First repot of Chaetomium globosum causing leaf spot on Averrhoa carambola in India.

The Star fruit (Averrhoa carambola L.) was globally distributed, particularly in countries like China, India, Indonesia and was renowned for its abundant vitamin, mineral and antioxidant content (Reddy et al., 2023). In early February 2023, leaf spot symptoms were observed on A. carambola at 2 hectare model orchard, College farm, Agricultural College, Aswaraopet (17.252038 latitude, 81.109574 longitude) and Horticulture nurseries of Aswaraopet, Bhadradri Kothagudem (Dist), Telangana, India. In the surveyed fields (February-2023 to February 2024), the disease was prevalent year round, with varying incidence i.e., July to February (35% to 40% with a yield loss of 35%) and from March to June (20% to 30% with a yield loss of 20%). The disease was initiated as small reddish spots, which grew over 8-10 days to 1-5 mm spots with a necrotic center, dark reddish brown margin and a prominent yellow halo around them, within 17 to 20 days, all spots coalesced, resulting in leaf yellowing and defoliation (SF 1). To isolate pathogen, diseased leaf tissues (n=20) (5 × 5 mm) were surface sterilized (70% alcohol (30 s), 1% sodium hypochlorite (30 s) and sterile distilled water (3 × 60 s), inoculated to PDA media and incubated at 26 ± 2°C with 12 hours photoperiod for 72 hours (Chi et al. 2022). The emerging hyphae from the diseased tissues were sub cultured and incubated on PDA at 26 ± 2 °C. Initially, the fungal colonies appeared white, later transitioning to light brown and finally developed into olivaceous grey colour (SF 2A). The ascospores (n=20) were lemon shaped, pointed at both ends, with a length of 10.3 µm (9.1 to 12.1 µm) and width of 8.6 µm (7.2 to 10.2 µm) (SF 2B and 2C). For further identification of the pathogen, four fungal isolates were cultured in potato dextrose broth and genomic DNA was extracted using the CTAB method. Identification of the pathogen was confirmed through amplification and sequencing the Internal Transcribed Spacer region (ITS), Translation Elongation Factor 1-α (TEF1) and RNA polymerase subunit (RPB1) genes. The resulting sequences were deposited in Gen Bank with accession numbers (OR337915, OR337916, OR337893 and OR337892 for ITS, OR669280, OR669281, OR669282, and OR669283 for TEF, and PP092153, PP092154, PP092155 and PP092156 for RPB1). To study pathogenicity of fungus, five isolates of C. globosum were isolated from five A. carambola plants, grown in potato dextrose broth. Spore suspension of 1x106 spores/mL were prepared by adjusting with hemacytometer and were sprayed onto the leaves of healthy, surface sterilized (50% ethanol), 3 months old A. carambola plants and incubated in greenhouse (T: 26°C; RH: 80%). For each of the five isolates, the spore suspension from each individual isolate was inoculated into three plants and three control plants were maintained for each isolate. The experiment was replicated thrice. After a period of 10 to 12 days, symptoms appeared on the inoculated leaves in the form of reddish spots, similar to original symptoms (Alam et al. 2021) (SF 1H). The fungus isolated from the inoculated leaves was morphologically similarities to C. globosum. Notably, C. globosum, a widespread leaf spot pathogen in crops like A. hypogaea, C. sativa and Pomegranate (Chaffin et al. 2020). To our knowledge, this is the first report of A. carambola leaf spot caused by C. globosum in India and worldwide. The result will be helpful for providing a basis for further research on the control of the disease.

Spatio-temporal Distribution of Bactrocera carambolae with and without Irrigation using CLIMEX Modeling.

The carambola fruit fly Bactrocera carambolae Drew and Hancock (Diptera: Tephritidae) is an invasive fruit fly reported in North Brazil that threatens Brazilian fruit culture. Assessing the potential risk of establishing this pest is necessary to reduce the threat of B. carambolae dispersion to other countries and Brazilian regions and to avoid damage to the fruit trade. In this study, the CLIMEX model was used to understand the response of B. carambolae to climate change and to determine its potential global distribution with and without irrigation practices. Based on ecophysiological parameters, the model simulates factors limiting species distribution concerning the climate. To assess the seasonal variation in the density of B. carambolae, monitoring data in Uiramutã municipality, Roraima, from 2013 to 2019 was used. According to the CLIMEX forecast, large parts of America, Africa, and Asia, mainly in areas closest to the equator, are highly suitable for the survival of B. carambolae. Brazil is a good part of its territory with high suitability for B. carambolae, especially the North, South, and Southeast regions and the entire coastal area. The periods of the highest climatic suitability in the five Brazilian regions were January-May and October-December. The potential distribution area expands under irrigation and is highly suitable for most areas without cold stress. The CLIMEX model for B. carambolae generated in the present study provides important information for the Brazilian eradication program and other surveillance activities established in pest-free areas.

First report of Cephalerous virescens causing Algal leaf spot of Averrhoa carambola in India.

Averrhoa carambola (Star fruit) is a drought resistant edible fruit belongs to family Oxalidaceae. It is native of Malaysia and further cultivation is extended to China, Southeast Asia, India and Northern South America. Star fruit has juicy texture and used in salads, beverages and traditionally it has been used for ayurvedic medicines in India, Brazil and China (Abduh et al. 2023). In early January 2023, we observed the symptoms of raised, more or less circular, orange to dark brown, velvet textured, scattered algal leaf spots (1-4 mm) on the upper surface of A. carambola leaves at College farm, Agricultural College, Aswaraopet (17.252039 latitude, 81.109573 longitude) (Supplementary Fig 1). The disease was observed in 2 hectare model orchard with incidence of 45% causing leaf defoliation and thereby reducing the yield and quality of fruits. Transverse section cutting of algal spots revealed the algal thalli at subcuticular region and causing necrosis of epidermal cells. Sporangiophores (n=20) raised from algal leaf spot were cylindrical, 4 to 5 celled, 200-450 µm long x 8-20 µm wide, and forming a head cell with suffultory cells and sporangia on the top. Sporangia (n=20) were spherical to elliptical, rusty brown and 17.5-29 µm long × 18-23.6 µm wide and the total number of sporangia produced by each sporangiophores varies from 1 to 6. Setae (n=20) were filamentous with three to six celled, 17.5-50 µm long × 2.5-7.5 µm wide (Supplementary Figure 2). In our collection, mature gametangia were not observed. Morphological characters were studied on 20 diseased leaf samples collected from randomly selected five plants. To isolate pathogen, fresh algal thalli (n=5) were scraped from host tissue, surface sterilized (70% alcohol (30 s), 1% sodium hypochlorite (30 s) and sterile distilled water (3 × 60 s), inoculated to trebouxia liquid media and incubated at 25 ± 2 °C with a 12 hours photoperiod for 72 hours (Vasconcelos et al. 2018). The resultant five algal filaments were subjected to PCR amplification. The primer pair PNS1/NS41 was used in a PCR to amplify a fragment of 18S rRNA (Davis and Kaur 2019). The 18S rRNA gene sequences of the algae were compared using the Basic Local Alignment Search Tool (BLAST; http://www.ncbi.nlm.nih.gov/Blast/Blast.cgi) showed that our partial sequence had 99.5% similarity to C. virescens (KM020142.1). Hence, it was classified as C. virescens and sequences was deposited in NCBI-GenBank with accession numbers (OR053653, OR243777, OR429406, OR429407 and OR243779). For proving pathogenicity, algal filaments obtained from trebouxia liquid media were inoculated to 6 months old healthy A. carambola plant. Pathogenicity test was negative and typical symptoms could not be produced even up to 150 days of inoculation. In previous studies also, due to difficulty with production of zoospores in synthetic media, Koch's postulates of C. virescens as a plant pathogen has not been demonstrated experimentally (Sunpapao et al. 2017; Sanahuja et al. 2018; Kumar et al. 2019). In the second experiment, zoosporangia spore suspension were prepared from small pieces of algal leaf spot tissue processed in a sterile pestle and mortar and filtered through sterile cheesecloth (Sunpapao et al. 2017). A total of five isolates of zoosporangia spore suspension (1 x 102 to 1 x 104/ml of water) was sprayed on healthy, surface sterilized leaves of A. carambola plants (n=5) until runoff with a handheld airpump sprayer and incubated in green house (T: 25 oC, H: 80%). During the experiment leaves were remain attached to plant (5 days old) and plants were 6 months old grown in plastic pots under controlled conditions. Two plants were inoculated with each isolate and three non inoculated control plants were included. Non inoculated controls were sprayed with sterile distilled water. The pathogenicity experiment was repeated. The initial symptoms were produced 60 days after inoculation and complete algal thalli was observed on 90 days after inoculation, control plants were without any symptoms upto 150 days. Reisolated algal thalli from symptomatic plants were morphologically similar to original algal thalli and molecularly identified as C. virescens (accession number OR067193 and OR243810). Red rust caused by C. virescens is a major algal disease in the world and causing severe leaf defoliation in various horticultural crops viz., Mangifera indica (Vasconcelos et al. 2018), Manilkara zapota (Sunpapao et al. 2017), Psidium guajava (Rajbongshi et al. 2022), Ziziphus mauritiana (Shareefa et al. 2022) and Anacardium occidentale (Dooh et al. 2022). The available literature suggest that, this is the first report of algal leaf spot on A. carambola caused by C. virescens in India. This report extends the range of known pathogens associated with A. carambola plant and serves as a basis for development and implementing disease management strategies.

Averrhoa carambola L. fruit and stem metabolites profiling and immunostimulatory action mechanisms against cyclosporine induced toxic effects in rat model as analyzed using UHPLC/MS-MS-based chemometrics and bioassays.

The Averrhoa carambola L. tree encompasses a myriad of phytochemicals contributing to its nutritional and health benefits. The current study aims at investigating the A. carambola L. the metabolite profile grown in tropical and temperate regions represented by fruit and stem, for the first time using UPLC/MS-based molecular networking and chemometrics. Asides, assessment of the immunostimulatory effect of ripe fruit and stem, was compared in relation to metabolite fingerprints. Eighty metabolites were identified, 8 of which are first-time to be reported including 3 dihydrochalcone-C-glycosides, 4 flavonoids, and one phenolic. Multivariate data analysis revealed dihydrochalcones as origin-discriminating metabolites between temperate and tropical grown fruits. Further, an in vivo immunomodulatory assay in a cyclosporine A-induced rat model revealed a potential immune-enhancing effect as manifested by down-regulation of inflammatory markers (IL-6, INF-γ, IL-1, TLR4, and ESR) concurrent with the up-regulation of CD4 level and the CD4/CD8 ratio. Moreover, both extracts suppressed elevation of liver and kidney functions in serum as well as reduction in oxidative stress with concurrent increased levels of T-protein, albumin, globulin, and A/G ratio. This study pinpoints differences in secondary metabolite profiles amongst A. carambola L. accessions from different origins and organ type and its immunomodulatory action mechanisms.

Integration of Volatilomics and Metabolomics Unveils Key Flavor-Related Biological Pathways in Different Carambola Cultivars.

Carambola is a tropical fruit that is highly sought after by consumers due to its unique flavor, star shape, and nutritional value. Enhancing the flavor quality of this fruit can increase the consumer acceptance and market demand. However, flavor is an intrinsic characteristic of fruits. Its decoding requires in-depth knowledge based on recognizing key biological pathways relevant to flavor formation and development. In this study, the volatile and non-volatile metabolites contributing to the flavor variation of five carambola cultivars were investigated by a novel strategy combining GC-MS/O-based volatilomics with LC-MS-based metabolomics. Several significant flavor-related pathways, involving biosynthesis or metabolism of amino acids, terpenoids, fatty acids, sugar and organic acid, and flavonoids were identified based on the enrichment analysis of important volatile and non-volatile metabolites. The results indicated that there were metabolites in the flavor-related pathways being up- or downregulated, leading to the differences in flavor traits of different carambola cultivars. This study could provide a valuable reference for breeders and researchers of interest in the mechanisms underlying the regulation of flavor, which would ultimately lead to the creation of carambola cultivars with more attractive flavor profiles and pleasurable consuming experiences.

Averrhoa carambola L. fruit polyphenols ameliorate hyperlipidemia, hepatic steatosis, and hyperglycemia by modulating lipid and glucose metabolism in mice with obesity.

BACKGROUND: Hyperlipidemia, hepatic steatosis, and hyperglycemia are common metabolic complications of obesity. The objective of the present study is to investigate the in vivo protective effect of Averrhoa carambola L. fruit polyphenols (ACFP) on hyperlipidemia, hepatic steatosis, and hyperglycemia in mice with high-fat diet (HFD)-induced obesity and elucidate the mechanisms of action underlying the beneficial effects of ACFP. Thirty-six specific pathogen-free male C57BL/6J mice (4 weeks old, weighing 17.1-19.9 g) were randomly divided into three groups and fed with a low-fat diet (LFD, 10% fat energy), HFD (45% fat energy), or HFD supplemented with ACFP by intragastric administration for 14 weeks. Obesity-related biochemical indexes and hepatic gene expression levels were determined. The statistical analyses were conducted using one-way analysis of variance (ANOVA) followed by Duncan's multiple range test. RESULTS: The results showed that the body weight gain, serum triglycerides, total cholesterol, glucose, insulin resistance index, and steatosis grade in the ACFP group decreased by 29.57%, 26.25%, 27.4%, 19.6%, 40.32%, and 40%, respectively, compared to the HFD group. Gene expression analysis indicated that ACFP treatment improved the gene expression profiles involved in lipid and glucose metabolism compared to the HFD group. CONCLUSION: ACFP protected from HFD-induced obesity and obesity-associated hyperlipidemia, hepatic steatosis, and hyperglycemia by improving lipid and glucose metabolism in mice. © 2023 Society of Chemical Industry.

Effect of Na and Al doping on ZnO nanoparticles for potential application in sunscreens.

This study investigated the environment-friendly production and characterization of zinc oxide nanoparticles (ZnO NPs) doped with sodium (Na) and aluminum (Al) metals to decrease the photocatalytic activity of ZnO for use in sunscreen. The metal-doped zinc oxide (ZnO) materials were prepared by the microwave method using extracts of Averrhoa carambola, also known as star fruit, as a reducing agent. The effects of metal-ion doping on the crystal structure, morphology, and optical characteristics of ZnO were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM), and ultraviolet-visible (UV-Vis) spectroscopy. The sun protection factor (SPF) of the sunscreen formulations containing undoped ZnO, Na-doped ZnO (Na/ZnO), and Al-doped ZnO (Al/ZnO) NPs were found to be 10.10, 25.10, and 43.08, respectively. Therefore, Na/ZnO and Al/ZnO showed increased SPF. Additionally, the prepared nanomaterials and sunscreens were effective against Gram-positive and Gram-negative bacteria and showed antioxidant activities. The methylene blue (MB) degradation was used to evaluate the photocatalytic activities of the undoped ZnO, Na/ZnO, and Al/ZnO NPs, which were found to be 66%, 46%, and 38%, respectively. Therefore, due to the structural defects of ZnO NPs, their photocatalytic activity was decreased with Na- and Al- doping. Additionally, Al/ZnO is an ideal candidate as an ingredient in sunscreens.

Slightly acidic electrolyzed water treatment improves the quality and storage properties of carambola fruit.

This study aimed to explore the impacts of slightly acidic electrolyzed water (SAEW) treatment on the physiology, quality, and storage properties of postharvest carambola. The carambolas were immersed in SAEW with a pH value of 6.0, ORP of 1340 mV and ACC of 80 mg/L. Results demonstrated that SAEW could significantly reduce the respiration rate, inhibit the increase in cell membrane permeability, and delay apparent color change. Relatively higher contents of bioactive compounds and nutritional components, such as flavonoids, polyphenols, reducing sugars, sucrose, vitamin C, total soluble sugar, and total soluble solid, as well as higher titratable acidity were maintained in SAEW-treated carambola. In addition, SAEW-treated carambola exhibited a higher commercial acceptability rate and a higher firmness, but lower weight loss and peel browning index than control fruits. Our results indicated that SAEW treatment achieved high fruit quality and nutritional values, potentially contributing to improve storage properties of harvested carambola.

Post-harvest Anthracnose of Carambola (Averrhoa carambola) Caused by Colletotrichum fructicola in China.

Carambola (star fruit), a popular fruit of Averrhoa carambola in many parts of the world, is considered to have many beneficial nutritional and medicinal effects (Lakmal, K., et al,2021). In March 2020, anthracnose disease was observed on carambola (about 15% of the fruit showed similar symptoms) in multiple local agricultural markets (113°36'E, 23°11'N) of the Yuancun district in Guangzhou, China. Initial symptoms of infected fruit samples appeared as water-soaked, brown lesions. As the disease progressed, numerous acervuli appeared on fruit surfaces. Salmon-colored spore masses were observed on some fruit. To isolate and identify the pathogen, small pieces (3-5 mm2) were excised from the lesion margins of the fruit, which were surface disinfested by 1% NaOCl (60 s), 70% ethanol (30 s) and then washed twice with sterile distilled water. After surface disinfestation, the tissues were cultured on potato dextrose agar (PDA). Pure cultures were obtained by transferring hyphal tips onto fresh PDA. Fungal isolates (YT-5/6/9) were obtained and the strain YT-5 was selected for further study. The colony of strain YT-5 grown on PDA for 7 days appeared to be cottony, white to pale gray with the presence of multiple masses of conidia. Conidia 13.5-20 × 4.8-6.5 µm (n = 50), hyaline, aseptate, straight and cylindrical with rounded ends. Perithecia were thick-walled and globose with a prominent, narrow neck. Asci 37.1-60.2 × 7.1-11.3 µm (n = 25), 4-8 spored, clavate to cymbiform. Ascospores 7.1-17.2 × 4.5-6.5 µm (n = 35), hyaline, large guttulate at the center, slightly curved with rounded ends. Based on the morphological characteristics, the strain was identified as Colletotrichum fructicola (Prihastuti et al. 2009). The molecular identity of the isolates was confirmed by sequencing the internal transcribed spacer (ITS) rDNA region, chitin synthase (CHS-1), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-tubulin (TUB2) genes (Prihastuti et al. 2009, Weir et al. 2012). BLASTN analysis of isolate YT-5 sequences, which were deposited in GenBank (ON428449, ON462353, ON886225, ON886224, ON462354) showed 100% identity with those of Colletotrichum fructicola (MW513778.1, MT918417.1, MW426526.1, MN525875.1, MT941526.1), respectively. A phylogenetic tree analysis based on the concatenated sequences confirmed the isolate YT-5 as C. fructicola. Pathogenicity tests were conducted on fresh fruit of carambola with the isolate YT-5. Healthy fruit was surface disinfested and inoculated with 5 mm mycelial discs of the strain YT-5 after being wounded with a needle or unwounded. Control fruit was inoculated with sterilized PDA plugs. All inoculated fruit was incubated at 26°C for 10 days post inoculation. Control fruit remained asymptomatic, whereas inoculated fruit developed symptomatic at the point of inoculation. The pathogenicity test was performed in duplicate. The pathogenic isolate of C. fructicola was successfully re-isolated on PDA from the symptomatic fruit, thus confirming Koch's postulates. C. fructicola has also been reported as a dominant and aggressive causal agent of anthracnose on sandy pear and avocado in China (Zhang et al. 2015; Li et al. 2022). To our knowledge, this is the first study to isolate and characterize C. fructicola causing carambola anthracnose and evaluate its pathogenicity in China, which will provide a better strategy for accurate diagnosis and effective management of anthracnose disease on carambola. References: Lakmal, K., et al. 2021. Food Sci Nutr 9.3. Prihastuti, H., et al. 2009. Fungal Divers. 39:89. Weir, B. S., et al. 2012. Stud Mycol. 73:115-180. Zhang P.F., et al. 2015. Eur J Plant Pathol.143:651-662. Li S.N., et al. 2022. Plant Dis. The authors declare no conflict of interest. Keywords: Anthracnose, Colletotrichum fructicola, carambola, China.

Anti-Obesity Evaluation of Averrhoa carambola L. Leaves and Assessment of Its Polyphenols as Potential α-Glucosidase Inhibitors.

Averrhoa carambola L. is reported for its anti-obese and anti-diabetic activities. The present study aimed to investigate its aqueous methanol leaf extract (CLL) in vivo anti-obese activity along with the isolation and identification of bioactive compounds and their in vitro α-glucosidase inhibition assessment. CLL improved all obesity complications and exhibited significant activity in an obese rat model. Fourteen compounds, including four flavone glycosides (1-4) and ten dihydrochalcone glycosides (5-12), were isolated and identified using spectroscopic techniques. New compounds identified in planta included (1) apigenin 6-C-(2-deoxy-ß-D-galactopyranoside)-7-O-ß-D-quinovopyranoside, (8) phloretin 3'-C-(2-O-(E)-cinnamoyl-3-O-ß-D-fucopyranosyl-4-O-acetyl)-ß-D-fucopyranosyl-6'-O-ß-D fucopyranosyl-(1/2)-α-L arabinofuranoside, (11a) phloretin3'-C-(2-O-(E)-p-coumaroyl-3-O-ß-D-fucosyl-4-O-acetyl)-ß-D-fucosyl-6'-O-(2-O-ß-D-fucosyl)-α-L-arabinofuranoside, (11b) phloretin3'-C-(2-O-(Z)-p-coumaroyl-3-O-ß-D-fucosyl-4-O-acetyl)-ß-D-fucosyl-6'-O-(2-O-ß-D-fucosyl)-α-L-arabinofuranoside. Carambolaside M (5), carambolaside Ia (6), carambolaside J (7), carambolaside I (9), carambolaside P (10a), carambolaside O (10b), and carambolaside Q (12), which are reported for the first time from A. carambola L. leaves, whereas luteolin 6-C-α-L-rhamnopyranosyl-(1-2)-ß-D-fucopyranoside (2), apigenin 6-C-ß-D-galactopyranoside (3), and apigenin 6-C-α-L-rhamnopyranosyl-(1-2)-ß-L-fucopyranoside (4) are isolated for the first time from Family. Oxalidaceae. In vitro α-glucosidase inhibitory activity revealed the potential efficacy of flavone glycosides, viz., 1, 2, 3, and 4 as antidiabetic agents. In contrast, dihydrochalcone glycosides (5-11) showed weak activity, except for compound 12, which showed relatively strong activity.

Genome-wide identification and expression profile of YABBY genes in Averrhoa carambola.

BACKGROUND: Members of the plant-specific YABBY gene family are thought to play an important role in the development of leaf, flower, and fruit. The YABBY genes have been characterized and regarded as vital contributors to fruit development in Arabidopsis thaliana and tomato, in contrast to that in the important tropical economic fruit star fruit (Averrhoa carambola), even though its genome is available. METHODS: In the present study, a total of eight YABBY family genes (named from AcYABBY1 to AcYABBY8) were identified from the genome of star fruit, and their phylogenetic relationships, functional domains and motif compositions, physicochemical properties, chromosome locations, gene structures, protomer elements, collinear analysis, selective pressure, and expression profiles were further analyzed. RESULTS: Eight AcYABBY genes (AcYABBYs) were clustered into five clades and were distributed on five chromosomes, and all of them had undergone negative selection. Tandem and fragment duplications rather than WGD contributed to YABBY gene number in the star fruit. Expression profiles of AcYABBYs from different organs and developmental stages of fleshy fruit indicated that AcYABBY4 may play a specific role in regulating fruit size. These results emphasize the need for further studies on the functions of AcYABBYs in fruit development.

Alleviation of Postharvest Chilling Injury of Carambola Fruit by γ-aminobutyric Acid: Physiological, Biochemical, and Structural Characterization.

Chilling injury is a physiological disorder affecting the quality of carambola fruit. In the present study, the effect of exogenous γ-aminobutyric acid (GABA) on CI development in carambola fruit during storage at 4°C for 15 days was investigated. The results showed that 2.5-mM GABA reduced CI index, maintained pericarp lightness, and decreased the electrolyte leakage (EL) and malondialdehyde content (MDA) while increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activities. Endogenous GABA content was significantly higher in the treated fruit than in the control fruit during the whole storage. Besides, the treatment promoted the accumulation of proline and ascorbic acid (AsA) under chilling stress. Compared to the control, GABA-treated fruit exhibited a higher activity of phenylalanine ammonia-lyase (PAL) and total phenolic compounds, and a lower activity of polyphenol oxidase (PPO). In addition, the Safranin O/fast green staining revealed via microscopic images that the GABA treatment reduced the cell walls degradation of carambola fruit. Moreover, the results displayed a lower activity of phospholipase D (PLD) and lipoxygenase (LOX) enzymes, which coincided with a higher content of oleic acid (C18:1), linoleic acid (C18:2n6), and α-linolenic acid (C18:3n3) after 15 days of treatment, leading to the maintenance of the integrity and prevention of the membrane of the rapid softening of carambola fruit. The findings of the present work showed particularly new insights into the crosstalk between GABA and fatty acids. GABA might preserve the pericarp of carambola fruit by increasing the content of the unsaturated fatty acid (UFA) γ-linolenic acid and reducing the saturated fatty acid (SFA) such as caproic acid (C6:0), caprylic acid (C8:0), myristic acid (C14:0), and palmitic acid (C16:0) progressively. GABA can be used as an appropriate postharvest technology for improving the quality of carambola fruit during low-temperature storage.

Traditional Uses, Phytochemical Constituents and Pharmacological Properties of Averrhoa carambola L.: A Review.

Averrhoa carambola L. (star fruit) is an edible fruit that is extensively cultivated in southern China, Southeast Asia, India, and northern South America. It has a sweet and juicy taste and is frequently used in fruit salads and fruit platters, as a garnish in cocktail drinks and beverages, or squeezed into juice and served as a beverage. Traditionally, it has been used for treating diabetes and diabetic nephropathy, arthralgia, vomiting, lithangiuria, coughing, hangovers, and chronic paroxysmal headache for thousands of years. Currently, approximately 132 compounds have been isolated from A. carambola. Among them, flavonoids, benzoquinone, and their glycosides have been considered as biologically active substances, which are responsible for various biological activities. Pharmacological studies have revealed that crude extracts or monomeric compounds from A. carambola exhibit multiple bioactivities, such as anti-oxidant, anti-hyperglycemic, anti-obesity, anti-hyperlipidemic, anti-tumor, anti-inflammatory, hepatoprotective, cardioprotective, anti-hypertensive, neuroprotective, and others. Thus, A. carambola is a valuable treatment in Chinese medicine with therapeutic potential for multiple diseases, especially diabetes and diabetes-related diseases. Even though it is a very promising candidate in the development of functional food and the pharmaceutical industry, reports on its bioactivities have only been conducted in vivo and in vitro and there is a gap in research regarding clinical settings and safety. This review therefore provides a comprehensive and systematic overview of current progress on botany, ethnopharmacology, phytochemistry, pharmacology, and toxicity of A. carambola, providing a valuable reference for further developments and applications of A. carambola in the pharmaceutical industry and functional food.

Phytochemical characterization, antioxidant potential and antimicrobial activity of Averrhoa carambola L. (Oxalidaceae) against multiresistant pathogens / Caracterização fitoquímica, potencial antioxidante e atividade antimicrobiana de Averrhoa carambola L. (Oxalidaceae) frente a patógenos multirresistentes

Abstract The objective of this work was to perform the phytochemical characterization, to determine total phenols, antioxidant (AAO%) and antimicrobial potential of the ethanolic extracts of carambola. The phytochemical study was carried out through a qualitative analysis of the chemical constituents and quantitative determination of the phenol content By the Folin-Ciocalteu test. Qualitative and quantitative antioxidant tests were performed using the DPPH method (2,2 diphenyl-1-picryl-hydrazila) and iron reduction (FRAP). The minimum inhibitory concentration (MIC) was determined by microdilution in 96-well plates. The presence of pyrogallic tannins, steroids and saponins has been identified. The highest total phenol content, quantified in the samples, was found in the stem bark (0.0866 mgEAG/g) and in the fruit (0.0734 mgEAG/g). In the antioxidant evaluation, the extracts of the green fruit bagasse (AAO% 71.9%,) and stem bark at 50 μg/mL (AAO% 94%) with CE50 23.7 μg/mL. Leaf extracts, stem bark, ripe fruit bagasse and green fruit bagasse presented MICs of 100 μg/mL against multiresistant pathogenic bacteria and fungi.

Resumo O objetivo desse trabalho foi realizar a caracterização fitoquímica, determinar fenóis totais, potencial antioxidante (AAO%) e antimicrobiano dos extratos etanólicos de carambola O estudo fitoquímico foi realizado por meio de análise qualitativa dos constituintes químicos e determinação quantitativa do teor de fenóis totais pelo teste de Folin-Ciocalteu. Os testes antioxidantes qualitativos e quantitativos foram realizados pelo método do DPPH (2,2 difenil-1- picril-hidrazila) e redução do ferro (FRAP). A concentração inibitória mínima (CIM) foi determinada por microdiluição em placas de 96 poços. Foi identificada a presença de taninos pirogálicos, esteroides e saponinas. O maior teor de fenóis totais, quantificado nas amostras, foi encontrado na casca do caule (0,0866 mg EAG/g) e no fruto (0,0734 mg EAG/g). Na avaliação antioxidante destacaram-se a 500 µg/mL os extratos do bagaço do fruto verde (AAO% 71,9%,), e casca do caule a 50 µg/mL (AAO% 94%) com CE50 23,7 µg/mL. Os extratos das folhas, casca do caule, bagaço do fruto maduro e bagaço do fruto verde apresentaram CIM de 100 µg/mL contra bactérias e fungos patogênicos multirresistentes.

Exogenous 2,4-Epibrassinolide Treatment Maintains the Quality of Carambola Fruit Associated With Enhanced Antioxidant Capacity and Alternative Respiratory Metabolism.

Brassinosteroids act by delaying fruit ripening. The effects of different concentrations of 2,4-epibrassinolide (eBL) treatments on carambola fruit ripening were investigated. The results show that treatment of 2.8 mg L-1, eBL with 10 min effectively delays ripening and maintains the quality of carambola fruit. This is achieved by retarding color changes and firmness losses while maintaining high level of soluble protein content and vitamin C, and low organic acid content. eBL-delayed senescence may be due to the inhibition of respiration rate and enhanced antioxidant system. It is noteworthy that eBL treatment markedly reduces the content of fructose-6-phosphate (6-P-F) and enhances the activity of cytochrome oxidase (CCO), and the total activity of glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphate gluconate dehydrogenase (6-PGDH). eBL treatment induces the IAA and GA contents but reduces that of ABA. In general, senescence retardation and quality improvement by eBL treatment may be due to the enhanced antioxidant capacity and altered respiratory pathways.

Identification and functional analysis of SWEET gene family in Averrhoa carambola L. fruits during ripening.

Sugar Will Eventually be Exported Transporters (SWEETs), a type of sugar efflux transporters, have been extensively researched upon due to their role in phloem loading for distant sugar transport, fruit development, and stress regulation, etc. Several plant species are known to possess the SWEET genes; however, little is known about their presence in Averrhoa Carambola L. (Oxalidaceae), an evergreen fruit crop (star fruit) in tropical and subtropical regions of Southeast Asia. In this study, we established an Averrhoa Carambola L. unigenes library from fruits of 'XianMiyangtao' (XM) by RNA sequencing (RNA-seq). A total of 99,319 unigenes, each longer than 200 bp with a total length was 72.00 Mb, were identified. A total of 51,642 unigenes (52.00%) were annotated. Additionally, 10 AcSWEET genes from the Averrhoa Carambola L. unigenes library were identified and classified, followed by a comprehensive analysis of their structures and conserved motif compositions, and evolutionary relationships. Moreover, the expression patterns of AcSWEETs in 'XM' cultivars during fruit ripening were confirmed using quantitative real-time PCR (qRT-PCR), combined with the soluble sugar and titratable acids content during ripening, showed that AcSWEET2a/2b and AcSWEET16b might participate in sugar transport during fruit ripening. This work presents a general profile of the AcSWEET gene family in Averrhoa Carambola L., which can be used to perform further studies on elucidating the functional roles of AcSWEET genes.

Nutritional and medicinal properties of Star fruit (Averrhoa carambola): A review.

Star fruit (Averrhoa carambola), a popular fruit in many parts of the world, is considered to have many beneficial nutritional and medicinal effects. However, harmful nephrotoxic and neurotoxic effects have also been described. In this review, we have discussed the reported beneficial effects of star fruit, explored the potential mechanisms for such beneficial effects, and outline factors that may affect the safe level of consumption. The beneficial effects include the following: antioxidant (mediated via L-ascorbic acid, epicatechin, and gallic acid), hypoglycemic (mediated via high fiber levels and 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione), hypotensive (mediated via apigenin), hypocholesterolemic (mediated via micronized fiber), anti-inflammatory, anti-infective, antitumor effects, and immune-boosting effects. The presence of chronic kidney disease, gastroenteropathies, chronic pancreatitis, dehydration, consumption on an empty stomach, and higher concentration of oxalate in fruit/juice consumed predisposes to toxicity. The level of ingestion at which the beneficial effects transition to nephrotoxicity and neurotoxicity is still to be accurately ascertained. Furthermore, the relationship between the amount of star fruit ingested and the severity of toxicity is not certain and warrants further study.

Nephrotoxicity and neurotoxicity following star fruit (Averrhoa carambola) ingestion: a narrative review.

In recent times, star fruit (Averrhoa carambola) nephrotoxicity and neurotoxicity have been increasingly reported, both in individuals with pre-existing renal disease and those with previously normal renal function. We summarise the clinical findings of star fruit toxicity in humans and outline the important pathogenetic insights provided by animal studies. Google Scholar, EMBASE, Scopus and PubMed were searched from 1995 through July 2020 for case reports/series on renal or neurological manifestations of star fruit toxicity in humans and mechanisms of star fruit toxicity in animal studies. Ten case series and 28 case reports in humans (total number of individuals=136) were included and 8 animal studies were analysed. Ninety-four (69.1%) patients had prior renal impairment. Renal histology showed acute oxalate nephropathy with tubulointerstitial nephritis or tubular necrosis. Neurotoxicity manifestations ranged from hiccups to status epilepticus. Oxalate and caramboxin are considered the main substances causing nephrotoxicity and neurotoxicity. Caramboxin inhibits GABA binding and activates the glutamatergic receptors. Haemodialysis improved outcomes in neurotoxicity. Nephrotoxicity and neurotoxicity need to be looked for with star fruit toxicity, both in individuals with abnormal or normal renal function. Once star fruit intoxication is identified, early renal replacement therapy should be considered. Further studies on the mechanisms of star fruit toxicity are needed.

Acute Kidney Injury Following Star Fruit Ingestion: A Case Series.

Star fruit (Averrhoa carambola) is a popular fruit in many tropical countries, including Sri Lanka. It is rich in oxalic acid, which is nephrotoxic in higher concentrations. The development of both acute (AKI) and chronic kidney injury after oxalate nephropathy is often underrecognized. Here we discuss the risk factors, clinical features, treatment, and outcomes of 4 patients who developed AKI after star fruit ingestion. Baseline clinical characteristics, the amount of star fruit ingested, clinical presentation, investigation, and outcome of the patients (ages 28, 50, 54, and 55 y; all male) were traced. More common symptoms of acute star fruit intoxication were nausea, vomiting, and abdominal and back pain, followed by low urine output and high serum creatinine over hours to days. Urinary analysis of all patients demonstrated oxalate crystals. Histopathologic examination of renal tissues of all 4 patients revealed acute tubular damage with calcium oxalate crystals, interstitial edema, and inflammatory cellular infiltration. The presence of calcium oxalate crystals was further confirmed with the brilliant birefringence seen under polarized light. Two patients needed intermittent hemodialysis over a week owing to oliguria and uremia. The other 2 patients did not require hemodialysis and had improvement of renal function with supportive treatment. All had high renal function on discharge but were back to normal within a month. This study highlights AKI as a serious complication of star fruit ingestion. The type and quantity of star fruit ingested and some patient factors may play a role in the pathogenesis of AKI. Public education about this serious uncommon complication is important.

Rapid Structure-Based Annotation and Profiling of Dihydrochalcones in Star Fruit (Averrhoa carambola) Using UHPLC/Q-Orbitrap-MS and Molecular Networking.

Dihydrochalcones are a subclass of flavonoids. There has been growing interest in dihydrochalcones for their health benefits and potential to modulate flavor, but their comprehensive profile in diverse plant species is lacking. Star fruit is a tropical fruit rich in dihydrochalcones. In this study, a systematic annotation using UHPLC/Q-Orbitrap-MS and molecular networking was established to rapidly identify dihydrochalcones in 12 star fruit cultivars. A total of 53 dihydrochalcones were characterized within a short retention time including one novel compound (phloretin-3'-C-(2-O-trans-p-coumaroyl)-ß-d-fucopyranoside) and 23 compounds identified from the Averrhoa genus for the first time. 3-Hydroxyphloretin was the most abundant dihydrochalcone in star fruit. All the identified dihydrochalcones had a higher abundance in leaves compared to fruits. This is the first report that systematically investigates dihydrochalcones in star fruit of multiple cultivars, and the results could provide a useful reference for the future development and utilization of plant genetic resources.