Cytotoxicity and Antimicrobial Activity ofNerium oleanderExtracts

A mechanistic study on the inhibition of bacterial growth and inflammation by Nerium oleander extract with comprehensive in vivo safety profile

Background

Nerium oleander (L.) is well known traditionally used medicinal plant with several pharmacological activities. However, the anti-bacterial, anti-inflammatory activity and in vivo toxicity potential of floral parts of this plant are not reported. Therefore the present study was designed to investigate these activities of Nerium oleander ethanolic flower extract (NOEE) in different animal models.

Methods

Antimicrobial activity of plant extract was compared with five different antibiotics using the disk diffusion method. The time-killing kinetic assay and bacterial killing mechanism of NOEE were also performed. Anti-inflammatory activity was assessed using granuloma induced by cotton-pellet, rat paw edema induced by carrageenan and levels of different inflammatory biomarkers on healthy Wistar rats. The protein and mRNA expressions of nitric oxide (NO), prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also measured. Acute (14 days) and sub-acute (28 days) oral toxicity studies were also performed on healthy Sprague Dawley rats.

Results

NOEE produced highly significant (P < 0.005) and significant (P < 0.05) zones of inhibition at 30 mg/mL and 20 mg/mL respectively against most of the tested bacterial strains. NOEE produced a more drop in viable counts of Gram-negative isolates within 20 min. After 12 h exposure with NOEE, the SEM images of MRSA showed the destruction of cell membrane. NOEE showed highly significant (P < 0.005) anti-inflammatory activity in cotton-pellet and carrageenan inflammatory models. In addition, treatment with NOEE also decreased the production of NO, PGE₂, TNF-α and IL-1β in the rat paw after treated with carrageenan. Similarly, NOEE also suppressed the inducible nitric oxide synthase (iNOS), TNF-α, IL-1β, and cyclooxygenase-2 (COX-2) mRNA expressions. It is also showed highly significant reduction in total leukocyte count (73.09%) and C-reactive protein levels (54.60%). NOEE also inhibited COX-1, COX-2, 5-LO and 12-LO in a highly significant manner. Moreover, acute and sub-acute toxicity studies of NOEE in rats confirm the toxicity with hepatotoxicity at higher doses (2000 mg/kg) i.e. four times greater than the therapeutic dose.

Conclusion

It is concluded that crude flower extract of N. oleander is a potent antimicrobial and anti-inflammatory agent with no toxicity potential at therapeutic doses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03308-z.

A Cellulosic Fruit Derived from Nerium oleander Biomaterial: Chemical Characterization and Its Valuable Use in the Biosorption of Methylene Blue in a Batch Mode

Cellulose substrate waste has demonstrated great potential as a biosorbent of pollutants from contaminated water. In this study, Neriumoleander fruit, an agricultural waste biomaterial, was used for the biosorption of methylene blue from synthetic solution. Fourier-transform infrared (FTIR) spectroscopy indicated the presence of the main absorption peak characteristics of cellulose, hemicellulose, and lignin compositions. X-ray diffraction (XRD) pattern exhibited peaks at 2θ = 14.9° and 2θ = 22°, which are characteristics of cellulose I. Scanning electron microscopy (SEM) showed a rough and heterogeneous surface intercepted by some cavities. Thermogravimetric analysis (TGA) showed more than a thermal decomposition point, suggesting that Nerium fruit is composed of cellulose and noncellulosic matters. The pH_pzc value of Nerium surface was experimentally determined to be 6.2. Nerium dosage, pH, contact time, dye concentration, and temperature significantly affected the adsorption capacity. The adsorption capacity reached 259 mg/g at 19 °C. The mean free energy ranged from 74.53 to 84.52 KJ mol⁻¹, suggesting a chemisorption process. Thermodynamic parameters define a chemical, exothermic, and nonspontaneous mechanism. The above data suggest that Nerium fruit can be used as an excellent biomaterial for practical purification of water without the need to impart chemical functionalization on its surface.

The pharmaco-toxicological conundrum of oleander: Potential role of gut microbiome

Nerium oleander L., commonly known as oleander, is a toxic shrub and also a medicinal plant. All parts of oleander are rich in cardiac glycosides that inhibits Na+/K+-ATPase and induce inotropic effect on the cardiomyocytes. Several pre-clinical and clinical reports indicate acute toxicity due to intentional, accidental and suicidal oleander consumption. Contrarily, oleander is used for the treatment of diverse ailments in traditional medicinal practices around the globe and several evidence-based pre-clinical studies indicated metabolic and immunological health benefits of polyphenol-rich oleander extracts. Thus, the current review aims to address this pharmaco-toxicological conundrum of oleander by addressing the possible role of gut microflora in the differential oleander toxicity. Additionally, a comprehensive account of ethnopharmacological usage, metabolic and immunological health benefits has been documented that supplement the conflicting arguments of pharmaco-toxicological properties of oleander. Finally, by addressing the gap of knowledge of ethnomedicinal, pharmacological and toxicological reports of oleander, the current review is expected to pave the way to address the differential pharmaco-toxicological effects of oleander.

DNA-damage and cell cycle arrest initiated anti-cancer potency of super tiny carbon dots on MCF7 cell line

While carbon-based materials have spearheaded numerous breakthroughs in biomedicine, they also have procreated many logical concerns on their overall toxicity. Carbon dots (CDs) as a respectively new member have been extensively explored in nucleus directed delivery and bioimaging due to their intrinsic fluorescence properties coupled with their small size and surface properties. Although various in vitro/in vivo studies have shown that CDs are mostly biocompatible, sufficient information is lacking regarding genotoxicity of them and underlying mechanisms. This study aims to analyze the real-time cytotoxicity of super tiny CDs (2.05 ± 0.22 nm) on human breast cancer cells (MCF7) and human primary dermal fibroblast cell cultures (HDFa) by xCELLigence analysis system for further evaluating their genotoxicity and clastogenicity to evaluate the anti-tumor potential of CDs on breast adenocarcinoma. As combined with flow cytometry studies, comet assay and cytokinesis-block micronucleus assay suggest that the CDs can penetrate to the cell nuclei, interact with the genetic material, and explode DNA damage and G0/G1 phase arrest in cancer cells even at very low concentrations (0.025 ppm) which provide a strong foundation for the design of potentially promising CD-based functional nanomaterials for DNA-damage induced treatment in cancer therapy.

A review on antimicrobial botanicals, phytochemicals and natural resistance modifying agents from Apocynaceae family: Possible therapeutic approaches against multidrug resistance in pathogenic microorganisms

Accelerated emergence of drug- resistant pathogenic microbes, their unbeatable virulence and a gradual loss of efficacy of currently used antimicrobial agents over the last decade, have expanded the scope of herbal medicine to combat this emerging challenge to have a wide spectrum of activity to develop effective medicines with lesser untoward side effects. Plant-based natural products should be of utmost interest to today's pharmaceutical industries since they are a primary source of new chemical entities directed at new drug targets. Apocynaceae or 'Dogbane' family has attained a global reputation as a source of some life-saving plant-derived products and novel compounds. Members of this family have also been extensively investigated against several nosocomial pathogenic microbes through in vitro and in vivo experimental settings. Several plant-derived components obtained from members of this family have also exhibited remarkable microbial growth inhibitory properties. Popular and widely accepted international databases such as PubMed, Science Direct, ResearchGate, Scopus, Google Scholar, JSTOR and more were searched using the various search strings such as Apocynaceae, antimicrobials, multidrug resistance, resistance modifying agents and pathogenic microorganisms were used in various combinations to retrieve several citations related to the topic. The current review encompasses recent developments in experimental studies and phytochemical analyses which correlates with antimicrobial efficacy of selected Apocynaceous plants along with synergistic mechanism and structural details. The present review recognizes and leverages the importance of Apocynaceae plants, which could be of significant interest in the development of more effective and less toxic antimicrobial drugs which may surmount multidrug resistance. Three different paradigm models harnessing clinical antimicrobial resistance (AMR) including the plant family Apocynaceae, Gram-positive and Gram-negative bacterial species have been broadly discussed in this review. In a nutshell, the present review represents a comprehensive account on the antimicrobials and resistance modifying agents obtained from the members of the plant family Apocynaceae and derived phytochemicals. It also gives an insight into the underlying mode of action of these phytochemicals against an array of pathogenic bacteria, their mechanism of antibiosis, plant parts from which the phytochemicals were isolated or the extracts was prepared with a critical discussion on the botanically-derived antibiotics as a template for antimicrobial drug development.

Study of troponin, creatine kinase biomarkers, and histopathological lesions in experimental Nerium oleander toxicity in rats and mice

Introduction

Nerium oleander is a plant of the Apocynaceae family toxic to humans, animals, and insects. This study was performed to determine the cardiac and neurotoxicity of the plant extract by oral administration in Wistar rats and Balb/c mice and to compare the susceptibility of these animal models to oleander toxicity.

Material and Methods

Four groups of eight mice and eight rats received N. oleander extract orally while a fifth group was the control. Serum concentrations of the biochemical toxicity indicators, namely troponin and creatine kinase (CK), were determined and histopathological evaluation of the heart and brain was performed.

Results

In mice, CK and troponin concentrations were respectively 1.5 and 7 times higher than in the control group (P < 0.05), while in rats, they were 6–7 and 11 times higher. Hyperaemia, haemorrhage, and myofibrolysis, without infiltration of inflammatory cells, were observed in the heart. In the brain the authors observed hyperaemia associated with perivascular and perineuronal oedema, and in higher-dosed rats multifocal haemorrhagic and liquefactive necrotic lesions.

Conclusion

Oleander can affect serum levels of CK and troponin due to nervous and cardiac injuries. Rats showed more severe changes in the biochemical indicators and histopathological lesions than mice. Therefore, biochemical and pathological findings indicate that Wistar rats are more susceptible to the cardiac toxicity and neurotoxicity effects of N. oleander poisoning than Balb/c mice.

Cardenolides from the leaves of Nerium oleander

Six new cardenolides (1-6), including three 14-hydroxylated cardenolides and three 14-carbonylated cardenolides were isolated from the dried aerial parts of Nerium oleander Linn in addition to twenty-seven known compounds (7-33). Their structures were elucidated on the basis of extensive spectroscopic evidences and single-crystal X-ray diffraction analysis. Compounds 1, 4, 7-10 and 13 exhibited significant cytotoxicity against four colon cancer cell lines (HCT116, HT29, SW620, RKO), one gastric cancer cell line (GT) and one cervical cancer cell line (HeLa) in vitro.

Toxicity studies of medicinal plants used in sub-Saharan Africa

In sub-Saharan Africa, traditional medicine is widely used in rural and urban areas also. This is essentially due to the prohibitive cost of pharmaceutical-based medicine and the low incomes of a major part of the population. In addition, the efficacies of many of these traditional and plant-based medicines are proven, but the fact remains that certain plants used in traditional medicine have toxic effects. It is in this perspective that we investigated by bibliographic literature on the toxicity of plants used in traditional medicine. It is crucial to gain knowledge on these plant-based medicines prepared and prescribed by practitioners, particularly in terms of toxicity, composition, specific efficacy of disease and to advise practitioners of this alternative medicine on the protection and security of patients.