A Portable Coring Device for Rapid Site-Sampling

Abstract

A portable hydraulic coring device facilitates rapid sampling of archaeological sites and collection of undisturbed sediment monoliths for reference in research and teaching. The modestly priced device may be used in dense forests or on terrain unsuited to more expensive, truck-mounted rigs.     

Impact of faunal complexity on nutrient supply in field mesocosms from a spruce forest soil

A field study in an acidic spruce forest soil using soil mesocosms was conducted to investigate the effects of mesofauna and macrofauna on exchangeable cations, organic matter content, base saturation, and Ca-lactate extractable nutrients. In the field, intact soil monoliths were taken from the ground, defaunated by deep-freezing and wrapped in nets of various mesh-sizes to control immigration of different faunal size classes. The monoliths were then replanted in the field. Three types of treatments for the mesocosms were prepared: (1) microbiota only, (2) microbiota and mesofauna, (3) microbiota, mesofauna, and macrofauna (=complex fauna). After eight months the mesocosms and unmanipulated control plots (treatment 4) were destructively sampled and submitted to chemical analysis. Generally, the exchangeable base cations and Mn²⁺ showed higher contents with increasing faunal complexity, whereas the exchangeable acidic cations of Fe³⁺ and Al³⁺ decreased in the monoliths with complex fauna. These effects were significant for K⁺, Mg²⁺ and Mn²⁺ in the L/F-layer and for Ca²⁺, Mn²⁺, Al³⁺ and Fe³⁺ in the H-layer. As a possible explanation a rise of ion-binding sites in the course of enhanced humification processes is discussed.In the L/F-layer base cations showed higher concentrations in the monoliths with complex fauna as compared to the control plot, which contained intact roots. This might be due to nutrient uptake by roots in the control plot or enhanced mineralization in the monoliths with complex fauna, where roots had been cut.     

Exchange of NO and NO2 between wheat canopy monoliths and the atmosphere

The fluxes of NO and NO₂ between wheat canopy monoliths and the atmosphere were investigated with the dynamic chamber technique. For this purpose monoliths were dug out at different plant growth stages from a field site, transported to the institute, and placed in an environmental growth chamber. The wheat canopy monoliths were exposed over a period of four days to the average ratios of atmospheric NO₂ and NO measured at the field site, i.e. NO₂ concentration of about 18 mL L^-1 plus NO concentration lower than 0.5 nL L^-1. Under these conditions NO emission into the atmosphere and NO₂ deposition into canopy monoliths was observed. Both fluxes showed diurnal variation with maximum rates during the light and minimum rates during darkness. NO₂ fluxes correlated with soil temperature as well as with light intensity. NO fluxes correlated with soil temperature but not with light intensity. From the investigation performed the diurnal variation of the NO and NO₂ compensation points, the maximum rates of NO and NO₂ emission, and the total resistances of NO and NO₂ fluxes were calculated. Under the assumption that the measured data are representative for the whole vegetation period, annual fluxes of NO and NO₂ were estimated. Annual NO emission into the atmosphere amounted to 87 mg N m^-2 y^-1 (0.87 kg ha^-1 y^-1), annual NO₂ deposition into canopy monoliths amounted to 1273 mg N m^-2 y^-1 (12.73 kg ha^-1 y^-1). Apparently, the uptake of atmospheric nitrogen by the wheat field from NO₂ deposition is about 15 times higher than the loss of nitrogen from NO emission. It can therefore be assumed that even in rural areas wheat fields are a considerable sink for atmospheric nitrogen. The annual sink strength estimated in the present study is ca. 12 kg N ha^-1 y^-1. The possible origin of the NO emitted and the fate of atmospheric NO₂ taken up by the wheat canopy monoliths are discussed.Preliminary results of this paper were presented at the Joint Workshop COST 611/Working Party 3 and EUROTRAC in Delft, The Netherlands (Ludwig et al., 1991).     

Responses of CO2, N2O and CH4 fluxes between atmosphere and forest soil to changes in multiple environmental conditions

To investigate the effects of multiple environmental conditions on greenhouse gas (CO₂, N₂O, CH₄) fluxes, we transferred three soil monoliths from Masson pine forest (PF) or coniferous and broadleaved mixed forest (MF) at Jigongshan to corresponding forest type at Dinghushan. Greenhouse gas fluxes at the in situ (Jigongshan), transported and ambient (Dinghushan) soil monoliths were measured using static chambers. When the transported soil monoliths experienced the external environmental factors (temperature, precipitation and nitrogen deposition) at Dinghushan, its annual soil CO₂ emissions were 54% in PF and 60% in MF higher than those from the respective in situ treatment. Annual soil N₂O emissions were 45% in PF and 44% in MF higher than those from the respective in situ treatment. There were no significant differences in annual soil CO₂ or N₂O emissions between the transported and ambient treatments. However, annual CH₄ uptake by the transported soil monoliths in PF or MF was not significantly different from that at the respective in situ treatment, and was significantly lower than that at the respective ambient treatment. Therefore, external environmental factors were the major drivers of soil CO₂ and N₂O emissions, while soil was the dominant controller of soil CH₄ uptake. We further tested the results by developing simple empirical models using the observed fluxes of CO₂ and N₂O from the in situ treatment and found that the empirical models can explain about 90% for CO₂ and 40% for N₂O of the observed variations at the transported treatment. Results from this study suggest that the different responses of soil CO₂, N₂O, CH₄ fluxes to changes in multiple environmental conditions need to be considered in global change study.     

One-step purification of YLLIP2 isoforms from Candida sp. 99–125 by polyethyleneimine modified poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) monolith

The extracellular lipase Yarrowia lipolytica (YLLIP2) crude extract was efficiently separated and purified from Candida sp. 99–125 by one-step ion-exchange chromatography on polyethyleneimine (PEI) functionalized monolithic columns. The preparative conditions for the functionalization of monoliths were optimized, including PEI molecular mass, PEI concentration, modification time and temperature. The monolithic skeleton was prepared in situ by polymerization of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) with a volume ratio of 8:2. Heptane was used as the porogen. PEI 30 kDa with the concentration of 10% (v/v) was applied for the modification of the monolith at 55 °C for 12 h. Lipase (EC.3.1.1.3) from Candida sp. 99–125 was separated to four isoforms (isoform A, isoform B, isoform C and isoform D). As analyzed on non-denaturing PAGE and MALDI-TOF–MS, the four isoforms are homogenous and have the same molecular mass of approximate 38 kDa. The monoliths can afford direct crude lipase loading without increasing too much back pressure, which explores the great potential of the application of monoliths for one-single step fast separation and purification of complicated proteins.     

Preparation and evaluation of lactose-modified monoliths for the adsorption and decontamination of plant toxins and lectins

A series of sugar-modified porous silica monoliths with different sugar ligands (β-lactoside, β-N-acetyllactosaminide, β-d-galactoside, β-d-N-acetylgalactosaminide and β-d-glucoside) and linkers were prepared and evaluated using plant toxins and lectins including ricin and a Ricinus communis agglutinin (RCA₁₂₀). Among these sugar monoliths, a lactose monolith carrying a triethylene glycol spacer adsorbed ricin and RCA₁₂₀ with the highest efficiency. The monolith showed no binding with albumin, globulin, and lectins from Jack beans, Osage orange, Amur maackia and wheat germ. All these data support the utility of the lactose-modified monolith as a tool for adsorption and decontamination of plant toxins.     

Short-term effects of changing water table on N2O fluxes from peat monoliths from natural and drained boreal peatlands

The effect of the water table on nitrous oxide (N₂O) fluxes from peat profiles representing boreal peatlands of differing nutrient status was studied in the laboratory. Lowering of the water table in peat monoliths taken from two natural waterlogged peatlands for 14 weeks in a greenhouse at 20 °C increased the fluxes of N₂O, an effect that was enhanced further by incubation in the dark. Raising of the water table in monoliths from two drained and forested peatlands caused cessation of the N₂O fluxes from the drained peats, which had previously been sources of N₂O. It is known that N₂O fluxes have increased in peatlands drained several decades ago. The results suggest that it is not necessary for the water table to be lowered for several years to change a boreal peatland from a N₂O sink to a source of the gas. In addition to the draining of peatlands, climate change can be expected to lower ground water levels during the summertime in the boreal zone, and this could cause marked changes in N₂O fluxes from boreal peatlands by enhancing the microbial processes involved in nitrogen transformations.     

Protein adsorption onto monoliths: A surface energetics study

This part of work was done to explore the basic understanding of the adsorption chromatography by determining the interaction of selected model proteins (n = 5) to monolithic chromatographic materials, with varying densities of butyl and phenyl ligands. Surface energetics approach was applied to study the interaction behavior. The physicochemical properties of the proteins and monolithic chromatographic materials were explored by contact angle and zeta potential values. These values were used to study protein to monolith interaction under various operating conditions. Surface energetics approach allowed the calculation of interaction energy as a function of distance, i.e. energy minimum values. Calculations were performed at various conditions to analyze the effect of major operating parameters on the interaction strength. The interaction strength exposed the hydrophobic nature of the monoliths which increases with increasing ligand density. Further, interaction energy of proteins were higher with monolith with butyl ligand compared to monolith with phenyl ligand. For instance, lactoferrin interaction to monoliths with butyl represents more interaction, i.e. 24.38 kT as compared to monoliths with phenyl i.e. 23.28 kT, keeping lambda as 0.2 nm and salt concentration as 100 mM of ammonium sulphate. Hence, more energy and time will be consumed for elution of proteins immobilized to monoliths with butyl. Similarly, the effect of solid surface for proteins immobilization, effect of ligand density and effect of lambda showed some interesting insights on the interaction behavior. The knowledge generated from the present work will help in the basic understanding as well as development of an efficient, low cost downstream processing design and may mimic the real chromatographic experiments.     

Effects of increased CO2 and N on CH4 efflux from a boreal mire: a growth chamber experiment

Increases in the supply of atmospheric CO₂ and N are expected to alter the carbon cycle, including CH₄ emissions, in boreal peatlands. These effects were studied in a glasshouse experiment with peat monoliths cored from an oligotrophic pine fen. The cores with living plants were kept in 720 ppm_v and 360 ppm_v CO₂ atmospheres for about 6 months under imitated natural temperature cycle. Fertilisation with NH₄NO₃ (3 g m⁻² for 25 weeks) was applied to 18 of the 36 monoliths. The rate of CH₄ flux was non-linearly dependent on the number of Eriophorum vaginatum shoots growing in the monoliths, probably due to the gas transport properties of the aerenchyma. The average CH₄ efflux rate, standardised by the number of shoots, was increased by a maximum of 10–20% in response to the raised CO₂ level. In the raised-NH₄NO₃ treatment, the increase in CH₄ release was lower. The effect of combined CO₂+NH₄NO₃ on CH₄ release was negligible and even lower than in the single treatments. Both potential CH₄ production and oxidation rates at 5, 15 and 25°C were higher near the surface than at the bottom of the core. As expected, the rates clearly depended on the incubation temperature, but the different treatments did not cause any consistent differences in either CH₄ production or oxidation. The determination of potential CH₄ production and oxidation in the laboratory is evidently too crude a method of differentiating substrate-induced differences in CH₄ production and oxidation in vivo. These results indicate that an increase in atmospheric CO₂ or N supply alone, at least in the short term, slightly enhances CH₄ effluxes from boreal peatlands; but together their effect may even be restrictive. Received: 18 June 1998 / Accepted: 25 January 1999     

An Insight to Chiral Monolith for Enantioselective Nano and Micro HPLC: Preparation and Applications

This review gives an overview of chiral separation principles and their application in enantioselective nano/micro high performance liquid chromatography (n/μ‐HPLC) using chiral monolith. In particular, developments in silica and polymer chiral monolithic stationary phases are presented. The preparation and applications of chiral monoliths, the basic chiral separation principles and the mechanisms are discussed. Chirality 25:314–323, 2013. © 2013 Wiley Periodicals, Inc.     

Porous polyacrylamide monoliths in hydrophilic interaction capillary electrochromatography of oligosaccharides

Capillary electrochromatography (CEC) of oligosaccharides in porous polyacrylamide monoliths has been explored. While it is possible to alter separation capacity for various compounds by copolymerization of suitable separation ligands in the polymerization backbone, “blank” acrylamide matrix is also capable of sufficient resolution of oligosaccharides in the hydrophilic interaction mode. The “blank“ acrylamide network, formed with a more rigid crosslinker, provides maximum efficiency for separations (routinely up to 350,000 theoretical plates/m for fluorescently-labeled oligosaccharides). These columns yield a high spatial resolution of the branched glycan isomers and large column permeabilities. From the structural point of view, some voids are observable in the monoliths at the mesoporous range (mean pore radius ca. 35 nm, surface area of 74 m²/g), as measured by intrusion porosimetry in the dry state.     

Preparation and characterization of long alkyl chain methacrylate-based monolithic column for capillary chromatography

This paper describes the fabrication of long alkyl chain methacrylate monolithic materials for using as stationary phases in capillary liquid chromatography. Following deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (γ-MAPS), monoliths were formed by co-polymerisation of stearyl methacrylate (SMA) with ethylene glycol dimethacrylate (EDMA) in the presence of the initiator AIBN and a mixture of porogens including iso-amyl alcohol and 1,4-butanediol. The monoliths were prepared in 100 μm i.d. capillaries and the composition of the polymerisation mixtures were optimised in terms of the ratio of SMA/EDMA, the porogen composition and ratio of porogen to monomers. As the porogen weight fraction decreased, the microglobules became smaller and as expected, the total porosity decreased. In order to determine the usability of such materials, the column permeability K was measured by pumping water through the columns at different linear flow rates. Good results were obtained when these capillaries were used to separate mixtures of weak acids, neutral and basic compounds.     

A randomization method for efficiently and accurately processing fine roots, and separating them from debris, in the laboratory

Background and Aims

We developed a method for processing roots from soil cores and monoliths in the laboratory to reduce the time and cost devoted to separating roots from debris and improve the accuracy of root variable estimates. The method was tested on soil cores from a California oak savanna, with roots from trees, Quercus douglasii, and annual grasses.

Methods

In the randomized sampling method, one isolates the sample fraction consisting of roots and organic debris?<?= 1 cm in length, and randomizes it through immersion in water and vigorous mixing. Sub-samples from the mixture are then used to estimate the percentage of roots in this fraction, thereby enabling an estimate of total sample biomass.

Results

We found that root biomass estimates, determined through the randomization method, differed from total root biomass established by meticulously picking every root from a sample with an error of 3.0 % +/? 0.6 %?s.e.

Conclusions

This method greatly reduces the time and resources required for root processing from soil cores and monoliths, and improves the accuracy of root variable estimates compared to standard methods. This gives researchers the ability to increase sample frequency and reduce the error associated with studying roots at the landscape and plant scales.     

Moisture Effects on Temperature Sensitivity of CO<Subscript>2</Subscript> Exchange in a Subarctic Heath Ecosystem

Carbon fluxes between natural ecosystems and the atmosphere have received increased attention in recent years due to the impact they have on climate. In order to investigate independently how soil moisture and temperature control carbon fluxes into and out of a dry subarctic dwarf shrub dominated heath, monoliths containing soil and plants were incubated at three different moisture levels and subjected to four different temperature levels between 7 and 20 °C. Ecosystem CO₂ exchange was monitored continuously day and night during the 16 to 18 days that each of three experiments lasted. Additionally, the carbon allocation pattern of the plants was investigated by labelling monoliths with ¹⁴CO₂ followed by harvest of above and below ground plant parts. The results revealed that the three different soil moisture levels caused distinctly differing levels of CO₂ fluxes. Also, both carbon fixation calculated as gross ecosystem production (GEP) and carbon release measured as ecosystem respiration (ER) increased with increasing temperatures, with ER increasing faster than GEP. Hence, short term carbon loss from the ecosystem accelerated with raised temperatures. Temperature sensitivity of the ecosystem was dependent on the soil moisture level, shown by differing Q10 values of both GEP and ER at different soil moisture levels. It is therefore highly important to take soil moisture levels into consideration when evaluating responses of ecosystem carbon balance to changes in temperature. The greatest C fixation took place via the two most dominant species of the ecosystem, Vaccinium uliginosum and Empetrum hermaphroditum, with the former being responsible for the different size of C fixation at the three moisture levels.     

Leaching of isothiocyanates through intact soil following simulated biofumigation

Biofumigation can be used as an alternative to conventional soil fumigation to control soil-borne pests. With biofumigation, plant tissue with a natural content of glucosinolates (cruciferous plants) is damaged and incorporated into the topsoil. When the plant tissue is damaged, the glucosinolates come into contact with the endogenous enzyme myrosinase, which catalyse the hydrolysis of glucosinolates into various products depending on the reaction conditions. Isothiocyanates are among the potential products formed from these reactions. We investigated if the isothiocyanates from rape plant material were leached through the soil to drain depth when a heavy rainstorm followed the biofumigation. We applied isothiocyanates from rape plant material (1,480 μmol m⁻²) to four large (0.6 m diameter, 1.0 m long) intact soil monoliths from a loamy and a sandy soil and conducted a leaching experiment under semi-field conditions. The soil monoliths were irrigated with 70–90 mm (10 mm h⁻¹) and the concentrations of three isothiocyanates (3-butenyl, 4-pentenyl and 2-phenethyl) were monitored in the leachate. Between 0 and 14.8 mmol isothiocyanates were leached for each mol of isothiocyanates applied during application of 70–90 mm irrigation. The distribution coefficient estimated from leached concentrations was 0.04–1.19 for 3-butenyl, 0.04–1.15 for 4-pentenyl isothiocyanate and 0.037–0.97 for 2-phenethyl isothiocyanate. The concentration of total isothiocyanates in the leachate was in the same order of magnitude as the LD₅₀ of isothiocyanates for sensitive aquatic organisms.     

Modeling and prediction of the mixed-mode retention mechanisms for puerarin and its analogues on n-octylamine modified poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) monoliths

n-Octylamine modified poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EGDMA)) monoliths were prepared for the rapid screening and determination of puerarin content of a crude extract Radix puerariae. The mixed-mode retention mechanisms for puerarin and its analogues on n-octylamine modified monoliths were investigated using a variety of solvent systems, chromatographic evaluation and molecular dynamics (MDs) modeling. The equilibrated conformations between cross-linked polymers and target molecules were obtained from MD modeling. Both the polymer skeleton and functional groups played important roles in the recognition process. The cross-linker formed a structural network skeleton, in which recognition cavities were formed surrounded by functional groups. The polymer network structures provided good interaction access for isoflavones. The active groups recognized isoflavones by both intermolecular hydrogen bonding and hydrophobic interaction. The interaction energies and retention factors between polymers and target molecules were also evaluated and compared. A higher value of interaction energy corresponded to a higher value of retention factor. The potential of using modeling technology for predicting the chromatographic performances of target molecules was explored.     

Nutrient relations in calcareous grassland under elevated CO2

Plant nutrient responses to 4 years of CO₂ enrichment were investigated in situ in calcareous grassland. Beginning in year 2, plant aboveground C:N ratios were increased by 9% to 22% at elevated CO₂ (P < 0.01), depending on year. Total amounts of N removed in biomass harvests during the first 4 years were not affected by elevated CO₂ (19.9 ± 1.3 and 21.1 ± 1.3 g N m⁻² at ambient and elevated CO₂), indicating that the observed plant biomass increases were solely attained by dilution of nutrients. Total aboveground P and tissue N:P ratios also were not altered by CO₂ enrichment (12.5 ± 2 g N g⁻¹ P in both treatments). In contrast to non-legumes (>98% of community aboveground biomass), legume C/N was not reduced at elevated CO₂ and legume N:P was slightly increased. We attribute the less reduced N concentration in legumes at elevated CO₂ to the fact that virtually all legume N originated from symbiotic N₂ fixation (%N_dfa ≈ 90%), and thus legume growth was not limited by soil N. While total plant N was not affected by elevated CO₂, microbial N pools increased by +18% under CO₂ enrichment (P = 0.04) and plant available soil N decreased. Hence, there was a net increase in the overall biotic N pool, largely due increases in the microbial N pool. In order to assess the effects of legumes for ecosystem CO₂ responses and to estimate the degree to which plant growth was P-limited, two greenhouse experiments were conducted, using firstly undisturbed grassland monoliths from the field site, and secondly designed `microcosm' communities on natural soil. Half the microcosms were planted with legumes and half were planted without. Both monoliths and microcosms were exposed to elevated CO₂ and P fertilization in a factored design. After two seasons, plant N pools in both unfertilized monoliths and microcosm communities were unaffected by CO₂ enrichment, similar to what was found in the field. However, when P was added total plant N pools increased at elevated CO₂. This community-level effect originated almost solely from legume stimulation. The results suggest a complex interaction between atmospheric CO₂ concentrations, N and P supply. Overall ecosystem productivity is N-limited, whereas CO₂ effects on legume growth and their N₂ fixation are limited by P. Received: 12 July 1997 / Accepted: 15 April 1998     

Enantioseparation of glycyl-dipeptides by CEC using particle-loaded monoliths prepared by ring-opening metathesis polymerization (ROMP)

Novel particle-loaded monolithic capillary electrochromatography (CEC) phases for chiral separations were prepared via ring-opening metathesis polymerization (ROMP) within the confines of fused silica columns with 200 microm i.d. using norborn-2-ene (NBE), 1,4,4a,5,8,8a-hexahydro-1,4,5,8,exo,endo-dimethanonaphthalene (DMN-H6) as monomers, 2-propanol and toluene as porogens, RuCl2(PCy3)2(CHPh) as initiator and silica-based particles containing the chiral selector. By suspending silica particles bearing the chiral selector in the polymerization mixture, particle-based monoliths are easily prepared. This approach has several advantages compared to particle-based separation media: (i) the concept of particle-based monoliths is broadly applicable, as any silica-based chiral phase can be used; (ii) they are inexpensive to prepare; and (iii) the manufacturing process is very simple, no sophisticated packing procedures or the preparation of end frits are required. To show the usefulness of this concept for chiral CEC, the chiral separation performance of particle-loaded CEC monoliths bearing teicoplanin aglycone, chemically bonded to 3 microm silica gel, was investigated for a set of glycyl-dipeptides. Particle-loaded ROMP CEC monoliths showed good separation performance for glycyl-dipeptides.     

How does the nature of living and dead roots affect the residence time of carbon in the root litter continuum?

Root litter transformation is an important determinant of the carbon cycle in grassland ecosystems. Litter quality and rhizosphere activity are species-dependent factors which depend on the attributes of the dead and living roots respectively. These factors were tested, using non-disturbed soil monoliths ofDactylis glomerata L. andLolium perenne L. monocultures.¹³C-labelled root litter from these monoliths was obtained from a first stand of each crop, cultivated under veryδ ¹³C-depleted atmospheric CO₂ (S1). In a factorial design,¹³C-labelled root litter of each species was submitted to a second, non¹³C-labelled, living stand of each species (S2). Carbon derived from S1 and from S2 was measured during an 18-month incubation in the root phytomass and in three particulate organic matter fractions (POM). The decay rate of each particle size fraction was fitted to the experimental data in a mechanistic model of litter transformation, whose outputs were mineralisation and stabilisation of the litter-C. Few differences were found between species, in the amount and biochemical composition of the initial root litter, butDactylis roots showed a greater C:N ratio, a lower mean root diameter and a greater specific root length compared toLolium. A transient accumulation of litter residues arose successively in POM fractions of decreasing particle size. The litter-continuum hypothesis was validated, i.e. that the attributes of the compartments (C:N, chemical composition and residence time) depended mainly on their particle size. The S1 species influenced the rate of litter decay while the S2 species controlled the efficiency of litter-C stabilisation versus mineralisation:Dactylis litter decomposed faster andLolium rhizosphere allowed a greater proportion of litter C stabilisation. Discussions focus on the processes responsible of species strategy in relation with the morphological root traits, and the implication of strategy diversity for rich grassland communities.     

Antimicrobial constituents of peel and seeds of camu-camu (Myrciaria dubia)

Various antimicrobial constituents of camu-camu fruit were isolated. Acylphloroglucinol (compound 1) and rhodomyrtone (compound 2) were isolated from the peel of camu-camu (Myrciaria dubia) fruit, while two other acylphloroglucinols (compounds 3 and 4) were obtained from camu-camu seeds. The structures of the isolated compounds were characterized by spectrophotometric methods. Compounds 1 and 4 were confirmed to be new acylphloroglucinols with different substituents at the C7 or C9 position of 2, and were named myrciarone A and B, respectively. Compound 3 was determined to be isomyrtucommulone B. This is the first report of the isolation of 3 from a natural resource. The antimicrobial activities of compounds 1, 3, and 4 were similar to those of 2, and the minimum inhibitory concentrations were either similar to or lower than that of kanamycin. These results suggest that the peel and seeds of camu-camu fruit could be utilized for therapeutic applications.