Dimocarpus Longan Lour Research Articles

Comparative Transcriptome Analysis of Mature Leaves of Dimocarpus longan cv. ‘Sijimi’ Provides Insight into Its Continuous-Flowering Trait

Longan (Dimocarpus longan Lour.) is an important tropical and subtropical fruit, and most of its cultivars bloom once a year (once-flowering, OF). Dimocarpus longan cv. ‘Sijimi’ (SJ) is a tropical ecotype variety that blooms several times a year (continuous-flowering, CF) without the need for low-temperature induction. Several studies have focused on the mechanism of continuous flowering in SJ longan; however, none used leaves as research material. As leaves are a key organ in sensing floral-induction signals, we compared gene-expression differences between mature leaves of CF (SJ) and OF (D. longan cv. ‘Shixia’ (SX) and D. longan cv. ‘Chuliang’ (CL)) longan by transcriptome sequencing. An average of 47,982,637, 43,833,340 and 54,441,291 clean reads were obtained for SJ, SX and CL respectively, and a total of 6745 differentially expressed genes (DEGs) were detected. Following Metabolic pathways, Plant-pathogen interaction and Biosynthesis of secondary metabolites, most of the other genes were assigned to the KEGG classifications of MAPK signaling pathway- plant, Plant hormone signal transduction, Amino sugar and nucleotide sugar metabolism and Starch and sucrose metabolism. WGCNA analysis clustered genes into 27 modules, among which bisque4 and darkorange2 module genes specifically were expressed at low and high levels in SJ, respectively. Different gene-expression patterns were detected between CF and OF longan in bisque4 and darkorange2 modules, especially the high levels of transcription factor (TF) expression and the large number of gibberellic acid (GA)-signaling-pathway-specific genes expressed at high levels in CF longan (SJ). Floral-induction-gene expression levels in CF longan, such as levels of GA-signaling-related and FT genes, were always high. In CF longan, after vegetative-growth accumulation, flowers could be directly induced, thereby eliminating the need for low-temperature induction.

An integrative metabolomics and metagenomics analysis of functional microbiota examines the extraction of bioactive products using longan pericarp

Longan (Dimocarpus longan Lour.) is a nutrient-rich fruit, widely cultivated in China. However, its seeds and pericarp, often discarded as waste, are rich in bioactive components, particularly polyphenolics. In this research, we develop microbiota-assisted extraction technique, which is efficient and environmentally friendly for extracting these valuable components. These results showcased superior efficiency in the diversity and richness of extracted bioactive components, although yielding slightly lower TP content than ethanol extraction. The active components extracted by microbiota-assisted extraction technique increased to 2.45 mg/g, which was higher 2.13 times and 3.10 times compared to optimized ethanol and water extraction, respectively. The numbers of active components extracted by these three methods were 39, 24 and 30, separately, and Quercetin 3-D-xyloside and Kaempferol 3-O-alpha-L-rhamnopyranosyl were identified in longan pericarp extracts by microbiota-assisted extraction. Metagenomics analysis revealed stable and diverse microbiota with functional capabilities for enhancing extraction efficiency. Functional annotations indicated significant roles in biosynthesis, carbohydrate degradation, and fatty acid metabolism. Microbiota-assisted extracts exhibited a broad spectrum of bioactive compounds with potential health benefits, including antioxidant and anti-inflammatory properties. These results provide a theoretical foundation for developing sustainable extraction technologies.

Genome-wide identification and expression analysis of the GAD family reveal their involved in embryogenesis and hormones responses in Dimocarpus longan Lour.

Glutamate decarboxylase (GAD) is involved in GABA metabolism and plays an essential regulatory role in plant growth, abiotic stresses, and hormone response. This study investigated the expression mechanism of the GAD family during longan early somatic embryogenesis (SE) and identified 6 GAD genes based on the longan genome. Homology analysis indicated that DlGAD genes had a closer relationship with dicotyledonous plants. The analysis of cis-acting elements in the promoter region suggests that the GAD genes were associated with various stress responses and hormones. RNA sequencing (RNA-Seq) and the qRT-PCR data indicated that most DlGAD genes were highly expressed in the incomplete compact pro-embryogenic cultures (ICpEC) and upregulated in longan embryogenic callus (EC) after treatments with 2,4-D, high temperature (35 °C), IAA, and ABA. Moreover, the RNA-Seq analysis also revealed that DlGADs exhibit different expression patterns in various tissues and organs. The subcellular localization results showed that DlGAD5 was localized in the cytoplasm, suggesting that it played a role in the cytoplasm. Transient overexpression of DlGAD5 enhanced the expression levels of DlGADs and increased the activity of glutamate decarboxylase in longan embryogenic callus (EC), while the content of glutamic acid decreased. Thus, the DlGAD gene can play an important role in the early somatic embryogenesis of longan by responding to hormones such as IAA and ABA. DlGAD5 can affect the growth and development of longan by stimulating the expression of the DlGAD gene family, thereby increasing the GAD activity in the early SE of longan, participating in hormone synthesis and signaling pathways.

Genome-Wide Identification and Expression Analysis of Bx Involved in Benzoxazinoids Biosynthesis Revealed the Roles of DIMBOA during Early Somatic Embryogenesis in Dimocarpus longan Lour.

Benzoxazinoids (BXs) are tryptophan-derived indole metabolites and play a role in various physiological processes, such as auxin metabolism. Auxin is essential in the process of somatic embryogenesis (SE) in plants. In this study, we used bioinformatics, transcriptome data, exogenous treatment experiments, and qPCR analysis to study the evolutionary pattern of Bx genes in green plants, the regulatory mechanism of DlBx genes during early SE, and the effect of 2,4-dihydroxy-7-methoxy-1,4-benzoxazine-3-one (DIMBOA) on the early SE in Dimocarpus longan Lour. The results showed that 27 putative DlBxs were identified in the longan genome; the Bx genes evolved independently in monocots and dicots, and the main way of gene duplication for the DlBx was tandem duplication (TD) and the DlBx were strongly constrained by purification selection during evolution. The transcriptome data indicated varying expression levels of DlBx during longan early SE, and most DlBxs responded to light, temperature, drought stress, and 2,4-dichlorophenoxyacetic acid (2,4-D) treatment; qRT-PCR results showed DlBx1, DlBx6g and DlBx6h were responsive to auxin, and treatment with 0.1mg/L DIMBOA for 9 days significantly upregulated the expression levels of DlBx1, DlBx3g, DlBx6c, DlBx6f, DlB6h, DlBx7d, DlBx8, and DlBx9b. The correlation analysis showed a significantly negative correlation between the expression level of DlBx1 and the endogenous IAA contents; DIMBOA significantly promoted the early SE and significantly changed the endogenous IAA content, and the IAA content increased significantly at the 9th day and decreased significantly at the 13th day. Therefore, the results suggested that DIMBOA indirectly promote the early SE by changing the endogenous IAA content via affecting the expression level of DlBx1 and hydrogen peroxide (H2O2) content in longan.

Assessment of variability and genetic divergence of longan genotypes (Dimocarpus longan Lour.) based on qualitative and quantitative traits

Assessment of variability and genetic divergence of longan genotypes (Dimocarpus longan Lour.) based on qualitative and quantitative traits

Cross amplification of 16S rRNA bacterial primer 27F/1492R on horticultural crop chloroplast genome

Molecular techniques have been applied as fast and accurate detection methods of plant pathogenic bacteria. Bacteria-specific primer 27F paired with the universal primer 1492R was used in PCR to detect plant pathogenic bacteria in symptomatic leaves of tomato (Solanum lycopersicum L.), chili pepper (Capsicum annum L.), napa cabbage (Brassica rapa subsp. pekinensis L.), cabbage (Brassica oleracea var. capitata L.), and longan (Dimocarpus longan Lour.). The targeted single bands with length of 1400 bp were obtained but bidirectional sequencing of the PCR products recovered partial sequence of chloroplast instead of bacterial genomes. Thus, this result confirmed cross amplification of 27F/1492R primer pair against chloroplast genome of plants. Phylogenetic tree was constructed to separate the tested isolates according to their taxonomic relations: Order Sapindales, Solanales, and Brassicales. In-silico analysis on the new five and nineteen selected sequences in NCBI GenBank detected at least seven conserved regions with some single nucleotide polymorphisms. This report might be a cautionary advice for other researchers to avoid false positive results which could lead to misdiagnosis of bacterial plant diseases.

FORMULATION AND EVALUATION OF HERBAL GEL CONTAINING DIMOCARPUS LONGAN LOUR SEEDS EXTRACT FOR TREATMENT OF SKIN ACNE

The present research work focuses on skin acne with the aim of developing an effective and safe herbal gel using Dimocarpus longan Lour. The ethanol extract of Dimocarpus longanLour was incorporated into an optimized Carbopol gel base. Physical characterization and phytochemical testing of the extract have been carried out. Antimicrobial studies showed no detectable microbial contamination and demonstrated good areas of inhibition. Overall, this research report concludes that herbal gel formulation can provide effective and safe formulations leading to patient tolerance and treatment compliance.

Genome-Wide Identification and Expression Analysis of GATA Family Genes in Dimocarpus longan Lour.

GATA transcription factors, which are DNA-binding proteins with type IV zinc finger binding domains, have a role in transcriptional regulation in biological organisms. They have an indispensable role in the growth and development of plants, as well as in improvements in their ability to face various environmental stresses. To date, GATAs have been identified in many gene families, but the GATA gene in longan (Dimocarpus longan Lour) has not been studied in previous explorations. Various aspects of genes in the longan GATA family, including their identification and classification, the distribution of their positions on chromosomes, their exon/intron structures, a synteny analysis, their expression at different temperatures, concentration of PEG, early developmental stages of somatic embryos and their expression levels in different tissues, and concentrations of exogenous hormones, were investigated in this study. This study showed that the 22 DlGATAs could be divided into four subfamilies. There were 10 pairs of homologous GATA genes in the synteny analysis of DlGATA and AtGATA. Four segmental replication motifs and one pair of tandem duplication events were present among the DlGATA family members. The cis-acting elements located in promoter regions were also found to be enriched with light-responsive elements, which contained related hormone-responsive elements. In somatic embryos, DlGATA4 is upregulated for expression at the globular embryo (GE) stage. We also found that DlGATA expression was strongly up-regulated in roots and stems. The study demonstrated the expression of DlGATA under hormone (ABA and IAA) treatments in embryogenic callus of longan. Under ABA treatment, DlGATA4 was up-regulated and the other DlGATA genes did not respond significantly. Moreover, as demonstrated with qRT-PCR, the expression of DlGATA genes showed strong up-regulated expression levels under 100 μmol·L-1 concentration IAA treatment. This experiment further studied these and simulated their possible connections with a drought response mechanism, while correlating them with their expression under PEG treatment. Overall, this experiment explored the GATA genes and dug into their evolution, structure, function, and expression profile, thus providing more information for a more in-depth study of the characteristics of the GATA family of genes.

Genome-Wide Identification and Expression Analysis Reveals the B3 Superfamily Involved in Embryogenesis and Hormone Responses in Dimocarpus longan Lour.

B3 family transcription factors play an essential regulatory role in plant growth and development processes. This study performed a comprehensive analysis of the B3 family transcription factor in longan (Dimocarpus longan Lour.), and a total of 75 DlB3 genes were identified. DlB3 genes were unevenly distributed on the 15 chromosomes of longan. Based on the protein domain similarities and functional diversities, the DlB3 family was further clustered into four subgroups (ARF, RAV, LAV, and REM). Bioinformatics and comparative analyses of B3 superfamily expression were conducted in different light and with different temperatures and tissues, and early somatic embryogenesis (SE) revealed its specific expression profile and potential biological functions during longan early SE. The qRT-PCR results indicated that DlB3 family members played a crucial role in longan SE and zygotic embryo development. Exogenous treatments of 2,4-D (2,4-dichlorophenoxyacetic acid), NPA (N-1-naphthylphthalamic acid), and PP333 (paclobutrazol) could significantly inhibit the expression of the DlB3 family. Supplementary ABA (abscisic acid), IAA (indole-3-acetic acid), and GA3 (gibberellin) suppressed the expressions of DlLEC2, DlARF16, DlTEM1, DlVAL2, and DlREM40, but DlFUS3, DlARF5, and DlREM9 showed an opposite trend. Furthermore, subcellular localization indicated that DlLEC2 and DlFUS3 were located in the nucleus, suggesting that they played a role in the nucleus. Therefore, DlB3s might be involved in complex plant hormone signal transduction pathways during longan SE and zygotic embryo development.

DlMYB113 mutation affects anthocyanin accumulation in red pericarp longan (Dimocarpus longan Lour.)

Fruit color influences fruit quality and commodity value. Most longan (Dimocarpus longan Lour.) varieties have a yellowish-brown or grayish-yellow pericarp, and the discovery of red pericarp (RP) longan expanded the color varieties of longan fruit. Our previous research showed that the red pericarp of RP fruit was mainly caused by anthocyanin accumulation; however, its underlying regulatory mechanism remains unknown. Herein, DlMYB113, an R2R3-MYB transcription factor, was discovered by examining differentially expressed genes in two longan cultivars. Dimocarpus longan MYB (v-myb avian myeloblastosis viral) 113 (DlMYB113) expression was significantly higher in the pericarp and leaves of RP longan than in ‘Shixia’ longan. Sequence alignment analysis revealed two amino acid substitutions in the R3 domain between DlMYB113rp in RP longan and DlMYB113sx in ‘Shixia’ longan. Transient expression of DlMYB113rp significantly increased anthocyanin accumulation in tobacco leaves, whereas DlMYB113sx had negligible effect. Meanwhile, DlMYB113 overexpression promotes anthocyanin accumulation in Arabidopsis and longan calli. Site-directed mutation detection revealed divergence in DlMYB113 function when the R3 repeat 197-position base T was replaced with G, and the 317- and 318-position AT bases were replaced with GA. Our findings indicate that DlMYB113 can regulate anthocyanin production in RP longan, and three mutations in its nucleic acid sequence lead to anthocyanin accumulation, thereby developing molecular markers associated with the anthocyanin accumulation trait in RP longan. This study will facilitate early screening of longan hybrids with desirable fruit color and be significant for breeding new characteristic varieties.

Longan Polysaccharides with Covalent Selenylation Combat the Fumonisin B1-Induced Cell Toxicity and Barrier Disruption in Intestinal Epithelial (IEC-6) Cells.

In this study, the soluble, but non-digestible, longan (Dimocarpus longan Lour.) polysaccharides (LP) were extracted from dried longan fruits and then chemically selenylated to produce two selenylated products, namely SeLP1 and SeLP2, with different selenylation extents. The aim was to investigate their protective effects on rat intestinal epithelial (IEC-6) cells exposed to the food toxin fumonisin B1 (FB1). LP only contained total Se content of less than 0.01 g/kg, while SeLP1 and SeLP2 were measured with respective total Se content of up to 1.46 and 4.79 g/kg. The cell viability results showed that these two selenylated products were more efficient than LP in the IEC-6 cells in alleviating FB1-induced cell toxicity, suppressing lactate dehydrogenase (LDH) release, and decreasing the generation of intracellular reactive oxygen species (ROS). These two selenylated products were also more effective than LP in combating FB1-induced barrier disruption via increasing the transepithelial electric resistance (TEER), reducing the paracellular permeability, decreasing the mitochondrial membrane potential (MMP) loss, and maintaining cell barrier integrity by upregulating the tight-junction-related genes and proteins. FB1 caused cell oxidative stress and barrier dysfunction by activating the MAPK and mitochondrial apoptosis signaling pathways, while SeLP1 and SeLP2 could regulate the tMAPK- and apoptosis-related proteins to suppress the FB1-mediated activation of the two pathways. Overall, SeLP2 was observed to be more active than SeLP1 in the IEC-6 cells. In conclusion, the chemical selenylation of LP caused an activity enhancement to ameliorate the FB1-induced cell cytotoxicity and intestinal barrier disruption. Meanwhile, the increased selenylation of LP would endow the selenylated product SeLP2 with more activity.

Potential Roles of Longan as a Natural Remedy with Tremendous Nutraceutical Values

Background: Longan (Dimocarpus longan Lour.) is a characteristic Sapindaceae fruit native to China and is a seasonal non-climacteric fruit with unique flavor, rich nutrients, and high economic value. Longan was used as a traditional Chinese medicine for various purposes, such as soothing nerves, relieving insomnia and increasing blood metabolism. Longan fruits are alternately eaten fresh, and they have elegant and sweet-tasting flesh. This fruit can also be processed to make dried pulp, jam, drinks, wine and canned fruit. Objective: The aim of this manuscript is to survey the chemical and natural constituents of longan and show the importance of longan in both modern and traditional pharmaceutical sciences. Methods: The goal of this article was to emphasize the most important benefits and pharmaceutical advantages of longan. The manuscript consists of randomized control experiments, review articles, observations and analytical studies, which have been gathered from various sources such as Scopus, Google Scholar, PubMed and Science Direct. A review of the literature was done by using the keywords such as longan Dimocarpus, longan natural products, traditional Chinese medicine, and pharmaceutical benefits. Results: The most important chemical constituents of the pericarp of longan are friedelin, friedelanol, (24R)-stigmast-4-en-3-one, β-sitosterol, β-(2-furly) acrylic acid, 6-hydroxy-7- methoxycoumarin, β-daucosterol, corilagin, gallic acid, heptyl p-hydroxybenzoate, methyl gallate, 4-O-α-L-rhamnopyranosyl-ellagic acid, and ellagic acid. The most notable antioxidant compounds extracted from longan shells are scopoletin, isovanillin, astragalin, quercetin, β- phenylethyl alcohol and hyperin. The most important biological properties of longan pericarp are tyrosinase inhibitory, antioxidant, anti-inflammatory, immunomodulatory, anti-glycated, anticancer, memory-increasing impact, and other parameters that have a significant contribution to human health. Conclusion: This review article finds that longan is an excellent source of constituents with beneficial nutritional and bioactive characteristics. More clinical research may be needed to reveal the countless substances and their impacts in longan that may affect public health.

Bloom Performances during Rainy Season of Off-season Longan (Dimocarpus longan Lour. ‘Phuang Thong’) Grown at Samut Sakhon Province, Thailand

Rainy season is an obstruction for efficient off-season longan production in Thailand. In this experiment, the bloom performances of off-season 'Phuang Thong' longan as affected by microclimate in a private longan orchard at Ban Phaeo district, Samut Sakhon province was evaluated during the rainy season of 2020. This study focused on the reproductive development at four different times (plots) of potassium chlorate application: May, June, July, and August. Air temperature, relative humidity and light intensity at the canopy level were recorded. Rainfall data was obtained from the Meteorological Department of Thailand. The results showed that inflorescence length, female flower number, and sex ratio of female to male of the May plot were the highest compared to other plots, and it was associated with early rainfall occurrence during flower development and blooming time. The August plot had a low growing degree day and a short flowering period, which coincided with frequent rainfall during the flower development period. However, the pollen viability and female flower characters were unaffected by environment. In conclusion, flower induction in the early rainy season, especially in May, was an effective time for the production of off-season ‘Phuang Thong’ longan in Ban Phaeo district, Samut Sakhon province, Thailand. Keywords: Floral biology, Flower, Pollen, Microclimate, Heat unit

The complete chloroplast genome of purple longan (Dimocarpus longan Lour., Sapindaceae)

Purple longan (Dimocarpus longan Lour.) is a new longan cultivar that arose in Soc Trang province, Vietnam. Although the economic value of purple longan has been revealed, genomic data have not been explored. In this study, the complete chloroplast genome of purple longan was sequenced and characterized, which was 160,763 bp in length. The genome had a quadripartite structure, including a large single copy (85,628 bp), a small single copy (18,247 bp), and two inverted repeat (28,444 bp) regions. This genome contained 79 protein-coding genes, 30 transfer RNAs, and four ribosomal RNAs, of which, 16 genes were duplicated in inverted repeat regions. Comparative genomic analysis revealed 11 highly variable regions (including matK-trnK_UUU, psbK-trnG_UCC, atpH-atpI, psbZ-rps14, pafI-trnL_UAA, psbJ-petG, clpP, rpl36-rpl14, rpl32-ccsA, rps15-ycf1, and ycf1). Additionally, 100 insertion and deletion sites were identified in the purple longan chloroplast genome. This study provided the first report on the complete chloroplast genome of purple longan, which is useful for further studies on cultivar identification, germplasm conservation, and plant breeding in the Dimocarpus genus and Sapindaceae family.

Condensed tannins from the leave of Dimocarpus longan Lour. exhibit anti-tyrosinase, anti-melanogenesis, anti-browning, anti-α-glucosidase, and anti-glycation activities

Dimocarpus longan Lour. is a valuable industrial crop for its broad applications in food, traditional Chinese medicine, and other fields. In this paper, condensed tannins were isolated from the leave of D. longan Lour., and their structure, anti-tyrosinase, anti-melanogenesis, anti-browning, anti-α-glucosidase, and anti-glycation properties were methodically clarified. The joint application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), electrospray ionization time-of-flight mass spectrometer (ESI+ TOF MS), and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) confirmed that the longan leave condensed tannins (LLCTs) were polymers of procyanidins (majority) and prodelphinidins. The polymers powerfully inhibit tyrosinase (TY) with a competitive mechanism. These compounds altered the microenvironment of the binding site through hydrophobic interaction and hydrogen bond, and caused conformational modification of the enzyme by changing the polypeptide framework and secondary structure, leading to a decrease in TY activity. Cell assays further suggested that LLCTs exhibited a strong inhibition against intracellular TY activity and melanin production, and caused apoptosis in B16F10 cells. Anti-browning studies demonstrated that LLCTs suppress the browning of fresh-cut apples. Furthermore, the LLCTs exhibited an impressive inhibition on both α-glucosidase and nonenzymatic glycation. Therefore, this study confirms the potential of LLCTs as new inhibitors of tyrosinase, melanogenesis, browning, α-glucosidase, and nonenzymatic glycation, which provided a theoretical basis for the potential utilization of these polymers in the cosmetics, pharmaceutical, and food industries.

Secondary metabolites from Pseudallescheria boydii and their anti-melanoma activity

A new asperitaconic acid (1) and an undescribe cyclotetrapeptide (2), together with nine known compounds (3–11), were isolated from the endophytic fungus Pseudallescheria boydii XL-0256 obtained from the leaves of Dimocarpus longan Lour. The structures of the new compounds have been successfully assigned based on the NMR spectroscopic data and the mass spectrometric analysis. Compound 3 was confirmed to significantly reduce B16–F10 cell viability in a dose- and time-dependent manner, as well as promoting cell apoptosis and inhibiting cell migration in B16–F10 cell. In addition, compound 3 was hypothesized to have an anti-melanoma effect through target proteins (ADAM17 and ADAMTS5) based on network pharmacological target prediction and molecular docking studies.

Transcription factors NF-YB involved in embryogenesis and hormones responses in Dimocarpus Longan Lour.

NF-YB transcription factor is an important regulatory factor in plant embryonic development. In this study, 15 longan NF-YB (DlNF-YB) family genes were systematically identified in the whole genome of longan, and a comprehensive bioinformatics analysis of DlNF-YB family was performed. Comparative transcriptome analysis of DlNF-YBs expression in different tissues, early somatic embryogenesis (SE), and under different light and temperature treatments revealed its specific expression profiles and potential biological functions in longan SE. The qRT-PCR results implied that the expression patterns of DlNF-YBs were different during SE and the zygotic embryo development of longan. Supplementary 2,4-D, NPA, and PP333 in longan EC notably inhibited the expression of DlNF-YBs; ABA, IAA, and GA3 suppressed the expressions of DlNF-YB6 and DlNF-YB9, but IAA and GA3 induced the other DlNF-YBs. Subcellular localization indicated that DlNF-YB6 and DlNF-YB9 were located in the nucleus. Furthermore, verification by the modified 5'RNA Ligase Mediated Rapid Amplification of cDNA Ends (5' RLM-RACE) method demonstrated that DlNF-YB6 was targeted by dlo-miR2118e, and dlo-miR2118e regulated longan somatic embryogenesis (SE) by targeting DlNF-YB6. Compared with CaMV35S- actuated GUS expression, DlNF-YB6 and DlNF-YB9 promoters significantly drove GUS expression. Meanwhile, promoter activities were induced to the highest by GA3 but suppressed by IAA. ABA induced the activities of the promoter of DlNF-YB9, whereas it inhibited the promoter of DlNF-YB6. Hence, DlNF-YB might play a prominent role in longan somatic and zygotic embryo development, and it is involved in complex plant hormones signaling pathways.

Antioxidant, Anti-Tyrosinase, Antiglycation and Safety of Longan Leaf Extract for Cosmeceutical Application

Abstract Many potential bioactive phytoconstituents in longan (Dimocarpus longan Lour.) leaf have been reported. Most chemical compounds belong to either phenolics or flavonoids, known as potent antioxidants. This research explores the multifunctional potential as a bioactive cosmetic ingredient used in skin care for adding value to longan leaves. The dried powder of longan leaves was extracted with 50%(v/v) ethanol in de-ionized water, then quantified for total phenolic and flavonoid contents. The hydroethanolic extract was investigated for various antioxidant methods including DPPH, nitric oxide (NO) scavenging and lipid peroxidation inhibition assays. The anti-tyrosinase activity was also evaluated for skin-whitening properties. Furthermore, Anti-aging activity in term of antiglycation was also conducted. The high number of polyphenols within the extract possessed a high antioxidant potential with IC50 0.023 ± 0.002, 0.478 ± 0.033 and 1.495 ± 0.153 mg/ml for DPPH scavenging, NO scavenging and lipid peroxidation inhibition, respectively. The extract could inhibit the tyrosinase enzyme with IC50 4.90 ± 0.50 and 6.60 ± 0.18 mg/ml for L-tyrosine and L-DOPA as substrates. The extract also exhibited a potent antiglycation activity with IC50 0.023 ± 0.003 mg/ml. Moreover, it showed no irritation effect on the chorioallantoic membranes (CAMs) within 5 min using the Hen’s Egg Test-Chorioallantoic Membranes (HET-CAMs). In conclusion, the polyphenolic-rich longan leaf extract displayed a good antioxidant, anti-tyrosinase and excellent antiglycation potential with safety that could constitute a promising multifunctional bioactive ingredient for skin care cosmeceutical products. Keywords: Longan leaf extract, Antioxidants, Anti-tyrosinase, Antiglycation, Irritation, HET-CAMs, Cosmeceutical

Effects of pretreatment methods on the physicochemical properties of dried longan (Dimocarpus longan Lour.) pulps.

Several pretreatment methods were used before hot air drying to determine the effects of pretreatment on the physicochemical properties of dried longan pulps to address issues of low efficiency and excessive browning of pulps in dried longan. The results showed that pretreatment methods such as sodium chloride steeping, hot blanching, and freeze-thawing reduced the moisture content in dried longan pulps and increased the hardness of dried longan pulps. Ultrasound, microwave, and hot blanching methods reduced the degree of browning of dried longan pulps. Freeze thawing led to a decrease in polysaccharide content in dried longan pulps. The use of ultrasound- and microwave-based pretreatment methods increased the contents of free phenolics and total phenolics and increased the oxygen radical absorbance capacity indices. Alkenes and alcohols constituted the primary volatile flavor substances in longan. It was inferred that it was favorable to use the hot blanching method before subjecting the samples to conditions of hot air drying as the moisture content and degree of browning could be reduced effectively. The results reported herein can potentially help manufacturers improve drying efficiency. The results provide a platform to produce high-quality products from dried longan pulps. PRACTICAL APPLICATION: Longan pulps should be subjected to conditions of the hot blanching method before subjecting the samples to conditions of hot air drying to reduce the moisture content and degree of browning. The results reported herein can help manufacturers improve the drying efficiency of pulps. The results can be exploited to produce high-quality products from dried longan pulps.

Genetic Diversity and Population Structure of a Longan Germplasm in Thailand Revealed by Genotyping-By-Sequencing (GBS)

Longan (Dimocarpus longan Lour.) is grown commercially in many countries, including China, Thailand, the Philippines, Malaysia, Vietnam, India, Australia, and Hawaii. Thailand is the second largest producer and largest exporter of longan in the world. Currently, there is limited information on the genetic background, population structure, and genetic relationships among longan cultivars in Thailand. In this study, a total of 50 longan accessions from a community-based germplasm collection in Thailand were analyzed using 10,619 SNPs from genotyping-by-sequencing (GBS). Based on the results of STRUCTURE analysis, 43 accessions were classified into 4 subpopulations, and the other 7 accessions were found to contain admixed genotypes. Based on UPGMA clustering analysis and PCoA analysis, the longan accessions could be divided into six major groups consistent with those identified by STRUCTURE. A relatively high degree of genetic variation was observed among the longan accessions, as quantified by the expected heterozygosity (He = 0.308). AMOVA results showed that 74% and 26% of the total variation occurred between and within populations, respectively. Obvious genetic differentiation between populations (FST = 0.25) was observed. The results of this study are useful for managing longan germplasm and may facilitate the genetic improvement of longan.