Identification and Profiling Analysis of microRNAs in Guava Fruit (Psidium guajava L.) and Their Role during Ripening.

The guava (Psidium guajava L.) is a climacteric fruit with an accelerated post-harvest overripening. miRNAs are small RNA sequences that function as gene regulators in eukaryotes and are essential for their survival and development. In this study, miRNA libraries were constructed, sequenced and analyzed from the breaker and ripe stages of guava fruit cv. Siglo XXI. One hundred and seventy-four mature miRNA sequences from 28 miRNA families were identified. The taxonomic distribution of the guava miRNAs showed a high level of conservation among the dicotyledonous plants. Most of the predicted miRNA target genes were transcription factors and genes involved in the metabolism of phytohormones such as abscisic acid, auxins, and ethylene, as revealed through an ontology enrichment analysis. The miRNA families miR168, miR169, miR396, miR397, and miR482 were classified as being directly associated with maturation, whereas the miRNA families miR160, miR165, miR167, miR3930, miR395, miR398, and miR535 were classified as being indirectly associated. With this study, we intended to increase our knowledge and understanding of the regulatory process involved in the ripening process, thereby providing valuable information for future research on the ripening of guava fruit.

Therapeutic indications, chemical composition and biological activity of native Brazilian species from Psidium genus (Myrtaceae): A review.

ETHNOPHARMACOLOGICAL IMPORTANCE: Brazilian medicinal species of the Psidium genus are rich in secondary metabolites such as terpenes and phenolic compounds and present biological activities for several human diseases. For the native Psidium species, there are no specific research reports for any member of the genus about ethnobotanical research, hindering the joint analysis of its therapeutic indications together with the scientific evidence already investigated. STUDY OBJECTIVE: Analyze the therapeutic indications, the main chemical constituents, and the biological activities of native species of the Psidium to Brazil. MATERIALS AND METHODS: Systematic research was carried out in the Scopus, ScienceDirect, PubMed, and Web of Science databases over a period of ten years. Articles in English, Portuguese and Spanish were used. The research was divided into three phases, seeking information on ethnobotany, chemical composition and biological activities. The words were combined to structure the descriptors used in the search. RESULTS: A total of 13 native species belonging to the Psidium genus were identified in this analysis, Psidium acutangulum DC., Psidium brownianum Mart. ex DC., Psidium cattleyanum Sabine, Psidium densicomum Mart. ex DC., Psidium grandifolium Mart. ex DC., Psidium guineense Sw., Psidium laruotteanum Cambess., Psidium myrsinites DC, Psidium myrtoides O. Berg, Psidium salutare (Kunth) O. Berg, Psidium schenckianum Kiaersk., Psidium sobralianum Proença & Landrum, Psidium striatulum Mart. ex DC. Of these, six were indicated in folk medicine, digestive system disorders being their main therapeutic indication. Most species presented an investigation of chemical composition and biological activity. They are rich in phenolic compounds, flavonoids, and terpenes and have antimicrobial, antioxidant, antiproliferative, and repellent activities. CONCLUSIONS: Native species of the Psidium genus are important sources of active ingredients in combating adversities that affect the human health, especially regarding the digestive system. They have a rich chemical composition, responsible for the biological activities demonstrated for the species.

Antihyperglycemic and hypoglycemic activity of Mayan plant foods in rodent models.

BACKGROUND: Postprandial hyperglycemia and decreased insulin secretion are relevant to risk factors in the development of type 2 diabetes and its complications. Plant foods with antidiabetic properties could be an affordable alternative in the prevention and treatment of this disease. In the present study, the antihyperglycemic and hypoglycemic activity of Bixa orellana, Psidium guajava L., Cucurbita moschata, Raphanus sativus L. and Brassica oleracea var. capitata - Mayan plant foods - were evaluated at doses of 5 and 10 mg kg-1 . Antihyperglycemic activity was measured in healthy Wistar rats and those with obesity induced by high-sucrose diet (group HSD) (20%). The hypoglycemic activity was measure in healthy CD1 mice. RESULTS: Fasting glucose, Lee index and the body weight of HSD rats increased significantly (P ≤ 0.05) after 12 weeks of induction compared to healthy rats. In healthy rats, P. guajava and Bixa orellana (10 mg kg-1 ) demonstrated higher and statistically different (P ≤ 0.05) antihyperglycemic activity compared to control acarbose (0.5 mg kg-1 ). In the HSD rat group, all Mayan plant foods (10 mg kg-1 ) demonstrated antihyperglycemic activity statistically equal (P ≤ 0.05) to control acarbose. However, Brassica oleracea and R. sativus registered the highest antihyperglycemic activity. Bixa orellana and P. guajava (5 mg kg-1 ) showed similar hypoglycemic activity (P ≤ 0.05) to glibenclamide (0.5 mg kg-1 ) but was not significant (P ≤ 0.05) compared to insulin (5 UI kg-1 ). CONCLUSION: The present study provides valuable evidence on the possible health benefits of Mayan plant foods. These foods could contribute to the development of therapeutic diet strategies for the prevention and treatment of diabetes. © 2021 Society of Chemical Industry.

Acerola (Malpighia glabra L.) and guava (Psidium guayaba L.) industrial processing by-products stimulate probiotic Lactobacillus and Bifidobacterium growth and induce beneficial changes in colonic microbiota.

AIMS: This study evaluated whether by-products from industrial processing of acerola (Malpighia glabra L.; AB) and guava (Psidium guajava L.; GB) fruit may stimulate the growth and metabolism of probiotic Lactobacillus and Bifidobacterium and induce changes in human colonic microbiota. METHODS AND RESULTS: The ability of non-digested and digested AB or GB to stimulate the growth ad metabolism of Lactobacillus acidophilus LA-05, Lactobacillus casei L-26 and Bifidobacterium animalis subsp. lactis BB-12 was evaluated. Changes in populations of distinct bacterial groups of human colonic microbiota induced by digested AB and GB were evaluated using an in vitro colonic fermentation system. Non-digested and digested AB and GB favoured probiotic growth. No difference among counts of probiotics in media with glucose, fructooligosaccharides and non-digested and digested AB and GB was found during a 48-h cultivation. Cultivation of probiotics in media with non-digested and digested AB and GB resulted in decreased pH, increased organic acid production and sugar consumption over time. Digested AB and GB caused overall beneficial changes in abundance of Bifidobacterium spp., Lactobacillus-Enterococcus, Eubacterium rectall-Clostridium coccoides and Bacteroides-Provotella populations, besides to decrease the pH and increase the short-chain fatty acid production during a 24-h in vitro colonic fermentation. CONCLUSION: AB and GB could be novel prebiotic ingredients because they can stimulate the growth and metabolism of probiotics and induce overall beneficial changes in human colonic microbiota. SIGNIFICANCE AND IMPACT OF THE STUDY: AB and GB stimulated the growth and metabolism of probiotics, in addition to induce beneficial alterations in human colonic microbiota composition and increase short-chain fatty acid production. These results characterize AB and GB as potential prebiotic ingredients and fruit processing by-products as sources of added-value compounds.

Profile of Terpenoid Compounds Mediating a Plant-Herbivore Interaction: Screening by Static Headspace Solid-Phase Microextraction-Gas Chromatography/Q-ToF Mass Spectrometry.

Conotrachelus dimidiatus (Coleoptera: Curculionidae) interacts with immature guava fruits (Psidium guajava L.) for feed, sleep, mate and oviposit. Determination of the volatile organic compounds (VOCs) emitted by the insect and immature fruits can help improve understanding of plant-insect and intraspecific insect interactions between females and males of C. dimidiatus. Daytime fruit setting emissions of immature guava consist mainly of limonene, caryophyllene, and aromadendrene. In addition to the host's volatiles, the aim of this study was to assess the VOCs released by the insect. Static headspace-solid phase microextraction (SHS-SPME), combined with gas chromatography/quadrupole time of flight mass spectrometry (GC/Q-ToF-MS), allowed the identification of the C10 terpenoids: grandlure I, II, II, IV, grandisoic acid, papayanol and papayanal bioactive compounds released by female and male C. dimidiatus under laboratory conditions. These chemical compounds are candidates for the preparation of a lure formulation.

Guava-fruit extract can improve the UV-protection efficiency of synthetic filters in sun cream formulations.

Increasing concerns about health safety, social impacts and fair trade have intensified the industrial interest for using natural products in commercial cosmetic formulations. Several studies are currently focusing on plant extracts, but tropical fruits, such as guava, remain yet unexplored and, consequently, underutilized. This research aims to evaluate the potential for using guava-fruit extract as a photoprotective additive agent for sun cream formulations. The phytochemical screening revealed the presence of flavonoids and tannins and the absence of coumarins. Although the Psidium guajava extract showed a low sun protection factor (SPF) value (1.0), it improved in about 134% the photoprotective result (8.1) of 7.5% 2-ethyl-hexyl methoxycinnamate formulation. Therefore, guava-fruit extract supplementation in the formulation shows the potential to reduce the use of synthetic photoprotectors in about 78.9% from the total synthetic organic filters used to achieve the SPF value of 18. Thus, sun cream supplemented with guava-fruit extract show the potential for minimizing the risk of synthetic agent toxicity, and a 65.8% reduction in the cost of the sunscreen production.

Guava-flavored whey beverage processed by cold plasma technology: Bioactive compounds, fatty acid profile and volatile compounds.

The effect of cold plasma processing time and gas flow on bioactive compounds such as vitamin C, carotenoids and phenolic compounds, DPPH, angiotensin-converting-enzyme (ACE) inhibitory activity, fatty acids profile, and volatile compounds of guava-flavored whey beverage was investigated. For comparative purposes, a pasteurized beverage was also manufactured. Cold plasma increased the concentration of bioactive and volatile compounds, and proportionated changes in the fatty acids profile. The milder conditions like lower flow rate and processing time, resulted in higher vitamin C and volatile compounds levels, and higher antioxidant activity, but with a lower carotenoids content and a less favorable fatty acids profile. More drastic conditions like higher flow rate and processing time resulted in products with lower vitamin C and volatile compounds levels, but with higher carotenoids content and ACE inhibitory activity. It can be concluded that the cold plasma processing can improve the properties of the guava-flavored whey beverages (increased concentration of bioactive and volatile compounds), while the effect on the fatty acid profile and ACE inhibitory activity is dependent on the process parameters (processing time and flow rate).

Effect of in vitro digestion on the functional properties of Psidium cattleianum Sabine (araçá), Butia odorata (Barb. Rodr.) Noblick (butiá) and Eugenia uniflora L. (pitanga) fruit extracts.

Brazilian native fruits are reported to be promising sources of bioactive compounds; however their bioactivity depends on their stability along the digestive process. This study evaluated the α-glucosidase inhibition, antioxidant activity and total phenolic content (TPC) stability of araçá, butiá and pitanga fruit extracts using an in vitro digestion model. Additionally, the individual phenolic compound recovery of the most stable and active extract was evaluated by HPLC-DAD-ESI-MS/MS. Overall, the antioxidant activity of all extracts decreased along the process. Araçá fruit extracts, at the end of digestion, showed α-glucosidase inhibition values similar to their non-digested extracts and the highest TPC recovery (28%). Recovery of individual phenolic compounds of red araçá fruit extract revealed a negative impact on the stability of ellagitannins. Araçá fruit extract seems to provide phenolic compounds with α-glucosidase inhibitory properties after the gastrointestinal digestion, indicating their potential to be used in the control of type II diabetes.

In silico optimization of a guava antimicrobial peptide enables combinatorial exploration for peptide design.

Plants are extensively used in traditional medicine, and several plant antimicrobial peptides have been described as potential alternatives to conventional antibiotics. However, after more than four decades of research no plant antimicrobial peptide is currently used for treating bacterial infections, due to their length, post-translational modifications or  high dose requirement for a therapeutic effect . Here we report the design of antimicrobial peptides derived from a guava glycine-rich peptide using a genetic algorithm. This approach yields guavanin peptides, arginine-rich α-helical peptides that possess an unusual hydrophobic counterpart mainly composed of tyrosine residues. Guavanin 2 is characterized as a prototype peptide in terms of structure and activity. Nuclear magnetic resonance analysis indicates that the peptide adopts an α-helical structure in hydrophobic environments. Guavanin 2 is bactericidal at low concentrations, causing membrane disruption and triggering hyperpolarization. This computational approach for the exploration of natural products could be used to design effective peptide antibiotics.

Psidium cattleianum fruits: A review on its composition and bioactivity.

Psidium cattleianum Sabine, commonly known as araçá, is a Brazilian native fruit, which is very juicy, with sweet to sub acid pulp and a spicy touch. The fruit can be eaten fresh or processed into juice, jellies and ice creams. Araçás are source of vitamin C, minerals, fatty acids, polysaccharides, volatile compounds, carotenoids and phenolic compounds, which can provide nutrients and phytochemical agents with different biological functions. Different pharmacological studies demonstrate that P. cattleianum exerts antioxidant, antidiabetic, anticarcinogenic, antimicrobial, anti-inflammatory and antiaging effects. Thus, this article aims to review the chemical composition and biological effects reported for araçá fruit in the last years.

Could the Extended Phenotype Extend to the Cellular and Subcellular Levels in Insect-Induced Galls?

Neo-ontogenesis of plant galls involves redifferentiation of host plant tissues to express new phenotypes, when new cell properties are established via structural-functional remodeling. Herein, Psidium cattleianum leaves and Nothotrioza cattleiani galls are analyzed by developmental anatomy, cytometry and immunocytochemistry of cell walls. We address hypothesis-driven questions concerning the organogenesis of globoid galls in the association of P. cattleianum-N. cattleianum, and P. myrtoides-N. myrtoidis. These double co-generic systems represent good models for comparing final gall shapes and cell lineages functionalities under the perspective of convergent plant-dependent or divergent insect-induced characteristics. Gall induction, and growth and development are similar in both galls, but homologous cell lineages exhibit divergent degrees of cell hypertrophy and directions of elongation. Median cortical cells in P. cattleianum galls hypertrophy the most, while in P. myrtoides galls there is a centrifugal gradient of cell hypertrophy. Cortical cells in P. cattleianum galls tend to anisotropy, while P. myrtoidis galls have isotropically hypertrophied cells. Immunocytochemistry evidences the chemical identity and functional traits of cell lineages: epidermal cells walls have homogalacturonans (HGAs) and galactans, which confer rigidity to sites of enhanced cell division; oil gland cell walls have arabinogalactan proteins (AGPs) that help avoiding cell death; and parenchyma cell walls have HGAs, galactans and arabinans, which confer porosity. Variations in such chemical identities are related to specific sites of hypertrophy. Even though the double co-generic models have the same macroscopic phenotype, the globoid morphotype, current analyses indicate that the extended phenotype of N. cattleiani is substantiated by cellular and subcellular specificities.

Ryegrass cv. Lema and guava cv. Paluma biomonitoring suitability for estimating nutritional contamination risks under seasonal climate in Southeastern Brazil.

The risks posed by nutrient deposition due to air pollution on ecosystems and their respective services to human beings can be appropriately estimated by bioindicator plants when they are well acclimated to the study region environmental conditions. This assumption encouraged us to comparatively evaluate the accumulation potential of ryegrass cv. Lema and guava cv. Paluma macro and micronutrients. We also indicated the most appropriate species for biomonitoring nutrient contamination risks in tropical areas of Southeastern Brazil, which are characterized by marked dry and wet seasons and complex mixtures of air pollutants from different sources (industries, vehicle traffic and agriculture). The study was conducted in 14 sites with different neighboring land uses, within the Metropolitan Region of Campinas, central-eastern region of São Paulo State. The exposure experiments with ryegrass and guava were consecutively repeated 40 (28 days each) and 12 (84 days each) times, respectively, from Oct/2010 to Sept/2013. Macro and micronutrients were analyzed and background concentrations and enrichment ratios (ER) were estimated to classify the contamination risk within the study region. Significantly higher ER suggested that ryegrass were the most appropriate accumulator species for N, S, Mg, Fe, Mn, Cu and Zn deposition and guava for K, Ca, P and B deposition. Based on these biomonitoring adjustments, we concluded that the nutrient deposition was spatially homogeneous in the study area, but clear seasonality in the contamination risk by nutritional inputs was evidenced. Significantly higher contamination risk by S, Fe, K and B occurred during the dry season and enhanced contamination risk by Mn, Cu and Zn were highlighted during the wet season. Distinctly high contamination risk was estimated for S, Fe and Mn in several exposure experiments.

Male Sexual Behavior and Pheromone Emission Is Enhanced by Exposure to Guava Fruit Volatiles in Anastrepha fraterculus.

BACKGROUND: Plant chemicals can affect reproductive strategies of tephritid fruit flies by influencing sex pheromone communication and increasing male mating competitiveness. OBJECTIVE AND METHODOLOGY: We explored whether exposure of Anastrepha fraterculus males to guava fruit volatiles and to a synthetic blend of volatile compounds released by this fruit affects the sexual performance of wild and laboratory flies. By means of bioassays and pheromone collection we investigated the mechanism underlying this phenomenon. RESULTS: Guava volatile exposure enhanced male mating success and positively affected male calling behavior and pheromone release in laboratory and wild males. Changes in male behavior appear to be particularly important during the initial phase of the sexual activity period, when most of the mating pairs are formed. Exposure of laboratory males to a subset of guava fruit volatiles enhanced mating success, showing that the response to the fruit might be mimicked artificially. CONCLUSIONS: Volatiles of guava seem to influence male mating success through an enhancement of chemical and physical signals related to the communication between sexes. This finding has important implications for the management of this pest species through the Sterile Insect Technique. We discuss the possibility of using artificial blends to improve the sexual competitiveness of sterile males.

Gas exchange, antioxidants and foliar injuries in saplings of a tropical woody species exposed to ozone.

Ozone (O(3)) reaches phytotoxical concentrations in the tropics, but the sensitivity of tropical plant species to O(3) remains unknown. Visible foliar injuries, carbon assimilation (A(sat)), stomatal conductance, superoxide dismutase enzyme (SOD) activity and ascorbic acid concentration (AA) were evaluated in different-aged leaves of Psidium guajava 'Paluma' saplings. We hypothesized that the old leaves are less capable of combating the stress induced by O(3) and hence exhibit more severe leaf injuries. Three O(3) exposure experiments were performed with 'Paluma' saplings in sites with high O(3) concentration and also under filtered air conditions. The exposure experiments corresponding to the seasons spring/2006, summer and autumn/2007. The decrease of A(sat) was greater in old leaves of saplings exposed to O(3), except in the second experiment, when the AA concentrations were more pronounced than in the other experiments. In second experiment, O(3) uptake was similar to that of the first experiment, but the injuries were less severe, probably due to the high AA concentrations. It was not possible to identify a pattern of superoxide dismutase enzyme (SOD) activity due to the high variability in the results from O(3) exposed and reference saplings. O(3) uptake/A(sat) was higher in leaves exhibiting greater injury, suggesting that decrease in A(sat) may have been the main feature associated with the visible foliar symptons.

Psidium guajava as a bioaccumulator of nickel around an oil refinery, southern Brazil.

To evaluate the potential of Psidium guajava as a biological accumulator of air pollutants, saplings were exposed at nine sites receiving atmospheric emissions from an oil refinery (five within, four outside the industrial area) and another reference site located at the Federal University of Rio Grande do Sul, 27 km from the refinery. Exposures lasted about 3 months each, coincided with the seasons, and totaled five exposures between 2005 and 2006. The following parameters were evaluated: dry weight of leaves, stems, and roots, leaf area, rate of relative height increase, Ni and S contents, maximum assimilation rate, and carboxylation efficiency invivo. P. guajava was found to be an efficient accumulator of Ni, since highly significant differences were observed (P<0.001) between sites within the industrial area and the reference site for all periods of exposure and a significant negative correlation between distance from emission source and Ni content. The S content showed significant differences (P<0.05) only at sites within the industrial area for two exposures. The dry weight, leaf area, rate of relative height increase, maximum assimilation rate, and carboxylation efficiency did not present significant differences for any period of exposure. In view of the above, we conclude that P. guajava is a good bioaccumulator for Ni.

Anthocyanins and tannins in ozone-fumigated guava trees.

Psidium guajava "Paluma", a tropical tree species, is known to be an efficient ozone indicator in tropical countries. When exposed to ozone, this species displays a characteristic leaf injury identified by inter-veinal red stippling on adaxial leaf surfaces. Following 30 days of three ozone treatments consisting of carbon filtered air (CF - AOT40=17 ppb h), ambient non-filtered air (NF - AOT40=542 ppb h) and ambient non-filtered air+40 ppb ozone (NF+O(3) - AOT40=7802 ppb h), the amounts of residual anthocyanins and tannins present in 10 P. guajava ("Paluma") saplings were quantified. Higher amounts of anthocyanins were found in the NF+O(3) treatment (1.6%) when compared to the CF (0.97%) and NF (1.30%) (p<0.05), and of total tannins in the NF+O(3) treatment (0.16%) compared to the CF (0.14%). Condensed tannins showed the same tendency as enhanced amounts. Regression analyses using amounts of tannins and anthocyanins, AOT40 and the leaf injury index (LII), showed a correlation between the leaf injury index and quantities of anthocyanins and total tannins. These results are in accordance with the association between the incidence of red-stippled leaves and ozone polluted environments.

Guava seed as an adsorbent and as a precursor of carbon for the adsorption of acid dyes.

The guava seed (SEGUVE) was characterized by ultimate and proximate analysis. In SEGUVE the principal thermal effect occurred at 363 degrees C and this can be attributed to the cellulose degradation, which was the main component ( approximately 61%). The guava seed has an acidic character with a high content of bulk functional groups (CO) and these characteristics were affected by carbonization. Two samples of carbon were prepared from the seeds at 600 and 1000 degrees C without chemical activation. Adsorption of eight acid dyes belonging to the monoazo and anthraquinone class was studied at 25 degrees C. The non-carbonized SEGUVE adsorbed the acid dyes more efficiently than SEGUVE-C600 and SEGUVE-C1000 although the specific surface of the raw material SEGUVE was low.

Effects of initial climatic conditions on growth and accumulation of fluoride and nitrogen in leaves of two tropical tree species exposed to industrial air pollution.

Saplings of Tibouchina pulchra and Psidium guajava, cultivated under standardized soil conditions, were placed in two sites at Cubatão (state of São Paulo, southeast Brazil) to study the effects of air pollution on growth, biomass allocation and foliar nitrogen and fluoride concentrations. Thirty-six potted plants were maintained over two periods of one year (Jul/00 to Jun/01; Dec/00 to Nov/01) at each of two experimental sites with distinct levels of air pollution: Pilões River Valley (PV) with vegetation virtually unaffected by air pollution; and Mogi River Valley (MV) severely affected by pollutants released mainly by chemical, fertilizer, iron and steel industries. For both species, saplings growing at MV showed alterations of growth and biomass allocation, as well as increased leaf concentrations of nitrogen and fluoride. Comparing both experimental periods, the one starting in winter (the driest season in Southeastern Brazil) seemed to affect the saplings more severely, the differences of the measured parameters between MV and PV being higher than in the second period. Multivariate analysis revealed two groups of data: one representing the MV and the other the PV saplings. For both species, saplings growing at MV showed differences in chemical composition, growth and biomass allocation, compared with the PV saplings. The results suggested that seasonal conditions of the first months of sapling exposure (summer or winter) modulate the intensity of responses to pollution stress.

Methyl jasmonate treatments reduce chilling injury and activate the defense response of guava fruits.

Tropical fruits cannot be stored at low temperatures due to the chilling injury phenomena. With the goal of reducing the chilling injury, we tested 10(-4) and 10(-5) M of methyl jasmonate (MJ) treatment before the storage of red and white cultivars of guava fruits at 5 degrees C for up to 15 days plus two days at 20 degrees C. Every five days, we evaluated chilling injury index, ion leakage percentage, vitamin C, sugars, total phenols, and the activity of the enzymes lipoxygenase (LOX) and phenylalanine-ammonia lyase (PAL). We found that methyl jasmonate treatments reduce the chilling injury index and the ion leakage percentage. Furthermore, MJ did not affect vitamin C, chlorophyll, and total phenols. MJ increased sugar content, PAL, and LOX activities. We concluded that MJ reduces chilling injury and activates the fruit defense response as indicated by the behavior of total phenols and the increase in sugar content, PAL, and LOX activities.