Antifungal activity of bark extracts of deciduous trees

Acetone extracts from the bark of 51 different deciduous tree species were investigated to determine their antifungal activity against plant pathogenic and wood decay fungi. In general, the deciduous trees showed only weak activities. The genusMagnolia, especiallyM. Obovata, however had potent antifungal activity.     

Antifungal activity of plant extracts against Arthrinium sacchari and Chaetomium funicola

Various plant extracts were examined for antifungal activity with the objective of improving the commercial sterility of aseptically filled tea beverage products in PET bottles. When the hot water extract and the methanol extract of 29 samples were measured for their antifungal activity against Arthrinium sacchari M001 and Chaetomium funicola M002 strains, five samples, Acer nikoense, Glycyrrhiza glabra, Lagerstroemia speciosa, Psidium guajava and Thea sinensis, showed high activity. Of these, the extracts from A. nikoense, G. glabra and T. sinensis were fractionated by extraction with CHCl3, and the CHCl3-soluble fractions from G. glabra showed antifungal activity with minimum inhibitory concentrations (MICs) between 62.5 and 125 microg/ml against the above-mentioned two fungi. When the EtOAc-soluble fraction of A. nikoense was used, the MIC against A. sacchari M001 was 62.5 microg/ml. However, none of the fractions from A. nikoense or T. sinensis showed high activity against C. funicola M002 and their MICs were greater than 500 microg/ml. A licorice preparation made from the commercially available oil-based extract of G. glabra showed a low MIC of 25 microg/ml against five tested strains of filamentous fungi, but not against Aspergillus fumigatus M008, in a blended tea. Consequently, the possibility of adding a licorice preparation made from the oil-based extract of G. glabra to tea beverages (aseptically filled into PET bottles) was suggested.     

11种中草药提取物对柑橘意大利青霉抑菌活性及机理研究

对11种中草药醇提物抑制柑橘意大利青霉的抑菌效果进行筛选,选用抑菌效果最佳的桂枝提取物从其对病原菌的孢子萌发率、细胞膜渗透性、菌丝形态及菌体内含物含量的影响来进行抑菌机理的研究。结果表明:桂枝、桂皮和黄柏提取液的抑制圈直径均大于30 mm,具有较好的抑菌效果。其中桂枝的抑菌活性最佳,对意大利青霉的抑制圈直径为(34.57±0.78)mm,最小抑菌浓度(MIC)和最小杀菌浓度(MFC)分别为3.125和6.25 mg/mL,且抑菌效果显著优于化学杀菌剂百可得。在抑菌机理方面,桂枝提取物可以抑制意大利青霉菌孢子萌发,影响菌丝的生长发育,其抑菌作用主要是通过破坏细胞膜结构,增加菌体细胞膜通透性,使菌体内容物外渗从而影响菌丝正常生长代谢来实现的。桂枝提取物对柑橘青霉菌有较好的抑菌活性,可作为天然杀菌剂的来源。     

Antifungal constituents in the bark ofMagnolia obovata Thunb

The acetone extract of the bark ofMagnolia obovata Thunb. had potent antifungal activity against plant pathogenic and wood destroying fungi. The active principles were isolated and identified to be eudesmols (I), magnolol (II) and honokiol (III). Eudesmols, which are main components of the volatile bark oil, showed strong antifungal activity against all of the fungi tested, especially basidiomycetes. It completely inhibited the growths ofCoriolus versicolor, Lepista sordida, Pycnoporus coccineus, Rhizoctonia solani, Serpula lacrymans andTyphula ishikariensis at a concentration of 500 μg mL^?1. Two biphenyl type neolignans, magnolol and honokiol, also exhibited potent antifungal activity against these fungi except againstC. versicolor andL. sordida. They completely depressed the growths ofS. lacrymans andT. ishikariensis at the same concentration.     

Fractionation of pine bark extracts: selecting procyanidins

Pine bark is a forest by-product that can be profitable as a source of polyphenols by its content in procyanidins. In this work, barks of two varieties of pine (Pinus pinaster and P. radiata) were extracted with ethanol, and partially purified to obtain a fraction named FOW, that contained mainly flavan-3-ol monomers and procyanidins oligomers. The mean degree of polymerization was 2.1 for pinaster (pOW) and 2.7 for radiata (rOW). FOWs were fractionated on C₁₈ Sep-Pak cartridges into three fractions for each variety by different organic solvents. The phenolic compositions of the fractions were analyzed using HPLC with UV diode array detection and electrospray-ionization mass spectrometry. The compounds identified were: catechin, dihydroquercetin, phenolic acids and their glucosides, procyanidins dimers, trimers and tetramers. FOWs and their fractions were characterized in antioxidant power by DPPH and β-carotene methods. In the former assay, pOW showed major effectiveness, with an antiradical specific activity of 46 units AR/mg procyanidins, whereas for the β-carotene bleaching test rOW (78 ± 0.71%) gave the best inhibition result. Despite this fact the derived fractions, presenting similar values, have advantages because the profile of their constituents is uniform for each one, and, hence, it is easier to investigate their action for potential applications in both medical or food fields     

Antifungal activity of plant extracts against Colletotrichum lagenarium, the causal agent of anthracnose in cucumber

BACKGROUND: Colletotrichum lagenarium is an important plant‐pathogenic fungus that causes anthracnose of cucumber, a disease that is widespread under both greenhouse and field cultivation. To find a promising method for the control of this disease, extracts of eight plants from China were screened in the study presented here. RESULTS: The results showed that the extract of Cinnamomum camphora (L.) Presl had significantly greater inhibitory activity against C. lagenarium than the other seven plant extracts tested in vitro. At 5 days after inoculation in a potted seedling experiment, C. camphora extract demonstrated 95% control of C. lagenarium at a concentration of 16 mg mL^?1, and the MIC₅₀ was 2.596 mg mL^?1. Microscopic observation showed that this extract had a significant impact on the morphology of the fungus, leading to shorter hyphae that were more branched; this observation was associated with the inhibition of mycelial growth. Stability assays revealed that the extract was relatively stable at 80 °C, under acidic conditions and when exposed to light and short periods of UV radiation. CONCLUSION: These results demonstrated that the extract from C. camphora could be used as a potent phytochemical fungicide. Copyright © 2012 Society of Chemical Industry     

Exterior plywood resins formulated from Pinus pinaster bark extracts

Phenol-tannin-formaldehyde resins prepared by copolymerization of resoles andPinus pinaster bark tannins were used for bonding eucalyptus plywood boards. The dependence of board quality on the formaldehyde/phenol ratio F/P, the overall soda/phenol ratio S/P and the viscosity of the resol was studied using a 2×2×2 factorial design. The most critical of the variables studied was S/P, the best results being obtained with its lower value. A follow-up study using a lower S/P value confirmed this trend, better results being obtained than with commercial phenolic resins. Moreover, the pine-based resins allowed a press temperature of 160°C to be used, which further improved board quality.     

Antifungal activity of octyl gallate

Antifungal activities of propyl (C3), octyl (C8) and dodecyl (C12) gallates (3,4,5-trihydroxybenzoate) were tested against Saccharomyces cerevisiae ATCC7754 and Zygosaccharomyces bailii ATCC 60483. Octyl gallate was found to be the only active compound with the minimum fungicidal concentration of 25 microg/ml (89 microM) against S. cerevisiae and of 50 microg/ml (177 microM) against Z. bailii, respectively. The inactivation study showed that octyl gallate was fungicidal against both S. cerevisiae and Z. bailii at any stage of growth. These fungicidal activities were not influenced by pH values. Octyl gallate at 100 microg /ml reduced plasma membrane fluidity to 48% of control. On the other hand, dodecyl gallate at the same concentration reduced it to 76% of control. Only octyl gallate inhibited glucose-induced medium acidification, indicating direct or indirect inhibition of plasma membrane H +-ATPase. The primary fungicidal activity of octyl gallate comes from its ability to act as a nonionic surface-active agent (surfactant), though it can not be inferred that membrane damage, such as a decrease in the membrane fluidity, is the only cause of the lethal effect.     

Comparative antioxidant activity of extracts from leaves,bark and catkins of Salix aegyptiaca sp.

Leaves, bark and catkins of Salix aegyptiaca L. were extracted into solvents of increasing polarity from cyclohexane (non-polar), butanol, ethanol and water (polar) and analysed for their antioxidant capacity, total phenol and flavonoids. The highest antioxidant activity (19 μg/ml IC₅₀ for inhibition of DPPH radical activity), total phenolic content (212 mg gallic acid equivalents/g of dried extract) and total flavonoid (479 mg catechin equivalents/g of dried extract) was observed in the ethanolic extract of bark. HPLC identification of phenolic compounds from the extracts indicated the presence of gallic acid, caffeic acid, vanillin and p-coumaric acid, myricetin, catechin, epigallocatechin gallate, rutin, quercetin as well as salicin. Our data indicates the presence of high amounts of phenols and flavonoids in different parts of S. aegyptiaca species and propose that extracts from this plant may be utilised as a source of health promoting antioxidants.     

Antioxidant activities of mangrove Rhizophora apiculata bark extracts

Depolymerisation of mangrove Rhizophora apiculata bark extracts in the presence of phloroglucinol nucleophiles in ethanol was carried out. The flavan-3-ols and their phloroglucinol adducts were separated using reversed phase liquid chromatography (HPLC). The HPLC analysis of mangrove R. apiculata showed that catechin was the most common component of the flavanoid monomers. The antioxidant activities of these mangrove tannins were evaluated and compared with several commercial tannins by using reducing power, DPPH and ABTS assays with butylated hydroxytoluene, BHT and l-(+)-ascorbic acid as standards. All tannins had reducing power and percentage scavenging activities similar to the (+)-catechin and l-(+)-ascorbic acid standards. In the DPPH assay, >90% of the maximum scavenging activity was attained at 30 μg ml⁻¹. Mangrove tannins had stronger antioxidant activity than the BHT standard in the DPPH assay. The results of the ABTS assay were correlated with the DPPH assay. Scavenging activity in the ABTS assay increased as the tannin concentration increased, up to a plateau at 50 μg ml⁻¹.     

Characteristics of Pinus pinaster bark extracts obtained under various extraction conditions

bark extracts obtained by lixiviation with water or alkaline solutions followed by spray drying. Extract yield was 2.5- to 6-fold higher with alkaline extractant solutions than with water. Within the ranges of temperature (T), NaOH dose (NaOH) and solid/liquid ratio (S/L) that were studied, the formaldehyde-condensable polyphenols content of spray-dried extracts obtained with NaOH as extractant was highest (27.3%) at T=90 °C, NaOH=5%, S/L=1/6. Polyphenols content fell with increasing particle size due to both diffusion limitations and the variation of particle composition with size, which is attributable to the dependence of both the chemical composition of the bark and its response to grinding on its anatomical origin. All the spray-dried extracts had Stiasny numbers high enough to allow their use in adhesives, although this application may require prior chemical modification to reduce the rapid rise in the viscosity of their aqueous solutions with increasing solids content. The reactivity of the extracts with formaldehyde is readily controlled by varying pH.     

亚麻籽环肽混合物抑制霉菌生长繁殖活性

选取宛氏拟青霉(AS 3.776)和黄曲霉(CICC 2476)作为试验菌株,于121℃高温灭菌前、后添加一定浓度梯度的亚麻籽环肽混合物(flaxseed cyclolinopeptides,FCLPs)到马铃薯葡萄糖琼脂培养基中。FCLPs对宛氏拟青霉孢子形成的半数抑制浓度IC50分别为0.53 mg/m L(高温灭菌)和0.34 mg/m L(未经高温灭菌);对黄曲霉孢子形成的IC50值分别为0.31 mg/m L(高温灭菌)和0.24 mg/m L(未经高温灭菌)。高温灭菌处理后,FCLPs保持了相当的抑菌活性,对宛氏拟青霉的抑制活性最低残留76.8%(菌落生长)和76.7%(孢子形成);对于黄曲霉的抑制活性,最低残留分别为61.6%(菌落生长)和41.7%(孢子形成)。FCLPs对孢子萌发率的平均抑制率为17.8%(宛氏拟青霉)和7.8%(黄曲霉)。采用高效液相色谱法分析霉菌培养后从培养基中提取的FCLPs,发现高温灭菌会降低环肽的含量,这可能是导致环肽抗菌活性下降的原因之一,但环肽中4种主要环肽的比例没有发生明显变化,且没有发现环肽霉菌代谢物产生。综上所述,FCLPs对霉菌具有一定抑制活性,对高温处理较为稳定,能耐食品的热加工,相比现有抗菌肽具有独特优势。     

Antifungal activity of some essential oil components

Fifteen essential oil components were evaluated for antifungal activity towards five spoilage-causing fungi. In liquid shake cultures, unsaturated aldehydes (citral, cinnamic aldehyde and cittronellal) followed by geraniol, an unsaturated alcohol were most inhibitory to Aspergillus niger, Fusarium oxysporum and Penicillium digitatum; their minimal inhibitory concentrations (MIC) was 100 μg ml⁻¹. Menthol, a terpene alcohol was most inhibitory to Rhizopus stolonifer and Mucor sp. with a MIC of 200 μg ml⁻¹. Hydrocarbons like camphene, limonene and α-terpinene were least inhibitory. When incorporated in agar medium different patterns of activity were found. Thus citral, cinnamic aldehyde, citronellal, geraniol and menthol not only failed to completely inhibit A. niger, F. oxysporum and P. digitatum but were more active against R. stolonifer and Mucor sp. than in liquid medium. The differences were due to the vapour of the volatile test compounds which accumulated over the agar medium. The growth inhibition due to the vapours alone was measured by using structurally modified petri-plates. The vapours were more active against R. stolonifer and Mucor sp. than against A. niger, F. Oxysporum and P. digitatum. Fungal growth inhibition by volatile compounds in agar medium reflects the combined activity of the vapour and the compound incorporated in the medium and the inhibition is different from that obtained in liquid medium. Regarding the structure-activity relationship of citral, the-CHO group in conjugation with a carbon to carbon double bond (C=C) was found to be responsible for the antifungal activity of the molecule.     

Antioxidant activity and protective effect against plasmid DNA strand scission of leaf, bark, and heartwood extracts from Acacia catechu

The antioxidant activity of methanol extract/fractions of leaf, bark, and heartwood of Acacia catechu was evaluated by various antioxidant assays, including free radical, superoxide and hydroxyl radical, reducing power, metal ion chelation, as well as hydroxyl radical induced DNA strand scission. The leaf, bark, and heartwood powder was extracted in methanol and the lyophilized methanol extract was fractionated with different solvents in the order of increasing polarity. The results indicate that ethyl acetate fraction of heartwood has the highest antioxidant capacities, presenting lower EC(50) values particularly in free radical scavenging activity, including DPPH radicals (4.76 ± 0.14 μg/mL), superoxide anions (26.21 ± 0.79 μg/mL), and hydroxyl radicals (33.69 ± 1.42 μg/mL), in direct assay systems. Reducing power was also highest in ethyl acetate fraction of heartwood (EC(50) of 79.05 ± 1.02 μg/mL). As for the chelating power on ferrous ions, leaf extract was more effective than bark and heartwood extracts. Furthermore, the ethyl acetate and acetone fractions of heartwood significantly protected pBR322 supercoiled plasmid DNA against strand scission induced by hydroxyl radicals in a Fenton's reaction mixture. PRACTICAL APPLICATION: The present investigation suggests that the three organs of A. catechu differ significantly in their antioxidant potential as seen in the DPPH radical scavenging assay, reducing power assay, metal ion chelating assay, superoxide radical scavenging assay and hydroxyl radical scavenging assay. Further, our results showed that crude methanol extract and ethyl acetate fraction of heartwood of A. catechu might have a good potential as a source for natural health products due to its antioxidant and DNA protective activities.     

A comparison between bark extracts from Pinus pinaster and Pinus radiata: Antioxidant activity and procyanidin composition

The composition and antiradical activity of procyanidins from the bark of two kinds of pine, Pinus pinaster and Pinus radiata, were compared. Both the total bark extract and the fraction soluble in both water and ethyl acetate (OW) were evaluated, because of their promising results in previous experiments.     

Antifungal activity of sodium acetate and Lactobacillus rhamnosus

The inhibition of molds by sodium acetate in deMan Rogosa Sharpe (MRS) medium, along with the antifungal activity of Lactobacillus rhamnosus VT1, was studied by the slope agar plate method. MRS agar prepared with and without sodium acetate was used as the agar substrate. A total of 42 strains of Aspergillus, Penicillium, Fusarium, Alternaria, Cladosporium, and Rhizopus were used to compare sensitivities to the inhibitory activity of sodium acetate and L. rhamnosus VT1. It was found that sodium acetate in MRS medium affected the growth of 33 of the 42 mold strains tested to various degrees. The highest sensitivity to sodium acetate was shown by strains of Fusarium, followed by strains of Penicillium, Aspergillus, and Rhizopus. L. rhamnosus VT1 also inhibited mold growth. A significant finding was that sodium acetate and L. rhamnosus VT1 in combination exhibited a possible synergistic action. Thirty-nine of the 42 mold strains tested were completely inhibited by the presence of both antifungal agents. This finding confirms that sodium acetate, a basic component of commercial MRS medium, has strong antifungal properties, and this must be taken into consideration when evaluating the antifungal activity of Lactobacillus cultures grown in MRS broth.     

灵芝不同培养基发酵液粗提物抑菌活性研究

采用不同培养基对灵芝进行液体发酵培养,研究其发酵液粗提物对植物病原真菌抑菌活性。结果表明,3种不同培养基的灵芝发酵液粗提物,对不同植物病原真菌的抑菌活性存在差异性。其中1#培养基的灵芝发酵液粗体物对苹果炭疽病菌、小麦根腐病菌和西瓜枯萎病菌具有显著的抑菌活性;2#培养基的灵芝发酵液粗提物对番茄早疫病菌的抑制作用明显;而3#培养基的灵芝发酵液粗提物对小麦根腐病菌具有较强的抑制作用。由此可见,不同培养基的灵芝发酵液对各种植物病原菌表现出不同的抑菌活性,揭示培养基成分的不同可能对灵芝发酵液的抑菌活性物质的产生有着重要的影响。     

Antifungal activity of some microorganisms against Penicillium expansum

Antifungal activity of eleven selected bacterial cultures and five microfungi in different phases of their growth were investigated in respect of their activity against Penicillium expansum (Link.) Thom. The dynamics of linear growth and mycelium mass growth as well as the ability to produce patulin were examined. The results indicate that two bacteria Bacillius megaterium and Bacillus subtilis species and three strains of the genus Lactobacillus: L. casei, L. delbrueckii ssp. bulgaricus, and L. lactis ssp. cremoris are active against Penicillium expansum.