Acer truncatum Bunge: A comprehensive review on ethnobotany, phytochemistry and pharmacology

Production of Conjugated Linoleic Acid (CLA) by Lactiplantibacillus plantarum: A Review with Emphasis on Fermented Foods

The term Conjugated Linoleic Acid (CLA) refers generically to a class of positional and geometric conjugated dienoic isomers of linoleic acid. Among the isomers of linoleic acid cis9, trans11-CLA (c9, t11-CLA) and trans10, cis12-CLA (t10, c12-CLA) are found to be biologically active isomers, and they occur naturally in milk, dairy products and meat from ruminants. In addition, some vegetables and some seafoods have also been reported to contain CLA. Although the CLA levels in these natural sources are insufficient to confer the essential health benefits, anti-carcinogenic or anti-cancer effects are of current interest. In the rumen, CLA is an intermediate of isomerization and the biohydrogenation process of linoleic acid to stearic acid conducted by ruminal microorganisms. In addition to rumen bacteria, some other bacteria, such as Propionibacterium, Bifidobacterium and some lactic acid bacteria (LAB) are also capable of producing CLA. In this regard, Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) has demonstrated the ability to produce CLA isomers from linoleic acid by multiple enzymatic activities, including hydration, dehydration, and isomerization. L. plantarum is one of the most versatile species of LAB and the bacterium is widely used in the food industry as a microbial food culture. Thus, in this review we critically analyzed the literature produced in the last ten years with the aim to highlight the potentiality as well as the optimal conditions for CLA production by L. plantarum. Evidence was provided suggesting that the use of appropriate strains of L. plantarum, as a starter or additional culture in the production of some fermented foods, can be considered a critical factor in the design of new CLA-enriched functional foods.

Acer truncatum leaves extract modulates gut microbiota, improves antioxidant capacity, and alleviates lipopolysaccharide-induced inflammation in broilers

This study investigated the appropriate way of dietary Acer truncatum leaves (ATL) addition, the effect of disease prevention and its mechanism of action. In experiment 1, 192 Arbor Acres broilers were assigned to 4 treatment groups, fed with basal diets containing 2% bran, replacing it with primary and fermented ATL, and additional 0.3% ATL extract to the basal diet for 42 d, respectively. In experiment 2, 144 broilers were assigned to 3 treatment groups for 21-d trial: (1) C-N group, basal diets, and injected with 0.9% (w/v) sterile saline; (2) C-L group, basal diets, and injected with lipopolysaccharide (LPS); (3) T-L group, ATL diets and injected with LPS. In experiment 1, ATL significantly decreased the index of abdominal fat at 42 d (P < 0.05). ATL extract had a better ability to improve antioxidant capacity and reduce inflammatory levels among all treatment groups, which significantly decreased the content of MDA in the liver and ileum mucosa at 21 d, and increased the expression of IL-10 and Occludin in jejunal mucosa at 42 d (P < 0.05). In experiment 2, ATL significantly increased the level of T-AOC in the liver, decreased the expression of NF-κB in the jejunal mucosa and ileum mucosa (P < 0.05), and restored LPS-induced the changed level of CAT in jejunal mucosa, the expression of IL-6, Claudin-1, and ZO-1 in jejunal mucosa and IL-1β in ileum mucosa (P < 0.05). Analysis of gut microbiota indicated that ATL enhanced the abundances of Bacteroidota and reduced the proportion of Firmicutes (P < 0.05), and the changed levels of T-AOC in body, IL-1β, IL-6, IL-10, and NF-κB in jejunum mucosa and propionic acid in cecal were associated with gut microbiota. Collectively, our data showed that the extract of ATL had a better antioxidant and anti-inflammatory effects than primality and fermented. Extraction of ATL modulated intestinal microbiota, and had a protective effect on oxidative stress, inflammation, and intestinal barrier function in broilers challenged with LPS.

Transcriptional Regulation of the Acer truncatum B. Response to Drought and the Contribution of AtruNAC36 to Drought Tolerance

Drought stress is one of the major environmental factors severely restricting plant development and productivity. Acer truncatum B, which is an economically important tree species, is highly tolerant to drought conditions, but the underlying molecular regulatory mechanisms remain relatively unknown. In this study, A. truncatum seedlings underwent a drought treatment (water withheld for 0, 3, 7, and 12 days), after which they were re-watered for 5 days. Physiological indices were measured and a transcriptome sequencing analysis was performed to reveal drought response-related regulatory mechanisms. In comparison to the control, the drought treatment caused a significant increase in antioxidant enzyme activities, with levels rising up to seven times, and relative electrical conductivity from 14.5% to 78.4%, but the relative water content decreased from 88.3% to 23.4%; these indices recovered somewhat after the 5-day re-watering period. The RNA sequencing analysis identified 9126 differentially expressed genes (DEGs), which were primarily involved with abscisic acid responses, and mitogen-activated protein kinase signaling. These DEGs included 483 (5.29%) transcription factor genes from 53 families, including ERF, MYB, and NAC. A co-expression network analysis was conducted and three important modules were analyzed to identify hub genes, one of which (AtruNAC36) was examined to clarify its function. The AtruNAC36 protein was localized to the nucleus and had a C-terminal transactivation domain. Moreover, it bounded specifically to the NACRS element. The overexpression of AtruNAC36 in Arabidopsis thaliana resulted in increased drought tolerance by enhancing antioxidant enzyme activities. These findings provide important insights into the transcriptional regulation mediating the A. truncatum response to drought. Furthermore, AtruNAC36 may be relevant for breeding forest trees resistant to drought stress.

Response Surface Optimization of Extraction Conditions for the Active Components with High Acetylcholinesterase Inhibitory Activity and Identification of Key Metabolites from Acer truncatum Seed Oil Residue

The State Council of China has called for the comprehensive development and utilization of Acer truncatum resources. However, research on one of its by-products, namely seed oil residue (ASR), from seed oil extraction is seriously insufficient, resulting in a waste of these precious resources. We aimed to optimize the conditions of ultrasound-assisted extraction (UAE) using a response surface methodology to obtain high acetylcholinesterase (AChE) inhibitory components from ASR and to tentatively identify the active metabolites in ASR using non-targeted metabolomics. Based on the results of the independent variables test, the interaction effects of three key extracting variables, including methanol concentration, ultrasonic time, and material-to-liquid ratio, were further investigated using the Box-Behnken design (BBD) to obtain prior active components with high AChE inhibitory activity. UPLC-QTOF-MS combined with a multivariate method was used to analyze the metabolites in ASR and investigate the causes of activity differences. Based on the current study, the optimal conditions for UAE were as follows: methanol concentration of 85.06%, ultrasonic time of 39.1 min, and material-to-liquid ratio of 1.06:10 (g/mL). Under these optimal conditions, the obtained extracts show strong inhibitions against AChE with half maximal inhibitory concentration (IC₅₀) values ranging from 0.375 to 0.459 µg/mL according to an Ellman's method evaluation. Furthermore, 55 metabolites were identified from the ASR extracted using methanol in different concentrations, and 9 biomarkers were subsequently identified as potential compounds responsible for the observed AChE inhibition. The active extracts have potential to be used for the development of functional foods with positive effects on Alzheimer's disease owing to their high AChE inhibition activity. Altogether, this study provides insights into promoting the comprehensive utilization of A. truncatum resources.

Protective effects of extracts from Acer truncatum leaves on SLS-induced HaCaT cells

Introduction:A. truncatum Bunge (Sapindaceae or formerly Aceraceae) is a tall deciduous tree native to China. Traditionally, the leaves of A. truncatum are decocted and used by Chinese Mongolians, Koreans, and Tibetans to treat skin itching, dry cracks, and other skin ailments, which indicates A. truncatum leaves may have a potential inhibitory effect on various skin inflammations.

Methods: To examine the protective effect against skin inflammations of A. truncatum leaf extract (ATLE), an in vitro dermatitis model was established using sodium dodecyl sulfate (SLS)-induced HaCaT cells. The anti-inflammatory effect of ATLE was evaluated by analyzing cell viability, apoptosis, reactive oxygen species (ROS), interleukin 6 (IL-6), and prostaglandin E2 (PGE2) levels.

Results: Orthogonal experiments showed that the pretreatment with ATLE can reduce the IL-6 levels, PGE2 levels, and apoptosis increased in SLS-stimulated HaCaT cells, which indicates that ATLE has positive efficacy for dermatitis. Furthermore, three flavonoid compounds kaempferol-3-O-α-L-rhamnoside, quercetin-3-O-α-L-rhamnopyranoside, kaempferol-3,7-di-O-α-L-rhamnoside, and 1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (PGG) were isolated and identified. Among them, kaempferol-3,7-di-O-α-L-rhamnoside was isolated from this plant for the first time. These compounds have been proven to have an anti-inflammatory effect. They may contribute to the efficacy of A. truncatumin treating skin inflammation.

Discussion: The results revealed that ATLE has the potential to be used as an additive in various skin care products to prevent skin inflammations and may be incorporated in formulations for topical application as a therapeutic approach against dermatitis.

Optimization technology and kinetic studies of Acer truncatum seed oil saponification and crystallization separation of nervonic acid

Acer truncatum seed oil (ATSO) contains abundant unsaturated fatty acids, with significant quantities of nervonic acid (NA, > 5%), which was authenticated as a new food resource in China. For the sake of minimizing animal consumption and the importance of NA for human health, extraction of NA from plants has become a research hotspot. In the present study, three extraction factors were determined to significantly influence the saponification reaction based on single-factor experiments: NaOH dosage, reaction time, and reaction temperature. These three factors were used to further optimize the saponification process through the response surface methodology, and the highest yield of mixed fatty acids was 83.12%. Moreover, the activation energy (40.8228 kJ/mol), the pre-exponential factor [2.568 × 10⁶ m³ /(kmol·min)], and the kinetic equation [r_A = kc_A c_B = 2.568 × 10⁶ ·exp(- 4970 . 1 T ) $\frac{{{\rm{4970}}{\rm{.1}}}}{{\rm{T}}})$ c_A c_B ] of the ATSO saponification reaction were determined by combining the chemical reaction rate equation of the elementary reaction, the Arrhenius equation, and the NaOH concentration in the substrate. Finally, the mixed fatty acids of ATSO were crystallized by triple-stage low-temperature crystallization, and we achieved 25.05% purity for NA. This study provides a technological basis and strategy for specific fatty acid production from ASTO, as well as other vegetable oils important in the field of food and health supplement products. PRACTICAL APPLICATION: Nervonic acid (NA) is an essential component of neural cells and neural tissue, and it is vital for maintaining the normal work of nerve tissues in organisms and promotes neurodevelopment. NA has traditionally been mainly obtained from shark hunting, which is now restricted due to an international ban on shark fishing. The alternative way to produce NA cheaply and in large quantities is from plant sources. The techniques utilized in this study provide an effective method of NA separation from Acer truncatum seed oil for industrial production.

Genome-Wide Identification and Analysis of the WRKY Gene Family and Cold Stress Response in Acer truncatum

WRKY transcription factors constitute one of the largest gene families in plants and are involved in many biological processes, including growth and development, physiological metabolism, and the stress response. In earlier studies, the WRKY gene family of proteins has been extensively studied and analyzed in many plant species. However, information on WRKY transcription factors in Acer truncatum has not been reported. In this study, we conducted genome-wide identification and analysis of the WRKY gene family in A. truncatum, 54 WRKY genes were unevenly located on all 13 chromosomes of A. truncatum, the highest number was found in chromosomes 5. Phylogenetic relationships, gene structure, and conserved motif identification were constructed, and the results affirmed 54 AtruWRKY genes were divided into nine subgroup groups. Tissue species analysis of AtruWRKY genes revealed which were differently exhibited upregulation in flower, leaf, root, seed and stem, and the upregulation number were 23, 14, 34, 18, and 8, respectively. In addition, the WRKY genes expression in leaf under cold stress showed that more genes were significantly expressed under 0, 6 and 12 h cold stress. The results of this study provide a new insight the regulatory function of WRKY genes under abiotic and biotic stresses.