Anticancer and antimicrobial activities of some antioxidant-rich cameroonian medicinal plants

New value chain Pentadesma nuts and butter from West Africa to international markets: Biological activities, health benefits, and physicochemical properties

The tallow or butter tree (Pentadesma butyracea Sabine) is a ligneous forest species of multipurpose use largely distributed in Sub-Sahara Africa. Owing to the biological properties of different parts of the tree and physicochemical properties, as well as the numerous benefits of its fruits, research on P. butyracea products, especially kernels and butter, has now gained more interest. Thus, the scientific literature revealed that Pentadesma butter is a more promising product with good physical and technological characteristics. It is traditionally preferred in households for food, medicine, and cosmetic use. Apart from the fruits, all other parts of the butter tree are used by local communities in folk medicine. The existing studies indicated that P. butyracea contains valuable health-promoting compounds such as phenolic compounds, vitamins, minerals, and essential fatty acids. P. butyracea and derived products have antioxidant, antimicrobial, anti-inflammatory, antiplasmodial, antitumor, estrogenic, anti-androgenic, and cholesterol-regulative effects. Since studies on the biological properties of the tree parts, nutritional composition, and physicochemical properties of food products from the tree have been very limited, this review attempts to summarize some results from recent investigations. Our intention in the present review was to give an overview of the biological activities of plants and an account of the potential properties of Pentadesma products (pulp, kernels, and butter) and outline the way for future relevant research to improve their state of knowledge.

An efficient synthesis of O- and N- alkyl derivatives of 4-aminobenzoic acid and evaluation of their anticancer properties

A series of twenty alkyl derivatives (2-21) of 4-amino benzoic acid (1, PABA) have been prepared using potassium carbonate and opportune alkylating agents under simple and mild reaction conditions. Compounds (16-21) are reported for the first time. Electron impact mass spectrometry (EIMS), Fourier transform infrared (FTIR) and Proton nuclear magnetic resonance (1H-NMR) spectroscopic techniques were adopted for the characterization of these analogues. In the present study, the cytotoxic screening of sixteen compounds (3, 5-11, 13 and 15-21) was also achieved against lung (NCI-H460) and oral squamous carcinoma (CAL-27) cell lines. Compound 20 has shown magnificent inhibitory properties against NCI-H460 cell line (IC50 15.59 and 20.04 µM, respectively) at a lower dose than that of the control (cisplatin; IC50 21.00 µM). One-way analysis of variance (ANOVA), t-test and Pearson correlation coefficient (PCC) have been performed to determine the reliability of current data through statistical package for the social sciences (SPSS).

Brown Macroalgae Sargassum cristaefolium Extract Inhibits Melanin Production and Cellular Oxygen Stress in B16F10 Melanoma Cells

The brown macroalgae Sargassum has been reported for its anti-UV and photoprotective potential for industrial applications. This study evaluated the melanin inhibition activity of Sargassum cristaefolium (SCE) ethanol extract. Melanogenesis inhibition by SCE was assessed in vitro with B16-F10 melanoma cell models and in silico against melanin regulatory proteins Tyrosinase (TYR) and Melanocortin 1 Receptor (MC1R). The regulatory properties evaluated were the melanin content, intracellular tyrosinase activity and cellular antioxidant activities. In addition, the bioactive compounds detected in SCE were subjected to molecular docking against TYR and MC1R. Based on the results, 150 µg/mL SCE effectively inhibited the production of melanin content and intracellular tyrosinase activity. Cellular tyrosinase activity was reduced by SCE-treated cells in a concentration-dependent manner. The results were comparable to the standard tyrosinase inhibitor kojic acid. In addition, SCE effectively decreased the intracellular reactive oxygen species (ROS) levels in B16-F10 cells. The antioxidant properties may also contribute to the inhibition of melanogenesis. In addition, LCMS UHPLC-HR-ESI-MS profiling detected 33 major compounds. The results based on in silico study revealed that the bioactive compound putative kaurenoic acid showed a strong binding affinity against TYR (-6.5 kcal/mol) and MC1R (-8.6 kcal/mol). However, further molecular analyses are needed to confirm the mechanism of SCE on melanin inhibition. Nevertheless, SCE is proposed as an anti-melanogenic and antioxidant agent, which could be further developed into cosmetic skin care products.

Medicinal plants used for the management of respiratory diseases in Zimbabwe: Review and perspectives potential management of COVID-19

Respiratory diseases have in the recent past become a health concern globally. More than 523 million cases of coronavirus disease (COVID19), a recent respiratory diseases have been reported, leaving more than 6 million deaths worldwide since the start of the pandemic. In Zimbabwe, respiratory infections have largely been managed using traditional (herbal) medicines, due to their low cost and ease of accessibility. This review highlights the plants' toxicological and pharmacological evaluation studies explored. It seeks to document plants that have been traditionally used in Zimbabwe to treat respiratory ailments within and beyond the past four decades. Extensive literature review based on published papers and abstracts retrieved from the online bibliographic databases, books, book chapters, scientific reports and theses available at Universities in Zimbabwe, were used in this study. From the study, there were at least 58 plant families comprising 160 medicinal plants widely distributed throughout the country. The Fabaceae family had the highest number of medicinal plant species, with a total of 21 species. A total of 12 respiratory ailments were reportedly treatable using the identified plants. From a total of 160 plants, colds were reportedly treatable with 56, pneumonia 53, coughs 34, chest pain and related conditions 29, asthma 25, tuberculosis and spots in lungs 22, unspecified respiratory conditions 20, influenza 13, bronchial problems 12, dyspnoea 7, sore throat and infections 5 and sinus clearing 1 plant. The study identified potential medicinal plants that can be utilised in future to manage respiratory infections.

Polyphenols from Dichrostachys cinerea Fruits Anti-Inflammatory, Analgesic, and Antioxidant Capacity in Freund’s Adjuvant-Induced Arthritic Rat Model

Dichrostachys cinerea (L.) Wigth & Arn. (DC) is widely used in traditional medicine against several inflammatory diseases, especially rheumatoid arthritis, because of its antioxidant and anti-inflammatory effects. This study aimed to characterize the polyphenol-rich DC fruit extracts and investigate the analgesic, anti-inflammatory, and antioxidant effects in a rat inflammation model induced by complete Freund’s adjuvant (CFA). Water and ethanolic extracts were characterized using liquid chromatography coupled with mass spectrometry (LC-MS), Fourier-transform infrared (FTIR) spectroscopy, and gas chromatography coupled with mass spectrometry (GC-MS). The polyphenol-rich extracts were administered in three different concentrations for 30 days. Pain threshold, thermal hyperalgesia, edema, and serum biomarkers specific to inflammatory processes or oxidative stress were evaluated. Both extracts were rich in polyphenolic compounds, mainly flavan-3-ols, proanthocyanidins, and flavone glycosides, which had important in vitro antioxidant capacity. DC fruit extracts administration had the maximum antinociceptive and anti-inflammatory effects after one day since the CFA injection and showed promising results for long-term use as well. The measurement of pro-inflammatory cytokines, cortisol, and oxidative stress parameters showed that DC extracts significantly reduced these parameters, being dose and extract-type dependent. These results showed potential anti-inflammatory, analgesic, and antioxidative properties and revealed the necessity of using a standardized polyphenolic DC extract to avoid result variability.

Evaluation of the Antidiabetic Activity of Hydromethanolic Roots Extracts of Rumex abyssinicus Jacq: (Polygonaceae) in Swiss Albino Mice

Introduction

Diabetes Mellitus isa chronic metabolic disorder that required long-lasting treatment. In Ethiopian traditional medicine practices, abundant plants have been used for the treatment of diabetes mellitus for a long period. The root of Rumex abyssinicus is employed for the treatment of diabetes mellitus by Ethiopians. This study aimed to investigate the antidiabetic activity of the crude extract of Rumex abyssinicus root in Swiss albino mice.

Methods

Cold maceration technique and hydro methanolic (80% methanol) solvent with occasionally shaking were employed during the crude extraction processes. To evaluate the antidiabetic activity of the crude extract, normoglycemic, glucose-loaded, and streptozotocin-induced diabetic models were used. In each model, the overnight fasted mice were randomly divided into five groups for normoglycemic and glucose-loaded models as a negative control, positive control, and three tested groups, whereas, in streptozotocin-induced diabetic models, the mice were grouped into six groups like one diabetic and one normal negative control groups, three diabetic tested groups, and one diabetic positive group. Each group comprised six mice. For all models, the tested groups received the crude extract at 100, 200, and 400 mg/kg doses, both diabetic and nondiabetic negative control groups received 10 ml/kg distilled water, and positive groups received 5 mg/kg glibenclamide.

Results

The crude extract of the plant did not show any sign of toxicity up to 2000 mg/kg dose. In normoglycemic and oral glucose tolerance tests, the crude extract significantly (p < 0.01) reduced the blood glucose level at 200 and 400 mg/kg doses. In the streptozotocin-induced diabetes models, a significant effect was observed at all tested doses.

Conclusion

The finding of this study revealed that the crude extract of the plant owned antidiabetic activity and supports the traditional use of Rumex abyssinicus root for the treatment of diabetes mellitus.

The PI3K/AKT Pathway-The Potential Key Mechanisms of Traditional Chinese Medicine for Stroke

Stroke is associated with a high disability and fatality rate, and adversely affects the quality of life of patients and their families. Traditional Chinese Medicine (TCM) has been used effectively in the treatment of stroke for more than 2000 years in China and surrounding countries and regions, and over the years, this field has gleaned extensive clinical treatment experience. The Phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway is important for regulation of cell migration, proliferation, differentiation, and apoptosis, and plays a vital role in vascularization and oxidative stress in stroke. Current Western medicine treatment protocols for stroke include mainly pharmacologic or mechanical thrombectomy to restore blood flow. This review collates recent advances in the past 5 years in the TCM treatment of stroke involving the PI3K/AKT pathway. TCM treatment significantly reduces neuronal damage, inhibits cell apoptosis, and delays progression of stroke via various PI3K/AKT-mediated downstream pathways. In the future, TCM can provide new perspectives and directions for exploring the key factors, and effective activators or inhibitors that affect occurrence and progression of stroke, thereby facilitating treatment.

The ethnobotanical relevance of the tribe Symphonieae (Clusiaceae) around the world

ETHNOPHARMACOLOGICAL RELEVANCE

The tribe Symphonieae (Clusiaceae) encompasses 48 species accommodated in seven genera (Lorostemon, Montrouziera, Moronobea, Pentadesma, Platonia, Symphonia and Thysanostemon). Parts of these plants, mainly the exudates and the seeds oil are useful for different purposes, especially for treating dermatological conditions. In addition to the role in the folk medicine, some species are of great economic and cultural importance for native people from different continents.

AIM OF THE REVIEW

The goal of this review is to critically summarize the current knowledge on systematics, ethnobotanical, chemical and pharmacological aspects of species from the tribe Symphonieae, as well as to provide support for future taxonomic and phylogenetic studies on the Clusiaceae family.

MATERIALS AND METHODS

The available information was gathered from many different databases (Web of Science, ScienceDirect, Scopus, Pubmed, ChemSpider, SciFinder, ACS Publications, Wiley Online Library, Useful Tropical Plants Database, Google Scholar). Additional data from books, theses and dissertations were also included in this review.

RESULTS

Chemical studies of Symphonieae have demonstrated that the genera are a source of benzophenones, xanthones and biflavonoids. Components as sesquiterpenoids, triterpenoids, flavonoids, free fatty acids, among others, have also been reported. Extracts and compounds isolated from a variety of species have been exhibiting antimicrobial, cytotoxic and antiprotozoal activities, corroborating part of their medicinal uses. In addition, certain species produce edible fruits and a kind of "butter" with economic importance. All species produce exudate, which often has great relevance in the daily lives of local people.

CONCLUSION

Several species of Symphonieae have potential therapeutic applications and some of them have been investigated to scientifically validate their popular uses. In addition, a number of species have proved to be a rich source of promising pharmacologically active compounds. Finally, the value of fruits, exudate and butter, for instance, should serve as a stimulus for the sustainable development of products that aim to take advantage of these natural resources.

Comparative study among Avicennia marina, Phragmites australis, and Moringa oleifera based ethanolic-extracts for their antimicrobial, antioxidant, and cytotoxic activities

Microbial resistance and other emerging health risk problems related to the side effects of synthetic drugs are the major factors that result in the research regarding natural products. Fruits, leaves, seeds, and oils-based phyto-constituents are the most important source of pharmaceutical products. Plant extract chemistry depends largely on species, plant components, solvent utilized, and extraction technique. This study was aimed to compare the ethanolic extracts of a mangrove plant, i.e., Avicennia marina (1E: Lower half of A. marina‘s pneumatophores, 2E: A. marina‘s leaves, 3E: Upper half of A. marina‘s pneumatophores, and 4E: A. marina‘s shoots), with non-mangrove plants, i.e., Phragmites australis (5E: P. australis‘s shoot), and Moringa oleifera (6E: M. oleifera‘s leaves) for their antimicrobial activities, total phenolic contents, antioxidant activity, and cytotoxicity potential. The antimicrobial activity assays were performed on gram-positive bacteria (i.e., Bacillus subtilis and Staphylococcus aureus), gram-negative bacteria (i.e., Escherichia coli, and Pseudomonas aeruginosa), and fungi (i.e., Aspergillus niger, Candida albicans, and Rhizopus spp.). We estimated antioxidant activity by TAC, DPPH, and FRAP assays, and the cytotoxicity was evaluated by MTT assay. The results of antimicrobial activities revealed that B. subtilis was the most sensitive to the tested plant extracts compared to S. aureus, while it only showed sensitivity to 6E and Imipenem. 5E and 6E showed statistically similar results against P. aeruginosa as compared to Ceftazidime. E. coli was the most resistant bacteria against tested plant extracts. Among the tested plant extracts, maximum inhibition activity was observed by 6E against A. niger (22 ± 0.57 mm), which was statistically similar to the response of 6E against C. albicans and 3E against Rhizopus spp. 2E did not show any activity against tested fungi. We found that 6E (208.54 ± 1.92 mg g⁻¹) contains maximum phenolic contents followed by 1E (159.42 ± 3.22 mg g⁻¹), 5E (131.08 ± 3.10 mg g⁻¹), 4E (i.e., 72.41 ± 2.96 mg g⁻¹), 3E (67.41 ± 1.68 mg g⁻¹), and 2E (48.72 ± 1.71 mg g⁻¹). The results depict a significant positive correlation between the phenolic contents and the antioxidant activities. As a result, phenolic content may be a natural antioxidant source.

Cytotoxic, Antibacterial, and Leishmanicidal Activities of Paullinia pinnata (Linn.) Leaves

Background: Paullinia pinnata leaves are employed traditionally for the treatment of various ailments which are of biological origin. Objectives: The aim of this study was to explore cytotoxic, antibacterial, and antileishmanial properties of the leaves of Paullinia pinnata using in vitro models. Methods: Brine shrimp lethality bioassay was used to determine the cytotoxic activity of the methanol leaf extract of Paullinia pinnata. The activity of the extract against the growth of cultured Leishmania major (DESTO) promastigotes was used to investigate the leishmanicidal activities. The agar well diffusion method was used to investigate the antibacterial activity against Salmonella typhi, Pseudomonas aeruginosa, Shigella flexneri, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. Results: The methanol leaf extract of P. pinnata had no activity against Artemia salina (brine shrimp) and L. major. It showed a non-significant activity against E. coli and B. subtilis and no activity against P. aeruginosa, S. flexneri, S. typhi, and S. aureus. Conclusion: The methanol leaf extract of P. pinnata did not exhibit any cytotoxic and anti-leishmanial properties. Moreover, the activity against various species of bacteria was not significant.

Antibacterial, antifungal and antioxidant activities of whole plant chemical constituents of Rumex abyssinicus

Background

Antibiotic resistance has contributed to the burden of infectious diseases both in the hospital and community setting, and represents a great threat to public health. Previous studies have revealed the role of reactive oxygen species as intermediate mediators of tissue damage, following antibiotherapies, indicating the need of associating antioxidants to these treatments. Therefore, the present work was designed to study the antibacterial, antifungal and antioxidant activities of extracts and compounds from Rumex abyssinicus Jacq. (Polygonaceae), as well as to investigate the antibacterial mechanisms of action of the most effective agents.

Methods

The plant extracts were prepared by maceration in organic solvents followed by column chromatography of the EtOAc fraction and purification of different fractions which led to the isolation and characterization of pure compounds. The antimicrobial activities of the extracts/compounds and their combinations with ciprofloxacin and fluconazole were evaluated using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The effects of the extracts on the bacterial cell membrane and microbial respiratory chain dehydrogenase enzyme activity were determined by spectrophotometric methods. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays.

Results

Chrysophanol (1), physcion (2), Ergosta-6,22-diene-3,5,8-triol (3), emodin (4), 6-hydroxyemodin (citreorosein) (5), chrysophanein (6) and physcionin (7) were isolated from EtOAc fraction of R. abyssinicus and displayed different degrees of antimicrobial activities (MIC = 8–256 μg/mL). The MeOH extract and compounds 2 and 4 exhibited synergistic effects with ciprofloxacin and fluconazole. Compounds 1, 2 and the combined mixture of 6 + 7 displayed the highest antioxidant activity (GAEAC = 83.38–106.03 μg/mL).

Conclusion

R. abyssinicus is a potential source of antibacterial, antifungal and antioxidant agents. The antibacterial mechanisms of action of the MeOH extract and compound 2 are due to disruption of the cytoplasmic membrane and inhibition of the microbial respiratory chain dehydrogenase enzyme activity. To the best of our knowledge, this is the first report of test samples and ciprofloxacin / fluconazole association against MDR strains. The observed activity of the isolated compounds against bacteria and fungi including MDR strains deserves further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03325-y.

African Herbal Medicines: Adverse Effects and Cytotoxic Potentials with Different Therapeutic Applications

The African continent is naturally endowed with various plant species with nutritional and medicinal benefits. About 80% of the people in developing countries rely on folk medicines to treat different diseases because of indigenous knowledge, availability, and cost-effectiveness. Extensive research studies have been conducted on the medicinal uses of African plants, however, the therapeutic potentials of some of these plants has remained unexploited. Over the years, several studies have revealed that some of these African floras are promising candidates for the development of novel drugs. Despite the plethora of studies on medicinal plant research in Africa, there is still little scientific data supporting the folkloric claims of these plants. Besides, safety in the use of folk medicines has been a major public health concern over the year. Therefore, it has become mandatory that relevant authority should take measures in safeguarding the populace on the use of herbal mixtures. Thus, the present review extracted relevant information from different scientific databases and highlighted some problems associated with folk medicines, adverse effects on reproductive systems, issue about safety due to the toxicity of some plants and their toxicity effects with potential therapeutic benefits are discussed.

Medicinal plants used by 'root doctors', local traditional healers in Bié province, Angola

ETHNOPHARMACOLOGICAL RELEVANCE

This study is one of the first post-civil war efforts to document traditional botanical knowledge in Bié province, central Angola, in a first step to bring more studies on the use of medicinal plant resources in this area so as to bring new insights into Angolan bio-cultural diversity.

AIM OF THE STUDY

Examine the variety of plant species used for medical purposes, as well as characterize their social and cultural values. Also, it is aimed to compare their uses in the studied region with those in Sub-Saharan Africa and report new ethnomedicinal uses.

MATERIALS AND METHODS

We documented traditional medicinal plant knowledge among professional herbalists in two areas in Bié province through participatory observation, semi-structured interviews and transect walks. Ethnobotanical information was quantified based on Use Reports to (1) rate traditional knowledge; and (2) determine most useful taxa.

RESULTS

In total, 10 traditional healers shared information on their knowledge. A total of 87 plant species distributed among 57 genera and 36 botanical families were documented with Fabaceae being the best-represented family with 18 species, followed by Phyllanthaceae (6), Apocynaceae (5), Asteraceae (5), Rubiaceae (5), Lamiaceae (4), and Ochnaceae (3). Most medicinal plants are usually gathered at a distance from human settlements because of the belief in the higher efficacy of 'wild' plants shared by all herbalists. Roots are the most common plant part used (79%), explaining why the consulted herbalists call themselves 'root doctors'.

CONCLUSIONS

The culturally most important medicinal species identified in this study, i.e. Securidaca longepedunculata, Garcinia huillensis, Annona stenophylla, Afzelia quanzensis and Strychnos cocculoides, were previously reported for the same use in neighbouring countries and elsewhere in Africa. Our study also indicates that there are several locally valuable species that have not yet been studied for their medical potential, to name a few: Alvesia rosmarinifolia, Diplorhynchus condylocarpon, Eriosema affine, Paropsia brazzaeana, Rhus squalida, Sclerocroton cornutus or Xylopia tomentosa. Moreover, the ethnomedicinal use of 26 species was reported for the first time to sub-Saharan Africa.

CLASSIFICATION

Ethnopharmacological field studies.

Preclinical study of the medicinal plants for the treatment of malignant melanoma

Melanoma is the most aggressive type of skin cancer and originates from pigment-containing cells called melanocytes. The incidence of melanoma has been increasing worldwide. In the current study, the cytotoxic and photo-cytotoxic activities of different medicinal plants from Lamiaceae (Salvia cedronella, Salvia chionantha, and Salvia adenophylla), Asteraceae (Klasea kurdica, Klasea bornmuelleri, and Achillea millefolium), Apiaceae (Cuminum cyminum, and Anethum graveolens), and Polygonaceae (Rumex crispus) families were studied against HT 144 (Human malignant melanoma) cancer cell lines. The activities were performed by employing the MTT assay. Moreover, the apoptotic effects of the plant extracts were investigated by flow cytometry with annexin V/PI dual staining technique. The production of intracellular ROS by DCFH-DA technique and the effects of TNF-α secretion on apoptosis were also investigated. All plant extracts exhibited cytotoxic, and photo-cytotoxic effects against HT 144 cancer cells. Salvia species and Klasea species induced apoptosis via intracellular ROS generation secreted by TNF-α. On the other hand, A. millefolium, C. cyminum, A. graveolens, and R. crispus extracts induced apoptosis due to the intracellular generation of ROS, but, via the different pathway. In conclusion, this study indicates that the tested medicinal plant extracts have the potential in the treatment of melanoma.

Anthelmintic A-Type Procyanidins and Further Characterization of the Phenolic Composition of a Root Extract from Paullinia pinnata

Extracts from the roots of Paullinia pinnata L. are used in West Africa as traditional remedies for a variety of diseases including infestations with soil-transmitted helminths. Based on the results of an ethnopharmacological survey in Ghana, an aqueous acetone (70%) extract was investigated for its anthelmintic and phytochemical properties. Partitioning of the crude extract followed by several fractionation steps of the ethyl acetate phase using Sephadex® LH-20, fast centrifugal partition chromatography, RP-18-MPLC and HPLC led to isolation of six oligomeric A-type procyanidins (1 to 6). To determine the anthelmintic activity, the crude extract, fractions and isolated compounds were tested in vitro against the model organism Caenorhabditis elegans. A significantly better activity was observed for the trimeric A-type procyanidin (1) compared to a B-type trimer. However, this effect could not be generalized for the tetrameric procyanidins, for which the type of the interflavan-linkage (4→6 vs. 4→8) had the greatest impact on the bioactivity. Besides the procyanidins, three novel compounds, isofraxidin-7-O-α-l-rhamnopyranosyl-(1″→6')-β-d-glucopyranoside (17), 4-methoxycatechol-2-O-(5''-O-vanilloyl-β-apiofuranosyl)-(1''→2')-β-glucopyranoside (18) and a 6-(3-methoxy-4-hydroxyphenyl)-hexane-2,4-diol-2-O-hexoside (19) were isolated together with further ten known compounds (7 to 16), mainly coumarins and coumarinolignans. Except for 3-β-d-glucopyranosyloxy-4-methyl-2(5H)-furanone (15), none of the isolated compounds has previously been described for P. pinnata. The anthelmintic activity was attributed to the presence of procyanidins, but not to any of the other compound classes. In summary, the findings rationalize the traditional use of P. pinnata root extracts as anthelmintic remedies.

Discovery of Helminthosporin, an Anthraquinone Isolated from Rumex abyssinicus Jacq as a Dual Cholinesterase Inhibitor

Natural products have extensively contributed toward the discovery of new leads for Alzheimer's disease. During our search for new inhibitors of cholinesterase enzymes from natural sources, the ethyl acetate (EtOAc) extract of Rumex abyssinicus Jacq was identified as a dual cholinesterase inhibitor with IC₅₀ values of 2.7 and 11.4 μg/mL against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively. The phytochemical investigation of the EtOAc extract has resulted in isolation of four anthraquinones, namely, helminthosporin, emodin, chrysophanol, and physcion, amongst which the helminthosporin has been isolated for the first time from Rumex sp. All isolated secondary metabolites have displayed significant inhibition of EeAChE with IC₅₀ values of 2.63, 15.21, 33.7, and 12.16 μM, respectively. In addition, the helminthosporin was also found to inhibit BChE with an IC₅₀ value of 2.99 μM. The enzyme kinetic study has indicated that helminthosporin inhibits AChE and BChE in a noncompetitive manner with k _i values of 10.3 and 12.3 μM, respectively. The results of molecular modeling and propidium iodide displacement assay have revealed that helminthosporin occupies the peripheral anionic site of the active site gorge of AChE. In the PAMPA-BBB permeability assay, helminthosporin was found to possess high BBB permeability (P _e = 6.16 × 10^-6 cm/s). In a nutshell, helminthosporin has been identified as a brain permeable dual cholinesterase inhibitor, and thus its further synthetic exploration is warranted for optimization of its potency.

Biochemical Activity and Hypoglycemic Effects of Rumex obtusifolius L. Seeds Used in Armenian Traditional Medicine

Diabetes mellitus (DM) is a serious chronic metabolic disorder. Various diseases are being treated with medicinal plants and that is because of the less side effects of the current therapy. The diversity of plants in Armenia is due to the singularity of natural environment. However, biochemical activity of these plants has not been studied well. Thus, the goal was to investigate biochemical activity and antihyperglycemic properties of Rumex obtusifolius L. in rabbits with hyperglycemia. The high content of total phenolic compounds, flavonoids, and tannins has been determined in this plant extract. Oral administration of ethanol extract showed significant effect on hyperglycemia, reducing fasting glucose levels (57.3%, p<0.05), improving glucose tolerance, and increasing liver glycogen content (1.5-fold, p<0.01) compared to the hyperglycemic control group. Furthermore, ethanol extract of R. obtusifolius reduced total cholesterol, low-density lipoprotein cholesterol levels, and vice versa increased high-density lipoprotein cholesterol levels and also decreased liver enzymes levels (alanine aminotransferase and aspartate aminotransferase) compared with untreated group. These findings suggest that R. obtusifolius may have beneficial effects and should be supplement, as herbal remedy in the treatment of DM.

The high affinity of small-molecule antioxidants for hemoglobin

Hemoglobin has previously been shown to display ascorbate peroxidase and urate peroxidase activity, with measurable Michaelis-Menten parameters that reveal a particularly low Km for ascorbate as well as for urate - lower than the respective in vivo concentrations of these antioxidants in blood. Also, direct detection of a hemoglobin-ascorbate interaction was possible by monitoring the 1H-NMR spectrum of ascorbate in the presence of hemoglobin. The relative difference in structures between ascorbate and urate may raise the question as to exactly what the defining structural features would be, for a substrate that binds to hemoglobin with high affinity. Reported here are Michaelis-Menten parameters for hemoglobin acting as peroxidase against a number of other substrates of varying structures - gallate, caffeate, rutin, 3-hydroxyflavone, 3,6-dihydroxyflavone, quercetin, epicatechin, luteolin - all with high affinities (some higher than those of physiologically-relevant redox partners of Hb - ascorbate and urate). Moreover, this high affinity appears general to animal hemoglobins. ¹H-NMR and ¹³C-NMR spectra reveal a general pattern wherein small hydrophilic antioxidants appear to all have their signals affected, presumably due to binding to hemoglobin. Fluorescence and calorimetry measurements confirm these conclusions. Docking calculations confirm the existence of binding sites on hemoglobin and on myoglobin for ascorbate as well as for other antioxidants. Support is found for involvement of Tyr42 in binding of three out of the four substrates investigated in the case of hemoglobin (including ascorbate and urate, as blood-contained relevant substrates), but also for Tyr145 (with urate and caffeate) and Tyr35 (with gallate).

Sources for developing new medicinal products: biochemical investigations on alcoholic extracts obtained from aerial parts of some Romanian Amaryllidaceae species

BACKGROUND

Although Galanthus nivalis L. (snowdrop) is known for the galanthamine content, used in the treatment of Alzheimer disease, the polyphenolic compounds of Amaryllidaceae species are less studied. Proper understanding of the polyphenolics in these extracts and of their antioxidant and antimicrobial properties may allow a reconsideration of their medicinal uses.

METHODS

The polyphenolic content of four selected Amaryllidaceae species harvested from Romania (Galanthus nivalis L., Narcissus pseudonarcissus L., N. poeticus L. and Leucojum vernum L.) was determined by spectrophotometric methods; the identification of phenolic compounds was performed by a HPLC-MS method, in order to establish their polyphenolic fingerprints. For the evaluation of the antioxidant potential the following methods were employed: DPPH radical scavenging, FRAP, hemoglobin ascorbate peroxidase activity inhibition (HAPX), inhibition of lipid peroxidation catalyzed by cytochrome c, and electron paramagnetic resonance (EPR) spectroscopy assays. Antimicrobial activity was assessed using the disc diffusion method.

RESULTS

Qualitative and quantitative analyses highlight important amount of polyphenols (over 15 mg/g); the main identified compounds are chlorogenic and p-coumaric acids in all species. Only G. nivalis shows antioxidant activity by all the used methods. G. nivalis and L. vernum strongly inhibits the growth of S. aureus, while N. poeticus shows a very good antifungal activity.

CONCLUSIONS

The results of this study provide a new approach to the properties and therapeutic uses of some Romanian widespread Amaryllidaceae species that could be considered sources of developing new medicinal products with anti anti-staphylococcal and antifungal activity.

Achillea schurii Flowers: Chemical, Antioxidant, and Antimicrobial Investigations

This study aims to evaluate the phenolic profile, and antioxidant and antimicrobial activity of Achillea schurii Sch.-Bip., an endemic species from Romania that has not been investigated yet. The chromatographic profile of the phenolic components was obtained using the HPLC-MS method, while the total polyphenol, flavonoid, caffeic acid derivative contents were quantified using spectrophotometric methods. The antioxidant activity was evaluated using different methods: DPPH radical scavenging, hemoglobin ascorbate peroxidase activity inhibition (HAPX), inhibition of lipid peroxidation catalyzed by cytochrome c, and direct detection of plant-derived free radicals using electron paramagnetic resonance (EPR). The antimicrobial test was performed using the disk diffusion assay. The phenolic profile has revealed high amounts of isoquercitrin, rutin, luteolin, and apigenin. The A. schurii extract exhibited a good antioxidant capacity, and high phenolic contents (76.93 mg/g polyphenols, 18.61 mg/g flavonoids and 41.48 mg/g caffeic acid derivatives, respectively). The antimicrobial tests reveal a remarkable inhibitory activity against Listeria monocytogenes, Staphylococcus aureus, and Salmonella typhimurium. Considering the above, A. schurii may be deemed to offer good perspectives for pharmaceutical and industrial applications.

Emodin from Polygonum multiflorum ameliorates oxidative toxicity in HT22 cells and deficits in photothrombotic ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonum multiflorum Thunb. has been used widely in East Asia in treatment of diseases associated with aging. Emodin, an active component from Polygonum multiflorum Thunb., provides benefits for brain disturbances induced by severe cerebral injury.

AIM OF THE STUDY

We investigated the neuroprotective effect of emodin from Polygonum multiflorum Thunb. against glutamate-induced oxidative toxicity and cerebral ischemia.

MATERIALS AND METHODS

For examination of neuroprotective effects of emodin, cell viability, cytotoxicity, flow cytometry, and Western blot were performed in HT22 cells and infarct volume, behavioral tests and Western blot in a mouse model of photothrombotic ischemic stroke.

RESULTS

Pretreatment with emodin resulted in significantly reduced glutamate-induced apoptotic cell death in HT22 cells. However, blocking of phosphatidylinositol-3 kinase (PI3K) activity with LY294002 resulted in significantly inhibited cell survival by emodin. Exposure of glutamate-treated cells to emodin induced an increase in the level of Bcl-2 expression, whereas the expression of Bax and active caspase-3 proteins was significantly reduced. In addition, treatment with emodin resulted in increased phosphorylation of Akt and cAMP response element binding protein (CREB), and expression of mature brain-derived neurotrophic factor (BDNF). This expression by emodin was also significantly inhibited by blocking of PI3K activity. In a photothrombotic ischemic stroke model, treatment with emodin resulted in significantly reduced infarct volume and improved motor function. We confirmed the critical role of the expression levels of Bcl-2/Bax, active caspase-3, phosphorylated (p)Akt, p-CREB, and mature BDNF for potent neuroprotective effects of emodin in cerebral ischemia.

CONCLUSIONS

These results suggest that emodin may afford a significant neuroprotective effect against glutamate-induced apoptosis through activation of the PI3K/Akt signaling pathway, and subsequently enhance behavioral function in cerebral ischemia.

The Genus Rumex: Review of traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The approximately 200 species of the genus Rumex (sorrel, Polygonaceae) are distributed worldwide (European, Asian, African and American countries). Some species have been used traditionally as vegetables and for their medicinal properties. Based on the traditional knowledge, different phytochemical and pharmacological activities have been at the focus of research. This review aims to provide an overview of the current state of knowledge of local and traditional medical uses, chemical constituents, pharmacological activities, toxicity, and safety of Rumex species, in order to identify the therapeutic potential of Rumex species and further directions of research.

MATERIALS AND METHODS

The selection of relevant data was made through a search using the keyword "Rumex" in "Scopus", "Google Scholar", "Web of Science", "PubMed", and "ScienceDirect" databases. Plant taxonomy was validated by the databases "The Plant List", and "Mansfeld's Encyclopedia". Additional information on traditional use and botany was obtained from published books and MSc dissertations.

RESULTS

This review discusses the current knowledge of the chemistry, the in vitro and in vivo pharmacological studies carried out on the extracts, and the main active constituents, isolated from plants of genus Rumex. Although, there are about 200 species in this genus, most of the phytochemical and pharmacological studies were performed on up to 50 species. The aerial parts, leaves and roots of the plants are used as vegetables and for the treatment of several health disorders such as mild diabetes, constipation, infections, diarrhoea, oedema, jaundice, and as an antihypertensive, diuretic and analgesic and in case of skin, liver and gallbladder disorders, and inflammation. Many phytochemical investigations on this genus confirmed that Rumex species are rich in anthraquinones, naphthalenes, flavonoids, stilbenoids, triterpenes, carotenoids, and phenolic acids. Moreover, it draws the attention that high level of oxalic acid in some species can cause toxicity (kidney stones) if consumed large quantity.

CONCLUSIONS

This review confirms that some Rumex species have emerged as a good source of the traditional medicine for treatment of inflammation, cancer and different bacterial infections and provides new insights for further promising investigations on isolated compounds, especially quercetin 3-O-glucoside, emodin, nepodin, torachrysone, and trans-resveratrol to find novel therapeutics and aid drug discovery. In addition, hepatoprotective, antiviral and antidiabetic activities should have priority in future pharmacological studies. However, for applying species to prevent or treat various diseases, additional pharmacological studies are needed to find the mechanism of actions, safety and efficacy of them before starting clinical trials.

Antiproliferative Activity of T. welwitschii Extract on Jurkat T Cells In Vitro

Triumfetta welwitschii is a plant used traditionally for the treatment of fever and diarrhoea. Previous work has shown that T. welwitschii has antibacterial activity. The purpose of this study was to investigate T. welwitschii extract for anticancer activity against Jurkat T cells. The Jurkat T cell line is used to study acute T cell leukaemia. An antiproliferation assay, determination of induction of apoptosis, the determination of the effect of the combination of the extract and GSH, and effects of the extract on DNA leakage were conducted. T. welwitschii was found to decrease cell viability in a dose- and time-dependent manner. T. welwitschii caused apoptosis in the Jurkat T cells as shown by DNA fragmentation. When T. welwitschii was combined with reduced GSH, it was found that the growth of the Jurkat T cells was significantly reduced compared to untreated cells after 72 h of treatment. This was unexpected, as cancer cells have elevated levels of GSH compared to normal cells. The results of this study show that T. welwitschii is a potential source of compounds that may serve as leads for anticancer compounds.

Effect of Rumex Abyssinicus on preneoplastic lesions in dimethylhydrazine induced colon carcinogenesis in rats

BACKGROUND

Cancer as a multistage process can be reversed or blocked by using chemopreventive agents. Colon cancer chemoprevention has been widely investigated using cyclooxygenase inhibitors and many other chemicals of synthetic or natural origin. This particular study was carried out to assess the colon cancer chemopreventive effect of hydro-methanol extract of Rumex abyssinicus rhizome on rats.

METHOD

Colon cancer chemopreventive potential of hydro-methanol extract of Rumex abyssinicus rhizome was determined based on the number and multiplicity of aberrant crypt foci (ACF). Fifteen DMH (1, 2-dimethylhydrazine) treated and five untreated Wistar female rats were used. DMH was administered subcutaneously 30 mg/kg, after its pH was adjusted to 6.5-7. Treatment groups started receiving extract after six weeks of weekly DMH injections. The rats were divided in to four groups: Group 1 received only oral normal saline, Group 2 received DMH and normal saline, Group 3 and 4 received DMH plus 250 mg/kg and 500 mg/kg extract, respectively. Specific phytoconstituents of the plant, which were reviewed from original articles, were virtually evaluated for cyclooxygenase-2 (COX-2) inhibition. The binding energies and interactions of the phytochemicals from Rumex abyssinicus against COX-2 were determined by Autodock4.2.

RESULTS

There was a statistically significant reduction (p-value < 0.05) in the number of aberrant crypt (AC) and aberrant crypt foci (ACF) at both administered doses. However, significant association (p-value > 0.05) was not observed in reducing crypt multiplicity. The docking process resulted in estimated binding energies [-6.83 kcal/mol to -7.9 kcal/mol] which are closer to the positive controls or Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) [-4.55 kcal/mol to -10.84 kcal/mol]. The phytochemical-COX-2 interaction indicated the involvement of key amino acid residues in inhibition of cyclooxygenase like ARG120, TYR355, TYR385, SER530 and GLY526.

CONCLUSIONS

Rumex abyssinicus had demonstrated a chemopreventive potential at post-initiation stage. As the virtual screening data suggested, COX-2 inhibition by the anthraquinones in the extract could be one mechanism for the observed chemopreventive effect.

Antioxidant activity evaluation by physiologically relevant assays based on haemoglobin peroxidase activity and cytochrome c-induced oxidation of liposomes

Two new protocols for exploring antioxidant-related chemical composition and reactivity are described: one based on a chronometric variation of a haemoglobin ascorbate peroxidase assay and one based on cytochrome c-induced oxidation of lecithin liposomes. Detailed accounts are given on their design, application, critical correlations with established methods and mechanisms. These assays are proposed to be physiologically relevant and bring new information regarding a real sample, both qualitative and quantitative. The well-known assays used for evaluation of antioxidant (re)activity are revisited and compared with these new methods. Extracts of the Hedera helix L. are examined as test case, with focus on seasonal variation and on leaf, fruit and flower with respect to chromatographic, spectroscopic and reactivity properties. According to the set of assays performed, winter are the most antioxidant, followed by summer leaves, and then by flowers and fruits.

Antimicrobial and antioxidant flavonoids from the leaves of Oncoba spinosa Forssk. (Salicaceae)

Background

Naturally occurring flavonoids have been reported to possess various pharmacological properties. The aim of this study was to evaluate the antimicrobial and antioxidant activities of the MeOH extract and flavonoids from the leaves of Oncoba spinosa, a plant used for the treatment of syphilis, wounds and sexual impotence.

Methods

The plant extract was prepared by maceration in methanol and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The MeOH extract and its isolated compounds were evaluated for their antibacterial and antifungal activities by broth microdilution method. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. The samples were tested spectrophotometrically for their hemolytic properties against human red blood cells.

Results

The fractionation of the MeOH extract afforded five known flavonoids including kaempferol (1), quercetin (2), apigenin-7-O-β-D-glucuronopyranoside (3), quercetin 3-O-β-D-galactopyranoside (4) and quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) β-D-glucopyranoside (5). The MeOH extract displayed weak to moderate antimicrobial activities (MIC = 256–2048 μg/ml). Quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) β-D-glucopyranoside (5) and quercetin (2) were respectively the most active compounds against bacteria (MIC = 8–64 μg/ml) and fungi (MIC = 64 – 128 μg/ml). These tested samples also showed high radical-scavenging activities (EC₅₀ = 5.08 – 70.56 μg/ml) and gallic acid equivalent antioxidant capacities (TEAC = 53.76 – 89.86 μg/ml) when compared with vitamin C (EC₅₀ = 4.72 μg/ml). The MeOH extract and compounds 2–5 were non-toxic to human red blood cells indicating their high selectivity to be used as antimicrobial and antioxidant drugs.

Conclusion

The MeOH extract of O. spinosa as well as compounds 2 – 5 could be a potential source of natural antimicrobial and antioxidant products.

The new esters derivatives of betulin and betulinic acid in epidermoid squamous carcinoma treatment - In vitro studies

BACKGROUND

Betulinic acid and betulin are triterpenes with documented cytotoxic properties toward various cell lines. Unfortunately both betulinic acid and its metabolic precursor, betulin, are very poorly soluble in aqueous buffers, thus their bioavailability and bio-distribution are insufficient in terms of medical applications.

OBJECTIVE

To investigate the specific anticancer role of the newly synthesized betulin derivatives in human epidermoid carcinoma cells.

METHODS

In the present study we synthesized five amino acid esters of betulin. For the synthesis we selected alanine (Boc-l-Ala-OH, negative control) and four basic amino acids - natural lysine (Boc-l-Lys(Boc)-OH) and three its unnatural derivatives (Boc-l-Dap(Boc)-OH, Boc-l-Dab(Boc)-OH, and Boc-l-Orn(Boc)-OH). Boc-protected amino acids were most convenient for the synthesis. All new esters have one (betulin-l-Ala-NH2) or two free amino groups which significantly increase their solubility in water and facilitate their transport through the cell membrane. It is worth noting that the biological activity of new esters of betulin is positive correlated with the length of the side chain of l-amino acid. The highest biological activity displayed compound containing lysine side chain (Lys, -CH2-CH2-CH2-CH2-NH2). Considering the biological activity, other derivatives can be set in the following series: Orn (-CH2-CH2-CH2-NH2)>Dab (-CH2-CH2-NH2)>Dap (-CH2-NH2)>Ala (CH3)>betulin. New betulin esters were tested in normal human keratinocytes (HaCaT) and human epidermoid carcinoma cells (A431). To assess cytotoxicity, MTT test was performed after 24, 48 and 72h of incubation with the test compounds at a concentration range of 0.75-100μM. In case of apoptotic activity, a TUNEL method and comet assay were performed. Additionally expression of caspase-3 and PARP1 was evaluated immunocytochemically.

RESULTS

The highest cytotoxicity in cells induced skin cancer new compounds, particularly compound containing a lysine side chain (IC50=7μM) and ornithine (IC50=10μM). The highest number of apoptotic cells was observed in case incubation with compound containing Orn, Dab and Dap side chain.

CONCLUSIONS

The new betulin ester derivatives display enhanced antitumor activity compared to their non-modified precursors. It is worth emphasizing their specific toxicity against epidermoid carcinoma cells.

A systematic approach to prioritize drug targets using machine learning, a molecular descriptor-based classification model, and high-throughput screening of plant derived molecules: a case study in oral cancer

Network-based and cheminformatics approaches identify novel lead molecules forCXCR4, a key gene prioritized in oral cancer.

Emodin enhances ATRA-induced differentiation and induces apoptosis in acute myeloid leukemia cells

Emodin, an extracted natural compound from the root and rhizome of Rheum palmatum L, has been shown to have multiple biological activities including anticancer functions in previous studies. In this study, we investigated the anti-leukemic activity of emodin alone or emodin in the presence all-trans retinoic acid (ATRA) in acute myeloid leukemia (AML) cells and the potential signaling pathway involved. We demonstrated that emodin could significantly enhance the sensitivity to ATRA and present additive differentiation-inducing effects in AML cell line NB4 cells and, especially, in NB4-derived ATRA-resistant MR2 cells. Further study showed that increasing dose of emodin could effectively induce growth inhibition and apoptotic effects in both cell lines as well as in primary leukemic cells from AML patients. Moreover, the apoptotic induction in AML cells was associated with the activation of caspase cascades involving caspase-9, caspase-3, and poly(ADP-ribose) polymerase (PARP) cleavage. In addition, leukemic cell response to emodin stimuli in vitro was observed through the decreased expression levels of Bcl-2 and retinoic acid receptor α (RARα). Importantly, emodin was demonstrated as a new inhibitor of PI3K/Akt in AML cells, even in primary AML cells. It inhibited Akt phosphoration (p-Akt) at Ser473 as efficiently as mTOR at Ser2448. Consistently, it exerted suppression effects on the phosphoration of mTOR downstream targets, 4E-BP1 and p70S6K. Taken together, these findings indicate that emodin might be developed as a promising anti-leukemic agent to improve the patient outcome in AML.

Evaluation of antioxidant and antimicrobial activities and phenolic profile for Hyssopus officinalis, Ocimum basilicum and Teucrium chamaedrys

This study was designed to examine the in vitro antioxidant and antimicrobial activities and to characterize the polyphenolic composition of the ethanolic extracts of Hyssopus officinalis, Ocimum basilicum and Teucrium chamaedrys. Qualitative and quantitative analysis of the major phenolic compounds were conducted using high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS). The total polyphenols, caffeic acid derivatives and flavonoids content was spectrophotometrically determined. The phenolic profile showed the presence of phenolic acid derivatives (caftaric, gentisic, caffeic, p-coumaric, chlorogenic and ferulic acids), flavonoid glycosides (rutin, isoquercitrin and quercitrin) and free flavonoid aglycons (luteolin, quercetin), in different concentrations. DPPH radical scavenging assay, Trolox equivalent antioxidant capacity (TEAC) method, hemoglobin ascorbate peroxidase activity inhibition (HAPX) assay, and electron paramagnetic resonance (EPR) radicals detection were employed, revealing several aspects of the antioxidant activities of these species. The antimicrobial tests were performed using the disk diffusion assay. These extracts contained a large amount of the polyphenolic compounds (77.72, 175.57, and 243.65 mg/g, respectively), and they showed a good antioxidant activity, as witnessed by a number of methods. T. chamaedrys had a high antimicrobial activity. Besides their antioxidant activity, the antimicrobial effect of these extracts confirms the biological activities of these herbal medicinal products.

Phytochemical analysis and free radical scavenging activity of medicinal plants Gnidia glauca and Dioscorea bulbifera

Gnidia glauca and Dioscorea bulbifera are traditional medicinal plants that can be considered as sources of natural antioxidants. Herein we report the phytochemical analysis and free radical scavenging activity of their sequential extracts. Phenolic and flavonoid content were determined. Scavenging activity was checked against pulse radiolysis generated ABTS^•+ and OH radical, in addition to DPPH, superoxide and hydroxyl radicals by biochemical methods followed by principal component analysis. G. glauca leaf extracts were rich in phenolic and flavonoid content. Ethyl acetate extract of D. bulbifera bulbs and methanol extract of G. glauca stem exhibited excellent scavenging of pulse radiolysis generated ABTS^•+ radical with a second order rate constant of 2.33×10⁶ and 1.72×10⁶, respectively. Similarly, methanol extract of G. glauca flower and ethyl acetate extract of D. bulbifera bulb with second order rate constants of 4.48×10⁶ and 4.46×10⁶ were found to be potent scavengers of pulse radiolysis generated OH radical. G. glauca leaf and stem showed excellent reducing activity and free radical scavenging activity. HPTLC fingerprinting, carried out in mobile phase, chloroform: toluene: ethanol (4: 4: 1, v/v) showed presence of florescent compound at 366 nm as well as UV active compound at 254 nm. GC-TOF-MS analysis revealed the predominance of diphenyl sulfone as major compound in G. glauca. Significant levels of n-hexadecanoic acid and octadecanoic acid were also present. Diosgenin (C₂₇H₄₂O₃) and diosgenin (3á,25R) acetate were present as major phytoconstituents in the extracts of D. bulbifera. G. glauca and D. bulbifera contain significant amounts of phytochemicals with antioxidative properties that can be exploited as a potential source for herbal remedy for oxidative stress induced diseases. These results rationalize further investigation in the potential discovery of new natural bioactive principles from these two important medicinal plants.

Phytochemical analysis, antimicrobial and radical-scavenging properties of Acalypha manniana leaves

Acalypha manniana (Euphorbiaceae) is a plant popularly used in Cameroon and in several parts of Africa for the treatment of various microbial diseases like diarrhea and skin infections. The present study was designed to evaluate the phytochemical composition, antimicrobial and radical-scavenging activities of A. manniana methanol leaf extract and its fractions. The methanol extract was partitioned into hexane, ethyl acetate and residual fractions and phytochemical analysis was conducted using standard methods. The broth microdilution method was used to evaluate the antimicrobial activity against nine bacterial species and four dermatophyte species. The free radical scavenging activities of the methanol extract and its fractions were evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The results obtained showed that A. manniana contains alkaloids, tannins, anthocyanins, flavonoids, phenols and steroids. The methanol extract as well as the hexane, ethyl acetate and residual fractions exhibited both antibacterial and antidermatophytic activities that varied between the microbial species (MIC = 0.12 - 2.04 mg/mL). These tested samples also showed high radical-scavenging activities (RaS50 = 3.34 - 4.80 μg/mL) when compared with vitamin C used as reference antioxidant (RaS50 = 1.74 μg/mL). These findings provide evidence that the studied plant possesses antimicrobial and antioxidant properties and may act as potential antioxidant for biological systems susceptible to free radical-mediated reactions.

Cytotoxicity of Elaoephorbia drupifera and other Cameroonian medicinal plants against drug sensitive and multidrug resistant cancer cells

Background

Multidrug resistance (MDR) is a major hurdle for cancer treatment worldwide and accounts for chemotherapy failure in over 90% of patients with metastatic cancer. Evidence of the cytotoxicity of Cameroonian plants against cancer cell lines including MDR phenotypes is been intensively and progressively provided. The present work was therefore designed to evaluate the cytotoxicity of the methanol extracts of twenty-two Cameroonian medicinal plants against sensitive and MDR cancer cell lines.

Methods

The methanol maceration was used to obtain the crude plant extracts whilst the cytotoxicity of the studied extracts was determined using a resazurin reduction assay.

Results

A preliminary assay on leukemia CCRF-CEM cells at 40 μg/mL shows that six of the twenty plant extract were able to enhance less than 50% of the growth proliferation of CCRF-CEM cells. These include Crinum zeylanicum (32.22%), Entada abyssinica (34.67%), Elaoephorbia drupifera (35.05%), Dioscorea bulbifera (45.88%), Eremomastax speciosa (46.07%) and Polistigma thonningii (45.11%). Among these six plants, E. drupifera showed the best activity with IC₅₀ values below or around 30 μg/mL against the nine tested cancer cell lines. The lowest IC₅₀ value of 8.40 μg/mL was recorded with the extract of E. drupifera against MDA-MB231 breast cancer cell line. The IC₅₀ values below 10 μg/mL were recorded with the extracts of E. drupifera against MDA-MB231 breast cancer cells, C. zeylanicum against HCT116 p53⁺/⁺ and HCT116p53^-/^- colon cancer cells and E. abyssinica against HCT116 p53⁺/⁺ cells.

Conclusion

The results of the present study provide evidence of the cytotoxic potential of some Cameroonian medicinal plants and a baseline information for the potential use of Elaoephorbia drupifera in the treatment of sensitive and drug-resistant cancer cell lines.

Cytotoxicity and Modes of Action of the Methanol Extracts of Six Cameroonian Medicinal Plants against Multidrug-Resistant Tumor Cells

Introduction. The present study aims at evaluating the cytotoxicity of twelve parts from six Cameroonian medicinal plants on sensitive and drug-resistant cancer cell lines. We also studied the mode of action of the most active plants, Gladiolus quartinianus, Vepris soyauxii, and Anonidium mannii. Methods. The cytotoxicity of the extracts was determined using a resazurin assay. Flow cytometry was used for cell-cycle analysis and detection of apoptosis, analysis of mitochondrial membrane potential (MMP), and measurement of reactive oxygen species (ROS). Results. At 40 g/mL, three extracts showed a growth of CCRF-CEM leukemia cells by less than 50%. This includes the extracts from G. quartinianus (GQW; 25.69%), Vepris soyauxii leaves (VSL; 29.82%), and Anonidium mannii leaves (AML; 31.58%). The lowest IC₅₀ values below 30 μg/mL were obtained with GQW, AML and VSL against 7/9, 8/9, and 9/9 tested cancer cell lines, respectively. The lowest IC₅₀ values for each plant were 4.09 μg/mL, and 9.14 μg/mL (against U87MG.ΔEGFR cells), respectively, for VSL and AML and 10.57 μg/mL (against CCRF-CEM cells) for GQW. GQW induced cell cycle arrest between G0/G1 and S phases, whilst VSL and AML induced arrest in G0/G1. All three extracts induced apoptosis in CCRF-CEM cells by loss of MMP, whilst AML also enhanced production of ROS. Conclusion. The three active plants may be a source for the development of new anticancer drugs.

Polyphenolic composition, antioxidant and antibacterial activities for two Romanian subspecies of Achillea distans Waldst. et Kit. ex Willd

The aim of this work was to study the chemical composition, antioxidant and antibacterial properties of Achillea distans Waldst. et Kit. subsp. distans and Achillea distans Waldst. et Kit. subsp. alpina Rochel, from the Rodna Mountains (Romania). The identification and quantification of major phenolic compounds was performed by a HPLC-MS method. The total polyphenolic and flavonoid content was determined spectrophotometrically. The antioxidant activity was evaluated using the DPPH bleaching method, trolox equivalent antioxidant capacity assay (TEAC), hemoglobin ascorbate peroxidase activity inhibition (HAPX) assay, and an Electron Paramagnetic Resonance (EPR) spectroscopy method. A data indicated that A. distans subsp. alpina extract has more antioxidant activity than A. distans subsp. distans extract. Luteolin, apigenin, quercetin, caffeic and chlorogenic acids were present in the two extracts of A. distans, but in different amounts. Three flavonoids were detected only in A. distans subsp. alpina. The polyphenol-richer A. distans subsp. alpina extract showed a higher antioxidant activity than A.distans subsp. distans extract. A.distans subsp. distans extract showed inhibitory activity for Gram-positive bacteria, as evaluated with four species. The quantitative and qualitative differences between the two subspecies of Achillea distans could be used as a potential taxonomic marker in order to distinguish the species.