Biologically Synthesized Silver Nanoparticles for Enhancing Tetracycline Activity Against Staphylococcus aureus and Klebsiella pneumoniae

Abstract Phytochemical content of plant extracts can be used effectively to reduce the metal ions to nanoparticles in one-step green synthesis process. In this study, six plant extracts were used for the synthesis of silver nanoparticles (AgNPs). Biologically synthesized AgNPs was characterized using UV-Vis Spectrophotometer, Field Emission Scanning Electron Microscope (FE-SEM), X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared (FTIR) spectroscopy. The individual and combined effects of AgNPs and tetracycline against S. aureus and K. pneumoniae were assessed. Ginger, onion and sidr extracts supported AgNPs formation while arak, garlic and mint extracts failed to convert the silver ions to AgNPs. The present findings revealed significant differences between the tested plant extracts in supporting AgNPs synthesis. AgNPs synthesized by ginger showed the highest individual and combined activity against tested strains followed by AgNPs prepared by sidr then that synthesized by onion. AgNPs significantly enhanced tetracycline activity (p≤0.05) against S. aureus and K. pneumoniae. The results of this study demonstrated that the combination of tetracycline and biologically synthesized AgNPs presented a useful therapeutically method for the treatment of bacterial infection and counterattacking bacterial resistance.

Avaliação das atividades antimicrobiana, citotóxica, moluscicida e antioxidante de Bromelia antiacantha Bertol: (Bromeliaceae) / Evaluation of antimicrobial, cytotoxic, molluscicidal and antioxidant activities of Bromelia antiacantha Bertol: (Bromeliaceae)

A Bromelia antiacantha Bertol. (Bromeliaceae), conhecida como gravatá ou caraguatá, apresenta características medicinais, alimentícias e ornamentais. Neste trabalho foram avaliadas as atividades antifúngica, antibacteriana, citotóxica, moluscicida e antioxidante de extratos alcoólicos das folhas e frutos desta espécie. Na avaliação da atividade antimicrobiana pelo método de microdiluição os extratos alcoólicos não foram eficientes frente à cepa referência do fungo Candida albicans (ATCC 90028), cepas clínicas de C. albicans e C. glabrata, e frente às bactérias S. aureus (ATCC 6538), P. aeruginosa (ATCC 9027) e E. coli (ATCC 8739). A atividade citotóxica, avaliada pelo bioensaio de toxicidade sobre náuplios de Artemia salina Leach (TAS), foi positiva para ambos extratos, com valores de DL50 variando em torno de 620 µg mL-1 e 360 µg mL-1, para os extratos alcoólicos dos frutos e das folhas, respectivamente. A atividade moluscicida, avaliada frente a caramujos da espécie Biomphalaria glabrata (Molusca, Gastropoda), não mostrou toxicidade aguda para soluções de 400 µg mL-1. As propriedades antioxidantes dos extratos investigadas in vitro mediante o método de DPPH• foram consideradas modestas (~ 35 por cento de inibição na concentração de 1000 µg mL-1). Dentre as atividades biológicas que foram testadas a atividade citotóxica foi a mais pronunciada.

Bromelia antiacantha Bertol. (Bromeliaceae), popularly known as "gravatá" or "caraguatá", shows medicinal, nutritional and ornamental properties. In the present study, the alcoholic extracts of leaves and fruits of this species were evaluated for antifungal, antibacterial, cytotoxic, molluscicidal and antioxidant activities. The alcoholic extracts evaluated by microdilution method were not efficient against the standard strain of Candida albicans (ATCC 90028), clinical strains of C. albicans and C. glabrata, and S. aureus (ATCC 6538), P. aeruginosa (ATCC 9027) and E. coli (ATCC 8739). The cytotoxic activity evaluated by toxicity bioassay on nauplii of Artemia salina Leach (TAS) was positive for both extracts, with LD50 values ranging around 620 µg mL-1 and 360 µg mL-1 for alcoholic extracts from leaves and fruits, respectively. The molluscicidal activity evaluated against Biomphalaria glabrata (Mollusca, Gastropoda) did not present acute toxicity for 400 µg mL-1 solutions. The antioxidant properties of the extracts investigated in vitro using the DPPH• method were considered modest (~ 35 percent of inhibition at 1000 µg mL-1). Among the evaluated biological activities, cytotoxic activity was the most marked.

Composición química y actividad antioxidante del alga marina roja Bryothamnion triquetrum (S. G. Gmelin) Howe / Chemical composition and antioxidant activity of the red marine algae Bryothamnion triquetrum (S. G. Gmelin) Howe

En la actualidad existe un marcado interés por la búsqueda de antioxidantes de fuentes naturales, incluidas las algas marinas. El objetivo de este trabajo fue evaluar la composición química y propiedades antioxidantes del alga Bryothamnion triquetrum. Se estudió la composición centesimal y de minerales, identificación de ácidos grasos y sustancias antioxidantes. La composición centesimal es la siguiente: Proteínas (9,5 por ciento), Lípidos (1,3 por ciento), Carbohidratos (5,9 por ciento), Fibras (10,2 por ciento) y Cenizas (43 por ciento). Los resultados de la actividad antioxidante para las diferentes metodologías empleadas fueron: atrapamiento de radicales DPPHò (38 por ciento, 4 mg de liofilizado), beta-Caroteno-Linoleico (12 por ciento, 4 mg de liofilizado), actividad atrapadora de radicales O2ò- (CI50 0,36 mg/mL), de radicales OHò (CI50 2,11 mg/mL) y unión al Fe (CI50 0,37 mg/mL). Las propiedades antioxidantes de esta alga parecen explicarse por la capacidad atrapadora de radicales libres, particularmente relacionada con mecanismos de dismutación de radicales O2ò-, inactivación de radicales OHò y quelación de Fe. En trabajos previos se identificaron ácidos cinámicos y fenólicos como moléculas que pudieran explicar la actividad antioxidante, sin embargo adicionalmente se debe considerar un efecto sumatorio y/o sinérgico de otros componentes antioxidantes del extracto, como los descritos en este trabajo, incluidos minerales, carotenoides y vitamina C.

An increasing interest has been growing during the past years for the search of natural origin antioxidants, particularly those from marine algae. In this context, the main objective of current research was to evaluate the chemical composition and some antioxidant properties of the aqueous extract of the seaweed Bryothamnion triquetrum. The extracts contains: Proteins (9.5 percent), Lipids (1.3 percent), Carbohydrates (5.9 percent), Fibers (10.2 percent) and Ashes (43 percent). In current approach, the following results were obtained for the different procedures assessed: DPPHò radicals scavenging (38 percent for 4 mg of lyophilized); beta-Carotene-Linoleic assay (12 percent for 4 mg of lyophilized); O2ò- radicals scavenging (IC50 0.36 mg/mL); OHò radicals scavenging (IC50 2.11 mg/mL) and iron quelation ability (IC50 0.37 mg/mL). Thus, antioxidant properties of this natural product seem to be related to its ability to scavenge free species. In previous reports of our group, cinnamic and phenolic acids were proposed as at least partially responsible for the antioxidant properties of the extract, but the necessity for the presence of other components was also shown. Then, the antioxidant properties of the extract could be envisioned as the result of the additive and/or synergic effect between phenolic constituents and the other antioxidant components, such as minerals, carotenes and ascorbic acid.

Sesquiterpene Lactones From Onopordum Ambiguum

The aerial parts of Onopordum ambiguum afforded a new dihydroxylated sesquiterpene lactone, namely, 8 alpha-[4-hydroxymethacryloyloxy]-1-epi-sonchucarpolide [1], a C-1 epimer of a perviously isolated eudesmanolide, in addition to the known germacranolide, onopordopicrin [2]. The known flavonoid 5,7,3',4'-tetrahydroxy-3-methoxyflavone was also isolated and characterized. The structure elucidation of the new compound was based primarily on 1D and 2D-NMR analyses