Cytotoxic phytochemicals from the crude extract of Tetrapleura tetraptera fruits towards multi-factorial drug resistant cancer cells

Contribution of Sub-Saharan African medicinal plants to cancer research: Scientific basis 2013-2023

Cancer incidence and mortality rates are increasing worldwide. Cancer treatment remains a real challenge for African countries, especially in sub-Saharan Africa where funding and resources are very limited. High costs, side effects and drug resistance associated with cancer treatment have encouraged scientists to invest in research into new herbal cancer drugs. In order to identify potential anticancer plants for drug development, this review aims to collect and summarize anticancer activities (in vitro/in vivo) and molecular mechanisms of sub-Saharan African medicinal plant extracts against cancer cell lines. Scientific databases such as ScienceDirect, Google Scholar and PubMed were used to search for research articles published from January 2013 to May 2023 on anticancer medicinal plants in sub-Saharan Africa. The data were analyzed to highlight the cytotoxicity and molecular mechanisms of action of these listed plants. A total of 85 research papers covering 204 medicinal plant species were selected for this review. These plants come from 57 families, the most dominant being the plants of the family Amaryllidaceae (16), Fabaceae (14), Annonaceae (10), Asteraceae (10). Plant extracts exert their anticancer activity mainly by inducing apoptosis and stopping the cell cycle of cancer cells. Several plant extracts from sub-Saharan Africa therefore have strong potential for the search for original anticancer phytochemicals. Chemoproteomics, multi-omics, genetic editing technology (CRISPR/Cas9), combined therapies and artificial intelligence tools are cutting edge emerging technologies that facilitate the discovery and structural understanding of anticancer molecules of medicinal plants, reveal their direct targets, explore their therapeutic uses and molecular bases.

Nutritive value, biological properties, health benefits and applications of Tetrapleura tetraptera: An updated comprehensive review

Due to the health benefits that medicinal plants present, they are applied in traditional healthcare in developing and developed countries alike. Tetrapleura tetraptera, a flowering plant mostly found in the western part of Africa has an essential chemical composition that gives it nutritive value and medicinal capacities. This review aims to highlight the nutritional attributes, biological properties, health benefits, and applications of T. tetraptera. The fruit of the plant has been revealed to possess about 58.48-63. 86% carbohydrates, 251.22-288.62 mg/g potassium, 182.11-200.02 mg/g calcium, 322.00-342.00 mg/g manganese, and 0.02-4.69 mg/g vitamins. Also, active phytochemical compounds including phenols (3.51 ± 0.03 mgGAE/g), flavonoids (0.87 ± 0.03 mgQE/g), saponins (4.27 ± 0.03 mgDE/g), tannins (23.87 ± 0.44 mg/100 g), and alkaloids (5.03 ± 0.15% w/w) have been discovered in the fruit of T. tetraptera. The plant's abundant phytochemicals account for its antioxidant, antimicrobial, anti-inflammatory, anti-diabetic, anti-parasitic, and anti-proliferative activities. These biological properties in turn translate to health benefits including lower blood pressure, enhanced immune system, malaria treatment, diabetes and hypertension management, and cancer prevention. The health-promoting assets of T. tetraptera underscore its applications in beverage production, food preservation and flavoring, feed supplementation, and pharmaceutical formulations. The data gathered in this piece is crucial for industrial food processing and the creation of potent pharmaceutical products and functional foods with superior health attributes.

Aridanin and oleanane-3- O-β-D-glucoside-2'-acetamide obtained from Tetrapleura tetraptera (Schumach. & Thonn) Taub. (Fabaceae) induces potent apoptotic activity in human prostate cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Tetrapleura tetraptera (Schumach. and Thonn.) Taub. (Fabaceae) is a tropical plant that is used in Cameroon pharmacopeia for the treatment of many cancers including prostate cancer (PCa), which is a major cause of men's death worldwide. The objective of this study was to evaluate the anticancer properties as well as underlying mechanisms of isolates from T. tetraptera on DU145, PC3 and LNCaP cancer cell lines.

MATERIALS AND METHODS

Eight (8) compounds were purified from T. tetraptera stem bark extract through silica gel column chromatography (CC) and characterized using spectroscopic techniques (1D and 2D NMR), HRESIMS. Cell growth was assessed by a well-characterized MTT assay, while BrdU and clonogenicity assays provided information on the cell proliferation index. Further, the impact of the compounds on cell cycle progression and cell death were performed through Flow cytometry. Cell adhesion, cell migration and chemotaxis along with some proteins of epithelial-mesenchymal transition (EMT) were assayed.

RESULTS

Out of the eight (1-8) isolates from T. tetraptera only oleanane-3-O-β-D-glucoside-2'-acetamide and aridanin showed potent cell growth arrest with an estimated CC50 of 15, 23, 16 and 17, 26, 16 μg/mL on DU145, PC3 and LNCaP cells, respectively. A 15% (DU145) and 25% (LNCaP) increase in apoptotic cells induced by oleanane-3-O-β-D-glucoside-2'-acetamide and aridanin at 10 μg/mL were noticed. Oleanane-3-O-β-D-glucoside-2'-acetamide and aridanin at 2.5 and 10 μg/mL reduced the number of cells in S-phase and raised cells in G2/M phase. At the same concentrations, they decreased the number of invading DU145 cells and increased the adherence of DU145 cells to fibronectin and collagen matrix at tested concentrations, accompanied by an increase in integrin β-1 (10 μg/mL) and integrin β-4 (2.5 μg/mL) expression. Furthermore, a down-regulation of pcdk1, cdk2, Bcl-2, N-Cad, vimentin and cytokeratine 8-18 was noticed while, p19, p27, p53 pAKT, Bax, caspase-3 and E-Cad were up-regulated.

CONCLUSIONS

This study outlines for the first time, the anticancer ability of compounds oleanane-3-O-β-D-glucoside-2'-acetamide (4) and aridanin (6) from Tetrapleura tetraptera and proposes their putative mechanisms of action.

Pharmacological Activities of Rhododendron afghanicum; an Endemic Species of Khyber Pakhtunkhwa, Pakistan

Majority of different kinds of metabolites having therapeutic characteristics are thought to be stored in medicinal plants. So, the present study was aimed to explore the crude extract of leaves and stem of R. afghanicum for phytochemical screening and various pharmacological activities. Toxicological studies at 100 mg/kg showed 60 % mortality where its safe dose level was 90 mg/kg. Phytochemical screening revealed the presence of alkaloids, glycosides, flavonoids and tannins in both extracts. Bacterial strains were susceptible to (RLEt) and (RLM) crude extracts except Staphylococcus aureus. RSM showed maximum anti-inflammatory activity (20.16 %) followed by RSEt (20.14 %) where lowest activity was displayed by RLEt (18.46 %). Phytotoxic activity showed a substantial dose-dependent phyto-inhibition of Lemna minor. An outstanding cytotoxic potential was displayed with LD50 values of 9.46 and 13.03 μg/ml in both stem extracts. RLEt demonstrated a dose-dependent pain relief at 30, 60 and 90 mg/kg which was 31 %, 40 % and 52 % respectively. A considerable spasmolytic action was observed by the shrinkage of jejunum muscle in albino mice. RLEt at 1000 ppm showed (17 mm) and RLM at 1000 ppm showed (16 mm) zone of inhibition against Aspergillus niger. These findings support and corroborate the traditional applications of R. afghanicum for treating digestive, analgesic and inflammatory ailments.

Cytotoxicity of the methanol extracts and compounds of Brucea antidysenterica (Simaroubaceae) towards multifactorial drug-resistant human cancer cell lines

BACKGROUND

Cancer remains a global health concern and constitutes an important barrier to increasing life expectancy. Malignant cells rapidly develop drug resistance leading to many clinical therapeutic failures. The importance of medicinal plants as an alternative to classical drug discovery to fight cancer is well known. Brucea antidysenterica is an African medicinal plant traditionally used to treat cancer, dysentery, malaria, diarrhea, stomach aches, helminthic infections, fever, and asthma. The present work was designed to identify the cytotoxic constituents of Brucea antidysenterica on a broad range of cancer cell lines and to demonstrate the mode of induction of apoptosis of the most active samples.

METHODS

Seven phytochemicals were isolated from the leaves (BAL) and stem (BAS) extract of Brucea antidysenterica by column chromatography and structurally elucidated using spectroscopic techniques. The antiproliferative effects of the crude extracts and compounds against 9 human cancer cell lines were evaluated by the resazurin reduction assay (RRA). The activity in cell lines was assessed by the Caspase-Glo assay. The cell cycle distribution, apoptosis via propidium iodide (PI) staining, mitochondrial membrane potential (MMP) through 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining, and the reactive oxygen species (ROS) via 2´,7´-dichlorodihydrofluoresceine diacetate (H2DCFH-DA) staining, were investigated by flow cytometry.

RESULTS

Phytochemical studies of the botanicals (BAL and BAS) led to the isolation of seven compounds. BAL and its constituents 3, (3-(3-Methyl-1-oxo-2-butenyl))1H indole (1) and hydnocarpin (2), as well as the reference compound, doxorubicin, had antiproliferative activity against 9 cancer cell lines. The IC₅₀ values varied from 17.42 µg/mL (against CCRF-CEM leukemia cells) to 38.70 µg/mL (against HCT116 p53^-/- colon adenocarcinoma cells) for BAL, from 19.11 µM (against CCRF-CEM cells) to 47.50 µM (against MDA-MB-231-BCRP adenocarcinoma cells) for compound 1, and from 4.07 µM (against MDA-MB-231-pcDNA cells) to 11.44 µM (against HCT116 p53^+/+ cells) for compound 2. Interestingly, hypersensitivity of resistant cancer cells to compound 2 was also observed. BAL and hydnocarpin induced apoptosis in CCRF-CEM cells mediated by caspase activation, the alteration of MMP, and increased ROS levels.

CONCLUSION

BAL and its constituents, mostly compound 2, are potential antiproliferative products from Brucea antidysenterica. Other studies will be necessary in the perspective of the discovery of new antiproliferative agents to fight against resistance to anticancer drugs.

Optimized pressurized hot water extraction, HPLC/LC-MS characterization, and bioactivity of Tetrapleura tetraptera L. dry fruit polyphenols

Despite the global preference for green extraction methods in the recovery of plant bioactives, Tetrapleura tetraptera fruit polyphenols (TTP) are yet to receive considerable attention. For the first time, pressurized hot water extraction (PHWE) of TTP was optimized for total phenol content (TPC) and antioxidant activity (AA) using the Box Behnken design of response surface methodology. Predictor variables were time, temperature, and liquid-to-solid ratio. An optimum solution with a desirability of 0.805 was selected and parameters were 43 min, 220°C, and 60 ml g^-1 liquid-to-solid ratio, yielding TPC of 8.92 mg gallic acid equivalent per gram of sample on dry weight basis (GAE g^-1  dw^-1 ) and AA of 70.35%. Purified, optimized TTP were characterized and quantified using HPLC/LC-MS. PHWE mainly extracted rutin (379.04 µg g^-1 ), cyanidin-3-O-glucoside (chloride) (299.55 µg g^-1 ), naringenin 7-O-glucoside (240.11 µg g^-1 ), p-coumaric acid (177.28 µg g^-1 ), isorientin (150.43 µg g^-1 ), and gallic acid (118.06 µg g^-1 ) whereas cyanidin-3-O-glucoside (chloride) (83.27 µg g^-1 ), protocatechuic acid (61.37 µg g^-1 ), rutin (28.03 µg g^-1 ), and gallic acid (22.62 µg g^-1 ) were mainly extracted by hot water extraction, which was a control. PHWE-obtained TTP showed higher cellular antioxidant activity, cytotoxicity in human liver cancer cell lines (HepG2), and antimicrobial property against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis than control. The potential mechanisms underlying the biological activities of some of the major polyphenols extracted were briefly discussed. Considering the wide use of the T. tetraptera (TT) fruit in Africa in foods and medicine, the use of more efficient green extraction methods such as PHWE is recommended. PRACTICAL APPLICATION: This study serves as a baseline for optimizing pressurized hot water extraction, purification, identification, and quantification of Tetrapleura tetraptera polyphenols (TTP) and their biological activities, being the first of its kind. The varied biological effects shown can be exploited further for applications of TTP as nutraceutical agents and preservatives in foods in different forms. Also, the high amounts of gallic acid and other phenolic acids and flavonoids confirmed in this study make TTP good candidates for the development of metal-phenol network nanoparticles to enhance adequate solubility and distribution in food systems in light of the above proposed applications.

Evaluation of Annona muricata extract against Staphylococcus aureus isolate and in-silico activity of bioactive compounds against Capsular protein (Cap5O)

Background

Staphylococcus aureus has prevailed against the majority of antibiotics currently in clinical use, making it a significant global public health problem. As a safer alternative, bioactive compounds have been explored. Annona muricata has been shown to possess antimicrobial activity. However, there are few reports on the molecular activity of A. muricata bioactive compounds against S. aureus. Thus, this study was aimed at evaluating the antimicrobial activity of its crude extract as well as investigating the potential of its bioactive compounds against the Cap5O capsular polysaccharides (CPS) of S. aureus via molecular docking.

Methods

Collection of plant leaves, preparation of extracts, anti-nutrient analysis, phytochemical screening via crude method and gas chromatography-mass spectrophotometer (GC-MS), isolation and characterization of S. aureus and the antimicrobial activity test were all done using standard protocols. Molecular docking was done using the MCULE online tool with emphasis on docking scores, toxicity, and other properties.

Results

Crude screening of the extracts showed the presence of polyphenols, hydroxyanthraquinones, reducing compounds, flavonoids, saponins, glycosides, alkaloids, anthraquinones, phlobatannins and tannins in different concentrations. Anti-nutrient analysis showed the presence of allowable levels of evaluated anti-nutrients. GC-MS revealed a total of twenty-nine (29) bioactive compounds, out of which only 4 (13.80%) docked without toxicity and these were bicyclo[4.1.0]heptan-2-one 6-methyl, trichloromethane, carbonic acid 2-dimethylaminoethyl propyl ester, and 1-methyl-4-phenyl-5-thioxo-1,2,4-triazolidin-3-one on either the NAD-binding or C-terminal substrate binding domain of Cap5O.

Conclusion

Results obtained show that Cap5O could be a potential drug target for multi-drug resistant S. aureus, however, further studies aimed at evaluating these bioactive compounds individually and in combination are highly needed.

Cytotoxicity, acute and sub-chronic toxicities of the fruit extract of Tetrapleura tetraptera (Schumm. & Thonn.) Taub. (Fabaceae)

Background

Tetrapleura tetraptera is a medicinal spice traditionally used to treat cancer, diabetes, and several other ailments. This study analyzed the cytotoxicity of the dichloromethane methanol extract of T. tetraptera fruits (TTF) and its constituents. The toxicity profile of the TTF extract was also evaluated in rats.

Methods

The Cytotoxicity of this extract was evaluated using the resazurin reduction assay (RRA). Acute and sub-chronic toxicity studies were performed according to the protocol described by the Organisation for Economic Cooperation, and Development (OECD). Hematological, serum, and urine biochemical parameters, as well as histological sections of the liver and kidney, were also evaluated based on standard methods.

Results

The TTF extract, compound 5, and the reference drug doxorubicin were active in all 9 tested cancer cell lines. The recorded IC₅₀ ranged from 18.32 μM (against B16-F1 murine melanoma cells) to 36.18 μM (against SKMel-505 BRAF wildtype melanoma cells) for TTF, from 10.02 μM (towards MaMel-80a BRAF-V600E homozygous mutant melanoma cells) to 31.73 μM (against SKMel-28 BRAF-V600E homozygous mutant melanoma cells) for compound 5, and from 0.22 μM (against B16-F1 cells) to 9.39 μM (against SKMel-505 cells) for doxorubicin. The study of acute toxicity test showed that the lethal dose (LD₅₀) of this extract was greater than 5000 mg/kg body weight. In the sub-chronic toxicity studies, variations were observed in some biochemical parameters, especially at higher doses.

Conclusion

TTF and its most active compound (5) are found to be potential cytotoxic agents, meanwhile, TTF was safe when given a single oral dose of 5000 mg/kg. However, caution is necessary in case of prolonged oral administration due to potential alterations of renal function at high doses (> 1000 mg/kg).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03659-1.

Chemical composition, antibacterial efficacy, and antioxidant capacity of essential oil and oleoresin from Monodora myristica and Tetrapleura tetraptera in Southeast Nigeria

Specific to the West African sub-region, previous studies involving fruit, stem, and bark of Tetrapleura tetraptera as well as seeds of Monodora myristica have largely focused on phytochemical properties of aqueous and methanolic and ethanolic extracts. To supplement existing information, the chemical composition, antibacterial efficacy (tested against Escherichia coli and Staphylococcus aureus), and antioxidant capacity (1,1-diphenyl-2-picrylhydrazyl (DPPH∙) radical scavenging, ferric reducing power, and total antioxidant capacity) of essential oil and oleoresin extracted from T. tetraptera fruit and M. myristica seeds cultivated in Southeast Nigeria, were studied. Essential oil and oleoresin were respectively extracted by steam distillation and aqueous maceration. By way of gas chromatograph mass spectrometry (GC-MS) analysis, the chemical compounds from essential oil and oleoresin from M. myristica and T. Tetraptera samples totaled 6 and 5, as well as 27 and 16, respectively. Besides the oleoresin of M. myristica and the essential oil of T. tetraptera showing some resistance against S. aureus, the oleoresins seemed highly susceptible to E. coli-all of which demonstrated concentration-dependence to the antibacterial inhibition zone. Scavenging DPPH radical, reduction power activity, and total antioxidant capacity increased with essential oil and oleoresin extracts' concentrations, which positions M. myristica and T. tetraptera spices as very promising for food preservation, especially against autoxidation and microbial spoilage.

In Vitro Cytotoxic Activity of African Plants: A Review

In African countries, cancer not only is a growing problem, but also a challenge because available funding and resources are limited. Therefore, African medicinal plants play a significant role in folk medicine and some of them are traditionally used for the treatment of cancer. The high mortality rate and adverse effects associated with cancer treatments have encouraged the search for novel plant-based drugs, thus, some African plants have been studied in recent years as a source of molecules with proven cytotoxicity. This review aims to discuss the cytotoxic activity, in vitro, of African plant crude extracts against cancer cell lines. For the period covered by this review (2017−2021) twenty-three articles were found and analyzed, which included a total of 105 plants, where the main cell lines used were those of breast cancer (MCF-7 and MDA-MBA-231) and colorectal cancer (HCT-116 and Caco-2), which are among the most prevalent cancers in Africa. In these studies, the plant crude extracts were obtained using different solvents, such as ethanol, methanol, or water, with variable results and IC50 values ranging from <20 µg/mL to >200 µg/mL. Water is the preferred solvent for most healers in African countries, however, in some studies, the aqueous extracts were the least potent. Apoptosis and the induction of cell cycle arrest may explain the cytotoxic activity seen in many of the plant extracts studied. Considering that the criteria of cytotoxicity activity for the crude extracts, as established by the American National Cancer Institute (NCI), is an IC50 < 30 μg/mL, we conclude that many extracts from the African flora could be a promising source of cytotoxic agents.

Prenylated Flavonoids and C-15 Isoprenoid Analogues with Antibacterial Properties from the Whole Plant of Imperata cylindrica (L.) Raeusch (Gramineae)

The local botanical Imperata cylindrica in Cameroon was investigated for its antibacterial potency. The methanol extract afforded a total of seven compounds, including five hitherto unreported compounds comprising three flavonoids (1–3) and two C-15 isoprenoid analogues (4 and 5) together with known derivatives (6 and 7). The novelty of the flavonoids was related to the presence of both methyl and prenyl groups. The potential origin of the methyl in the flavonoids is discussed, as well as the chemophenetic significance of our findings. Isolation was performed over repeated silica gel and Sephadex LH-20 column chromatography and the structures were elucidated by (NMR and MS). The crude methanol extract and isolated compounds showed considerable antibacterial potency against a panel of multi-drug resistant (MDR) bacterial strains. The best MIC values were obtained with compound (2) against S. aureus ATCC 25923 (32 µg/mL) and MRSA1 (16 µg/mL).

Antiproliferative Activities of Methanolic Extract and Fractions of Tetrapleura Tetraptera Fruit

Most of the current cancer chemotherapeutics are associated with harsh and undesirable side effects, including toxicity and chemoresistance, driving the need for safer and more effective alternatives. In this study, the antiproliferative activities of the methanolic extract of Tetrapleura tetraptera fruits and nine different fractions (C1-C9) from the column chromatographic separation of the extract against leukemia (Jurkat) and human breast cancer (MCF-7) cell lines were investigated using a tetrazolium-based colorimetric assay. Phytochemical screening of the extract and fractions found alkaloids, carbohydrates, flavonoids, glycosides, phenols, saponins, steroids, tannins, and terpenoids in the methanolic extract. Most of the fractions exhibited antiproliferative activity (>100 μg/mL) with the Jurkat cells being more susceptible than the MCF-7 cells. Four of the collected fractions C4, C3, C5, and C2 had good selective indices in decreasing order of activity, in the case of Jurkat cells. Liquid chromatography-mass spectrometry analysis of all samples (except for C4 and C9) revealed that C1, C2, C3, and C5 each had a single component. More importantly, fractions C2, C3, and C5, which were selective to Jurkat cells, also had the same retention time of 1.846 min. Fractions C6 and C8 had two components, with C7 having four components. This study serves as a basis for further work to isolate and characterize potential anticancer agents from the fractions of extracts of T. tetraptera fruits.