fruit peel and the participation of nitric oxide, opioid receptors, and ATP-sensitive potassium channels

Introduction: Nephelium lappaceum L. (Sapindaceae) is a plant known as rambutan. It is used for various purposes in traditional medicine. Objective: We aimed to evaluate the antinociceptive effects of the ethanol extract of the fruit peel of N. lappaceum (EENL), the mechanisms involved in these effects, and the acute toxicity in zebrafish. Methods: We performed chromatography coupled to mass spectrometry, acute toxicity assay in zebrafish, and evaluation in mice submitted to models of nociception and locomotor activity. Results: We identified (epi)-catechin, procyanidin B, and ellagic acid and its derivatives in EENL. We did not find any toxicity in zebrafish embryos incubated with EENL. The locomotor activity of mice submitted to oral pretreatment with EENL was not changed, but it reduced the abdominal constrictions induced by acetic acid, the licking/biting time in both the first and second phase of formalin testing and capsaicin testing, and carrageenan-induced paw mechanical allodynia. Oral pretreatment with EENL increased latency time in the hot plate test. This antinociceptive effect was significantly reversed by naloxone, L-arginine, and glibenclamide respectively showing the participation of opioid receptors, nitric oxide, and KATP channels as mediators of EENL-induced antinociception. Conclusion: EENL causes antinociception with the participation of opioid receptors, nitric oxide, and KATP channels, and is not toxic to zebrafish.

Fatty acid acylated flavonol glycosides from the seeds of Nephelium lappaceum and their nitric oxide suppression activity

Five undescribed fatty acid esters of flavonol glycosides, nephelosides A-E, along with eight known compounds, were isolated from the seeds of Nephelium lappaceum L. The structures were elucidated by extensive analysis of spectroscopic data in combination with GC-MS analysis. Potency of compounds toward nitric oxide suppression was assessed by monitoring the inhibition of lipopolysaccharide-stimulated nitric oxide production in J744.A1 macrophage cells. Nepheloside D, kaempferol and kaempferol 7-O-α-L-rhamnopyranoside showed significant activity with IC₅₀ values of 26.5, 11.6 and 12.0 μM, respectively.

The Potential Use of Nephelium lappaceum Seed as Coagulant-Coagulant Aid in the Treatment of Semi-Aerobic Landfill Leachate

Chemical-based coagulants and flocculants are commonly used in the coagulation-flocculation process. However, the drawbacks of using these chemical materials have triggered researchers to find natural materials to substitute or reduce the number of chemical-based coagulants and flocculants. This study examines the potential application of Nephelium lappaceum seeds as a natural coagulant-coagulant aid with Tin (IV) chloride (SnCl4) in eliminating suspended solids (SS), colour, and chemical oxygen demand (COD) from landfill leachate. Results showed that the efficiency of Nephelium lappaceum was low when used as the main coagulant in the standard jar test. When SnCl4 was applied as a single coagulant, as much as 98.4% of SS, 96.8% of colour and 82.0% of COD was eliminated at an optimal dose of 10.5 g/L and pH 7. The higher removal efficiency of colour (88.8%) was obtained when 8.40 g/L of SnCl4 was applied with a support of 3 g/L of Nephelium lappaceum. When SnCl4 was utilised as a coagulant, and Nephelium lappaceum seed was used as a flocculant, the removal of pollutants generally improved. Overall, this research showed that Nephelium lappaceum seed is a viable natural alternative for treating landfill leachate as a coagulant aid.

Review of Nephelium lappaceum and Nephelium ramboutan-ake: A High Potential Supplement

Nephelium lappaceum (N. lappaceum) and Nephelium ramboutan-ake (N. ramboutan-ake) are tropical fruits that gain popularity worldwide due to their tastiness. Currently, their potential to be used as pharmaceutical agents is underestimated. Chronic diseases such as cancer, diabetes and aging have high incidence rates in the modern world. Furthermore, pharmaceutical agents targeting pathogenic microorganisms have been hampered by the growing of antimicrobial resistance threats. The idea of food therapy leads to extensive nutraceuticals research on the potential of exotic fruits such as N. lappaceum and N. ramboutan-ake to act as supplements. Phytochemicals such as phenolic compounds that present in the fruit act as potent antioxidants that contribute to the protective effects against diseases induced by oxidative stress. Fruit residuals such as the peel and seeds hold greater nutraceutical potential than the edible part. This review highlights the antioxidant and biological activities (anti-neoplastic, anti-microbial, hypoglycemic actions and anti-aging), and chemical contents of different parts of N. lappaceum and N. ramboutan-ake. These fruits contain a diverse and important chemical profile that can alleviate or cure diseases.

Phytochemical evaluation and anticancer activity of rambutan (Nephelium lappaceum) fruit endocarp extracts against human hepatocellular carcinoma (HepG-2) cells

The current investigation was taken to screen the phytoconstituents present in fruit endocarp various extracts of Nephelium lappaceum commonly called as Rambutan fruit and its anticancer property against human hepatocellular carcinoma (HepG-2) cells. Different analytical techniques including qualitative phytochemical analysis, cell viability assay (MTT), apoptotic nuclear staining (DAPI), DNA fragmentation assay, Attenuated total reflection (ATR) and Gas chromatography–mass spectrometry (GC–MS) spectral analysis were carried out. ATR and GC–MS study revealed the presence of functional groups and 9 compounds, respectively in methanol endocarp extract. The results obtained depicts that methanol endocarp extract profoundly controlled cell proliferation and caused shrinkage of HepG-2 cells from polygonal to spherical shape. DAPI staining revealed that methanol endocarp extract caused increased fragmentation of nucleus and DNA fragmentation, which can be taken as a sign of apoptosis. The anticancer potential of methanol fruit endocarp extract of Nephelium lappaceum than other extracts and could be used successfully in future drug delivery systems and other biomedical concerns.

Chloroplast Genome of Rambutan and Comparative Analyses in Sapindaceae

Rambutan (Nephelium lappaceum L.) is an important fruit tree that belongs to the family Sapindaceae and is widely cultivated in Southeast Asia. We sequenced its chloroplast genome for the first time and assembled 161,321 bp circular DNA. It is characterized by a typical quadripartite structure composed of a large (86,068 bp) and small (18,153 bp) single-copy region interspersed by two identical inverted repeats (IRs) (28,550 bp). We identified 132 genes including 78 protein-coding genes, 29 tRNA and 4 rRNA genes, with 21 genes duplicated in the IRs. Sixty-three simple sequence repeats (SSRs) and 98 repetitive sequences were detected. Twenty-nine codons showed biased usage and 49 potential RNA editing sites were predicted across 18 protein-coding genes in the rambutan chloroplast genome. In addition, coding gene sequence divergence analysis suggested that ccsA, clpP, rpoA, rps12, psbJ and rps19 were under positive selection, which might reflect specific adaptations of N. lappaceum to its particular living environment. Comparative chloroplast genome analyses from nine species in Sapindaceae revealed that a higher similarity was conserved in the IR regions than in the large single-copy (LSC) and small single-copy (SSC) regions. The phylogenetic analysis showed that N. lappaceum chloroplast genome has the closest relationship with that of Pometia tomentosa. The understanding of the chloroplast genomics of rambutan and comparative analysis of Sapindaceae species would provide insight into future research on the breeding of rambutan and Sapindaceae evolutionary studies.

Development of novel microsatellite markers using RAD sequencing technology for diversity assessment of rambutan (Nephelium lappaceum L.) germplasm

The trend of microsatellite marker discovery and development revolved as a result of the advancement of next generation sequencing (NGS) technology as it has developed numerous microsatellites within a short period of time at a low cost. This study generated microsatellite markers using RAD sequencing technologies for the understudied Nephelium lappaceum. A total of 1403 microsatellite markers were successfully designed, which consisted of 853 di-, 525 tri-, 17 tetra-, 5 penta-, and 3 hexanucleotide microsatellite markers. Subsequently, selection of 39 microsatellites was made for the evaluation of genetic diversity of the selected 22 rambutan varieties. Twelve microsatellites, which exhibited high call rates across the samples, were used to assess the diversity of the aforementioned rambutan varieties. The analysis of 12 microsatellites revealed the presence of 72 alleles and six alleles per locus in average. Furthermore, the polymorphic information content (PIC) value ranged from 0.326 (NlaSSR20) to 0.832 (NlaSSR32), which included an average of 0.629 per locus, while the generated Neighbour Joining dendrogram showed two major clusters. The pairwise genetic distance of shared alleles exhibited a range of values from 0.046 (R134↔R170) to 0.818 (R5↔R170), which suggested highest dissimilarity detected between R5 and R170. Notably, these research findings would useful for varietal identification, proper management and conservation of the genetic resources, and exploitation and utilization in future breeding programs.

Metabolite Profiling of Rambutan (Nephelium lappaceum L.) Seeds Using UPLC-qTOF-MS/MS and Senomorphic Effects in Aged Human Dermal Fibroblasts

Nephelium lappaceum (rambutan) is an edible tropical fruit that is widely grown in Southeast Asia. In general, the seeds contain high nutrients, but rambutan seeds are thrown out during processing. In this study, the anti-aging activity of rambutan seeds was evaluated with a new approach through the selective inhibition of the senescence-associated secretory phenotype (senomorphics). Luciferase promoter assays using p16INK4A and SA-β-gal promoters for rambutan showed that its seeds possessed strong senomorphic activity. Molecular networking using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-qTOF-MS) with a tandem database (UPLC-qTOF-MS/MS) was applied to determine the chemical composition of rambutan. Based on the activity results, nine compounds, one new (7) and eight known kaempferol type compounds, were isolated from the seeds. Compounds 2, 4 and 9 significantly reduced the mRNA expression levels of senescence markers, such as p16INK4A, p21CIP1, p53 and SA-β-gal. These compounds also significantly increased the level of SIRT1, a longevity modulator. Compounds 2, 4 and 9 decreased the mRNA expression levels of senescence-associated secretory phenotypes (SASPs) and subsequently decreased the number of SA-β-gal-positive cells. Thus, rambutan seeds and its constituents might be able to protect against age-related problems.

Acute oral toxicity of the ellagitannin geraniin and a geraniin-enriched extract from Nephelium lappaceum L rind in Sprague Dawley rats

Despite the lack of its toxicity evaluation, traditional herbal products are being widely used for various health indications. Geraniin, an ellagitannin, is a bioactive compound found in many traditional herbal medicines. In spite its numerous health benefits ranging from anti-inflammatory, anti-hyperglycaemic, hepatoprotective, anti-cancer and anti-microbial, no toxicity data on geraniin is available. The objective of this study is to evaluate the acute oral toxicity of geraniin and an enriched geraniin-extract of Nephelium lappaceum L rind. This study followed the guidelines of the OECD 423 acute oral toxicity test. Subsequent to a single oral administration of the test compounds, the rats were observed for 14 days for signs of toxicity and mortality. Following euthanasia, full blood count, biochemistry of blood and histopathology assessment of organs were carried out. All parameters analysed indicated insignificant difference compared to control. The LD₅₀ cut-off values for both geraniin and geraniin-enriched extract was established to be 2000 mg/kg b. w., following a single oral dose. It was however observed that the hepatocytes of three geraniin-administered rats exhibited a ‘foamy appearance’. As such, the no-observed-adverse-effect level of geraniin is below 2000 mg/kg, while that of geraniin-enriched extract is up to 2000 mg/kg. Further detailed toxicity studies are required to establish geraniin or its enriched extract from Nephelium lappaceum L rind safe for human consumption.

Geraniin extracted from the rind of Nephelium lappaceum binds to dengue virus type-2 envelope protein and inhibits early stage of virus replication

Background

The rapid rise and spread in dengue cases, together with the unavailability of safe vaccines and effective antiviral drugs, warrant the need to discover and develop novel anti-dengue treatments. In this study the antiviral activity of geraniin, extracted from the rind of Nephelium lappaceum, against dengue virus type-2 (DENV-2) was investigated.

Methods

Geraniin was prepared from Nephelium lappaceum rind by reverse phase C-18 column chromatography. Cytotoxicity of geraniin towards Vero cells was evaluated using MTT assay while IC₅₀ value was determined by plaque reduction assay. The mode-of-action of geraniin was characterized using the virucidal, attachment, penetration and the time-of-addition assays’. Docking experiments with geraniin molecule and the DENV envelope (E) protein was also performed. Finally, recombinant E Domain III (rE-DIII) protein was produced to physiologically test the binding of geraniin to DENV-2 E-DIII protein, through ELISA competitive binding assay.

Results

Cytotoxicity assay confirmed that geraniin was not toxic to Vero cells, even at the highest concentration tested. The compound exhibited DENV-2 plaque formation inhibition, with an IC₅₀ of 1.75 μM. We further revealed that geraniin reduced viral infectivity and inhibited DENV-2 from attaching to the cells but had little effect on its penetration. Geraniin was observed to be most effective when added at the early stage of DENV-2 infection. Docking experiments showed that geraniin binds to DENV E protein, specifically at the DIII region, while the ELISA competitive binding assay confirmed geraniin’s interaction with rE-DIII with high affinity.

Conclusions

Geraniin from the rind of Nephelium lappaceum has antiviral activity against DENV-2. It is postulated that the compound inhibits viral attachment by binding to the E-DIII protein and interferes with the initial cell-virus interaction. Our results demonstrate that geraniin has the potential to be developed into an effective antiviral treatment, particularly for early phase dengue viral infection.