In vitro immunomodulatory activity of water-soluble glucans from fresh and dried Longan (Dimocarpus longan Lour.)

Safety of medicinal and edible herbs from fruit sources for human consumption: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal and edible herbs from fruit sources have been increasingly used in traditional Chinese medicine dietotherapy. There are no restrictions on who could consume the medicinal and edible fruits or on the dosage of consumption. However, their safety for human consumption has yet to be established.

AIM OF THE STUDY

This systematic review aimed to assess the safety of human consumption of 30 medicinal and edible fruits.

MATERIALS AND METHODS

Seven English and Chinese databases were searched up to May 31, 2023, to collect AE reports following human consumption of medicinal and edible fruits. Eligible reports should include details on the occurrence, symptoms, treatments, and outcomes of AEs. AEs that were life-threatening or caused death, permanent or severe disability/functional loss, or congenital abnormality/birth defects were classified as serious AEs (SAEs). The causality between the consumption of fruits and AEs was graded as one of four ranks: "certain", "probable", "possible", or "unlikely".

RESULTS

Thirty AE reports related to the consumption of medicinal and edible fruits were included, involving 12 species of fruits: Crataegi fructus, Gardeniae fructus, Mori fructus, Hippophae fructus, Cannabis fructus, Siraitiae fructus, Perillae fructus, Rubi fructus, Longan arillus, Anisi stellati fructus, Zanthoxyli pericarpium, and Lycii fructus. No AE reports were found for the remaining 18 species. A total of 97 AEs, featuring predominantly gastrointestinal symptoms, followed by allergic reactions and neuropsychiatric symptoms, were recorded. Thirty SAEs were noted, with Zanthoxyli pericarpium accounting for the most (14 cases), followed by Perillae fructus (7 cases), Anisi stellati fructus (6 cases), and Gardeniae fructus, Rubi fructus, and Mori fructus (1 case each). Mori fructus was associated with one death. All AEs were concordant with a causality to fruit consumption, judged to be "certain" for 37 cases, "probable" for 53 cases, and "possible" for 7 cases.

CONCLUSIONS

Our findings suggest that among medicinal and edible fruits, 12 species have AE reports with a causality ranging from "possible" to "definite". SAEs were not scarce. Most AEs may be associated with an excessive dose, prolonged consumption, or usage among infants or young children. No AE reports were found for the remaining 18 species.

Antioxidant and anti-aging activities of Longan crude and purified polysaccharide (LP-A) in nematode Caenorhabditis elegans

Oxidative damage is an important cause of aging. The antioxidant and anti-aging activities of Longan polysaccharides, especially purified Longan polysaccharides, have not been thoroughly investigated. Therefore, this study aimed to investigate the antioxidant and anti-aging activities and mechanisms of crude polysaccharides and purified polysaccharides from Longan. A purified acidic Longan polysaccharide LP-A was separated from Longan crude polysaccharide LP. Subsequently, its structural characterization, anti-aging activity and mechanism were studied. The results showed that LP-A was an acidic heteropolysaccharide with an average molecular weight (Mw) of 4.606 × 104 Da which was composed of nine monosaccharides. The scavenging rate of ABTS free radical in vitro reached 99 %. In the nematode life experiment, 0.3 mg/mL LP group and LP-A group could prolong the average lifespan of nematodes by 9.31 % and 25.80 %, respectively. Under oxidative stress stimulation, LP-A group could prolong the survival time of nematodes by 69.57 %. In terms of mechanism, Longan polysaccharide can regulate insulin / insulin-like growth factor (IIS) signaling pathway, increase the activity of antioxidant enzymes, reduce lipid peroxidation, enhance the body's resistance to stress damage, and effectively prolong the lifespan of nematodes. In conclusion, LP-A has better anti-aging activity than crude polysaccharide LP, which has great potential for developing as an anti-aging drug.

Potential of longan (Dimocarpus longan Lour.) in functional food: A review of molecular mechanism-directing health benefit properties

Longan (Dimocarpus longan Lour.) has received widespread attention worldwide as a therapeutic food with nutritional, economic, and medicinal value. Its fruit, seed, pericarp, and flower becoming dietary tools for health maintenance when it comes to targeting chronic diseases or sub-health conditions. In recent years, research focusing on longan and human health has intensified, and the high-value products of the whole fruit, including polyphenols, polysaccharides, angiotensin-I-converting enzyme (ACE)-inhibiting peptides, gamma-aminobutyric acid (GABA), and Maillard reaction products etc., may have beneficial effects on human health by preventing the onset of chronic diseases and cancer, maintaining intestinal homeostasis and skin health. Here, we review and summarize the new available evidence on the bioactive role of phytochemicals in longan and explore the relationship between longan bioactive compounds and health benefits, with a focus on the molecular mechanisms of the health effects.

The Pea Oligosaccharides Could Stimulate the In Vitro Proliferation of Beneficial Bacteria and Enhance Anti-Inflammatory Effects via the NF-κB Pathway

The oligosaccharides extracted from the seeds of peas, specifically consisting of raffinose, stachyose, and verbascose, fall under the category of raffinose family oligosaccharides (RFOs). The effect of RFOs on intestinal microflora and the anti-inflammatory mechanism were investigated by in vitro fermentation and cell experiments. Firstly, mouse feces were fermented in vitro and different doses of RFOs (0~2%) were added to determine the changes in the representative bacterial community, PH, and short-chain fatty acids in the fermentation solution during the fermentation period. The probiotic index was used to evaluate the probiotic proliferation effect of RFOs and the optimal group was selected for 16S rRNA assay with blank group. Then, the effects of RFOs on the inflammatory response of macrophage RAW264.7 induced by LPS were studied. The activity of cells, the levels of NO, ROS, inflammatory factors, and the expression of NF-κB, p65, and iNOS proteins in related pathways were measured. The results demonstrated that RFOs exerted a stimulatory effect on the proliferation of beneficial bacteria while concurrently inhibiting the growth of harmful bacteria. Moreover, RFOs significantly enhanced the diversity of intestinal flora and reduced the ratio of Firmicutes-to-Bacteroides (F/B). Importantly, it was observed that RFOs effectively suppressed NO and ROS levels, as well as inflammatory cytokine release and expression of NF-κB, p65, and iNOS proteins. These findings highlight the potential of RFOs in promoting intestinal health and ameliorating intestinal inflammation.

Acetylation at the O-6 position of t-Glc improved immunoactivity of α-1,6-glucan from longan by additionally activating Dectin-1 and CD14 receptors

Acetylation is an important approach to improve the bioactivity of polysaccharides; however, the mechanisms have not been fully understood. As a key component of longan for exerting health promoting function, longan polysaccharide was hypothesized may achieve elevated immunoregulatory activity after acetylation. A bioactive longan polysaccharide (LP) composed of (1 → 6)-α-d-glucan (84.1 %) and with an average Mw of 9.68 × 104 kDa was acetylated to different degree of substitutions (DS) in this study. Key structural changes responsible for improvement in immunoregulatory activity were identified, and underlying mechanisms were investigated. Acetylated LP (Ac-LP) with DS 0.37, 0.78 and 0.92 were obtained. Structural characterization identified the substitution of acetyl groups occurs at O-6 positions of t-Glc non-selectively, while the backbone structure was not apparently changed. This resulted in increased expression of cytokines (IL-10, IL-6 and TNF-α) and ROS production in RAW264.7 macrophages, indicating improved immune activity which is positively related to the DS of Ac-LP. This is attribute to additional cellular receptors for Ac-LP (CD14 and Dectin-1) apart from receptors for LP (TLR4 and Ca2+ receptors), as well as the relative higher protein expression of TLR4-MyD88 signaling pathways. These results would provide guidance for the utilization of acetylated polysaccharides with improved immunoactivity.

Structural analysis and attenuates hyperuricemic nephropathy of dextran from the Imperata cylindrica Beauv. var. major (Nees) C. E. Hubb

ICPC-a was from the Imperata cylindrica with a molecular weight of 45 kDa, which was composed of α-D-1,3-Glcp and α-D-1,6-Glcp. The ICPC-a showed thermal stability, maintaining its structural integrity up to 220°C. X-ray diffraction analysis confirmed its amorphous nature, while scanning electron microscopy revealed a layered morphology. ICPC-a significantly ameliorated uric acid stimulation-induced HK-2 cell injury and apoptosis and reduced uric acid levels in mice with hyperuricemic nephropathy. ICPC-a protected against renal injury by inhibiting lipid peroxidation levels, increasing antioxidant damage and defense levels, inhibiting secretion of pro-inflammatory factors, regulating purine metabolism, PI3K-Akt signaling pathway, NF-κB signaling pathway, inflammatory bowel disease, mTOR signaling pathway, and MAPK signaling pathway. These findings indicate that ICPC-a is a promising natural substance with multiple targets, multiple pathways of action, and without toxicity, making it a valuable subject for further research and development.

In vitro immunomodulatory activity study of Garcinia cowa Roxb. fraction

OBJECTIVES

The objective of this study is to determine the activity of Garcinia cowa Roxb. n-hexane, ethyl acetate, and butanol fractions as an immunomodulator in vitro and obtain the fraction that has the potential as an immunomodulator.

METHODS

Raw 264.7 macrophages were used to asses G. cowa Roxb. immunomodulatory activity. The MTT assay was chosen to measure cell viability to evaluate the cytotoxic effect on cells. ELISA method was used to measure the concentration of Interleukin-6 (IL-6) and Tumor Necrosis Factor Alpha (TNF-α) secreted by cells after being treated with G. cowa Roxb. fraction. The neutral red uptake assay determined the effect of Garcinia cowa Roxb. on the phagocytic activity.

RESULTS

After Raw 264.7 macrophages were given the Hexan fraction (Hex) at concentrations of 12.5 and 25 μg/mL, there was a decrease in the concentration of IL-6, TNF-α, and the phagocytosis index of cells. Administration of the Ethyl Acetate fraction (EtOAc) at concentrations of 12.5 and 25 μg/mL on cells caused a decrease in IL-6 and TNF-α levels but did not affect the phagocytosis index. There was an increase in the level of TNF-α and the phagocytosis index after being given the Butanol fraction (BuOH) with concentrations of 12.5 and 25 μg/mL but there was a slight decrease in the level of IL-6.

CONCLUSIONS

Both Hex and EtOAc fractions could suppress immune responses through decreasing IL-6, TNF-α, and slightly decreased phagocytic activity. BuOH fraction could stimulate immunomodulatory activities through enhanced TNF-α levels and phagocytic index, but less potent in enhancing IL-6 production. The BuOH fraction could be developed as an immunostimulant.

Structural characterization and antinociceptive activity of polysaccharides from Anoectochilus elatus

Anoectochilus elatus is a new record species from Yunnan province in China discovered by our group in 2018, used in folk as the most popular Anoectochilus species A. roxburghii for medicinal and culinary purposes. The crude polysaccharide of Anoectochilus elatus (AEP) exhibited significant antinociceptive effects against both chemical and thermal nociception in vivo. Bio-guided isolation identified GJXL-1 as the leading analgesic polysaccharide in AEP. Detailed structural analyses rationalized GJXL-1 (molecular weight: 10.3 kDa) as an α-D-1,4-linked glucan unexpectedly branched at O-3, and O-6 position. GJXL-1 dose-dependently suppressed acetic acid-induced writhing in mice and decreased the serum levels of NO, IL-6 and TNF-α, which also repressed the licking times in both the first and second phases in formalin test. Furthermore, only L-nitroarginine partly reversed the analgesic activity of GJXL-1, indicating that GJXL-1's efficacy was partially mediated by NO regulation, possibly through inhibiting IRAK4/TAK1/NF-κB signaling pathway, and modulating gut microbiota and short-chain fatty acids production. In addition, the motor impairment and hypnotic effects of GJXL-1 were excluded. Our study suggests that GJXL-1 can be regarded as a promising and safe drug candidate for diverse pain disorders, and also a promising prebiotic candidate to maintain intestinal homeostasis and promote human gut health.

Effects of simulated digestion on the structural characteristics and dendritic cell activation of longan polysaccharides

An active polysaccharide (LP) from longan was purified and characterized. LP consisted of galactose and glucose in a molar ratio of 1.5: 98.5, with a molecular weight of 4.67 × 10⁷ g/mol. The main backbone of LP was T-α-D-Glcp-[(1 → 6)-α-D-Glcp-(1 → 6)-α-D-Glcp]_n. After simulated gastrointestinal digestion, the molecular weight distribution, monosaccharide composition, and major glycosidic bonds of LP were not significantly changed. LP and digested LP (DLP) reduced phagocytosis and promoted IL-10 and IL-12 secretion of dendritic cells. In addition, the effects of LP and DLP on activating dendritic cells showed no significant difference. This study helps to illuminate the potential mode of immunomodulatory action of longan polysaccharides in vivo.

Isolation, Characterization, and Compositional Analysis of Polysaccharides from Pinot Noir Wines: An Exploratory Study

It has been reported that polysaccharides in wine can interact with tannins and other wine components and modify the sensory properties of the wine. Unfortunately, the contribution of polysaccharides to wine quality is poorly understood, mainly due to their complicated structure and varied composition. In addition, the composition and molecular structure of polysaccharides in different wines can vary greatly. In this study, the polysaccharides were isolated from pinot noir wine, then separated into high-molecular-weight (PNWP-H) and low-molecular-weight (PNWP-L) fractions using membrane-based ultrafiltration. Each polysaccharide fraction was further studied using size exclusion chromatography, UV-Vis, FT-IR, matrix-assisted laser desorption/ionization-high-resolution mass spectrometry, and gas chromatography-mass spectrometry (GC-MS). The results showed that PNWP-L and PNWP-H had different chemical properties and compositions. The FT-IR analysis showed that PNWPs were acidic polysaccharides with α- and β-type glycosidic linkages. PNWP-L and PNWP-H had different α- and β-type glycosidic linkage structures. FT-IR showed stronger antisymmetric and symmetric stretching vibrations of carboxylate anions of uronic acids in PNWP-L, suggesting more uronic acid in PNWP-L. The size exclusion chromatography results showed that over 72% of the PNWP-H fraction had molecular sizes from 25 kDa to 670 kDa. Only a small percentage of smaller molecular polysaccharides was found in the PNWP-H fraction. In comparison, all of the polysaccharides in the PNWP-L fraction were below 25 KDa, with a majority distributed approximately 6 kDa (95.1%). GC-MS sugar composition analysis showed that PNWP-L was mainly composed of galacturonic acid, rhamnose, galactose, and arabinose, while PNWP-H was mainly composed of mannose, arabinose, and galactose. The molecular size distribution and sugar composition analysis suggested that the PNWP-L primarily consisted of rhamnogalacturonans and polysaccharides rich in arabinose and galactose (PRAG). In comparison, PNWP-H were mostly mannoproteins and polysaccharides rich in arabinose and galactose (PRAG). Further research is needed to understand the impacts of these fractions on wine organoleptic properties.

The variation on structure and immunomodulatory activity of polysaccharide during the longan pulp fermentation

In the current study, the effects of fermentation manners on the structure and immunomodulatory activity of polysaccharide in longan wine or vinegar were investigated. Compared to longan polysaccharide (CP1), polysaccharide in longan wine (CP2) or vinegar (CP3 and CP4) had smaller molecular weights, and was consisted of more mannose, arabinose, rhamnose, galactose and less glucose. After purification, the major fraction (P1-P4) was obtained from CP1-CP4, respectively. The structures and immunoregulatory activities of P1-P4 were characterized. Fermentation and purification were favorable to increase the immunoregulatory activities of P2-P4, which were contributed to their different structural features. The structure-activity relationship analysis indicated that molecular weight, mannose, rhamnose, glucuronic acid, glucose and arabinose were significantly associated with the cytokines secretion. Compared with other polysaccharides, P3 displayed better immunomodulatory activity due to its lower molecular weight, lower contents of rhamnose and glucose, and higher levels of mannose and arabinose by activating MAPK and PI3K/Akt signaling pathways.

Extraction, purification, structural features and biological activities of longan fruit pulp (Longyan) polysaccharides: A review

Dimocarpus longan Lour. (also called as longan) is a subtropical and tropical evergreen tree belonging to the Sapindaceae family and is widely distributed in China, Southeast Asia and South Asia. The pulp of longan fruit is a time-honored traditional medicinal and edible raw material in China and some Asian countries. With the advancement of food therapy in modern medicine, longan fruit pulp as an edible medicinal material is expected to usher in its rapid development as a functional nutrient. As one of the main constituents of longan fruit pulp, longan fruit pulp polysaccharides (LPs) play an indispensable role in longan fruit pulp-based functional utilization. This review aims to outline the extraction and purification methods, structural characteristics and biological activities (such as immunoregulatory, anti-tumor, prebiotic, anti-oxidant, anti-inflammatory and inhibition of AChE activity) of LPs. Besides, the structure-activity relationship, application prospect and patent application of LPs were analyzed and summarized. Through the systematic summary, this review attempts to provide a theoretical basis for further research of LPs, and promote the industrial development of this class of polysaccharides.