00 mg gallic acid equivalents/g of extract) and flavonoids (62.00 ± 0.01 mg rutin equivalents/g of extract). Additionally, acetic ether extract exhibited a high antioxidation effect (ferric reducing activity power: 0.15 ± 0.01 mg/mL; 1,1-diphenyl-2-picrylhydrazyl: 0.18 ± 0.01 mg/mL; 2,2-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid: 0.06 ± 0.01 mg/mL). Further, the nitric oxide concentration in lipopolysaccharide-simulated macrophage RAW 264.7 cells and the pro-inflammatory cytokines (TNF-α and IL-6) were suppressed by acetic ether extract. These findings support the notion that E. ribes is an ideal antioxidant and anti-inflammatory agent.

Purification of thonningianins A and B and four further derivatives from Thonningia sanguinea by one- and two-dimensional centrifugal partition chromatography

Thonningia sanguinea is a parasitic herb widely used in traditional African medicine. Dihydrochalcone glucosides (unsubstituted, substituted with hexahydroxydiphenoyl or galloyl moieties) are the main constituents in the subaerial parts of this plant. In the present study, purification of the six major compounds from a methanol extract of the plant's subaerial parts was achieved by centrifugal partition chromatography. A first dimension centrifugal partition chromatography separation with the solvent system methyl tert-butyl ether/1,2-dimethoxyethane/water (1:2:1) in the ascending mode enabled the isolation of the two major bioactive compounds thonningianin A and B from 350 mg of methanol extract within only 16 min with respectable yields (25.7 and 21.1 mg), purities (87.1 and 85%), and recoveries (71.2 and 70.4%). Using a multiple heart-cutting strategy, the remaining four major dihydrochalcone glucosides of the extract were further separated in a second dimension centrifugal partition chromatography with the solvent system ethyl acetate/1,2-dimethoxyethane/water (2:1:1) in the descending mode with high purities (88.9-98.8%).

Conservation and sustainable use of the medicinal Leguminosae plants from Angola

Leguminosae is an economically important family that contains a large number of medicinal plants, many of which are widely used in African traditional medicine. Angola holds a great socio-cultural diversity and is one of the richest floristic regions of the world, with over 900 native Leguminosae species. This study is the first to assess the medicinal uses of the legumes in Angola and provides new data to promote the conservation and the sustainable use of these unique resources. We document the ethnobotanical knowledge on Angola by reviewing the most important herbarium collections and literature, complemented by recent field surveys. Our results revealed that 127 native legume species have medicinal uses and 65% of them have other important uses by local populations. The species with most medicinal applications are Erythrina abyssinica, Bauhinia thonningii and Pterocarpus angolensis. The rich flora found in Angola suggests an enormous potential for discovery of new drugs with therapeutic value. However, the overexploitation and the indiscriminate collection of legumes for multiple uses such as forage, food, timber and medical uses, increases the threats upon the native vegetation. Efforts to assess the conservation status of these species are urgently needed, and future actions should promote the sustainable use of medicinal plants in Angola together with the implementation of conservation strategies.

Dihydrochalcone Glucosides from the Subaerial Parts of Thonningia sanguinea and Their in Vitro PTP1B Inhibitory Activities

Six new and four known dihydrochalcone glucoside derivatives (1-10), the phenylpropanoid coniferin (11), and the lignans (+)-pinoresinol (12) and lariciresinol (13) were isolated from the subaerial plant parts of Thonningia sanguinea in the course of a screening campaign for new antidiabetic lead compounds. The structures of the new substances were elucidated by HRESIMS, NMR, GC-MS, and ECD data evaluation. 2'- O-(3-Galloyl-4,6- O- S_a-hexahydroxydiphenoyl-β-d-glucopyranosyl)-3-hydroxyphloretin (4), 2'- O-(4,6- O- S_a-hexahydroxydiphenoyl-β-d-glucopyranosyl)phloretin (5), 2'- O-(3- O-galloyl-4,6- O- S_a-hexahydroxydiphenoyl-β-d-glucopyranosyl)phloretin (6), and thonningianin B (9) showed moderate protein tyrosine phosphatase-1B inhibition in an enzyme assay (IC₅₀ values ranging from 19 to 25 μM), whereas thonningianin A (10) was identified as a more potent inhibitor (IC₅₀ = 4.4 μM). The observed activity differences could be explained by molecular docking experiments. The activity of 10 could further be confirmed in HEPG2 liver carcinoma cells, where the compound was able to increase the level of phosphorylated insulin receptors in a concentration-dependent manner.