Antimicrobial diterpenoids and triterpenoids from the stem bark of Croton macrostachys

Antimicrobial-guided fractionation of the EtOAc extract of the stem bark of Croton macrostachys afforded five known compounds including two lupane triterpenoids, lupeol (1) and betulin (2), and three clerodane diterpenoids, floridolide A (3), hardwickic acid (4) and 12-oxo-hardwickic acid (5). Their structures were elucidated on the basis of spectral studies and comparison with published data. The EtOAc extract and compounds 1, 2, 4 and 5 were evaluated for their antibacterial and antifungal activities by macro-dilutionmethod. The extract displayed significant antibacterial and antifungal activities (MIC = 31.25-1000 μg/ml). Betulin (2) and 12-oxo-hardwickic acid (5) were the most active compounds (MIC = 7.81-500 μg/ml). Themost sensitive microorganisms were Staphylococcus aureus ATCC 25922 for bacteria and two Candida species, Candida albicans ATCC 24433 and Candida krusei ATCC 6258, for fungi. The isolation of these active antibacterial and antifungal principles supports the use of C. macrostachys in traditional medicine for the treatment of microbial infections.Keywords: Croton macrostachys; Euphorbiaceae; triterpenes; diterpenes; antibacterial; antifungal

Capital Structure Choices and Survival in a Deregulated Environment

We examine the impact of capital structure choices for survival in a deregulated industry. Financial leverage in particular has been identified by numerous prior studies as a major determinant of the probability of survival in most industries. In the course of a deregulation, the debt overhang effect stemming from high leverage negatively affects the ability of existing firms to survive when a regulatory shock occurs (Zingales, 1998). Following such a regulatory shock, and consistent with the tradeoff and debt overhang theories of capital structure, firms are more likely to reduce their level of leverage (Ovtchinnikov, 2010). This causes the expected costs of financial distress to rise higher and we can expect a negative association between leverage and survival in a deregulated industry. However, in a highly competitive setting, firms may signal their level of quality by contracting for more debt instead of equity (Ross, 1977). This signaling perspective can therefore induce the existence of a positive association between leverage and survival in a deregulated context. Using a sample of private trucking firms, we test this hypothesis and find a negative association between leverage and survival. In a refined analysis aimed at distinguishing high “quality” versus low “quality” firms, we adopt the “excess capacity” approach of De Vany and Saving (1977). Consistent with our initial findings, we find that the negative association between leverage and survival increases with the level of excess capacity

Morphological and molecular identification of pathogenic fungi of Monodora myristica Dunal kernels and their response to different phytoextracts

Identification of fungi from calabash nutmeg kernels was based on their morphological characteristics and analysis of the internal transcribed spacer (ITS) sequences of their genomic DNA. Antifungal activity of aqueous, methanolic and ethanolic extracts of four plants species (Azadirachta indica, Citrus sinensis, Moringa oleifera and Tithonia diversifolia) was tested in vitro at 50, 75, 100 and 125 mg/ml for aqueous extracts and 40, 60, 80 and 100 mg/ml for methanolic and ethanolic extracts. Mancozeb (1 mg/ml) and distilled water were used as positive and negative controls, respectively. The most frequently isolated fungi were Cercospora purpurea (34.28%), Fusarium oxysporum (23.81%) and Aspergillus flavus (17.14%). C. purpurea and F. oxysporum isolates were more aggressive after inoculation on healthy kernels. All the extracts tested, inhibited the growth of the fungi compared to the negative control, except the aqueous extract of T. diversifolia against C. purpurea and F. oxysporum and the methanolic extract of M. oleifera against F. oxysporum at 75 mg/ml. The efficiency of aqueous extracts of M. oleifera and C. sinensis was significantly lower (P<0.05) as compared to the reference fungicide on growth of A. niger at 125 mg/ml. Antifungal activity of methanolic extracts of A. indica, C. sinensis and T. diversifolia as well as ethanolic extracts of A. indica and M. oleifera was significantly equal to mancozeb at 100 mg/ml on A. flavus. Aqueous extracts of M. oleifera and methanolic extracts of A. indica and C. sinensis could be used for protection of Monodora myristica kernels against post-harvest fungi

Morphological and molecular identification of pathogenic fungi of Monodora myristica Dunal kernels and their response to different phytoextracts

Identification of fungi from calabash nutmeg kernels was based on their morphological characteristics and analysis of the internal transcribed spacer (ITS) sequences of their genomic DNA. Antifungal activity of aqueous, methanolic and ethanolic extracts of four plants species (Azadirachta indica, Citrus sinensis, Moringa oleifera and Tithonia diversifolia) was tested in vitro at 50, 75, 100 and 125 mg/ml for aqueous extracts and 40, 60, 80 and 100 mg/ml for methanolic and ethanolic extracts. Mancozeb (1 mg/ml) and distilled water were used as positive and negative controls, respectively. The most frequently isolated fungi were Cercospora purpurea (34.28%), Fusarium oxysporum (23.81%) and Aspergillus flavus (17.14%). C. purpurea and F. oxysporum isolates were more aggressive after inoculation on healthy kernels. All the extracts tested, inhibited the growth of the fungi compared to the negative control, except the aqueous extract of T. diversifolia against C. purpurea and F. oxysporum and the methanolic extract of M. oleifera against F. oxysporum at 75 mg/ml. The efficiency of aqueous extracts of M. oleifera and C. sinensis was significantly lower (P<0.05) as compared to the reference fungicide on growth of A. niger at 125 mg/ml. Antifungal activity of methanolic extracts of A. indica, C. sinensis and T. diversifolia as well as ethanolic extracts of A. indica and M. oleifera was significantly equal to mancozeb at 100 mg/ml on A. flavus. Aqueous extracts of M. oleifera and methanolic extracts of A. indica and C. sinensis could be used for protection of Monodora myristica kernels against post-harvest fungi

Antibacterial and dermal toxicological profiles of ethyl acetate extract from Crassocephalum bauchiense (Hutch.) Milne-Redh (Asteraceae)

<p>Abstract</p> <p>Background</p> <p>The emergence in recent years of numerous resistant strains of pathogenic bacteria to a range of formerly efficient antibiotics constitutes a serious threat to public health. <it>Crassocephalum bauchiense</it>, a medicinal herb found in the West Region of Cameroon is used to treat gastrointestinal infections as well as liver disorders. The ethyl acetate extract from the leaves of <it>C. bauchiense </it>was evaluated for its antibacterial activity as well as acute and sub-acute toxicities.</p> <p>Methods</p> <p>The plant extract was prepared by maceration in ethyl acetate. Its phytochemical screening was done by standard methods. The broth microdilution method was used to evaluate the <it>in vitro </it>antibacterial activity. The <it>in vivo </it>antibacterial activity of a gel formulation (0.05, 1 and 2% w/v) of this extract was evaluated using a <it>Staphylococcus aureus</it>-induced dermatitis in a murine model. Selected haematological and biochemical parameters were used to evaluate the dermal sub-acute toxicity of the extract in rats.</p> <p>Results</p> <p>Phytochemical screening of the <it>C. bauchiense </it>extract revealed the presence of alkaloids, phenols, tannins and sterols. <it>In vitro </it>antibacterial activities were observed against all the tested microorganisms (MIC = 0.04-6.25 mg/ml). Formulated extract-gel (2% w/v) and gentamycin (reference drug) eradicated the microbial infection after five days of treatment. A single dermal dose of this extract up to 32 g/kg body weight (bw) did not produce any visible sign of toxicity. Also, daily dermal application of the <it>C. bauchiense </it>extract gel formulation for 28 days did not show any negative effect, instead some biochemical parameters such as alanine aminotransferase (ALT and AST), low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides were significantly (p < 0.05) affected positively.</p> <p>Conclusion</p> <p>These results indicate that the <it>C. bauchiense </it>ethyl acetate extract can be used safely for the treatment of some bacterial infections.</p

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

Degraded diterpenoids from the stem bark of Neoboutonia mannii

Neoboutomannin (1), a degraded diterpenoid dimer, and manniorthoquinone (2), another degraded diterpenoid, have been isolated from the stem bark of Neoboutonia mannii Benth (Euphorbiaceae), together with the known 3-acetylaleuritolic acid (3), 3,6-dihydroxy-9-methoxy-1,7-dimethylphenanthrene (4) and sitosterol 3-O-beta-D-glucopyranoside (5). Their structures were elucidated on the basis of spectral studies and comparison with published data. Compounds 1, 3, 4 and 5 were evaluated for their antibacterial and antifungal activities. 1, 3 and 4 were active against Enterococcus faecalis, Staphylococcus aureus, Proteus mirabilis and three Candida species, Candida albicans ATCC 9002, Candida tropicalis and Candida parapsilosis. Compound 5 was inactive against all the bacterial and fungal species used.

Anthocleistenolide, a new rearranged nor-secoirldoid derivative from the stem bark of Anthocleista vogelii

A new rearranged nor-secoiridoid, anthocleistenolide (1), along with the known 1-hydroxy-3,7-dimethoxyxanthone (2), 1-hydroxy-3,7,8-trimethoxyxanthone (3), 7 alpha-hydroxysitosterol (4) and sitosterol 3-O-beta-D-glucopyranoside (5), were isolated from the stem bark of Anthocleista vogelii. Their structures were elucidated on the basis of spectral studies and comparison with published data. Compounds 1 - 3 and 5 were evaluated for their antibacterial and antifungal activities. Relatively low anti-staphylococcal (MIC=200 mu g/mL against Staphylococcus aureus) and anti-enterococcal (MIC = 100 mu g/mL against Enterococcus faecalis) activities were observed for 1, while compounds 2 and 3 were active against Candida parapsilosis (MIC = 200 mu g/mL for 2 and 25 mu g/mL for 3). Compound 5 was inactive against all the bacterial and fungal species used