Overnutrition as a risk factor for more serious respiratory viral infections in children: A retrospective study in hospitalized patients.

BACKGROUND: The prevalence of obesity has increased dramatically in children worldwide. Obesity has been recognized as a risk factor for more serious viral respiratory infections, mainly in adults. OBJECTIVE: To study the relationship between overnutrition (obesity and overweight) and clinical severity in children hospitalized with acute respiratory infections of viral origin. METHODS: One hundred and forty-three clinical records of children between 2 and 18 years old hospitalized for acute respiratory infection at Clínica Dávila (2014-2018) were analyzed, recording the respiratory viruses detected at the time of hospitalization, weight, and height. Nutritional status was estimated using Z score or body mass index, according to age. RESULTS: Eighty-tree3 children (58%) were positive for more than one respiratory virus. The main virus detected in monoinfection was adenovirus (9.8%), followed by respiratory syncytial virus (7.7%) and parainfluenza virus (7.7%). There were no deaths. Patients with obesity presented more days of hospitalization (P = .04), oxygen therapy (P = .03) and mechanical ventilation (P < .001), as well as a higher probability of requiring mechanical ventilation (P = .001) and of ICU admission (P = .003) compared with children with normal weight. Patients with overweight presented more days of mechanical ventilation (P < .001) than patients with normal weight. No significant differences were found between the presence of viral coinfection and nutritional status. CONCLUSION: Overnutrition is associated with greater severity of viral respiratory infection in hospitalized children.

Microbiota Profile of the Nasal Cavity According to Lifestyles in Healthy Adults in Santiago, Chile.

BACKGROUND: The respiratory microbiome is dynamic, varying between anatomical niches, and it is affected by various host and environmental factors, one of which is lifestyle. Few studies have characterized the upper respiratory tract microbiome profile according to lifestyle. We explored the association between lifestyles and microbiota profiles in the upper respiratory tract of healthy adults. METHODS: We analyzed nasal samples from 110 healthy adults who were living in Santiago, Chile, using 16S ribosomal RNA gene-sequencing methods. Volunteers completed a structured questionnaire about lifestyle. RESULTS: The composition and abundance of taxonomic groups varied across lifestyle attributes. Additionally, multivariate models suggested that alpha diversity varied in the function of physical activity, nutritional status, smoking, and the interaction between nutritional status and smoking, although the significant impact of those variables varied between women and men. Although physical activity and nutritional status were significantly associated with all indexes of alpha diversity among women, the diversity of microbiota among men was associated with smoking and the interaction between nutritional status and smoking. CONCLUSIONS: The alpha diversity of nasal microbiota is associated with lifestyle attributes, but these associations depend on sex and nutritional status. Our results suggest that future studies of the airway microbiome may provide a better resolution if data are stratified for differences in sex and nutritional status.

Overnutrition, Nasopharyngeal Pathogenic Bacteria and Proinflammatory Cytokines in Infants with Viral Lower Respiratory Tract Infections.

Background: Little is known about the interaction between the nasopharyngeal bacterial profile and the nutritional status in children. In this study, our main goal was to evaluate the associations between overnutrition and the presence of four potentially pathogenic bacteria in the nasopharynx of infants with viral lower respiratory tract infections (LRTI). In addition, we determined whether changes in the nasopharyngeal bacterial profile were associated with mucosal and serum proinflammatory cytokines and with clinical disease severity. Methods: We enrolled 116 children less than 2 years old hospitalized for viral LRTI during two consecutive respiratory seasons (May 2016 to August 2017); their nutritional status was assessed, and nasopharyngeal and blood samples were obtained. S. aureus, S. pneumoniae, H. influenzae, M. catarrhalis, and respiratory viruses were identified in nasopharyngeal samples by qPCR. Cytokine concentrations were measured in nasopharyngeal and blood samples. Disease severity was assessed by the length of hospitalization and oxygen therapy. Results: Nasopharyngeal pathogenic bacteria were identified in 96.6% of the enrolled children, and 80% of them tested positive for two or more bacteria. The presence and loads of M. catarrhalis was higher (p = 0.001 and p = 0.022, respectively) in children with overnutrition (n = 47) compared with those with normal weights (n = 69). In addition, the detection of >2 bacteria was more frequent in children with overnutrition compared to those with normal weight (p = 0.02). Multivariate regression models showed that the presence and loads of S. pneumoniae and M. catarrhalis were associated with higher concentrations of IL-6 in plasma and TNF-α in mucosal samples in children with overnutrition. Conclusions: The nasopharyngeal profile of young children with overnutrition was characterized by an over representation of pathogenic bacteria and proinflammatory cytokines.

Factors Influencing the Acceptance of COVID-19 Vaccines in a Country with a High Vaccination Rate.

Control of the COVID-19 pandemic largely depends on the effectiveness of the vaccination process. An understanding of the factors that underlie the willingness to accept vaccination contributes pivotal information to controlling the pandemic. We analyzed the association between the willingness to accept the available COVID-19 vaccines and vaccine determinants amidst the Chilean vaccination process. Individual-level survey data was collected from 744 nationally representative respondents and multivariate regression models were used to estimate the association between outcome and explanatory variables. We found that trust in COVID-19 vaccines, scientists, and medical professionals significantly increased the willingness to: accept the vaccines and booster doses, as well as annual vaccinations and the vaccination of children. Our results are critical to understanding the acceptance of COVID-19 vaccines in the context of a country with one of the world's highest vaccination rates. We provide useful information for decision-making and policy design, in addition to establishing guidelines regarding how to effectively explain vaccination programs to citizens.

El consumo de un extracto de calafate (Berberis microphylla) modifica marcadores de respuesta inmune en ratones delgados y obesos

RESUMEN La obesidad ha sido identificada como factor de riesgo de severidad de infecciones respiratorias. Apoyar la respuesta inmune en sujetos obesos es de interés. El presente trabajo evaluó el efecto del consumo de un extracto de calafate sobre marcadores de respuesta inmune en ratones delgados y obesos. Ratones C57BL/6J machos fueron expuestos por 82 días a dieta estándar (DE) y alta en grasas (DAG). A un subgrupo de ambos grupos, se les administró 50 y 100 mg [polifenoles totales]/kg peso de animal/día, de extracto, en las últimas dos semanas. Se evaluó expresión génica y secreción de marcadores de respuesta inmune, en tejido pulmonar y plasma. Se observó un efecto del tratamiento con extracto en la expresión de IFN-ϓ. Se observaron efectos inducidos por la DAG y el tratamiento con extracto de manera independiente, en la expresión de IL-12. Se observó un efecto global de la DAG sobre IFN-ϓ plasmático, específicamente una disminución en animales alimentados con DAG. Se observó una interacción entre la dieta y el tratamiento con extracto sobre IL-12 plasmática. El tratamiento utilizado modula marcadores que activan la respuesta inmune ante infecciones respiratorias principalmente de origen viral, en animales delgados y obesos.

ABSTRACT Obesity has been identified as a risk factor for severity of respiratory infections. Thus, the support of the immune response in obese subjects is of interest. The present work evaluated the effect of the consumption of a calafate extract on markers of the immune response in lean and obese mice. Male C57BL/6J mice were exposed for 82 days to a standard or a high-fat diet (HFD). A subgroup of both groups was given 50 and 100 mg [total polyphenols]/kg body weight/day of extract in the last two weeks. Gene expression and secretion of immune response markers were evaluated in lung tissue and plasma. An effect of extract treatment on IFN-ϓ expression was observed. Effects induced by the HFD and treatment with extract were observed independent of the expression of IL-12. An overall effect of the HF diet on plasma IFN-ϓ was observed, specifically a decrease in animals fed the HFD. An interaction between diet and extract treatment was observed over plasma IL-12. The treatment used modulates markers that activate the immune response to respiratory infections, mainly of viral origin, in lean and obese animals.

SARS-CoV-2 en atención odontológica: vías de transmisión y sus consideraciones en la práctica clínica

We analyze the transmission routes, possible viral reservoirs in the oral cavity and considerations about dental care of SARS-CoV-2 virus infection. We also analyze the protocols required before and after a dental procedure, aiming to increase the awareness of dentists about the importance of virus spread prevention among health care workers and patients. The evaluation of symptoms associated with SARS- CoV-2 such as fever, fatigue, dry cough, myalgia, dyspnea, and the inquiry about possible contacts with infected people is of utmost importance. The tongue and oral mucosa are important viral reservoirs and the transmission of the virus occurs primarily by saliva droplets. Therefore, elective dental care should be postponed, attending only dental emergencies during this period, incorporating the use of protective personal equipment (PPE) and using manual instruments to prevent the production of aerosols.

Overnutrition in Infants Is Associated With High Level of Leptin, Viral Coinfection and Increased Severity of Respiratory Infections: A Cross-Sectional Study.

Objective: To investigate the relationship of overnutrition (obese and overweight) with severity of illness in children hospitalized with acute lower respiratory infections (ALRIs), frequency of viral coinfections and leptin levels. Methods: We studied 124 children <2 years old that were hospitalized for ALRI. Nutritional status was calculated by z-scores according to weight-for-age z-scores, length or height-for-age z-scores, and weight-for-height z-scores. Nasopharyngeal aspirates (NPAs) were obtained and viral respiratory pathogens were identified using reverse transcription polymerase chain reactions (RT-PCR). Respiratory syncytial virus (RSV) load was assessed using quantitative RT-PCR. NPA and plasma leptin level were measured. Clinical data and nutritional status were recorded, and patients were followed up until hospital discharge. Viral coinfection was defined as the presence of two or more viruses detected in the same respiratory sample. Severity of illness was determined by length of hospitalization and duration of oxygen therapy. Results: Children with overnutrition showed a greater frequency of viral coinfection than those with normal weight (71% obese vs. 37% normal weight p = 0.013; 68% overweight vs. 37% normal weight p = 0.004). A lower RSV load was found in obese (5.91 log10 copies/mL) and overweight children (6.49 log10 copies/mL) compared to normal weight children (8.06 log10 copies/mL; p = 0.021 in both cases). In multivariate analysis, obese, and overweight infants <6 months old were associated with longer hospital stays (RR = 1.68; CI: 1.30-2.15 and obese: RR = 1.68; CI: 1.01-2.71, respectively) as well as a greater duration of oxygen therapy (RR = 1.80; IC: 1.41-2.29 and obese: RR = 1.91; CI: 1.15-3.15, respectively). Obese children <6 months showed higher plasma leptin level than normal weight children (7.58 vs. 5.12 ng/µl; p <0.046). Conclusions: In infants younger than 6 months, overnutrition condition was related to increased severity of infections and high plasma leptin level. Also, children with overnutrition showed a greater frequency of viral coinfection and low RSV viral load compared to normal weights children. These findings further contribute to the already existent evidence supporting the importance of overnutrition prevention in pediatric populations.

[Dental care during SARS-CoV-2 pandemic]. / SARS-CoV-2 en atención odontológica: vías de transmisión y sus consideraciones en la práctica clínica.

We analyze the transmission routes, possible viral reservoirs in the oral cavity and considerations about dental care of SARS-CoV-2 virus infection. We also analyze the protocols required before and after a dental procedure, aiming to increase the awareness of dentists about the importance of virus spread prevention among health care workers and patients. The evaluation of symptoms associated with SARS- CoV-2 such as fever, fatigue, dry cough, myalgia, dyspnea, and the inquiry about possible contacts with infected people is of utmost importance. The tongue and oral mucosa are important viral reservoirs and the transmission of the virus occurs primarily by saliva droplets. Therefore, elective dental care should be postponed, attending only dental emergencies during this period, incorporating the use of protective personal equipment (PPE) and using manual instruments to prevent the production of aerosols.

Drought and soil amendment effects on monoterpene emission in rosemary plants.

The aim of this work was to study the changes during 15days in the monoterpene emission rates of the Mediterranean shrub rosemary (Rosmarinus officinalis L.), in response to increasing drought stress and fertilisation using two different composts derived from livestock anaerobic digestates (cattle and pig slurry). Drought stress considerably reduced photosynthetic rates, stomatal conductance and isoprenoid emissions and also induced a change in blend composition. In the drought stressed rosemary plants, a positive relationship of non-oxygenated monoterpene emissions and a negative relationship of oxygenated monoterpene with photosynthesis were observed, indicating a different control mechanism over the emissions of the two types of isoprenoids. The emission of non-oxygenated monoterpenes seemed to depend more on photosynthesis and "de novo" synthesis, whereas emission of oxygenate monoterpenes was more dependent on volatilisation from storage, mainly driven by cumulative temperatures. In the short term, the addition of composted organic materials to the soil did not induce a significant effect on isoprenoid emission rates in the rosemary plants. However, the effect of the interaction between fertilisation and seasonality on isoprenoid emission rates was influenced by the amendment origin. Also, we emphasized changes in potential isoprenoid emission factors throughout the experiment, probably indicating changes in the leaf developmental stage.

Role of Biogenic Volatile Organic Compounds (BVOC) emitted by urban trees on ozone concentration in cities: a review.

Biogenic Volatile Organic Compounds (BVOC) play a critical role in biosphere-atmosphere interactions and are key factors of the physical and chemical properties of the atmosphere and climate. However, few studies have been carried out at urban level to investigate the interactions between BVOC emissions and ozone (O3) concentration. The contribution of urban vegetation to the load of BVOCs in the air and the interactions between biogenic emissions and urban pollution, including the likely formation of O3, needs to be investigated, but also the effects of O3 on the biochemical reactions and physiological conditions leading to BVOC emissions are largely unknown. The effect of BVOC emission on the O3 uptake by the trees is further complicating the interactions BVOC-O3, thus making challenging the estimation of the calculation of BVOC effect on O3 concentration at urban level.

Characterization of juvenile and adult leaves of Eucalyptus globulus showing distinct heteroblastic development: photosynthesis and volatile isoprenoids.

Heteroblastic Eucalyptus (Eucalyptus globulus L.) leaves were characterized for their functional diversity examining photosynthesis and photosynthesis limitations, transpiration, and the emission of isoprene and monoterpenes. In vivo and combined analyses of gas-exchange, chlorophyll fluorescence, and light absorbance at 830 nm were made on the adaxial and abaxial sides of juvenile and adult leaves. When adult leaves were reversed to illuminate the abaxial side, photosynthesis and isoprene emission were significantly lower than when the adaxial side was illuminated. Monoterpene emission, however, was independent on the side illuminated and similarly partitioned between the two leaf sides. The abaxial side of adult leaves showed less diffusive resistance to CO(2) acquisition by chloroplasts, but also lower ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, than the adaxial leaf side. In juvenile leaves, photosynthesis, isoprene, and monoterpene emissions were similar when the adaxial or abaxial side was directly illuminated. In the abaxial side of juvenile leaves, photosynthesis did not match the rates attained by the other leaf types when exposed to elevated CO(2), which suggests the occurrence of a limitation of photosynthesis by ribulose bisphosphate (RuBP) regeneration. Accordingly, a reduced efficiency of both photosystems and a high non-radiative dissipation of energy was observed in the abaxial side of juvenile leaves. During light induction, the adaxial side of juvenile leaves also showed a reduced efficiency of photosystem II and a large non-radiative energy dissipation. Our report reveals distinct functional properties in Eucalyptus leaves. Juvenile leaves invest more carbon in isoprene, but not in monoterpenes, and have a lower water use efficiency than adult leaves. Under steady-state conditions, in adult leaves the isobilateral anatomy does not correspond to an equal functionality of the two sides, while in juvenile leaves the dorsiventral anatomy does not result in functional differences in primary or secondary metabolism in the two sides. However, photochemical limitations may reduce the efficiency of carbon fixation in the light, especially in the abaxial side of juvenile leaves.

Stomatal uptake and stomatal deposition of ozone in isoprene and monoterpene emitting plants.

Volatile isoprenoids were reported to protect plants against ozone. To understand whether this could be the result of a direct scavenging of ozone by these molecules, the stomatal and non-stomatal uptake of ozone was estimated in plants emitting isoprene or monoterpenes. Ozone uptake by holm oak (Quercus ilex, a monoterpene emitter) and black poplar (Populus nigra, an isoprene emitter) was studied in whole plant enclosures (continuously stirred tank reactors, CSTR). The ozone uptake by plants was estimated measuring ozone concentration at the inlet and outlet of the reactors, after correcting for the uptake of the enclosure materials. Destruction of ozone at the cuticle or at the plant stems was found to be negligible compared to the ozone uptake through the stomata. For both plant species, a relationship between stomatal conductance and ozone uptake was found. For the poplar, the measured ozone losses were explained by the uptake of ozone through the stomata only, and ozone destruction by gas phase reactions with isoprene was negligible. For the oak, gas phase reactions of ozone with the monoterpenes emitted by the plants contributed significantly to ozone destruction. This was confirmed by two different experiments showing a) that in cases of high stomatal conductance but under low CO(2) concentration, a reduction of monoterpene emission was still associated with reduced O(3) uptake; and b) that ozone losses due to the gas phase reactions only can be measured when using the exhaust from a plant chamber to determine the gas phase reactivity in an empty reaction chamber. Monoterpenes can therefore relevantly scavenge ozone at leaf level contributing to protection against ozone.

Isoprene emission and primary metabolism in Phragmites australis grown under different phosphorus levels.

Aquatic plants are generally used for wastewater purification and phytoremediation, but some of them also emit large amounts of isoprene, the most abundant biogenic volatile organic compound. Since isoprenoid biosynthesis requires high amounts of phosphorylated intermediates, the emission may also be controlled by inorganic phosphorus concentration (Pi) in leaves. We carried out experiments to determine the emission of isoprene from Phragmites australis plants used in reconstructed wetlands to phytoremediate elevated levels of phosphorus contributed by urban wastes. Four groups of plants were grown hydroponically in water containing different levels of KH(2)PO(4). High levels of phosphorus in the water resulted in high Pi in the leaves. High Pi stimulated photosynthesis at intercellular CO(2) concentrations lower and higher than ambient, implying higher ribulose 1,5-bisphosphate carboxylase (Rubisco) activity and higher ribulose 1,5-bisphosphate regeneration rates, respectively. However, isoprene emission was substantially lower at high Pi than at low Pi, and was not associated to photosynthesis rates at high Pi. This surprising result suggests that isoprene is limited by processes other than photosynthetic intermediate availability or by energetic (ATP) requirements under high Pi levels. Irrespective of the mechanism responsible for the observed reduction of isoprene emission, our results show that Phragmites plants may effectively remove phosphorus from water without concurrently increase isoprene emission, at least on a leaf area basis. Thus, Phragmites used in reconstructed wetlands for phytoremediation of urban wastes rich of phosphates will not contribute high loads of hydrocarbons which may influence air quality over urban and peri-urban areas.

Physiological responses of forest trees to heat and drought.

The heat wave of summer 2003 was the largest and the most persistent ever experienced in Central Europe and has fuelled concern about the effects of climate change on European ecosystems. Since forests constitute the most important European ecosystems, in this review article we assess current knowledge on the effects of heat and drought on key metabolic processes for growth and productivity of forest trees. In particular, the general consequences of heat and drought on (1) photosynthesis and respiration at the cellular and community level, and (2) on nutrient uptake, partitioning and competition for nutrients are summarized. The latter are a major sink for photosynthetic energy and, therefore, are indirectly but strongly connected to the performance of photosynthesis. In addition, the interaction of heat and drought with stress compensation mechanisms and emission of biogenic volatile organic compounds (BVOC) are discussed, since these processes are directly connected to carbon metabolism. Effects on the emission of BVOC are also included because they constitute an important feedback mechanism on ozone formation and, thus, on atmospheric pollution. As far as available, data collected during the 2003 heat wave are included and discussed.

Inefficient photosynthesis in the Mediterranean orchid Limodorum abortivum is mirrored by specific association to ectomycorrhizal Russulaceae.

Among European Neottieae, Limodorum abortivum is a common Mediterranean orchid. It forms small populations with a patchy distribution in woodlands, and is characterized by much reduced leaves, suggesting a partial mycoheterotrophy. We have investigated both the photosynthetic abilities of L. abortivum adult plants and the diversity of mycorrhizal fungi in Limodorum plants growing in different environments and plant communities (coniferous and broadleaf forests) over a wide geographical and altitudinal range. Despite the presence of photosynthetic pigments, CO2 fixation was found to be insufficient to compensate for respiration in adult plants. Fungal diversity was assessed by morphological and molecular methods in L. abortivum as well as in the related rare species Limodorum trabutianum and Limodorum brulloi. Phylogenetic analyses of the fungal internal transcribed spacer (ITS) sequences, obtained from root samples of about 80 plants, revealed a tendency to associate predominantly with fungal symbionts of the genus Russula. Based on sequence similarities with known species, most root endophytes could be ascribed to the species complex encompassing Russula delica, Russula chloroides, and Russula brevipes. Few sequences clustered in separate groups nested within Russula, a genus of ectomycorrhizal fungi. The morphotypes of ectomycorrhizal root tips of surrounding trees yielded sequences similar or identical to those obtained from L. abortivum. These results demonstrate that Limodorum species with inefficient photosynthesis specifically associate with ectomycorrhizal fungi, and appear to have adopted a nutrition strategy similar to that known from achlorophyllous orchids.

Diffusive and metabolic limitations to photosynthesis under drought and salinity in C(3) plants.

Drought and salinity are two widespread environmental conditions leading to low water availability for plants. Low water availability is considered the main environmental factor limiting photosynthesis and, consequently, plant growth and yield worldwide. There has been a long-standing controversy as to whether drought and salt stresses mainly limit photosynthesis through diffusive resistances or by metabolic impairment. Reviewing in vitro and in vivo measurements, it is concluded that salt and drought stress predominantly affect diffusion of CO(2) in the leaves through a decrease of stomatal and mesophyll conductances, but not the biochemical capacity to assimilate CO(2), at mild to rather severe stress levels. The general failure of metabolism observed at more severe stress suggests the occurrence of secondary oxidative stresses, particularly under high-light conditions. Estimates of photosynthetic limitations based on the photosynthetic response to intercellular CO(2) may lead to artefactual conclusions, even if patchy stomatal closure and the relative increase of cuticular conductance are taken into account, as decreasing mesophyll conductance can cause the CO(2) concentration in chloroplasts of stressed leaves to be considerably lower than the intercellular CO(2) concentration. Measurements based on the photosynthetic response to chloroplast CO(2) often confirm that the photosynthetic capacity is preserved but photosynthesis is limited by diffusive resistances in drought and salt-stressed leaves.

Isoprene produced by leaves protects the photosynthetic apparatus against ozone damage, quenches ozone products, and reduces lipid peroxidation of cellular membranes.

Many plants invest carbon to form isoprene. The role of isoprene in plants is unclear, but many experiments showed that isoprene may have a role in protecting plants from thermal damage. A more general antioxidant action has been recently hypothesized on the basis of the protection offered by exogenous isoprene in nonemitting plants exposed to acute ozone doses. We inhibited the synthesis of endogenous isoprene by feeding fosmidomycin and observed that Phragmites australis leaves became more sensitive to ozone than those leaves forming isoprene. Photosynthesis, stomatal conductance, and fluorescence parameters were significantly affected by ozone only in leaves on which isoprene was not formed. The protective effect of isoprene was more evident when the leaves were exposed for a long time (8 h) to relatively low (100 nL L(-1)) ozone levels than when the exposure was short and acute (3 h at 300 nL L(-1)). Isoprene quenched the amount of H(2)O(2) formed in leaves and reduced lipid peroxidation of cellular membranes caused by ozone. These results indicate that isoprene may exert its protective action at the membrane level, although a similar effect could be obtained if isoprene reacted with ozone before forming active oxygen species. Irrespective of the mechanism, our results suggest that endogenous isoprene has an important antioxidant role in plants.

Ozone quenching properties of isoprene and its antioxidant role in leaves.

Isoprene is formed in and emitted by plants and the reason for this apparent carbon waste is still unclear. It has been proposed that isoprene stabilizes cell and particularly chloroplast thylakoid membranes. We tested if membrane stabilization or isoprene reactivity with ozone induces protection against acute ozone exposures. The reduction of visible, physiological, anatomical, and ultrastructural (chloroplast) damage shows that clones of plants sensitive to ozone and unable to emit isoprene become resistant to acute and short exposure to ozone if they are fumigated with exogenous isoprene, and that isoprene-emitting plants that are sensitive to ozone do not suffer damage when exposed to ozone. Isoprene-induced ozone resistance is associated with the maintenance of photochemical efficiency and with a low energy dissipation, as indicated by fluorescence quenching. This suggests that isoprene effectively stabilizes thylakoid membranes. However, when isoprene reacts with ozone within the leaves or in a humid atmosphere, it quenches the ozone concentration to levels that are less or non-toxic for plants. Thus, protection from ozone in plants fumigated with isoprene may be due to a direct ozone quenching rather than to an induced resistance at membrane level. Irrespective of the mechanism, isoprene is one of the most effective antioxidants in plants.