Medicinal plants from Mali: Chemistry and biology

Applied Analytical Methods for Detecting Heavy Metals in Medicinal Plants

For thousands of years, medicinal plants (MPs) have been one of the main sources of drugs worldwide. However, recently, heavy metal pollution has seriously affected the quality and safety of MPs. Consuming MPs polluted by heavy metals such as Pb, Hg, and Cu significantly threaten the health of consumers. To manage this situation, the levels of heavy metals in MPs must be controlled. In recent years, this field has attracted significant attention, but few researchers have systematically summarized various analytical methods. Therefore, it is necessary to investigate methods that can accurately and effectively detect the amount of heavy metals in MPs. Herein, some important analytical methods used to detect heavy metals in MPs and their applications have been introduced and summarized in detail. These include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry, X-ray fluorescence spectrometry, neutron activation analysis, and anodic stripping voltammetry. The characteristics of these methods were subsequently compared and analyzed. In addition, high-performance liquid chromatography, ultraviolet spectrophotometry, and disposable electrochemical sensors have also been used for heavy metal detection in MPs. To elucidate the systematic and comprehensive information, these methods have also been briefly introduced in this review.

Structural analysis and biological effects of a neutral polysaccharide from the fruits of Rosa laevigata

A neutral water-soluble polysaccharide (RLP50-2) was extracted and purified from the fruits of Rosa laevigata. The absolute molecular weight was determined as 1.26 × 10⁴ g/mol. Monosaccharide composition analysis showed that RLP50-2 mainly consisted of glucose, arabinose, and galactose. Structural analysis revealed that RLP50-2 consisted of →5)-α-L-Araf-(1→, →2,5)-α-L-Araf-(1→, →3,5)-α-L-Araf-(1→, →4)-α-D-Glcp-(1→, →6)-α-D-Glcp-(1→, →3,6)-β-D-Glcp-(1→, →4)-α-D-Galp-(1→, →6)-β-D-Galp-(1→, →2)-β-D-Xylp-(1→, terminal α-L-arabinose, and terminal β-D-mannose. Biological assays showed that RLP50-2 had immunomodulatory activities using cell and zebrafish models. Moreover, RLP50-2 showed significantly antitumor activities by inhibiting tumor cell proliferation and migration and blocking angiogenesis. These results suggested that RLP50-2 could be developed as a potential immunomodulatory agent or antitumor candidate drug in biomedicine field.

Ethnopharmacological uses, phytochemistry and pharmacological activities of Guiera senegalensis J.F. Gmel. (Combretaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Guiera senegalensis J.F. Gmel. (Combretaceae), commonly known as "Gubeish" in Sudan, is a small shrub abundant in semi-desert areas of the Sudano-Sahelian zone. It is widely used in African traditional medicine as a tonic and for the treatment of many complications such as respiratory and gastrointestinal disorders, microbial and parasitic infections.

AIM OF THE REVIEW

The aim of this review is to critically analyze the reports on the traditional uses, ethnopharmacological studies, chemical constituents and pharmacological activities of G. senegalensis.

METHODS

Scientific information on G. senegalensis was retrieved from the online bibliographic databases (e.g. like MEDLINE/PubMed, SciFinder, Web of Science, Google Scholar, Scopus, Elsevier, SpringerLink). Other scientific information was acquired from secondary resources including books and proceedings, library catalogs, and dissertations.

RESULTS

G. senegalensis is reported to be widely used traditionally for the treatment of various diseases in many African countries. Most of these studies are reported from Burkina Faso, Guinea, Mali, Nigeria, Senegal, and Sudan. Phytochemical studies have revealed the presence of a total of 46 compounds belonging to major phytochemical classes namely; phenolic compounds, alkaloids, and triterpenes. Among them, galloylquinic acid derivatives and flavonoids are the most frequently reported constituents. The extracts and compounds have shown diverse biological activities including antimicrobial, anti-inflammatory, antiprotozoal activities and activities against gastrointestinal and respiratory disorders.

CONCLUSION

G. senegalensis is widely used in most African traditional medicine systems and used among African people for the treatment of many diseases. Although there are many reports on its biological activities, most of these studies are based on in vitro systems and only very few are based on in vivo systems. Also, some of these pharmacological data are insufficient and lack essential parameters such as proper positive and negative controls, and calculating the minimum inhibitory concentration (MIC) values. From these studies, it is difficult to assess the future clinical potential of this plant without detailed studies in animal models or in humans. Similarly, there are not many reports on the action mechanism of the extracts and compounds. Future studies should focus to explore the therapeutic potential of G. senegalensis with advance experimental protocols and cutting-edge technologies.

The ancient Thracian endemic plant Haberlea rhodopensis Friv. and related species: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Haberlea rhodopensis (HR) use dates back to the Thracian and Roman periods. Bulgarians call it Orpheus flower and exploit its leaves for making tea and extracts with detoxifying, tonic, restorative and rejuvenating effects. HR was traditionally applied in wound healing and treatment of cattle diseases.

AIM OF THE STUDY

The general aim of the review was to analyze the progress of phytochemical and pharmacological studies on HR, focusing on its radioprotective and immunomodulating effects.

MATERIALS AND METHODS

The main source material for the review was collected using several global search engines with the phrase: Haberlea rhodopensis, as well as Bulgarian books and dissertations.

RESULTS

HR metabolite profile includes large amounts of free sugars, polyols, polysaccharides (PS), flavonoids, phenolic acids and carotenoids. The radioprotective effect of 70% ethanolic leaf extract (70HREE) is explained by preservation of lymphocytes, other blood cells and testicular tissue from aberration under γ-radiation via stimulation of antioxidant enzymes and neutralization of free radicals. The extract immunomodulating activity results from raised antibody response, stem and neutrophil cell count, complement system activation, anti-tumour and anti-inflammatory effects. The detoxifying, restorative, rejuvenating and wound healing plant properties known to ethnomedicine were supported by radioprotective and immunomodulating studies.

CONCLUSIONS

Metabolites of phenolic origin involved in HR resurrection are supposed to contribute to its radioprotective, immunomodulatory, anti-mutagenic and anti-aging effects. However, there is no chemical characterization of 70HREE in the investigations with humans and animals. Structure-activity relationship studies on HR immunomodulating and radioprotective compounds, and on their mode of action are required. They should include not only phenols but PS and other unexplored molecules. The metabolic activity of phagocytes, platelets and lymphocytes triggered by HR extracts has to be examined to elucidate their immunostimulatory potential. HR formulations can be tested in cosmetic, food and medical products as adjuvants to treat infectious, chronic inflammatory and tumour diseases, and especially in patients undergoing radiotherapy.

Ethnobotanical study of medicinal plants in the Adrar Province, Mauritania

ETHNOPHARMACOLOGICAL RELEVANCE

Mauritania is a country in which few ethnobotanical studies have been conducted and consequently the ethnomedical data is scarce. Since the geographical region reflects the transition between tropical and Northern Africa, influenced by the Mediterranean floristic region, the traditional knowledge was influenced by several cultures from tropical Africa as well as Arab, Berber and Islamic societies.

AIM OF THE STUDY

This paper aims to explore and compile the diversity of ethnomedical knowledge in one of the regions of Mauritania and to compare the data with similar studies from surrounding territories.

MATERIALS AND METHODS

Surveys and interviews were carried out in 11 villages of Adrar province in northern Mauritania. Data were collected through open, semi-structured interviews (with individuals and focus groups). A sample of 120 people aged between 20 and 70 years, including 24 herbalists and 28 traditional healers was included.

RESULTS

Ethnomedical data for 68 plant species belonging to 27 families were obtained. They are used to treat 50 health conditions grouped in 14 pathological groups. Remedies for digestive system disorders, skin problems and respiratory ailments were among the most frequent indications. Leaves were the most frequently used plant part and remedies generally used as a powder for the various applications and a total of 2'317 use reports were gathered. About 55% of the reported species were not cited previously in the literature focusing on Mauritania and neighbouring countries. Moreover, only 6 species are also cited by Ibn al-Baytar (13th century CE).

CONCLUSIONS

This work shows a promising perspective for future studies, shedding light on the richness and the risk for conservation of traditional knowledge of herbal medicine in Mauritania.

Pectic oligosaccharides hydrolyzed from citrus canning processing water by Fenton reaction and their antiproliferation potentials

Citrus canning processing water contains a valuable and renewable source of biopolymers and bioactive compounds including pectic polysaccharides. Upgrading these processing wastes can not only alleviate environmental pollution but also add value to the commodity's production. In a previous study we recovered pectic polysaccharides from citrus canning processing water. In the present study, pectic polysaccharides recycled from citrus canning processing water was depolymerized by an optimized Fenton system. The hydrolyzate was fractionated via size-exclusion chromatography into six fractions: 500 Da < LMP1 < 3 kDa; 3 kDa < LMP2 < 5 kDa; 5 kDa < LMP3 < 12 kDa; 12 kDa < LMP4 < 25 kDa; 25 kDa < LMP5 < 100 kDa and LMP6 > 10 wDa. Structure analyses showed that LMP1 were homogalacturonans-enriched non-esterified polysaccharides. While LMP2 contained both HG and rhamnogalacturonan-I (RG-I). Further antitumor assay showed that in comparison with the native pectic polysaccharide with moderate antitumor activity, both LMP1 and LMP2 possessed significant antitumor activity, while the inhibitory effect of LMP1 was higher than that of LMP2, suggesting that the biological properties of LMPs was influenced by structural characteristics, including molecular weight and monosaccharide composition.

Tilia tomentosa pectins exhibit dual mode of action on phagocytes as β-glucuronic acid monomers are abundant in their rhamnogalacturonans I

Silver linden flowers contain different pectins (PSI-PSIII) with immunomodulating properties. PSI is a low-esterified pectic polysaccharide with predominant homogalacturonan region, followed by rhamnogalacturonan I (RGI) with arabinogalactan II and RGII (traces) domains. PSII and PSIII are unusual glucuronidated RGI polymers. PSIII is a unique high molecular weight RGI, having almost completely O-3 glucuronidated GalA units with >30% O-3 acetylation at the Rha units. Linden pectins induced reactive oxygen species (ROS) and NO generation from non-stimulated whole blood phagocytes and macrophages, resp., but suppressed OZP-(opsonized zymosan particles)-activated ROS generation, LPS-induced iNOS expression and NO production. This dual mode of action suggests their anti-inflammatory activity, which is known for silver linden extracts. PSI expressed the highest complement fixation and macrophage-stimulating activities and was active on intestinal Peyer's patch cells. PSIII was active on non-stimulated neutrophils, as it induced ß₂-integrin expression, revealing that acetylated and highly glucuronidated RGI exhibits immunomodulating properties via phagocytes.

Acidic polysaccharide complexes from purslane, silver linden and lavender stimulate Peyer's patch immune cells through innate and adaptive mechanisms

Three polysaccharide complexes (PSCs) were isolated from the aerial parts of common purslane (Portulaca oleracea L.), and the flowers of common lavender (Lavandula angustifolia Mill.) and silver linden (Tilia tomentosa Moench) by boiling water extraction and ethanol precipitation. The chemical composition and immunomodulating effects of isolated PSCs were characterized. The chemical characterization revealed that the three samples contain mainly pectic polysaccharides. They exhibited ex vivo intestinal immunomodulating activity through the murine Peyer's patch-mediated bone marrow cell proliferation test at 100μg/ml concentration. At the same time, they stimulated ex vivo human blood T-cell populations (CD4⁺/CD25⁺ and CD8⁺/CD25⁺), phagocytic leukocytes (CD14⁺ and CD64⁺ cells) and induced IL-6 production from human white blood cells and Peyer's patch cells. The herbal PSCs stimulated ex vivo ROS production from whole blood phagocytes and showed unspecific in vitro anti-proliferative activity against normal and A549, HeLa and LS180 tumor cells. This is the first report on immunomodulating studies of linden flower pectins and chemical and biological activity characterization of lavender polysaccharides. Our study demonstrates that similarly to purslane, lavender and silver linden herbal materials contain immunomodulating polysaccharides that could be useful for support of compromised immune system.

Polysaccharides in Human Health Care

Polysaccharides are abundant natural polymers found in plants, animals and microorganisms with exceptional properties and essential roles to sustain life. They are well known for their high nutritive value and the positive effects on our immune and digestive functions and detoxification system. The knowledge and recognition of the important role they play for promoting and maintaining human health and wellbeing is continuously increasing. This review describes some important polysaccharides (e.g. mucilages and gums, glycosamine glycans and chitin/chitosan) and their medical, cosmetic and pharmaceutical applications, with emphasis on the relationship between structure and function. Next, the use of polysaccharides as nutraceuticals and vaccines is discussed in more detail. An analysis of the trends and challenges in polysaccharide research concludes the paper.

Ethnopharmacology, Chemistry and Biological Properties of Four Malian Medicinal Plants

The ethnopharmacology, chemistry and pharmacology of four Malian medicinal plants, Biophytum umbraculum, Burkea africana, Lannea velutina and Terminalia macroptera are reviewed. These plants are used by traditional healers against numerous ailments: malaria, gastrointestinal diseases, wounds, sexually transmitted diseases, insect bites and snake bites, etc. The scientific evidence for these uses is, however, limited. From the chemical and pharmacological evidence presented here, it seems possible that the use in traditional medicine of these plants may have a rational basis, although more clinical studies are needed.

Effects of Morinda officinalis Polysaccharide on Experimental Varicocele Rats

Morinda officinalis is a traditional Chinese herbal medicine, which has been used to tonify the kidney and strengthen yang for a long time in China. In this study, the effects of M. officinalis Polysaccharide (MOP) on experimental varicocele adolescent rats were investigated. The result showed that varicocele destroyed the structure of the seminiferous epithelium and decreased the TJ protein expression (Occludin, Claudin-11, and ZO-1), testosterone (T) concentration in the left testicular tissue and serum, and serum levels of inhibin B (INHB), while increasing the levels of cytokines (TGF-β3 and TNF-α) in the left testicular tissue, as well as serum levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and antisperm antibody (AsAb). MOP repaired the damaged seminiferous epithelium and TJ and reduced the levels of cytokines (TGF-β3 and TNF-α) as well as serum levels of GnRH, FSH, LH, and AsAb, while upregulating TJ protein expression, T level in the left testicular tissue and serum, and serum INHB levels. In summary, we conclude that MOP promotes spermatogenesis and counteracts the varicocele-induced damage to the seminiferous epithelium and TJ, probably via decreasing cytokines (TGF-β3 and TNF-α) levels and regulating the abnormal sex hormones levels in experimental varicocele rats.

Flavonoids, gallotannins and ellagitannins in Syzygium guineense and the traditional use among Malian healers

ETHNOPHARMACOLOGICAL RELEVANCE

Syzygium guineense has been traditionally used in Mali in West Africa for the treatment of different diseases such as stomach problems, wounds, inflammations and various female disorders.

AIMS OF THE STUDY

(1) To perform an ethnopharmacological survey on the traditional use of S. guineense among Malian healers. (2) To isolate and identify chemical constituents from S. guineense leaves and to study their radical scavenging and enzyme inhibitory effects.

MATERIALS AND METHODS

In four different districts in Mali, 44 healers were interviewed about their medicinal use of S. guineense. A methanol extract of the leaves of this tree was prepared and further fractionated using different chromatographic methods. Isolated compounds were identified by 1D and 2D NMR spectroscopy. Extracts and isolated compounds were investigated as DPPH radical scavengers and as inhibitors of xanthine oxidase and 15-lipoxygenase, and the methanol extract was tested for toxicity towards Artemia salina nauplii.

RESULTS

Major uses by Malian healers were against dermatosis, pain, malaria/fever and for wound healing. There was little consensus about the use in the different districts. Leaves were most commonly used. From the methanol leaf extract, the flavonoids gallocatechin (1), myricetin (2), myricetin-3-O-glucoside (3), myricetin-3-O-rhamnoside (4), myricetin-3-O-glucuronide (5) and myricetin-3-O-β-D-(6″-galloyl)galactoside (6), the gallotannins 1,2,3,6-tetra-O-galloyl-β-D-glucose (7) and 1,2,3,4,6-penta-O-galloyl-β-D-glucose (8), and the ellagitannins casuarictin (9) and casuarinin (10) were isolated. These ten polyphenols are all new for the species. The crude methanol extract was active as a radical scavenger and as an inhibitor of xanthine oxidase and 15-lipoxygenase. Among the isolated compounds, pentagalloylglucose was the best enzyme inhibitor (IC₅₀ 25±4μM for 15-lipoxygenase, 8±1μM for xanthine oxidase), while casuarictin (IC₅₀ 3.9±0.1μM), casuarinin (IC₅₀ 4.5±0.3μM) and pentagalloylglucose (IC₅₀ 5±1μM) showed the highest radical scavenging activity. The methanol extract was non-toxic to Artemia salina nauplii.

CONCLUSION

S. guineense leaves are commonly used among Malian healers, however the traditional practice varies a lot between different regions. The leaves of S. guineense are rich in polyphenols; several are galloylated, either as galloylated flavonoids, gallotannins or ellagitannins. The high content of biologically active polyphenols might be important for medicinal effects of this plant and might give a rationale for the widespread usage of S. guineense in Mali.