Identification and analysis of UGT genes associated with triterpenoid saponin in soapberry (Sapindus mukorossi Gaertn.).

BACKGROUND: Soapberry (Sapindus mukorossi) is an economically important multifunctional tree species. Triterpenoid saponins have many functions in soapberry. However, the types of uridine diphosphate (UDP) glucosyltransferases (UGTs) involved in the synthesis of triterpenoid saponins in soapberry have not been clarified. RESULTS: In this study, 42 SmUGTs were identified in soapberry, which were unevenly distributed on 12 chromosomes and had sequence lengths of 450 bp to 1638 bp, with an average of 1388 bp. The number of amino acids in SmUGTs was 149 to 545, with an average of 462. Most SmUGTs were acidic and hydrophilic unstable proteins, and their secondary structures were mainly α-helices and random coils. All had conserved UDPGT and PSPG-box domains. Phylogenetic analysis divided them into four subclasses, which glycosylated different carbon atoms. Prediction of cis-acting elements suggested roles of SmUGTs in plant development and responses to environmental stresses. The expression patterns of SmUGTs differed according to the developmental stage of fruits, as determined by transcriptomics and RT-qPCR. Co-expression network analysis of SmUGTs and related genes/transcription factors in the triterpenoid saponin synthesis pathway was also performed. The results indicated potential roles for many transcription factors, such as SmERFs, SmGATAs and SmMYBs. A correlation analysis showed that 42 SmUGTs were crucial in saponin synthesis in soapberry. CONCLUSIONS: Our findings suggest optimal targets for manipulating glycosylation in soapberry triterpenoid saponin biosynthesis; they also provide a theoretical foundation for further evaluation of the functions of SmUGTs and analyses of their biosynthetic mechanisms.

Physiology and transcriptome of Sapindus mukorossi seeds at different germination stages.

Sapindus mukorossi has a wide distribution range, high application value, and broad developmental potential. Previous studies have mostly focused on the medicinal and economic value of soapberry; however, few studies have been conducted on its seed germination. This study measured the physiological indicators and hormone content of soapberry seeds at different germination stages and preliminarily determined that abscisic acid (ABA) and indole-3-acetic acid (IAA) are the key hormones that affect the germination of soapberry seeds. Both Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG enrichment) analyses detected hormone transduction pathways, further confirming the key role of plant hormones in the germination process of soapberry seeds. Through transcriptome analysis, we speculated that CYP707A and IPA are key genes in the ABA and IAA synthesis pathways, respectively. This study revealed the close relationship between plant hormones and soapberry seed germination and provided new ideas for further exploration of the germination mechanism of soapberry seeds.

Metabolome and Transcriptome Analysis Reveals the Transcriptional Regulatory Mechanism of Triterpenoid Saponin Biosynthesis in Soapberry (Sapindus mukorossi Gaertn.).

Soapberry (Sapindus mukorossi Gaertn.) pericarps are rich in valuable bioactive triterpenoid saponins. However, the saponin content dynamics and the molecular regulatory network of saponin biosynthesis in soapberry pericarps remain largely unclear. Here, we performed combined metabolite profiling and transcriptome analysis to identify saponin accumulation kinetic patterns, investigate gene networks, and characterize key candidate genes and transcription factors (TFs) involved in saponin biosynthesis in soapberry pericarps. A total of 54 saponins were tentatively identified, including 25 that were differentially accumulated. Furthermore, 49 genes putatively involved in sapogenin backbone biosynthesis and some candidate genes assumed to be responsible for the backbone modification, including 41 cytochrome P450s and 45 glycosyltransferases, were identified. Saponin-specific clusters/modules were identified by Mfuzz clustering and weighted gene coexpression network analysis, and one TF-gene regulatory network underlying saponin biosynthesis was proposed. The results of yeast one-hybrid assay and electrophoretic mobility shift assay suggested that SmbHLH2, SmTCP4, and SmWRKY27 may play important roles in the triterpenoid saponin biosynthesis by directly regulating the transcription of SmCYP71D-3 in the soapberry pericarp. Overall, these findings provide valuable information for understanding the molecular regulatory mechanism of saponin biosynthesis, enriching the gene resources, and guiding further research on triterpenoid saponin accumulation in soapberry pericarps.

Metabolomics analysis of the soapberry (Sapindus mukorossi Gaertn.) pericarp during fruit development and ripening based on UHPLC-HRMS.

Soapberry (Sapindus mukorossi Gaertn.) is a multi-functional tree with widespread application in toiletries, biomedicine, biomass energy, and landscaping. The pericarp of soapberry can be used as a medicine or detergent. However, there is currently no systematic study on the chemical constituents of soapberry pericarp during fruit development and ripening, and the dynamic changes in these constituents still unclear. In this study, a non-targeted metabolomics approach using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) was used to comprehensively profile the variations in metabolites in the soapberry pericarp at eight fruit growth stages. The metabolome coverage of UHPLC-HRMS on a HILIC column was higher than that of a C18 column. A total of 111 metabolites were putatively annotated. Principal component analysis and hierarchical clustering analysis of pericarp metabolic composition revealed clear metabolic shifts from early (S1-S2) to late (S3-S5) development stages to fruit ripening stages (S6-S8). Furthermore, pairwise comparison identified 57 differential metabolites that were involved in 18 KEGG pathways. Early fruit development stages (S1-S2) were characterized by high levels of key fatty acids, nucleotides, organic acids, and phosphorylated intermediates, whereas fruit ripening stages (S6-S8) were characterized by high contents of bioactive and valuable metabolites, such as troxipide, vorinostat, furamizole, alpha-tocopherol quinone, luteolin, and sucrose. S8 (fully developed and mature stage) was the most suitable stage for fruit harvesting to utilize the pericarp. To the best of our knowledge, this was the first metabolomics study of the soapberry pericarp during whole fruit growth. The results could offer valuable information for harvesting, processing, and application of soapberry pericarp, as well as highlight the metabolites that could mediate the biological activity or properties of this medicinal plant.

Quantitative HPLC-MS/MS analysis of toxins in soapberry seeds: Methylenecyclopropylglycine and hypoglycin A.

Methylenecyclcopropylglycine (MCPG) and hypoglycin A (HGA) are naturally occurring amino acids found in various soapberry (Sapindaceae) fruits. These toxins have been linked to illnesses worldwide and were recently implicated in Asian outbreaks of acute hypoglycemic encephalopathy. In a previous joint agricultural and public health investigation, we developed an analytical method capable of evaluating MCPG and HGA concentrations in soapberry fruit arils as well as a clinical method for the urinary metabolites of the toxins. Since the initial soapberry method only analyzed the aril portion of the fruit, we present here the extension of the method to include the fruit seed matrix. This work is the first method to quantitate both MCPG and HGA concentrations in the seeds of soapberry fruit, including those collected during a public health investigation. Further, this is the first quantitation of HGA in litchi seeds as well as both toxins in mamoncillo and longan seeds.

Cellular Structural Changes in Candida albicans Caused by the Hydroalcoholic Extract from Sapindus saponaria L.

Vulvovaginal candidiasis (VVC) is a disease caused by the abnormal growth of yeast-like fungi in the mucosa of the female genital tract. Candida albicans is the principal etiological agent involved in VVC, but reports have shown an increase in the prevalence of Candida non-C. albicans (CNCA) cases, which complicates VVC treatment because CNCA does not respond well to antifungal therapy. Our group has reported the in vitro antifungal activity of extracts from Sapindus saponaria L. The present study used scanning electron microscopy and transmission electron microscopy to further evaluate the antifungal activity of hydroalcoholic extract from S. saponaria (HE) against yeast obtained from VVC and structural changes induced by HE. We observed the antifungal activity of HE against 125 vaginal yeasts that belonged to four different species of the Candida genus and S. cerevisae. The results suggest that saponins that are present in HE act on the cell wall or membrane of yeast at the first moments after contact, causing damage to these structures and cell lysis.

Combining a synthetic spermicide with a natural trichomonacide for safe, prophylactic contraception.

STUDY QUESTION: Can a specifically acting synthetic spermicide (DSE-37) be combined with a natural microbicide (saponins) for safe, prophylactic contraception? SUMMARY ANSWER: A 1:1 (w/w) combination of DSE-37 and Sapindus saponins can target sperm and Trichomonas vaginalis precisely without any noticeable off-target effects on somatic cells at effective concentrations. WHAT IS KNOWN ALREADY: Broad-spectrum vaginal agents like nonoxynol-9 (N-9) and cellulose sulfate have failed clinically as microbicides due to non-specific off-target effects, whereas agents that specifically target retroviruses have shown promise in clinical trials. DSE-37 and Sapindus saponins, respectively, specifically target human sperm and T. vaginalis in vitro. STUDY DESIGN, SIZE, DURATION: A comprehensive study of efficacy and safety was undertaken using in vitro (human cells) and in vivo (rabbit) models. The 1:1 combination of DSE-37 and Sapindus saponins was based on the in vitro spermicidal and anti-Trichomonal activities of the two components. N-9, the spermicide in clinical use, served as reference control. Free sperm thiols were fluorescently glinted to reveal differences in the targets of the test agents. PARTICIPANTS/MATERIALS, SETTING, METHODS: On/off-target effects were evaluated in vitro against human sperm, T. vaginalis, HeLa, Vk2/E6E7, End1/E6E7 and Lactobacillus jensenii, using standard assays of drug susceptibility, cell viability, flow cytometric assessment of cell apoptosis and qPCR for expression of pro-inflammatory cytokine mRNAs. The spermicidal effect was also recorded live and free thiols on sperm were fluorescently visualized using a commercial kit. In vivo contraceptive efficacy (pregnancy/fertility rates) and safety (vaginal histopathology and in situ immune-labeling of inflammation markers VCAM-1, E-selectin and NFkB) were evaluated in rabbits. MAIN RESULTS AND THE ROLE OF CHANCE: A 0.003% drug 'combination' containing 0.0015% each of DSE-37 and Sapindus saponins in physiological saline irreversibly immobilized 100% human sperm in ∼30 s and eliminated 100% T. vaginalis in 24 h, without causing any detectable toxicity to human cervical (HeLa) cells and Lactobacilli in 24-48 h, in vitro. N-9 at 0.003% exhibited lower microbicidal activity against Trichomonas but failed in spermicidal assays while causing severe toxicity to HeLa cells and Lactobacilli in 12-24 h. The 'combination' of DSE-37 and Sapindus saponins completely prevented pregnancy in rabbits at a vaginal dose of 20 mg (1% in K-Y Jelly), while application of 5% 'combination' in K-Y Jelly for 4 consecutive days caused negligible alterations in epithelial lining of rabbit vagina with only minor changes in levels of inflammation markers. N-9 at a 20 mg vaginal dose prevented pregnancy in 33% animals and a 4-day repeat application of 2% N-9 gel caused severe local toxicity to vaginal epithelium with molecular expression of acute inflammation markers. LIMITATIONS, REASONS FOR CAUTION: The number of animals used for the in vivo efficacy study was limited by the approval of the animal ethics committee. WIDER IMPLICATIONS OF THE FINDINGS: Anti-Trichomonal contraceptives with specifically acting synthetic component and clinically-proven safe natural component may define a new concept in empowering women to control their fertility and reproductive health. STUDY FUNDING/COMPETING INTEREST(S): The study was funded by CSIR-Network Project 'PROGRAM' (BSC0101) and partly by the Ministry of Health and Family Welfare, Government of India (GAP0001). The funding agencies did not play any role in this study and none of the authors had any competing interest(s).

Vegetative storage protein with trypsin inhibitor activity occurs in Sapindus mukorassi, a sapindaceae deciduous tree.

A vegetative storage protein (VSP) with trypsin inhibitor activity in a deciduous tree, Sapindus mukorassi, was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot, immuno-histochemical localization, light- and electro-microscopy, together with analysis of proteinase inhibitor activity of the purified VSP in vitro. There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S. mukorassi in leafless periods. The proteins decreased markedly during young shoot development, indicating their role in seasonal nitrogen storage. Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells. The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope. So, the 23 kDa protein was a typical VSP in S. mukorassi. The 23 and 27 kDa proteins shared no immuno-relatedness, whereas the 23 kDa protein was immuno-related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity. The 23 kDa protein may confer dual functions: nitrogen storage and defense.

The dynamics of major fibrolytic microbes and enzyme activity in the rumen in response to short- and long-term feeding of Sapindus rarak saponins.

AIMS: To investigate the short- and long-term effects of an extract of Sapindus rarak saponins (SE) on the rumen fibrolytic enzyme activity and the major fibrolytic micro-organisms. METHODS AND RESULTS: Two feeding trials were conducted. In the short-term trial, four fistulated goats were fed a basal diet containing sugar cane tops and wheat pollard (65:35, w/w) and were supplemented for 7 days with SE at a level of 0.6 g kg(-1) body weight. Rumen liquor was taken before, during and after SE feeding. In the long-term trial, 28 sheep were fed the same basal diet as the goats and were supplemented for 105 days with 0.24, 0.48 and 0.72 g kg(-1) body mass of the extract. Rumen liquor was taken on days 98 and 100. Protozoal numbers were counted under the microscope. Cell wall degradation was determined by enzyme assays and the major fibrolytic micro-organisms were quantified by dot blot hybridization. Sapindus extract significantly depressed rumen xylanase activity in both trials and carboxymethylcellulase activity in the long-term trial (P < 0.01). Fibrobacter sp. were not affected by the SE in both trials, while ruminococci and the anaerobic fungi showed a short-term response to the application of saponins. Protozoal counts were decreased only in the long-term trial with sheep. CONCLUSION: These data suggest that there is an adaptation of Ruminococcus albus, Ruminococcus flavefaciens and Chytridiomycetes (fungi) to saponin when fed over a long period. The fact that no correlation between the cell wall degrading enzyme activities and the cell wall degrading micro-organisms was observed suggests that the organisms tracked in this experiment are not the only key players in ruminal cell wall degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: Sapindus rarak saponins partially defaunate the rumen flora. Their negative effect on cell wall degradation, however, is not related to rumen organisms currently recognized as the major cell wall degrading species. The adaptation of microbes in the long-term feeding experiment suggests that the results from short-term trial on the ruminal microbial community have to be interpreted carefully.