Antimicrobial and antioxidant properties of methanol extract, fractions and compounds from the stem bark of Entada abyssinica Stend ex A. Satabie

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to evaluate the antimicrobial and antioxidant activities of the methanol extract, fractions and isolated compounds from <it>Entada abyssinica </it>stem bark, plant used traditionally against gastrointestinal infections.</p> <p>Methods</p> <p>The methanol extract of <it>E. abyssinica </it>stem bark was pre-dissolved in a mixture of methanol and water, and then partitioned between <it>n</it>-hexane, ethyl acetate and <it>n</it>-butanol. The ethyl acetate portion was fractionated by column chromatography and the structures of isolated compounds elucidated by analysis of spectroscopic data and comparison with literature data. Antimicrobial activity was assayed by broth microdilution techniques on bacteria and yeasts. The antioxidant activity was determined by DPPH radical scavenging method.</p> <p>Results</p> <p>Four known compounds [(5<it>S</it>,6<it>R</it>,8a<it>R</it>)-5-(carboxymethyl)-3,4,4a,5,6,7,8,8a-octahydro-5,6,8a-trimethylnaphthalenecarboxylic acid (<b>1</b>), methyl 3,4,5-trihydroxybenzoate (<b>2</b>), benzene-1,2,3-triol (<b>3</b>) and 2,3-dihydroxypropyltriacontanoate (<b>4</b>)] were isolated. Compared to the methanol extract, fractionation increased the antibacterial activities of the <it>n</it>-hexane and ethyl acetate fractions, while the antifungal activities increased in ethyl acetate, <it>n</it>-butanol and aqueous residue fractions. The isolated compounds were generally more active on bacteria (9.7 to 156.2 μg/ml) than yeasts (78.1 to 312.5 μg/ml). Apart from compound <b>1</b>, the three others displayed DPPH^·scavenging activity (RSa), with RSa₅₀values of 1.45 and 1.60 μg/ml.</p> <p>Conclusion</p> <p>The results obtained from this study support the ethnomedicinal use of <it>E. abyssinica </it>in the treatment of gastrointestinal infections and the isolated compounds could be useful in the standardisation of antimicrobial phytomedicine from this plant.</p

Antimicrobial activity and rutin identification of honey produced by the stingless bee Melipona compressipes manaosensis and commercial honey

Background: Honey has been identified as a potential alternative to the widespread use of antibiotics, which are of significant concern considering the emergence of resistant bacteria. In this context, this study aimed to evaluate the antimicrobial activity of honey samples produced by a stingless bee species and by Apis sp. against pathogenic bacteria, as well as to identify the presence of phenolic compounds.Methods: Honey samples from the stingless bee M. compressipes manaosensis were collected twice, during the dry and rainy seasons. Three commercial honey samples from Apis sp. were also included in this study. Two different assays were performed to evaluate the antibacterial potential of the honey samples: agar-well diffusion and broth macrodilution. Liquid-liquid extraction was used to assess phenolic compounds from honey. HPLC analysis was performed in order to identify rutin and apigenin on honey samples. Chromatograms were recorded at 340 and 290 nm.Results: Two honey samples were identified as having the highest antimicrobial activity using the agar diffusion method. Honey produced by Melipona compressipes manaosensis inhibited the growth of Staphylococcus aureus, Escherichia coli (0157: H7), Proteus vulgaris, Shigella sonnei and Klebsiella sp. A sample of honey produced by Apis sp. also inhibited the growth of Salmonella paratyphi. The macrodilution technique presented greater sensitivity for the antibacterial testing, since all honey samples showed activity. Flavonoid rutin was identified in the honey sample produced by the stingless bee.Conclusions: Honey samples tested in this work showed antibacterial activity against Gram-positive and Gram-negative bacteria. The results reported herein highlight the potential of using honey to control bacterial growth. © 2013 Pimentel et al.; licensee BioMed Central Ltd

Formulation and profile of pharmaceutical availability from a model oral solid form of a drug of phytochemicals contained in dry Taraxacum officinale extract

Introduction: Dandelion (Taraxacum officinale coll.), also called the common dandelion grows wild throughout Europe, Asia and the Americas. It is a perennial plant of the family of Asteraceae, having powerful healing properties. The entire plant – flowers, roots and leaves – is the medicinal raw material. Objective: The aim of this study was to manufacture model tablets of pharmacopoeial disintegration time by direct compression of dry titrated extract of dandelion with selected excipients. Methods: Tablets were obtained by direct compression using reciprocating tableting machine (Erweka). Morphological parameters – hardness, friability, disintegration time in pharmacopoeial acceptor fluids were investigated using Erweka equipment. Their actual surface area was also calculated. There was also tested the rate of dissolution of phytochemicals from model tablets in the presence of excipients in pharmacopoeial acceptor fluids ( V=1.0 dm3) by the method of a basket in Erweka apparatus. Spectrophotometric determinations were performed. Results: It results from the morphological studies of model tablets containing Ext. Taraxaci e radix cum herba aqu. siccum that they are characterized by comparable surface and friability at varying hardness, the latter depending on the applied excipients. This is reflected in the effective disintegration time in model acceptor fluids consistent with pharmacopoeial requirements. Conclusions: The used excipients enabled to produce model tablets containing dry extract of dandelion by direct compression. The obtained results demonstrated that microcrystalline Prosolv-type cellulose, Vivapur 200 and Emdex were compatible with the structure of the extract of dandelion. They allow to manufacture a model solid oral dosage forms of the desired morphological parameters and effective disintegration time complying with the pharmacopoeial requirements.Wstęp: Mniszek lekarski (Taraxacum officinale coll.) zwany też mniszkiem pospolitym, rośnie dziko w całej Europie, Azji i obu Amerykach. Jest wieloletnią rośliną z rodziny astrowatych (Asteraceae). Wykazuje wszechstronne właściwości lecznicze. Surowcem zielarskim jest cała roślina: kwiaty, korzenie i liście. Cel: Celem pracy było wytworzenie przez bezpośrednie tabletkowanie suchego mianowanego ekstraktu z mniszka lekarskiego z użyciem wybranych substancji pomocniczych modelowych tabletek o farmakopealnym czasie rozpadu. Metody: Tabletki otrzymano metodą bezpośredniego tabletkowania przy użyciu tabletkarki uderzeniowej firmy Erweka. Zbadano parametry morfologiczne, tj. twardość, ścieralność, czas rozpadu w farmakopealnych płynach biorczych (akceptorowych) za pomocą urządzeń firmy Erweka, a także wyliczono ich powierzchnię rzeczywistą. Przeprowadzono również badanie szybkości procesu rozpuszczania się fitozwiązków w obecności substancji pomocniczych z modelowych tabletek w środowisku farmakopealnych płynów biorczych w aparacie firmy Erweka metodą koszyczkową w objętości płynu akceptorowego V=1,0 dm3. Wykonano oznaczenia spektrofotometryczne. Wyniki: Z uzyskanych rezultatów badań morfologicznych modelowych tabletek zawierających Ext. Taraxaci e radix cum herba aqu. siccum wynika, że charakteryzują się one porównywalną powierzchnią rzeczywistą i ścieralnością przy zróżnicowanej twardości, która jest wynikiem zastosowanych substancji pomocniczych. Znajduje to odzwierciedlenie w efektywnym czasie rozpadu w modelowych płynach biorczych, zgodnym z wymogami farmakopealnymi. Wnioski: Zastosowane substancje pomocnicze umożliwiły otrzymanie modelowych tabletek metodą bezpośredniego tabletkowania, zawierających suchy mianowany wyciąg z mniszka lekarskiego. Z uzyskanych rezultatów badań wynika, że mikrokrystaliczna celuloza typu Prosolv oraz Vivapur 200 i Emdex są kompatybilne ze strukturą wyciągu z mniszka lekarskiego. Umożliwiają one wytworzenie modelowej stałej doustnej postaci leku o oczekiwanych parametrach morfologicznych i efektywnym, zgodnym z wymogami farmakopealnymi czasem rozpadu