Phytonanotherapy for the Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease.

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as nonalcoholic fatty liver disease, is a steatotic liver disease associated with metabolic syndrome (MetS), especially obesity, hypertension, diabetes, hyperlipidemia, and hypertriglyceridemia. MASLD in 43-44% of patients can progress to metabolic dysfunction-associated steatohepatitis (MASH), and 7-30% of these cases will progress to liver scarring (cirrhosis). To date, the mechanism of MASLD and its progression is not completely understood and there were no therapeutic strategies specifically tailored for MASLD/MASH until March 2024. The conventional antiobesity and antidiabetic pharmacological approaches used to reduce the progression of MASLD demonstrated favorable peripheral outcomes but insignificant effects on liver histology. Alternatively, phyto-synthesized metal-based nanoparticles (MNPs) are now being explored in the treatment of various liver diseases due to their unique bioactivities and reduced bystander effects. Although phytonanotherapy has not been explored in the clinical treatment of MASLD/MASH, MNPs such as gold NPs (AuNPs) and silver NPs (AgNPs) have been reported to improve metabolic processes by reducing blood glucose levels, body fat, and inflammation. Therefore, these actions suggest that MNPs can potentially be used in the treatment of MASLD/MASH and related metabolic diseases. Further studies are warranted to investigate the feasibility and efficacy of phytonanomedicine before clinical application.

The Cytotoxicity of Cotyledon orbiculata Aqueous Extract and the Biogenic Silver Nanoparticles Derived from the Extract.

Green synthesized silver nanoparticles (AgNPs) have become popular because of their promising biological activities. However, for most of these nanoparticles, the cytotoxic effects have not been determined and their safety is not guaranteed. In a previous study, we successfully synthesized AgNPs (Cotyledon-AgNPs) using an extract of Cotyledon orbiculata, a medicinal plant traditionally used in South Africa to treat skin conditions. Cotyledon-AgNPs were shown to have significant antimicrobial and wound-healing activities. Fibroblast cells treated with extracts of C. orbiculata and Cotyledon-AgNPs demonstrated an enhanced growth rate, which is essential in wound healing. These nanoparticles therefore have promising wound-healing activities. However, the cytotoxicity of these nanoparticles is not known. In this study, the toxic effects of C. orbiculata extract and Cotyledon-AgNPs on the non-cancerous skin fibroblast (KMST-6) were determined using in vitro assays to assess oxidative stress and cell death. Both the C. orbiculata extract and the Cotyledon-AgNPs did not show any significant cytotoxic effects in these assays. Gene expression analysis was also used to assess the cytotoxic effects of Cotyledon-AgNPs at a molecular level. Of the eighty-four molecular toxicity genes analysed, only eight (FASN, SREBF1, CPT2, ASB1, HSPA1B, ABCC2, CASP9, and MKI67) were differentially expressed. These genes are mainly involved in fatty acid and mitochondrial energy metabolism. The results support the finding that Cotyledon-AgNPs have low cytotoxicity at the concentrations tested. The upregulation of genes such as FASN, SERBF1, and MKI-67 also support previous findings that Cotyledon-AgNPs can promote wound healing via cell growth and proliferation. It can therefore be concluded that Cotyledon-AgNPs are not toxic to skin fibroblast cells at the concentration that promotes wound healing. These nanoparticles could possibly be safely used for wound healing.

The Antioxidant and In Vitro Wound Healing Activity of Cotyledon orbiculata Aqueous Extract and the Synthesized Biogenic Silver Nanoparticles.

The synthesis of silver nanoparticles using biogenic methods, particularly plants, has led to the discovery of several effective nanoparticles. In many instances, plant-derived silver nanoparticles have been shown to have more activity than the plant extract which was used to synthesize the nanoparticles. Silver nanoparticles have been successfully synthesized using the medicinal plant, Cotyledon orbiculata. This is a shrub found in the Western Cape province of South Africa. It has a long history of use in traditional medicine in the treatment of wounds and skin infections. The C. orbiculata synthesized silver nanoparticles (Cotyledon-AgNPs) were reported to have good antimicrobial and anti-inflammatory activities; however, their wound-healing properties have not been determined. This study aimed to determine the wound healing activity of Cotyledon-AgNPs using the scratch assay. Gene expression studies were also done to determine the nanoparticles' mechanism of action. The Cotyledon-AgNPs showed good antioxidant, growth-promoting and cell migration properties. Gene expression studies showed that the C. orbiculata water extract and Cotyledon-AgNPs promoted wound healing by upregulating genes involved in cell proliferation, migration and growth while downregulating pro-inflammatory genes. This confirms, for the first time that a water extract of C. orbiculata and silver nanoparticles synthesized from this extract are good wound-healing agents.

Broad Spectrum Anti-Bacterial Activity and Non-Selective Toxicity of Gum Arabic Silver Nanoparticles.

Silver nanoparticles (AgNPs) are the most commercialized nanomaterials and presumed to be biocompatible based on the biological effects of the bulk material. However, their physico-chemical properties differ significantly to the bulk materials and are associated with unique biological properties. The study investigated the antimicrobial and cytotoxicity effects of AgNPs synthesized using gum arabic (GA), sodium borohydride (NaBH4), and their combination as reducing agents. The AgNPs were characterized using ultraviolet-visible spectrophotometry (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The anti-bacterial activity was assessed using agar well diffusion and microdilution assays, and the cytotoxicity effects on Caco-2, HT-29 and KMST-6 cells using MTT assay. The GA-synthesized AgNPs (GA-AgNPs) demonstrated higher bactericidal activity against all bacteria, and non-selective cytotoxicity towards normal and cancer cells. AgNPs reduced by NaBH4 (C-AgNPs) and the combination of GA and NaBH4 (GAC-AgNPs) had insignificant anti-bacterial activity and cytotoxicity at ≥50 µg/mL. The study showed that despite the notion that AgNPs are safe and biocompatible, their toxicity cannot be overruled and that their toxicity can be channeled by using biocompatible polymers, thereby providing a therapeutic window at concentrations that are least harmful to mammalian cells but toxic to bacteria.

Flavonoid and Phenolic Acid Profiles of Dehulled and Whole Vigna subterranea (L.) Verdc Seeds Commonly Consumed in South Africa.

Bambara groundnut (BGN) is an underexploited crop with a rich nutrient content and is used in traditional medicine, but limited information is available on the quantitative characterization of its flavonoids and phenolic acids. We investigated the phenolic profile of whole seeds and cotyledons of five BGN varieties consumed in South Africa using UPLC-qTOF-MS and GC-MS. Twenty-six phenolic compounds were detected/quantified in whole seeds and twenty-four in cotyledon, with six unidentified compounds. Flavonoids include flavan-3-ol (catechin, catechin hexoside-A, catechin hexoside-B), flavonol (quercetin, quercetin-3-O-glucoside, rutin, myricetin, kaempherol), hydroxybenzoic acid (4-Hydroxybenzoic, 2,6 Dimethoxybenzoic, protocatechuic, vanillic, syringic, syringaldehyde, gallic acids), hydroxycinnamic acid (trans-cinnamic, p-coumaric, caffeic, ferulic acids) and lignan (medioresinol). The predominant flavonoids were catechin/derivatives, with the highest content (78.56 mg/g) found in brown BGN. Trans-cinnamic and ferulic acids were dominant phenolic acid. Cotyledons of brown and brown-eyed BGN (317.71 and 378.59 µg/g) had the highest trans-cinnamic acid content, while red seeds had the highest ferulic acid (314.76 µg/g) content. Colored BGN had a significantly (p < 0.05) higher content of these components. Whole BGN contained significantly (p < 0.05) higher amount of flavonoids and phenolic acids, except for the trans-cinnamic acid. The rich flavonoid and phenolic acid content of BGN seeds highlights the fact that it is a good source of dietary phenolics with potential health-promoting properties.

In vitroanti-oxidant and cytotoxic activities of gold nanoparticles synthesized from an aqueous extract of theXylopia aethiopicafruit.

The development of gold nanoparticles (AuNPs) using a green approach has drawn considerable interest in the field of nanomedicine. Its wide application in clinical diagnosis, imaging and therapeutics portrays its importance for human existence. In this study, we reported on the biogenic synthesis of AuNPs using the aqueous extract of theXylopia aethiopicafruit (AEXAf), which acts as both a reducing and stabilizing agent. The characterization of AEXAf-AuNPs was performed using ultraviolet-visible spectroscopy, dynamic light scattering and zeta potential measurements, high-resolution transmission electron microscopy and Fourier transform-infrared spectroscopy. Thein vitroanti-oxidant activities of the AEXAf-AuNPs and AEXAf were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing anti-oxidant power. Thein vitrocytotoxic activities of the AEXAf-AuNPs and AEXAf against breast and colorectal cancer cells were evaluated using 3,-(4,5 dimethylthiazol)-2,5 diphenyl tetrazolium bromide (MTT) viability and annexin V/PI assays. The AEXAf-AuNPs exhibited surface plasmon absorption maximum at 522 nm and were stable for 4 weeks. The average size of the AEXAf-AuNPs was 10.61 ± 3.33 nm on the high-resolution transmission electron microscopy images. Thein vitroanti-oxidant activities of the AEXAf-AuNPs and AEXAf were concentration dependent. The AEXAf-AuNPs were cytotoxic to the cancer cells and non-toxic to the non-cancerous human fibroblast cells (KMST-6) (up to 200µg ml-1). From these results, the AEXAf-AuNPs showed good anti-oxidant and anti-cancer activities, and can be suggested as a possible therapeutic agent for breast and colorectal cancer.

Citrate-capped gold nanoparticles with a diameter of 14 nm alter the expression of genes associated with stress response, cytoprotection and lipid metabolism in CaCo-2 cells.

Advancements in nanotechnology have provided insight into the unique opportunities for the application of nanomaterials such as gold nanoparticles (AuNPs) in medicine due to their remarkable properties, which includes low toxicity, large surface area, and the ease of synthesis and conjugation to other molecules. Therefore, AuNPs are often preferred for bio-applications. Citrate-capped AuNPs (cAuNPs) have been reported to be non-cytotoxic and are used in numerous studies as drug delivery vehicles to treat various diseases. However, the limitations of bioassays often used to assess the toxicity of AuNPs have been well documented. Herein, we investigate the cytotoxicity of 14 nm cAuNPs in the human colorectal adenocarcinoma (Caco-2) cell line. Treatment conditions (i.e. dose and exposure time) that were established to be non-toxic to Caco-2 cells were used to investigate the effect of cAuNPs on the expression of a Qiagen panel of 86 genes involved in cytotoxicity. Out of 86 studied, 23 genes were differentially expressed. Genes involved in oxidative stress and antioxidant response, endoplasmic reticulum (ER) stress and unfolded protein response, heat shock response, and lipid metabolism were more affected than others. While low concentrations of 14 nm cAuNPs was not cytotoxic and did not cause cell death, cells treated with these nanoparticles experienced ER and oxidative stress, resulting in the activation of cytoprotective cellular processes. Additionally, several genes involved in lipid metabolism were also affected. Therefore, 14 nm cAuNPs can safely be used as drug delivery vehicles at low doses.

Development of Effective Therapeutic Molecule from Natural Sources against Coronavirus Protease.

The SARS-CoV-2 main protease (Mpro) is one of the molecular targets for drug design. Effective vaccines have been identified as a long-term solution but the rate at which they are being administered is slow in several countries, and mutations of SARS-CoV-2 could render them less effective. Moreover, remdesivir seems to work only with some types of COVID-19 patients. Hence, the continuous investigation of new treatments for this disease is pivotal. This study investigated the inhibitory role of natural products against SARS-CoV-2 Mpro as repurposable agents in the treatment of coronavirus disease 2019 (COVID-19). Through in silico approach, selected flavonoids were docked into the active site of Mpro. The free energies of the ligands complexed with Mpro were computationally estimated using the molecular mechanics-generalized Born surface area (MM/GBSA) method. In addition, the inhibition process of SARS-CoV-2 Mpro with these ligands was simulated at 100 ns in order to uncover the dynamic behavior and complex stability. The docking results showed that the selected flavonoids exhibited good poses in the binding domain of Mpro. The amino acid residues involved in the binding of the selected ligands correlated well with the residues involved with the mechanism-based inhibitor (N3) and the docking score of Quercetin-3-O-Neohesperidoside (-16.8 Kcal/mol) ranked efficiently with this inhibitor (-16.5 Kcal/mol). In addition, single-structure MM/GBSA rescoring method showed that Quercetin-3-O-Neohesperidoside (-87.60 Kcal/mol) is more energetically favored than N3 (-80.88 Kcal/mol) and other ligands (Myricetin 3-Rutinoside (-87.50 Kcal/mol), Quercetin 3-Rhamnoside (-80.17 Kcal/mol), Rutin (-58.98 Kcal/mol), and Myricitrin (-49.22 Kcal/mol). The molecular dynamics simulation (MDs) pinpointed the stability of these complexes over the course of 100 ns with reduced RMSD and RMSF. Based on the docking results and energy calculation, together with the RMSD of 1.98 ± 0.19 Å and RMSF of 1.00 ± 0.51 Å, Quercetin-3-O-Neohesperidoside is a better inhibitor of Mpro compared to N3 and other selected ligands and can be repurposed as a drug candidate for the treatment of COVID-19. In addition, this study demonstrated that in silico docking, free energy calculations, and MDs, respectively, are applicable to estimating the interaction, energetics, and dynamic behavior of molecular targets by natural products and can be used to direct the development of novel target function modulators.

Advances in Nanotechnology towards Development of Silver Nanoparticle-Based Wound-Healing Agents.

Since antiquity, silver-based therapies have been used in wound healing, wound care and management of infections to provide adequate healing. These therapies are associated with certain limitations, such as toxicity, skin discolouration and bacterial resistance, which have limited their use. As a result, new and innovative wound therapies, or strategies to improve the existing therapies, are sought after. Silver nanoparticles (AgNPs) have shown the potential to circumvent the limitations associated with conventional silver-based therapies as described above. AgNPs are effective against a broad spectrum of microorganisms and are less toxic, effective at lower concentrations and produce no skin discolouration. Furthermore, AgNPs can be decorated or coupled with other healing-promoting materials to provide optimum healing. This review details the history and impact of silver-based therapies leading up to AgNPs and AgNP-based nanoformulations in wound healing. It also highlights the properties of AgNPs that aid in wound healing and that make them superior to conventional silver-based wound treatment therapies.

Antibacterial activity of biogenic silver and gold nanoparticles synthesized from Salvia africana-lutea and Sutherlandia frutescens.

Nanoparticles (NPs) synthesized using various chemical and physical methods are often cytotoxic which restricts their use in biomedical applications. In contrast, metallic biogenic NPs synthesized using biological systems such as plant extracts are said to be safer and their production more cost effective. NPs synthesized from plants with known medicinal properties can potentially have similar bioactivities as these plants. It has been shown that Salvia africana-lutea (SAL) and Sutherlandia frutescens (SF) have antibacterial activities. This study used water extracts of SAL and SF to produce biogenic silver NPs (AgNPs) and gold NPs (AuNPs). The antibacterial activity of AgNPs and AuNPs was tested against two pathogens (Staphylococcus epidermidis and P. aeruginosa). NP synthesis was optimized by varying the synthesis conditions which include synthesis time and temperature, plant extract concentration, silver nitrate (AgNO3) concentration and sodium tetrachloroaurate (III) dihydrate (NaAuCl4 · 2H2O) concentration. The NPs were characterized using Ultraviolet-visible (UV-vis) spectroscopy, dynamic light scattering, high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infrared (FT-IR) spectroscopy. SAL was able to synthesize both Ag (SAL AgNP) and Au (SAL AuNP) nanoparticles, whilst SF synthesized Ag (SF AgNP) nanoparticles only. The absorbance spectra revealed the characteristic surface plasmon resonance peak between 400-500 nm and 500-600 nm for AgNP and AuNP, respectively. HR-TEM displayed the presence of spherical and polygon shaped nanoparticles with varying sizes whilst the Energy Dispersive x-ray spectra and selected area diffraction pattern confirmed the successful synthesis of the AgNPs and AuNPs by displaying the characteristic crystalline nature, optical adsorption peaks and lattice fringes. FT-IR spectroscopy was employed to identify the functional groups involved in the NP synthesis. The microtitre plate method was employed to determine the minimum inhibitory concentration (MIC) of the NPs and the extracts. The water extracts and SAL AuNP did not have significant antibacterial activity, while SAL AgNP and SF AgNP displayed high antibacterial activity. In conclusion, the data generated suggests that SAL and SF could be used for the efficient synthesis of antibacterial biogenic nanoparticles.

In Vitro Antidiabetic and Antioxidant Effects of Different Extracts of Catharanthus roseus and Its Indole Alkaloid, Vindoline.

The Catharanthus roseus plant has been used traditionally to treat diabetes mellitus. Scientific evidence supporting the antidiabetic effects of this plant's active ingredient-vindoline has not been fully evaluated. In this study, extracts of C. roseus and vindoline were tested for antioxidant activities, alpha amylase and alpha glucosidase inhibitory activities and insulin secretory effects in pancreatic RIN-5F cell line cultured in the absence of glucose, at low and high glucose concentrations. The methanolic extract of the plant showed the highest antioxidant activities in addition to the high total polyphenolic content (p < 0.05). The HPLC results exhibited increased concentration of vindoline in the dichloromethane and the ethylacetate extracts. Vindoline showed noticeable antioxidant activity when compared to ascorbic acid at p < 0.05 and significantly improved the in vitro insulin secretion. The intracellular reactive oxygen species formation in glucotoxicity-induced cells was significantly reduced following treatment with vindoline, methanolic and the dichloromethane extracts when compared to the high glucose untreated control (p < 0.05). Plant extracts and vindoline showed weaker inhibitory effects on the activities of carbohydrate metabolizing enzymes when compared to acarbose, which inhibited the activities of the enzymes by 80%. The plant extracts also exhibited weak alpha amylase and alpha glucosidase inhibitory effects.

Synthesis of Biogenic Gold Nanoparticles from Terminalia mantaly Extracts and the Evaluation of Their In Vitro Cytotoxic Effects in Cancer Cells.

Scientists have demonstrated the potential of plant materials as 'green' reducing and stabilizing agents for the synthesis of gold nanoparticles (AuNPs) and opened new ecofriendly horizons to develop effective and less harmful treatment strategies. The current study demonstrated the use of Terminalia mantaly (TM) extracts to synthesize AuNPs with enhanced cytotoxic effects. The TM-AuNPs were synthesized at 25 and 70 °C using water (WTM) and methanolic (MTM) extracts of the leaf, root and stem/bark parts of the plant. The TM-AuNPs were characterized using UV-visible spectrophotometry, dynamic light scattering (DLS), transmission electron microscopy, energy dispersive X-ray (EDX), selection area electron diffraction (SAED) and Fourier transform infrared (FTIR) spectroscopy. Majority of the TM-AuNPs were spherical with a mean diameter between 22.5 and 43 nm and were also crystalline in nature. The cytotoxic effects of TM-AuNPs were investigated in cancer (Caco-2, MCF-7 and HepG2) and non-cancer (KMST-6) cell lines using the MTT assay. While the plant extracts showed some cytotoxicity towards the cancer cells, some of the TM-AuNPs were even more toxic to the cells. The IC50 values (concentrations of the AuNPs that inhibited 50% cell growth) as low as 0.18 µg/mL were found for TM-AuNPs synthesized using the root extract of the plant. Moreover, some of the TM-AuNPs demonstrated selective toxicity towards specific cancer cell types. The study demonstrates the potential of TM extracts to produce AuNPs and describe the optimal conditions for AuNPs using TM extracts. The toxicity of some the TM-AuNPs can possibly be explored in the future as an antitumor treatment.

An Insight into the Mechanism of Holamine- and Funtumine-Induced Cell Death in Cancer Cells.

Holamine and funtumine, steroidal alkaloids with strong and diverse pharmacological activities are commonly found in the Apocynaceae family of Holarrhena. The selective anti-proliferative and cell cycle arrest effects of holamine and funtumine on cancer cells have been previously reported. The present study evaluated the anti-proliferative mechanism of action of these two steroidal alkaloids on cancer cell lines (HT-29, MCF-7 and HeLa) by exploring the mitochondrial depolarization effects, reactive oxygen species (ROS) induction, apoptosis, F-actin perturbation, and inhibition of topoisomerase-I. The apoptosis-inducing effects of the compounds were studied by flow cytometry using the APOPercentageTM dye and Caspase-3/7 Glo assay kit. The two compounds showed a significantly greater cytotoxicity in cancer cells compared to non-cancer (normal) fibroblasts. The observed antiproliferative effects of the two alkaloids presumably are facilitated through the stimulation of apoptosis. The apoptotic effect was elicited through the modulation of mitochondrial function, elevated ROS production, and caspase-3/7 activation. Both compounds also induced F-actin disorganization and inhibited topoisomerase-I activity. Although holamine and funtumine appear to have translational potential for the development of novel anticancer agents, further mechanistic and molecular studies are recommended to fully understand their anticancer effects.

Encapsulation of Variabilin in Stearic Acid Solid Lipid Nanoparticles Enhances Its Anticancer Activity in Vitro.

The use of natural products as chemotherapeutic agents is well established; however, many of these are associated with undesirable side effects, including high toxicity and instability. Furthermore, the development of drug resistant cancers makes the search for new anticancer lead compounds a priority. In this study, the extraction of an Ircinia sp. sponge resulted in the isolation of an inseparable mixture of (7E,12E,20Z)-variabilin (1) and (7E,12Z,20Z)-variabilin (2) and structural assignment was established using standard 1D and 2D NMR experiments. The cytotoxic activity of the compound against three solid tumour cell lines displayed moderate anti-cancer activity through apoptosis, together with a general lack of selectivity among the cancer cell lines studied. Structural assignment and cytotoxic evaluation of variabilin was complicated and further aggravated by its inherent instability. Variabilin was therefore incorporated into solid lipid nanoparticles (SLNs) and the stability and cytotoxic activity evaluated. Encapsulation of variabilin into SLNs led to a marked improvement in stability of the natural product coupled with enhanced cytotoxic activity, particularly against the prostate (PC-3) cancer cell line, with IC50 values of 87.74 µM vs. 8.94 µM for the variabilin alone and Var-SLN, respectively. Both variabilin and Var-SLN revealed comparable activity to Ceramide against the MCF-7 breast cancer cell line, revealing IC50 values of 34.8, 38.1 and 33.6 µM for variabilin, Var-SLN and Ceramide, respectively. These samples revealed no activity (>100 µM for all) against HT-29 (colon) cell lines and MCF-12 (normal breast) cell lines. Var-SLNs induced 47, 48 and 59% of apoptosis in HT-29, MCF-7 and PC-3 cells, respectively, while variabilin alone revealed 38, 29 and 29% apoptotic cells for HT-29, MCF-7 and PC-3 cell lines, respectively. The encapsulation of natural products into SLNs may provide a promising approach to overcome some of the issues hindering the development of new anticancer drugs from natural products.

Nanotechnology advances towards development of targeted-treatment for obesity.

Obesity through its association with type 2 diabetes (T2D), cancer and cardiovascular diseases (CVDs), poses a serious health threat, as these diseases contribute to high mortality rates. Pharmacotherapy alone or in combination with either lifestyle modification or surgery, is reliable in maintaining a healthy body weight, and preventing progression to obesity-induced diseases. However, the anti-obesity drugs are limited by non-specificity and unsustainable weight loss effects. As such, novel and improved approaches for treatment of obesity are urgently needed. Nanotechnology-based therapies are investigated as an alternative strategy that can treat obesity and be able to overcome the drawbacks associated with conventional therapies. The review presents three nanotechnology-based anti-obesity strategies that target the white adipose tissues (WATs) and its vasculature for the reversal of obesity. These include inhibition of angiogenesis in the WATs, transformation of WATs to brown adipose tissues (BATs), and photothermal lipolysis of WATs. Compared to conventional therapy, the targeted-nanosystems have high tolerability, reduced side effects, and enhanced efficacy. These effects are reproducible using various nanocarriers (liposomes, polymeric and gold nanoparticles), thus providing a proof of concept that targeted nanotherapy can be a feasible strategy that can combat obesity and prevent its comorbidities.

Mycobacterium Tuberculosis and Interactions with the Host Immune System: Opportunities for Nanoparticle Based Immunotherapeutics and Vaccines.

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a deadly infectious disease. The thin pipeline of new drugs for TB, the ineffectiveness in adults of the only vaccine available, i.e. the Bacillus Calmette-Guerin vaccine, and increasing global antimicrobial resistance, has reinvigorated interest in immunotherapies. Nanoparticles (NPs) potentiate the effect of immune modulating compounds (IMC), enabling cell targeting, improved transfection of antigens, enhanced compound stability and provide opportunities for synergistic action, via delivery of multiple IMCs. In this review we describe work performed in the application of NPs towards achieving immune modulation for TB treatment and vaccination. Firstly, we present a comprehensive review of M. tuberculosis and how the bacterium modulates the host immune system. We find that current work suggest great promise of NP based immunotherapeutics as novel treatments and vaccination systems. There is need to intensify research efforts in this field, and rationally design novel NP immunotherapeutics based on current knowledge of the mycobacteriology and immune escape mechanisms employed by M. tuberculosis.

Large Scale Screening of Southern African Plant Extracts for the Green Synthesis of Gold Nanoparticles Using Microtitre-Plate Method.

The preparation of gold nanoparticles (AuNPs) involves a variety of chemical and physical methods. These methods use toxic and environmentally harmful chemicals. Consequently, the synthesis of AuNPs using green chemistry has been under investigation to develop eco-friendly nanoparticles. One approach to achieve this is the use of plant-derived phytochemicals that are capable of reducing gold ions to produce AuNPs. The aim of this study was to implement a facile microtitre-plate method to screen a large number of aqueous plant extracts to determine the optimum concentration (OC) for the bio-synthesis of the AuNPs. Several AuNPs of different sizes and shapes were successfully synthesized and characterized from 17 South African plants. The characterization was done using Ultra Violet-Visible Spectroscopy, Dynamic Light Scattering, High Resolution Transmission Electron Microscopy and Energy-Dispersive X-ray Spectroscopy. We also studied the effects of temperature on the synthesis of the AuNPs and showed that changes in temperatures affect the size and dispersity of the generated AuNPs. We also evaluated the stability of the synthesized AuNPs and showed that some of them are stable in biological buffer solutions.

Enhanced Antimicrobial and Anticancer Activity of Silver and Gold Nanoparticles Synthesised Using Sargassum incisifolium Aqueous Extracts.

A detailed, methodical approach was used to synthesise silver and gold nanoparticles using two differently prepared aqueous extracts of the brown algae Sargassum incisifolium. The efficiency of the extracts in producing nanoparticles were compared to commercially available brown algal fucoidans, a major constituent of brown algal aqueous extracts. The nanoparticles were characterised using TEM, XRD and UV/Vis spectroscopy and zeta potential measurements. The rate of nanoparticle formation was assessed using UV/Vis spectroscopy and related to the size, shape and morphology of the nanoparticles as revealed by TEM. The antioxidant, reducing power and total polyphenolic contents of the aqueous extracts and fucoidans were determined, revealing that the aqueous extracts with the highest contents produced smaller, spherical, more monodisperse nanoparticles at a faster rate. The nanoparticles were assessed against two gram-negative bacteria, two gram-positive bacteria and one yeast strain. In contrast to the literature, the silver nanoparticles produced using the aqueous extracts were particularly toxic to Gram-negative bacteria, while the gold nanoparticles lacked activity. The cytotoxic activity of the nanoparticles was also evaluated against cancerous (HT-29, MCF-7) and non-cancerous (MCF-12a) cell lines. The silver nanoparticles displayed selectivity, since the MCF-12a cell line was found to be resistant to the nanoparticles, while the cancerous HT-29 cell line was found to be sensitive (10% viability). The gold nanoparticles displayed negligible toxicity.

Pleiocarpa pycnantha leaves and its triterpenes induce apoptotic cell death in Caco-2 cells in vitro.

BACKGROUND: Recently, we reported that the crude fractions and pure triterpenes; ursolic acid (C1), 27-E and 27-Z p-coumaric esters of ursolic acid (C2, C3), together with a new triterpene 2,3-seco-taraxer-14-en-2,3-lactone [pycanocarpine (C4)] and its hydrolysed derivative - (2,3-seco-taraxen-4-hydroxy-14-en-2-oic acid) [pycanocarpene (C5)] from Pleiocarpa pycnantha leaves inhibit cell proliferation. However, there has not been any specific report on the use of Pleiocarpa pycnantha leaves and its constituents to kill colorectal adenocarcinoma cancer CaCo-2 cells. We performed in vitro study to evaluate the cytotoxic properties of the ethanolic extract of P. pycnantha P, compounds C2 and C3. A preliminary study of the potential mechanisms were also undertaken. METHODS: Cell viability was measured by WST-1 assay. The Apoptosis level was evaluated by staining with APOPercentage(™) dye and the induction of caspases 3/7 and 9 using Caspase-Glo(®) assays. RESULTS: The exposure of an ethanolic extract from the leaves of P. pycnantha (0.1-1000 µg/ml) and the isolated compounds C2 and C3 (6,25-100 µg/ml) to human colorectal cancer cells reduced the cell viability with an IC50 > 100, 40.9, 36.3 µg/ml for P, C2 and C3 respectively, after 24 h of incubation. The APOPercentage(TM) assay also showed a considerable increase in the percentage of apoptotic cells after 24 h; (25-38% for P, 5-23% for C2 and 6-47 % for C3). Caspase 3 was also activated which is a hallmark of apoptosis. CONCLUSION: These findings suggest that the P. pycnantha and the isolated compounds induce cell apoptosis in human colorectal adenocarcinoma cells. A further study with other cell lines is also recommended.

An unusual 2,3-secotaraxerene and other cytotoxic triterpenoids from Pleiocarpa pycnantha (Apocynaceae) leaves collected from Nigeria.

Three known triterpenoids, namely ursolic acid (1), and the 27-E- and 27-Z-p-coumaric esters of ursolic acid (compounds 2, 3), were isolated together with a new triterpene 2,3-seco-taraxer-14-en-2,3-lactone [pycanocarpine (4)] from an ethanolic extract of Pleiocarpa pycnantha leaves. The structure of 4 was unambiguously assigned using NMR, HREIMS and X-ray crystallography. The cytotoxic activities of the compounds were evaluated against HeLa, MCF-7, KMST-6 and HT-29 cells using the WST-1 assay. Ursolic acid (1) displayed potent cytotoxic activity against HeLa, HT-29 and MCF-7 cells with IC50 values of 10, 10 and 20 µM respectively. The new compound 4 and its hydrolysed derivative 5 were selectively cytotoxic to the breast cancer cell line, MCF-7 with IC50 values 20 and 10 µM respectively. This is the first report on isolation of a 2,3-seco-taraxerene derivative from the Apocynaceae family and cytotoxic activity of P. pycnantha constituents.