Antioxidant effect and active components of litchi (Litchi chinensis Sonn.) flower

Proanthocyanidin A2 attenuates the activation of hepatic stellate cells by activating the PPAR-γ signalling pathway

Liver fibrosis is the pathological process of chronic liver diseases induced by hepatic stellate cells. Proanthocyanidin A2 (PA2) has multiple pharmacological activities. In this study, we aimed to explore the effects of PA2 on hepatic stellate cell (HSC) activation in liver fibrosis. LX-2 cells were treated with TGF-β1 to establish a fibrosis cell model. Cell viability was evaluated using cell counting kit-8. The levels of fibrosis-related factors (collagen I, fibronectin, and α-SMA) were examined using quantitative real-time polymerase chain reaction, western blot, and immunofluorescence assay. The molecular mechanisms of PA2 were evaluated by RNA-seq, bioinformatic analysis, and western blot. The results showed that PA2 suppressed cell viability, and downregulated fibrosis-related factors induced by TGF-β1, suggesting PA2 suppressed the activation of HSCs. PA2 treatment-induced differentially expressed mRNAs are predicted to be associated with the PPAR-γ pathway. PA2 reversed the downregulation of PPAR-γ and the upregulation of phosphorylated (p)-Smad2 and Smad3. A rescue experiment illustrated that the inactivation of the PPAR-γ pathway reversed the effects of PA2 on cell viability and HSC activation. In conclusion, PA2 inhibited TGF-β1-induced activation of HSCs by activating the PPAR-γ/Smad pathway. The findings suggested that PA2 may be an effective treatment for liver fibrosis.

Ixodicidal effect of extracts from Cordia boissieri, Artemisia ludoviciana and Litchi chinensis on Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The ixodicidal activity of the methanolic extracts of Artemisia ludoviciana (Astereceae), Cordia boissieri (Boraginaceae) and Litchi chinensis (Sapindaceae) against two field populations of Rhipicephalus (Boophilus) microplus from the state of Nuevo Leon (NL) and Veracruz (VER) was evaluated. The extract of L. chinensis in the concentration of 150 mg/ml showed efficacies of 100% and 99% against engorged females and mortalities of 98% and 99% against larvae. C. boissieri in the same concentration showed efficacies of 71% and 37% against engorged adults and mortalities of 33.04% and 10.33% against larvae and A. ludoviciana had efficacies of 94% and 83% in adults and mortalities of 89.39% and 89.21% against larvae in both populations respectively. The enzymatic activity of Acetylcholinesterase (AChE), Carboxylesterase (CaE), Glutathione-S-Transferase (GST) and Alkaline Phosphatase (ALP) was measured in both populations of ticks. As a result, a significant difference between both populations was shown, being the VER population the one that exhibited a higher enzymatic activity (p ≤ 0.05). It can be concluded that the methanolic extract of the seed of L. chinensis shows potential ixodicidal activity and can be used as an alternative source of tick control, however, prior characterization, toxicity and formulation studies are necessary.

Litchi flower essential oil balanced lipid metabolism through the regulation of DAF-2/IIS, MDT-15/SBP-1, and MDT-15/NHR-49 pathway

Many litchi flowers are discarded in China every year. The litchi flower is rich in volatile compounds and exhibits strong anti-obesity activity. Litchi flower essential oil (LFEO) was extracted by the continuous phase transformation device (CPTD) independently developed by our research group to recycle the precious material resources in litchi flowers. However, its fat-reducing effect and mechanism remain unclear. Employing Caenorhabditis elegans as a model, we found that LFEO significantly reduced fat storage and triglyceride (TG) content in normal, glucose-feeding, and high-fat conditions. LFEO significantly reduced body width in worms and significantly decreased both the size and number of lipid droplets in ZXW618. LFEO treatment did not affect energy intake but increased energy consumption by enhancing the average speed of worms. Further, LFEO might balance the fat metabolism in worms by regulating the DAF-2/IIS, sbp-1/mdt-15, and nhr-49/mdt-15 pathways. Moreover, LFEO might inhibit the expression of the acs-2 gene through nhr-49 and reduce β-oxidation activity. Our study presents new insights into the role of LFEO in alleviating fat accumulation and provides references for the large-scale production of LFEO to promote the development of the litchi circular economy.

Polyphenols extracted from Enteromorpha clathrata alleviates inflammation in lipopolysaccharide-induced RAW 264.7 cells by inhibiting the MAPKs/NF-κB signaling pathways

ETHNOPHARMACOLOGY RELEVANCE

Enteromorpha has long been recorded in traditional Chinese medicine, with cholesterol-lowering, anti-cancer, anti-inflammatory and antibacterial effects. Recently, we extracted the polyphenol-enriched fraction from Enteromorpha clathrata (E. clathrata) by ethyl acetate (ECPs), and isolated six individual polyphenols from ECPs via high-speed counter-current chromatography (HSCCC) with high-performance liquid chromatography (HPLC).

AIM OF THE STUDY

In this study, we explored the anti-inflammatory activity and underlying mechanism of ECPs in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages.

MATERIALS AND METHODS

ECPs and the six polyphenols were used for nitric oxide (NO) assay to identify the components with potent inflammation inhibitory effect. Enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (qPCR), flow cytometry, and Western blot analysis were applied to further investigate their anti-inflammatory effects and underlying mechanism in LPS-stimulated RAW264.7 cells.

RESULTS

ECPs and the three individual polyphenols, including (-)-epicatechin, epigallocatechin-3-O-gallate and (-)-epicatechin-3-O-gallate, showed in vitro immunosuppressive activity by altering the cell biology at the gene, protein and functional levels in a dose- and species-dependent manner. Their anti-inflammatory effects were achieved by inhibiting LPS-induced production of nitric oxide and its upstream enzyme inducible nitric oxide synthase (iNOS), the pro-inflammatory cytokines including interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), as well as the phagocytotic capacity, without cytotoxicity. The mechanism study further revealed that these anti-inflammatory properties were, at least partly, attributed to the suppressed activation of nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signaling pathways.

CONCLUSIONS

These findings indicated for the first time the correlation between the anti-inflammatory activity of ECPs and NF-κB and MAPK signaling pathways, suggesting that polyphenol-enriched organic fraction of E. clathrata could be potential candidate as therapeutic agent for treating inflammatory diseases.

Effects of three drying methods on polyphenol composition and antioxidant activities of Litchi chinensis Sonn

The aim of this study was to investigate the effects of three different drying methods, freeze drying (FD), vacuum drying (VD) and oven drying (OD) on phenolic contents and antioxidant activities of litchi fruits. 20 polyphenols were exactly identified in the litchi fruits by UPLC-QqQ/MS. Significant losses were observed in the contents of total polyphenols and antioxidant activities in the dried litchi when compared with the fresh litchi. Principle component analysis indicated that there was significant difference of phenolic component between the use of thermal drying (VD and OD) and FD. Our results suggest that FD is the optimum drying method for litchi fruits considering the content of total polyphenols and antioxidant activities.

Litchi (Litchi chinensis Sonn.) flower proanthocyanidin fraction exhibited protective efficacy to suppress nickel-induced expression for vascular endothelial growth factor in HepG2 cells

The protective efficacy of litchi (Litchi chinensis Sonn.) flower proanthocyanidin fraction (LFPF) composed of (-)-epicatechin and proanthocyanidin A2 against vascular endothelial growth factor (VEGF) generation induced by nickel (Ni) in hepatocellular carcinoma (Hep G2) cells was studied. VEGF is an angiogenic inducer, which promotes tumor angiogenesis, leading to rapid tumor growth and metastasis. VEGF could be substantially induced in the Ni-mediated Hep G2 cells. Through LFPF treatment, the Ni-induced VEGF generation could be suppressed significantly. The inhibition of HIF-1α expression by blocking phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathways, and the suppression of Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT 3), and Raf-1 proto-oncogene, serine/threonine kinase (RAF1)/mitogen-activated protein kinase (MEK1/2)/extracellular-signal-regulated kinase (ERK1/2) pathways are important molecular mechanisms for the LFPF action. LFPF should probably reduce the risk of liver cancer in Ni-contaminated environments by inhibiting VEGF expression. PRACTICAL APPLICATIONS: LFPF mainly contained (-)-epicatechin and proanthocyanidin A2. Our results demonstrated that LFPF considerably suppressed the Ni-induced VEGF expression through inhibition of JAK2/STAT 3 and RAF1/MEK1/2/ERK1/2 pathways and prohibited HIF-1α expression through blocking PI3K/AKT/mTOR pathway. Litchi flowers might have the potential to diminish the liver cancer risk in a Ni-contaminated environment through suitable treatment.

Litchi chinensis as a Functional Food and a Source of Antitumor Compounds: An Overview and a Description of Biochemical Pathways

Litchi is a tasty fruit that is commercially grown for food consumption and nutritional benefits in various parts of the world. Due to its biological activities, the fruit is becoming increasingly known and deserves attention not only for its edible part, the pulp, but also for its peel and seed that contain beneficial substances with antioxidant, cancer preventive, antimicrobial, and anti-inflammatory functions. Although literature demonstrates the biological activity of Litchi components in reducing tumor cell viability in in vitro or in vivo models, data about the biochemical mechanisms responsible for these effects are quite fragmentary. This review specifically describes, in a comprehensive analysis, the antitumor properties of the different parts of Litchi and highlights the main biochemical mechanisms involved.

Extraction, chemical characterization and antioxidant activity of Litchi chinensis Sonn. and Avena sativa L. seeds extracts obtained from pressurized n-butane

The extraction of litchi (Litchi chinensis Sonn.) and oat (Avena sativa L.) seeds were investigated using n-butane as pressurized solvent by evaluating the effect of pressure in the range of 7-100 bar and temperature from 25 to 70 °C on the extract yield and chemical composition together with the antioxidant activity of the extracts obtained. It was experimentally observed extraction yields for both seeds up to ~3.5 wt%, with a total phenolic content around 126.4 mg GAE/100 g of extract, and an antioxidant activity up to 78.36%. Oat seeds extract presented higher values of these parameters evaluated compared to litchi extract. Based on the results found, it seems that n-butane may be a promising solvent to conventional extraction methods, as mild operating conditions and eco-friendly solvent can be used to provide good results without any residues in the final product.

Effective compounds in the fruit of Muntingia calabura Linn. cultivated in Taiwan evaluated with scavenging free radicals and suppressing LDL oxidation

The effective antioxidant compounds ofM. calaburaLinn. fruit.

Biological and Phytopharmacological Descriptions of Litchi Chinensis

Plants remain a vital source of drugs and at present, much emphasis is given to nutraceuticals. Herbal medicines have been the basis of treatment and cure for various diseases and physiological conditions in the traditional methods practiced such as ayurveda and homeopathy. Litchi chinensis belongs to the Sapindaceae family and is well-known in the Indian traditional system for its traditional uses. The parts of the plant used are leaves, flowers, fruits, seed, pulp, and pericarp. All parts of the plant are rich sources of phytochemicals--epicatechin; procyanidin A2 and procyanidin B2; leucocyanidin; cyanidin glycoside, malvidin glycoside, and saponins; butylated hydroxytoluene; isolariciresinol; kaempferol; rutin; and stigmasterol. In the present review, we explore the lychee's description, traditional medicinal uses, and phytoconstituents, and investigate the pharmacological activities in various parts of the lychee to show its importance in ethanopharmacology. This is so that this review can serve as a ready-to-use material for further research on the plant.

Litchi chinensis: medicinal uses, phytochemistry, and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Litchi chinensis Sonn. (Sapindaceae) has been widely used in many cultures for the treatment of cough, flatulence, stomach ulcers, diabetes, obesity, testicular swelling, hernia-like conditions, and epigastric and neuralgic pains. The ethnopharmacologial history of L. chinensis indicated that it possesses hypoglycemic, anticancer, antibacterial, anti-hyperlipidemic, anti-platelet, anti-tussive, analgesic, antipyretic, hemostatic, diuretic, and antiviral activities.

AIM OF THE REVIEW

The aim of this review is to provide up-to-date information on the botanical characterization, distribution, traditional uses, and chemical constituents, as well as the pharmacological activities and toxicity of L. chinensis. Moreover, the focus of this review is the possible exploitation of this plant to treat different diseases and to suggest future investigations.

MATERIALS AND METHODS

To provide an overview of the ethnopharmacology, chemical constituents, and pharmacological activities of litchi, and to reveal their therapeutic potentials and being an evidence base for further research works, information on litchi was gathered from scientific journals, books, and worldwide accepted scientific databases via a library and electronic search (PubMed, Elsevier, Google Scholar, Springer, Scopus, Web of Science, Wiley online library, and pubs.acs.org/journal/jacsat). All abstracts and full-text articles were examined. The most relevant articles were selected for screening and inclusion in this review.

RESULTS

A comprehensive analysis of the literature obtained through the above-mentioned sources confirmed that ethno-medical uses of L. chinensis have been recorded in China, India, Vietnam, Indonesia, and Philippines. Phytochemical investigation revealed that the major chemical constituents of litchi are flavonoids, sterols, triterpenens, phenolics, and other bioactive compounds. Crude extracts and pure compounds isolated from L. chinensis exhibited significant antioxidant, anti-cancer, anti-inflammatory, anti-microbial, anti-viral, anti-diabetic, anti-obesity, hepato-protective, and immunomodulatory activities. From the toxicological perspective, litchi fruit juice and extracts have been proven to be safe at a dose 1 g/kg.

CONCLUSIONS

Phytochemical investigations indicated that phenolics were the major bioactive components of L. chinensis with potential pharmacological activities. The ethnopharmacological relevance of L. chinensis is fully justified by the most recent findings indicating it is a useful medicinal and nutritional agent for treating a wide range of human disorders and aliments. Further investigations are needed to fully understand the mode of action of the active constituents and to fully exploit its preventive and therapeutic potentials.

Identification of proanthocyanidins from litchi (Litchi chinensis Sonn.) pulp by LC-ESI-Q-TOF-MS and their antioxidant activity

Content of total proanthocyanidins as well as total phenolics, flavonoids, antioxidant activities were evaluated for litchi (Litchi chinensis Sonn.) pulp of 32 cultivars. One cultivar, Hemaoli, showed the highest total proanthocyanidins and total phenolics, and DPPH or ABTS radical scavenging activities. ESI-MS and NMR analysis of the Hemaoli pulp crude extracts (HPCE) showed that procyandins composed of (epi)catechin unites with degree of polymerization (DP) of 2–6 were dominant proanthocyanidins in HPCE. After the HPCE was fractionated by a Sephadex LH-20 column, 32 procyanidins were identified by LC-ESI-Q-TOF-MS in litchi pulp for the first time. Quantification of individual procyanidin in HPCE indicated that epicatechin, procyanidin B2, procyanidin C1 and A-type procyanidin trimer were the main procyanidins. The radical scavenging activities of different fractions of HPCE as well as six procyanidins standards were evaluated by both DPPH and ABTS assays. HPCE fractions showed similar antioxidant activities with those of Vc and six individual procyanidins, the IC₅₀ of which ranged from 1.88 ± 0.01 to 2.82 ± 0.10 μg/ml for DPPH assay, and from 1.52 ± 0.17 to 2.71 ± 0.15 μg/ml for ABTS assay. Such results indicate that litchi cultivars rich in proanthocyanidins are good resources of dietary antioxidants and have the potential to contribute to human health.

Genetic analysis of litchi (Litchi chinensis Sonn.) in southern China by improved random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR)

Litchi (Litchi chinensis Sonn., L. chinensis), a type of tree growing in most areas of southern China, produces an edible fruit that is also a source of traditional medicine. Genetic identification of litchi species or cultivars using molecular markers is very important. In this study, a total of six litchi samples from Fujian, Hainan, Guangdong, Guangxi and Sichuan province, as well as one wild Dimocarpus confinis (D. confinis) sample from Guangxi province were collected for genetic analysis. The cluster dendrograms were constructed for genetic analysis on the basis of DNA amplification results by RAPD and ISSR. The improved RAPD amplified DNA with consistent and clear banding patterns. A total of 176 bands were found, indicating a 72.7 % polymorphism in L. chinensis DNA samples. Significant genetic distances were found among the different species or cultivars, with an index of similarity coefficient ranging from 0.59 to 0.87. Similar to RAPD results, ISSR analysis of the L. chinensis DNA samples showed a range of 0.70-0.93 similarity coefficients. The genetic distance between Hainan sample and Sichuan samples was the farthest, which is consistent with their geographic distance. Furthermore, the index of similarity coefficient between D. confinis and L. chinensis was 0.35-0.41 by RAPD and 0.38-0.48 by ISSR, indicating that these two species have significant genetic difference. This study reveals the high level of genetic differences between different litchi species or cultivars, and confirms the significance of the improved RAPD method in genetic characterization of organisms. Taken together, the improved RAPD combined with ISSR analysis can be used frequently for the genetic diversity, germplasm resources preservation, molecular-assisted breeding, and genetic characterization of various organisms.

Inhibitory effect of litchi (Litchi chinensis Sonn.) flower on lipopolysaccharide-induced expression of proinflammatory mediators in RAW264.7 cells through NF-κB, ERK, and JAK2/STAT3 inactivation

Litchi (Litchi chinensis Sonn.) flower ethanolic extract (LFEE) was found to contain five flavanoids [total amount, 102.73 ± 5.50 mg/g of dried extract (gDE)], nine phenolic acids (total amount, 60.31 ± 4.52 mg/gDE), and proanthocyanidin A2 (79.31 ± 2.95 mg/gDE). LFEE was used to evaluate the inhibitory effects on lipopolysaccharide- (LPS-) induced pro-inflammatory mediators in RAW264.7 cells. The results showed that LFEE treatment could suppress the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the productions of nitric oxide (NO) and prostaglandin E2 (PGE2), and the secretions of pro-inflammatory cytokines [interleukin-1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α)] in the LPS-mediated RAW264.7 cells. The attenuation of LPS-induced inflammatory responses by LFEE was found to be closely related to the inhibition of the translocation of nuclear factor κB (NF-κB) p50/p65 subunits correlated with suppression of the activation of the inhibitor of κB kinase (IKK) α/β and downregulation of activation of extracellular signal-regulated kinase (ERK) and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3).