Kinetic and Mechanistic Modelling of Pyrimethanil Fungicide Adsorption onto Soils of Varying Physico-chemical Properties.

Pesticide transport in the environment is impacted by the kinetics of its adsorption onto soil. The adsorption kinetics of pyrimethanil was investigated in ten soil samples of varying physicochemical properties. The highest adsorption was in the soil having the maximum silt and CaCO3 contents, pH and electrical conductance but the lowest amorphous Fe oxides and CaCl2 extractable Mn. Pseudo-second order kinetics and intra-particle diffusion model best accounted the adsorption kinetics of pyrimethanil. The equilibrium adsorption estimated by pseudo-second order kinetics (q02) was significantly and positively correlated with CaCl2 extractable Cu content (r = 0.709) while rate coefficient (k02) had a negative correlation with crystalline iron oxides content (r = -0.675). The intra-particle diffusion coefficient (ki.d.) had inverse relationship with CaCl2 extractable Mn content in soils (r = -0.689). FTIR spectra showed a significant interaction of pyrimethanil with micronutrient cations. Adsorption kinetic parameters of pyrimethanil could be successfully predicted by soil properties. The findings may help to evolve fungicide management decisions.

Effect of boron fertilization on productivity and sustainability of rice-wheat cropping system in Tarai region, North-West India.

Extensive global dependency on rice and wheat crops has necessitated the adoption of intensive cultivation practices, thereby compelling to closely monitor the potential yield-limiting factors, among which, boron (B) deficiency stands out to be a prime concern. The present study explores the effects of B fertilization strategies within the Rice-Wheat Cropping System (RWCS) in the Tarai region of North-West India. A comprehensive six-year field experiment was conducted (2013-2019) at G.B. Pant University of Agriculture and Technology, Uttarakhand, India. The experiment tested graded B doses (0.5, 1.0, 1.5, and 2.0 kg ha-1) at varied frequencies (single, alternate, and annual) in a factorial design. The study revealed significant impacts of alternate B application at 1.5 kg ha-1 on crop yields and the Sustainable Yield Index (SYI). The System Rice Equivalent Yield (SREY) exhibited an increase of 6.7% with B supplementation over B-deprived plots, highlighting the pivotal role of B fertilizer in enhancing productivity within the RWCS. The economic optimum B dose was found to be 1.422 kg ha-1 using a linear plus plateau model, resulting in a calculated annual SREY of 9.73 t ha-1 when applied alternately to the cropping system. Continuous application and higher B rates demonstrated substantial increases in various B fractions, while the mobility factor remained within 10%, depicting safe ecological limits. The distribution of fractions in B-treated plots on average followed the order: residual B > organically-bound B > oxide bound B > specifically adsorbed B > readily soluble B. Similarities in the distribution patterns of B fractions between B-treated plots and the control indicated potential influence of biotic or abiotic processes on B fraction dynamics, even in the absence of external B application. To sum up, B application in alternate years at 1.5 kg ha-1 was most sustainable in enhancing the SREY, SYI, available soil B, and B fractions and lowering the environmental hazards.

An insight into the sorption kinetics of boscalid onto soils: Effect of general soil properties.

Boscalid is a carboxamide fungicide widely used for crop protection, however owing to its high persistence, it is detected in high concentrations in various environments. Since the fate of such xenobiotics is strongly influenced by its interaction with soil components a better understanding of its adsorption onto soils of varying properties could allow the adjustment of its application in a given agro-ecological region to limit the consequent environmental burden. The present investigation was carried out to examine the kinetics of boscalid adsorption onto ten Indian soils of varying physico-chemical properties. Kinetic data of boscalid for all soils under investigation fitted well to both pseudo-first-order and pseudo-second-order kinetic models. However, based on the standard error of estimate (S.E.est.) values pseudo-first-order model was better for all soil samples, except one soil which had the lowest readily oxidizable organic carbon. Adsorption of boscalid by soils appeared to be controlled by the diffusion-chemisorption process while for soils especially rich in readily oxidizable organic carbon or clay + silt content the intra-particle diffusion process seemed to be more important. Stepwise regression of kinetic parameters on soil properties revealed that the inclusion of a set of some soil properties could help better prediction of adsorbed amounts of boscalid and kinetic constants. These findings may help assess the fate and possible transport of boscalid fungicide in different soils.

Evaluation of three novel soil bacterial strains for efficient biodegradation of persistent boscalid fungicide: Kinetics and identification of microbial biodegradation intermediates.

Boscalid, a new fungicide of anilide group, is intended to prevent and treat grey mould (Botrytis cinerea), primarily in vines and other fruit plants. In many regions, its long half-life in soil and water poses a serious environmental threat. Boscalid is reported to be toxic to a variety of aquatic organisms. One of the best ways to lessen the amount of boscalid that gets into surface and ground waters is to reduce its concentration in soil. Soil microbes are crucial for the degradation of organic pollutants including pesticides. The present study reports the assessment of three novel soil bacterial strains isolated from pesticide-contaminated soil of Crop research centre, Pantnagar, Uttarakhand, India, which possess boscalid degradation ability. Two of these bacterial isolates could degrade boscalid up to 85-95% within 36 h of incubation period under shaking conditions in the minimal medium. The growth pattern of degrading bacterial isolates was monitored by recording the optical density (OD) of bacterial suspension using an ultra violet (UV)-visible spectrophotometer, whereas the concentration of primary boscalid was recorded by High-Performance Liquid Chromatography (HPLC-UV). A linear relationship was observed between the bacterial growth and the decrease in the residual concentration of boscalid. The concentration of boscalid during incubation with different bacterial strains could be best predicted by a second-order polynomial relationship with time and OD of the suspension as independent variables. Three degradation intermediates of boscalid namely, N-(1,1'-biphenyl-2-yl)pyridine-3-carboxamide (C18H14N2O, N-{[1,1'-biphenyl]-2-yl}-2-chloropyridine-3-carboxamide (C18H13N2OCl), and N-{[4'-chloro-1,1'-biphenyl]-2-yl}-2-chloropyridine ({C17H11NCl2}OH) were identified by the liquid chromatography-mass spectrometry (LC-MS) analysis of biodegraded samples. The biodegradation of boscalid through bacterial isolates seemed to be an economical and eco-friendly method for degrading a highly persistent boscalid fungicide.

Efficacy of Different Decontamination Processes in Mitigation of Pesticide Residues from Chili Crop.

ABSTRACT: This study was conducted to evaluate the efficacy of seven decontamination processes in reducing the pesticide mixture load of six insecticides (quinalphos, profenophos, ethion, lambda-cyhalothrin, imidacloprid, and acetamiprid) from chili (Capsicum annuum L.). In the control treatment, the pesticide residues were extracted without following any decontamination procedure. The extraction of the insecticides from chili was initiated after 48 h of pesticide mixture spray and was done using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. The quantitative analysis of four insecticides, namely quinalphos, profenophos, ethion, and lambda-cyhalothrin, was done by coupled gas chromatography-electron capture detection and that of imidacloprid and acetamiprid by high-performance liquid chromatography-UV detection. The results depicted reduction of pesticide residues in all the decontamination treatments compared with the control, although it varied for different insecticides. Solutions of 1 and 5% NaCl and 5% CH3COOH served as efficient decontaminants in removal of quinalphos, profenophos, ethion, and lambda-cyhalothrin residues from chili to ca. 90%, whereas for imidacloprid and acetamiprid there was a mild decontamination only (33.33 to 52.44%). The solutions of 5% NaHCO3 and 0.01% KMnO4 were effective only in removing lambda-cyhalothrin residues from the chili crop, but for all other pesticides the decontamination was not much pronounced.

Pre-monsoon spatial distribution of available micronutrients and sulphur in surface soils and their management zones in Indian Indo-Gangetic Plain.

The efficient (site-specific) management of soil nutrients is possible by understanding the spatial variability in distribution of phyto-available nutrients (here after called available nutrients) and identifying the soil management zones (MZs) of agricultural landscapes. There is need for delineating soil MZs of agricultural landscapes of the world for efficient management of soil nutrients in order to obtain sustainability in crop yield. The present study was, therefore, undertaken to understand the spatial distribution pattern of available micronutrients (zinc (Zn), boron (B), iron (Fe), manganese (Mn) and copper (Cu)), available sulphur (S), and soil properties (soil acidity (pH), electrical conductivity (EC) and organic carbon (SOC) content) in soils of intensively cultivated Indo-Gangetic Plain (IGP) of India and to delineate soil MZs for efficient management of soil nutrients. Totally, 55101 soil samples from 0-15 cm depth were obtained from 167 districts of IGP during 2014 to 2017 and were analysed for different soil parameters. Soil pH, EC and SOC content varied from 4.44 to 9.80, 0.02 to 2.13 dS m-1 and 0.10 to 1.99%, respectively. The concentration of available Zn, B, Fe, Mn, Cu and S varied from 0.01 to 3.27, 0.01 to 3.51, 0.19 to 55.7, 0.05 to 49.0, 0.01 to 5.29 and 1.01 to 108 mg kg-1, respectively. Geostatistical analysis resulted in varied distribution pattern of studied soil parameters with moderate to strong spatial dependence. The extent (% area) of nutrient deficiencies in IGP followed the order: S > Zn > B > Mn > Cu > Fe. Principal component analysis and fuzzy c-means clustering produced six distinctly different soil MZs of IGP for implementation of zone-specific soil nutrient management strategies for attaining sustainability in crop yield. The developed MZ maps could also be utilized for prioritization and rationalization of nutrients supply in IGP of India.

Discovery of an Exceptionally Strong ß-Decay Transition of

A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on ^{20}Ne in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of ^{20}Ne and ^{20}F, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood.

Single and Double Beta-Decay Q Values among the Triplet

The atomic mass relations among the mass triplet ^{96}Zr, ^{96}Nb, and ^{96}Mo have been determined by means of high-precision mass measurements using the JYFLTRAP mass spectrometer at the IGISOL facility of the University of Jyväskylä. We report Q values for the ^{96}Zr single and double ß decays to ^{96}Nb and ^{96}Mo, as well as the Q value for the ^{96}Nb single ß decay to ^{96}Mo, which are Q_{ß}(^{96}Zr)=163.96(13), Q_{ßß}(^{96}Zr)=3356.097(86), and Q_{ß}(^{96}Nb)=3192.05(16) keV. Of special importance is the ^{96}Zr single ß-decay Q value, which has never been determined directly. The single ß decay, whose main branch is fourfold unique forbidden, is an alternative decay path to the ^{96}Zr ßß decay, and its observation can provide one of the most direct tests of the neutrinoless ßß-decay nuclear-matrix-element calculations, as these can be simultaneously performed for both decay paths with no further assumptions. The theoretical single ß-decay rate has been re-evaluated using a shell-model approach, which indicates a ^{96}Zr single ß-decay lifetime within reach of an experimental verification. The uniqueness of the decay also makes such an experiment interesting for an investigation into the origin of the quenching of the axial-vector coupling constant g_{A}.

Sorption kinetics of fipronil on soils.

Sorption kinetics of fipronil was studied on five soils of varying physico-chemical properties by batch equilibration method. Fipronil sorption on soils conformed to pseudo-second order kinetics and both the initial uptake rate and rate constant had a significant and positive correlation with clay content. The sorption kinetics of fipronil onto soils could be explained by intraparticle diffusion model consisting of an initial faster step followed by later slower step. The intraparticle diffusion rate constants for the initial faster and later slower step showed a significant and positive correlation with clay content (r = 0.978, significant at p ≤ 0.01) and soil electrical conductance (r = 0.901, significant at p ≤ 0.05), respectively.

Effect of different zinc levels on activity of superoxide dismutases & acid phosphatases and organic acid exudation on wheat genotypes.

A field study was carried out to investigate the effect of three Zn levels 0, 20 kg ZnSO4 ha(-1) and 20 kg ZnSO4 ha(-1)+ foliar spray of 0.5 % ZnSO4 on superoxide dismutase activity, acid phosphatase activity and grain yield and a pot experiment to study the effect of zinc deficient and sufficient conditions on organic acid exudation. Increasing Zn levels was established as beneficial in improving the enzyme activities of genotypes. Combined foliar and soil application of Zn proved to be superior of all the treatments. Zinc application resulted in a maximum increment limit of 96.8 % in superoxide dismutase activity, 75.76 % in acid phosphatase activity, and a decrement limit of 88.57 % in oxalic acid exudation irrespective of stages and year of study. The increased enzyme activities had a positive impact on grain yield. As an average of all genotypes an improvement of 19.88 % in 2009 and 21.29 % in 2010 due to soil application while of 16.45 % in 2009 and 13.01 % in 2010 due to combined application was calculated for grain yield. There existed a variation among genotypes in showing responses towards zinc application and the genotypes UP 2584 and PBW 550 were found to be more responsive.

Utilization of molasses based distillery effluent for fertigation of sugarcane.

A field study was carried out to monitor the effect of application of molasses based distillery effluent on yields of sugarcane and soil properties. The treatments consisted of main plots: control (I0), first pre-sowing irrigation with undiluted effluent (I1), one irrigation with effluent: tube-well water (1:3) at tillering stage (I2), two irrigations with effluent: tube-well water (1:4) at tillering and 30 d after tillering stage (I3). The subplots either received no fertilizer application (F0) or had 50 % of recommended dose (50 kg N, 60 kg P(2)O(5) and 40 kg K(2)O ha(-1) as basal dose (F1) with top dressing of 50 kg N ha(-1) at tillering and in June before the onset of monsoon. Nitrogen to the ratoon crops was applied in three equal splits. Application of 50 % recommended fertilizer dose increased the cumulative cane yields under different effluent treatments. Use of distillery effluent irrespective of the method of application significantly increased the cumulative yields of sugarcane over no application of effluent significantly at p ≤ 0.05. After the harvest of second ratoon crop, no significant effect of different treatments was noted on soil pH, electrical conductance and exchangeable Na. Significantly higher build-up of organic C in surface soil was noted under I2 treatment in comparison to I0 treatment at p ≤ 0.05. With no fertilizer application, both I1 and I2 significantly increased accumulation of alkaline KMnO(4) hydrolysable N in 30-45 cm layer in comparison to I0F0 at p ≤ 0.05. In comparison to I0, use of I2 increased the content of Olsen's P significantly (p ≤ 0.05) in 30-45 and 45-60 cm layers while I3 increased it significantly at p ≤ 0.05 in 0-15 and 45-60 cm layers. Use of distillery effluent as pre-sowing or standing crop irrigation increased ammonium acetate extractable K in surface and sub-surface layers significantly in comparison to I0 at p ≤ 0.05. Thus, use of distillery effluent in sugarcane crop as pre-sown or standing crop irrigation had no adverse impact on soil reaction or electrical conductivity and could save at least fifty percent of basal NPK application with significantly higher cumulative millable cane yields of main crop and two subsequent ratoons.

Direct observation of two protons in the decay of 54Zn.

The two protons emitted in the decay of 54Zn have been individually observed for the first time in a time projection chamber. The total decay energy and the half-life measured in this work agree with the results obtained in a previous experiment. Angular and energy correlations between the two protons are determined and compared to theoretical distributions of a three-body model. Within the shell model framework, the relative decay probabilities show a strong contribution of the p2 configuration for the two-proton emission. After 45Fe, the present result on 54Zn constitutes only the second case of a direct observation of the ground state two-proton decay of a long-lived isotope.

Persistence behavior of Fantac biostimulant in chili and soil under subtropical conditions.

The persistence of the biostimulant Fantac (N-ATCA) in chili and soil was evaluated at two application rates (0.25 and 0.50 microg g(-1)) by high-performance liquid chromatography. At 0.25 microg g(-1) Fantac persisted up to 3 days in soil and 5 days in chili. However, at 0.50 microg g(-1) Fantac residues persisted up to 5 days both in soil and chili. The dissipation of the biostimulant from soil and chili appeared to occur in a single phase and conformed to first-order kinetics. Half-lives of Fantac in soil and chili were calculated.

Buildup of heavy metals in soil-water-plant continuum as influenced by irrigation with contaminated effluent.

Accumulation of heavy metals in soil-water-plant continuum as a result of irrigation with metals contaminated effluent has been studied. Effluents being used for irrigating agricultural fields had normal pH 7.3-7.5, high Cr and Cl content as per the prescribed standards for irrigation. Among the heavy metals, buildup of total Iron was highest (9 times) and that of cadmium (1.3 times) was lowest in effluent irrigated soil as compared to tubewell irrigated soils. In most of the hand pump water samples, Pb, Cd and Cr were above the permissible limits for drinking. Bioaccumulation of Pb and Cr in vegetables was found to be above the critical concentrations for plant growth while Pb and Cd were above the prescribed limit in the diet of animals. Most of the heavy metals were above the maximum allowable limit in soil.

Effect of farmyard manure application on boron adsorption-desorption characteristics of some soils.

Boron (B) availability to crop plants depends on soil properties as well as management practices like liming, fertilization and use of organic manures. To assess the effect of farmyard manure (FYM) application on availability of added B, adsorption-desorption of B was investigated in five different soils receiving varying doses of FYM (0, 5 and 10 g FYM kg(-1) soil). Two surfaces Freundlich model was found best to account for B adsorption-desorption data of all soils. Application of FYM increased B adsorption capacities pertaining to low (K1) and high (K2) concentration ranges in all soils, except Soil C (Alfisol) having a pH of 9.8, in which the higher rate of FYM decreased the value of K2. Application of FYM did not change B desorption capacities of soils corresponding to low B concentration range (K(1)(1)) significantly, however, it increased B desorption capacity pertaining to high B concentration (K(1)(2)) in all soils, except Soils C (Alfisol) and E (Entisol) having pH of 9.8 and 5.1, respectively. Application of FYM increased the desorption slope factor applicable to low concentration range (1/n(1)(1)) in Soil A (Inceptisol), but decreased it in Soil E (Entisol). The 1/n(1)(2) (desorption slope factor applicable to high concentration range) decreased with FYM application in all soils except Soil E (Entisol), where it was increased. Boron desorption index (slope(ads)/slope(des)) decreased with FYM application in low B concentration range, but increased in high concentration range for all soils except soil E (Entisol, pH 5.1), in which a reverse trend was observed. Application of FYM increased the retention of added B in soils and may help reducing the leaching losses.

Effect of metal spiking on different chemical pools and chemically extractable fractions of heavy metals in sewage sludge.

A laboratory experiment was conducted to study the effect of metal spiking and incubation on some properties and sequentially extractable chemical pools of some heavy metals (F1, two extractions with 0.1 M Sr(NO3)2; F2, one extraction with 1 M NaOAc (pH 5.0); F3, three extractions with 5% NaOCl (pH 8.5) at 90-95 degrees C; F4, three extractions with 0.2 M oxalic acid + 0.2 M ammonium oxalate + 0.1 M ascorbic acid (pH 3.0); and F5, dissolution of sample residue in HF-HClO4 (residual fraction,) and also 1 M CaCl2 and 0.005 M DTPA extractable heavy metals in sewage sludge. Metal spiking and incubation decreased pH and easily oxidizable organic C content of sludge but increased electrical conductivity. Metal spiking and incubation increased F1 fraction of all heavy metals, F2 fraction of Ni, Pb, Cu, and Cd, F3 fraction of Pb, Cu, and Cd, F4 or reducible fraction of Ni, Cu, and Cd and residual fraction of Zn and Pb, but decreased F2 fraction of Zn, F3 of Zn and Ni, F4 fraction of Zn and F5 fraction of Ni, Cu, and Cd. Metal spiking and incubation increased 1 M CaCl2 and 0.005 M DTPA extractable amounts of all heavy metals in sludge except for 0.005 M DTPA extractable Zn, which registered only very marginal decrease.

Association between sarcoidosis and lymphoma revisited.

AIMS: To investigate the relation between sarcoidosis and lymphoma. METHODS: The hospital notes of five patients with sarcoidosis and a lymphoproliferative disorder were reviewed. Histological material on which the diagnoses of sarcoidosis and lymphoma were made was re-analysed. RESULTS: Four of the five patients had well documented sarcoidosis preceding the development of lymphoma by 18 months to 28 years; the fifth patient had lymphoplasmacytic lymphoma with a reactive granuloma reaction. Two patients had chronic sarcoidosis and three were treated with prednisolone. The types of lymphoma were: Hodgkin's disease (n = 1), B cell lymphoma (n = 2) (mantle cell and lymphoplasmacytic/local plasmacytoma) and large granular lymphocyte leukaemia (T cell) (n = 1). CONCLUSIONS: The association between sarcoidosis and lymphoma is confirmed, suggesting that sarcoidosis may be a predisposing factor for the development of a lymphoid malignancy due to disturbance of the immune system. All types of lymphoma may develop. The first case of T cell granular lymphocytic leukaemia in a patient with sarcoidosis has been documented.

2-substituted thioadenine nucleoside and nucleotide analogues: synthesis and receptor subtype binding affinities (1).

The design, synthesis, and receptor subtype binding affinities of several 2-substituted thioadenosine nucleoside and nucleotide analogues are described. Alkylation of 2-thioadenosine (1) with iodopentenylboronic acid followed by iododeboronation gave 2-((E)-1-iodo-1-penten-5-yl) thioadenosine (9). Compound 1 on treatment with 4-nitrobenzyl bromide and propargyl bromide furnished compounds 3 and 5, respectively. The 5'-monophosphate analogues of compounds 3, 5, 7, and 9 were prepared similarly using 2-thioadenosine 5'-monophosphate (2). Treatment of 1 with bromoethylamine hydrobromide provided 2-[(aminoethyl)thio]adenosine (11) which on coupling with N-succinimidyl 3-(4-hydroxyphenyl)propionate gave 2-[[[3-(4-hydroxyphenyl)propionamido]ethyl]thio]adenosine (12). Iodination of 12 gave 2-[[[3-(4-hydroxy-3-iodophenyl)propionamido]ethyl]thio]adenosine (13). Compounds 3-13 were evaluated for their affinities toward A1 and A2 adenosine receptors in rat brain cortex and striatum, respectively using [3H]DPCPX and [3H]CGS21680 as ligands. The nucleotide analogues 4, 6, 8, and 10 inhibited binding of [3H]DPCPX by 10-20% and of [3H]CGS21680 by 40-50% at a concentration of 100 microM suggesting weak affinity toward adenosine receptors. The nucleoside analogues 3, 5, 7, 9, 12, and 13 inhibited the A2 receptor binding of [3H]CGS21680 with Ki values of 1.2-3.67 microM, while A1 receptor binding of [3H]DPCPX was inhibited with Ki values 10-17 microM. The A1/A2 ratios suggest 4-8-fold A2 receptor selectivity.

Edaphological characteristics of unweathered and weathered fly ashes from Gondwana and lignite coal.

Naturally weathered and unweathered samples of fly ashes produced from Gondwana and lignite coals were characterized for their edaphological properties. The particle size distribution in these fly ashes varied widely, and the percentage of [Formula: see text] size particles governed their water holding capacity. All fly ashes were noncoherent in the dry state and had lower particle density than quartz and mulite. The fly ashes were low in available N, but were sufficient in available P, K, Ca, Mg, S, Cu, Fe, Mn, Zn and B. Among the fly ashes, unweathered lignite fly ash was the richest source of K, Ca, Mg, S and Fe, while weathered lignite fly ash had the highest amounts of Mn, Zn and B. The pH of the fly ashes was closely related to the ratio of exchangeable Ca to exchangeable Al. The fly ashes were high in soluble salt, but were poor in cation exchange capacity. As an amendment to correct soil pH, the fly ashes had a poor buffering capacity. Weathering decreased the total Fe, available S and exchangeable Na percentages, but increased the organic C content of the fly ashes. Invariably, an excess of soluble salts and exchangeable Na could limit plant growth on fly ash dumps. Toxic levels of B and Al existed in only some fly ashes.

Synthesis and biological studies of unsaturated acyclonucleoside analogues of S-adenosyl-L-homocysteine hydrolase inhibitors.

The design, synthesis, and biological evaluation of several unsaturated acyclonucleosides related to augustmycin A are described. The (propargyloxy)methyl acyclonucleoside analogues of 6-chloropurine, adenine, 6-methoxypurine, hypoxanthine, 6-mercaptopurine, and azathioprine have been prepared. The 9-[(propargyloxy)methyl]adenine (5) and 9-[(propargyloxy)methyl]hypoxanthine (12) analogues were converted to the corresponding 5'-tributylstannyl intermediates (9 and 13), respectively, which gave 9-[[[(Z)-5-iodo-5-propenyl]oxy]methyl]adenine (10) and 9-[[[(Z)-5-iodo-5-propenyl]oxy]methyl]hypoxanthine (14), respectively, after iododestannylation. The [125I]-radiolabeled congeners of 10 and 14 were prepared as potential metabolic markers. Among the unsaturated acyclonucleosides tested, 9-[(propargyloxy)methyl]-6-chloropurine (3), 9-[(propargyloxy)methyl]-6-mercaptopurine (15), 9-[(propargyloxy)methyl]azathioprine (17), and angustmycin A analogue 10 showed inhibition of cancer cell growth, but only at a minimal level, and 17 also showed 14% cancer cell death in vitro. Compound 10 provided approximately 50% protection against HIV at 10(-4) M concentrations. Biodistribution results of [125I]-10 in mice indicate that compound 10 is readily metabolized via deiodination in vivo, possibly by serving as a substrate for the enzyme S-adenosyl-L-homocysteine hydrolase.