Silver nanoparticles are one of the most extensively studied nanomaterials due to their high stability and low chemical reactivity in comparison to other metals. They are commonly synthesized using toxic chemical reducing agents which reduce metal ions into uncharged nanoparticles. However, in the last few decades, several efforts were made to develop green synthesis methods to avoid the use of hazardous materials. The natural biomolecules found in plants such as proteins/enzymes, amino acids, polysaccharides, alkaloids, alcoholic compounds, and vitamins are responsible for the formation of silver nanoparticles. The green synthesis of silver nanoparticles is an eco-friendly approach, which should be further explored for the potential of different plants to synthesize nanoparticles. In the present review we describe the green synthesis of nanoparticles using plants, bacteria, and fungi and the role of plant metabolites in the synthesis process. Moreover, the present review also describes some applications of silver nanoparticles in different aspects such as antimicrobial, biomedicine, mosquito control, environment and wastewater treatment, agricultural, food safety, and food packaging.
The antibacterial potency of garlic extract (Allium sativum) against gram positive and gram negative skin pathogenic bacteria including; Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and Pseudomonas aeruginosa were studied using agar well diffusion and broth dilution assays.Agar well diffusion assay for aqueous garlic extract (AGE) was characterized with zones of inhibition ranging from 4.40 -3.80cm, 4.13 -3.57cm, 3.40 -2.67cm for S. aureus, S. epidermidis and Strep. pyogenes, respectively, however, Ps. aeruginosa had lesser zone of inhibition ranging from 2.32 -1.55cm. Studying the antibacterial potency of AGE against the selected isolates, revealed that it is affected by temperature of storage. Current results showed that storage of AGE at low temperature of -20 o C, does not affect its potency, however, its potency was slightly lost at high temperatures above 37 o C.
The broth dilution test was performed to investigate the Minimum inhibitory concentration (MIC) andMinimum bactericidal concentration (MBC) of the AGE against the bacterial isolates at 37 o C.Investigating the activity of AGE loaded on Gel dressing revealed that it can have potency when applied on patients with Staphylococcal skin infections. Findings from this study encourage and support the use of AGE in treating bacterial skin infections especially in developing countries like Africa, as it is available, economic and have no side effects.
Malaria is a life threatening infectious disease that has affected economic development in many parts of the world. Although preventable, malaria has claimed the lives of thousands of individuals in endemic African countries. Antimalarial drug resistance, lack of vaccines in clinical use as well as complexities of malaria parasite genomes remains a serious threat to malaria eradication efforts. The search for antimalarials from plant sources has yield significant success in drug discovery approaches. The specific objective of this study is to establish the acute toxic effect and antiplasmodial efficacy of crude methanolic leaf extract of Senna occidentalis in an in vivo assay. The four (4) days suppressive test was used in Swiss mice experimentally infected with chloroquine sensitive (CQS) Plasmodium berghei (ANKA). Results obtained revealed no lethality nor any sign of acute toxic reactions following the administration of 2000 mg/kg body weight of the extract. Percent reduction of parasite growth obtained was observed to be dose dependent in all groups treated with the herbal extract and ranges between 66% and 73%. Relative to the negative and positive control groups, a significant reduction in parasitaemia (P≤ 0.01) was observed in all groups treated with the plant extracts. A gradual increase in body weight was observed in extract treated groups throughout the period of the investigation. The antiplasmodial efficacy observed may well be attributed to the presence of alkaloids, flavonoids and other important phytochemicals present. S. occidentalis is therefore, considered a good candidate source for development of novel antimalarial drugs.
Poverty and lack of access to health facilities had necessitated the less privileged to depend on herbal remedies to treat a number of diseases including malaria. The successes recorded from the discovery of novel antimalarials from plant sources had paved the way for the search of antimalarial compounds from traditional pharmacopeia. Phytochemical analysis as well as GC-MS analysis of crude leaves extract of Senna siamea was conducted, with a view to identifying compounds with biological activities. Further antimalarial assessment of the crude extracts was also performed in an in vitro assay. The phytochemicals; phenols, tannins, anthraquinones, alkaloid and flavonoids were detected from hexane and methanol extracts. GC-MS analysis revealed the presence of Saponins specifically, triterpenoids (Lupeol, α-amyrin), Sesquiterpene (Octadecane), Diterpenes (Eicosane), Esters of pthalic acids (Diethyl phthalate) Squalene, α-Tocopherol (a fat soluble Vitamin E) and hexadecanoic acid butyl ester. A dose dependent suppression of parasite growth was observed for all extracts, with methanolic extract showing less antimalarial potency (IC50= 3.74 μg/mL) when compared to the hexane extract (IC50=4.349 μg/mL). Extracts and compounds detected from the leaves of this plant could be used as novel lead compounds to develop new drugs.
Keywords: Phytochemical analysis; GC-MS; antimalarial; Senna siamea; medicinal plants.
The antimalarial efficacy of crude hexane, methanol and lyophilized aqueous Moringa oleifera leaf extract was evaluated on chloroquine sensitive (CQS) strain of Plasmodium falciparum (3D7) in vitro, with a view to validate traditional use of M. oleifera as antimalarial. A dose dependent suppression of parasite growth was observed for all extracts, at microgram per mills (µg/mL) concentrations. At the lowest concentration of extract (6.25 µg/mL), the hexane, methanol and lyophilized aqueous extracts showed 63.52%, 71.42% and 60.65% suppression of plasmodium growth respectively. The extracts showed potent biological activity at the highest concentration of extract, with a strong inhibition of plasmodium growth (71.31%, 83.06% and 80.36%) observed for the hexane, methanol and lyophilized aqueous extracts. Although some extracts are observed to be more potent than others, all extracts are observed to be biologically active against the 3D7 strain of P. falciparum (Hexane extract IC50 = 3.36 µg/mL; methanol IC50 = 3.44 µg/mL and aqueous IC50 = 4.09 µg/mL respectively). The antiplasmodial activities observed may well be attributed to the presence of phenols, tannins, alkaloids and flavonoids in all solvent extracts.
Key words: Antiplasmodial, Moringa oleifera, Phytochemical screening, Plasmodium falciparum
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