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• ATP, ADP, and AMP levels declined with increasing pulp autolysis index. • Arabinogalactan was the main component of WSP in litchi pulp. • Storage induced WSP depolymerization but did not change its structure. • Except for some LcPME , LcPL, LcGAL and LcPME were downregulated. Water-soluble polysaccharides (WSP) were extracted from the pulp of litchi. Its main component was identified as arabinogalactan. The dominant monosaccharide constituents were arabinose and galactose. Galactose and mannose accumulated at the end of storage. ATP, ADP and AMP levels declined with increasing pulp breakdown index. WSP depolymerized which was characterized by a decrease in its content and molecular weight, while its structure remained stable during storage. Polygalacturonase and pectate lyase (PL) were active at the early storage time, and β-galactosidase (GAL) and α- l -arabinofuranosidase followed thereafter. Except for some pectin methylesterase (LcPME), LcPL, LcGAL and LcPME gene expression was downregulated. It was deduced that depolymerization of polysaccharides was mainly caused by the rupture of the branched side chain and glacturonic acid backbone to smaller repeating units, and both cell wall-degrading enzymes and nonenzymatic factors, such as energy level, participated in the degradation of polysaccharides, and consequently pulp breakdown of litchi. [ABSTRACT FROM AUTHOR]

Abstract: Intervention studies with A-type oligomeric procyanidins from litchi (Litchi chinensis) pericarp (LPOPC) suggested its protective effect against cardiovascular diseases. However, there is no consensus on the absorption and metabolism of LPOPC. It was demonstrated that the main components in LPOPC were (−)-epicatechin, A-type procyanidin dimers, trimers and tetramers. Rats were orally administered different levels of LPOPC (150 and 300mg/kgbw), the procyanidins and their microbial metabolites in urine were identified by HPLC–MS/MS analysis 18h post-administration. Data indicated that seven aromatic acid metabolites excreted were significantly increased by 300mg/kgbw of LPOPC (P < 0.01). However, only (−)-epicatechin and its methylated derivatives were detected in rat plasma 1h after 300mg/kgbw of LPOPC administration. The total EC content absorbed in plasma was only 2.54±0.53μmol/L, indicating that the biological properties of LPOPC should be probably explained by its microbial degraded phenolic acids. [Copyright &y& Elsevier]

Abstract: Litchi (Litchi chinensis Sonn.) is a delicious fruit widely accepted by consumers all over the world. In this work, phytochemical investigation of litchi pericarp methanol extracts led to the isolation of a novel phenolic, 2-(2-hydroxyl-5-(methoxycarbonyl) phenoxy) benzoic acid, together with kaempferol, isolariciresinol, stigmasterol, butylated hydroxytoluene, 3,4-dihydroxyl benzoate, methyl shikimate and ethyl shikimate. Most were found in litchi pericarp for the first time. Their structures were mainly elucidated by NMR and MS evidences. Antioxidant activities of the eight compounds were determined by a DPPH radical scavenging assay and the results showed that 2-(2-hydroxy-5-(methoxycarbonyl) phenoxy)benzoic acid, kaempferol, isolariciresinol, butylated hydroxytoluene and 3,4-dihydroxy benzoate exhibited good antioxidant activities. An interesting finding was that butylated hydroxytoluene was detected as a natural antioxidant in this work, which was usually taken as a synthesized antioxidant. Furthermore, the novel compound exhibited no inhibitory effects against tyrosinase and α-glucosidase activities. [Copyright &y& Elsevier]

Abstract: Procyanidin oligomers from litchi pericarp (Litchi chinensis) were isolated and identified by online analysis. Accurate molecular weight (MW) distribution and composition of the procyanidin extracts were recorded on an Apex-Qe–FT–ICR mass spectrometer. The MW range of litchi procyanidins was from 289.07151 to 1439.30529 m/z and composed of A- and B-series oligomeric procyanidins. The variety of the main procyanidins (DP<5) was identified by HPLC and LC–ESI-MS analysis. There are more than 41.7% of A-series procyanidins in the oligomeric procyanidins, however, B-series procyanidins takes only 24.1% of the litchi pericarp extracts. In this study, we determined the effects of (−)-epicatechin, A-type procyanidin dimer (A2) and trimer, epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin from litchi pericarp on free radical scavenging. The results showed that A-type procyanidin dimer and trimer both had a strong scavenging ability on DPPH and OH, indicating that litchi is a new plant source of A-type procyanidins and natural antioxidant. [Copyright &y& Elsevier]

Abstract: Using a bioactivity-guided method, a new and a previously reported flavanone glycoside were isolated from 50% ethanol extract of litchi (Litchi chinensis Sonn.) seeds. Column chromatography using macroporous resin, silica gel and Sephadex LH-20 was applied during the isolation, and the method of PMP derivatisation was performed to investigate the component sugar of the compounds. The structures of the compounds were elucidated by 1H, 13C, and 2D NMR (HMQC, HMBC) spectroscopy and HR-ESIMS. Compound 1 was identified as (2R)-naringenin-7-O-(3-O-α-l-rhamnopyranosyl-β-d-glucopyranoside), a new, natural product that had been synthesised previously. Compound 2 was (2S)-pinocembrin-7-O-(6-O-α-l-rhamnopyranosyl-β-d-glucopyranoside). The two isolated compounds showed activity in the α-glucosidase inhibition assay. [Copyright &y& Elsevier]

Abstract: Litchi (Litchi chinensis Sonn.) is widely accepted as a delicious fruit in China and its seeds have been commonly used in traditional Chinese medicine to relieve neuralgic pain. In the present study, chemical investigation of the 95% ethanol extract of Litchi chinensis seeds led to the isolation of four new compounds, 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β-8-catechin) (5), 2β,3β-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4α-8-epicatechin) (7), litchiol A (9) and litchiol B (12), together with 11 known ones, 2,5-dihydroxy-hexanoic acid (1), soscopoletin (2), coumaric acid (3), protocatechuic acid (4), 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β−8)-epicatechin (6), pterodontriol d-6-O-β-d-glucopyranoside (8), Narirutin (10), naringin (11), dihydrocharcone-4′-O-β-d-glucopyranoside (13), pinocembrin-7-rutinoside (14), pinocembrin-7-neohesperidoside (15). Their structures were mainly elucidated on the basis of NMR, MS, IR, CD and UV spectral evidences. Antioxidant activities of 14 compounds were determined by DPPH radical-scavenging assay and Trolox equivalent antioxidant capacity assay, and the results showed that four compounds, protocatechuic acid (4), 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β-8-catechin (5), 2α,3α-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4β−8)-epicatechin (6), 2β,3β-epoxy-5,7,3′,4′-tetrahydroxyflavan-(4α-8)-epicatechin (7), exhibited moderate antioxidant activities. [ABSTRACT FROM AUTHOR]

Abstract: In an earlier study, radiation treatment (0.5kGy) and low temperature (4°C) storage were found to extend the shelf life of litchi fruit var. ‘Shahi’ and ‘China’ from India up to 28days, while maintaining its physical, biochemical and organoleptic properties. The current study was aimed to elucidate the antioxidant and radioprotective properties of the litchi fruit, and the effect of radiation processing on these properties. The litchi fruit was found to be significantly rich in antioxidant and radioprotective properties, and the antioxidant parameters were found to be well correlated with the phenolic and flavonoid contents. A significant protection to pBR322 plasmid DNA and Escherichia coli cells from radiation induced damage was observed in the presence of litchi juice. Plasmid DNA was well protected even at the dose of 5kGy, whereas, bacterial cells could be protected up to 0.5kGy. Neither of these properties was found to be sensitive to radiation processing or low temperature storage. [ABSTRACT FROM AUTHOR]

Abstract: Two new sesquiterpene glucosides, litchiosides A (1) and B (2), were obtained along with pumilaside A (3) and funingensin A (4) from lychee (Litchi chinensis Sonn.) seed. Their structures were elucidated on the basis of spectroscopic and chemical evidence. The in vitro antitumour activity of compounds 1–4 against A549, LAC, Hela, and Hep-G2 cell lines was determined using the MTT colourimetric assay. Pumilaside A (3) exhibited significant activity against all the tested cell lines with IC50 values of 0.012–6.29μM, and funingensin A (4) showed moderate activity against Hep-G2 cells (IC50 =39.27μM), while litchiosides A (1) and B (2) were found to be inactive. [Copyright &y& Elsevier]

Abstract: The antioxidant capacities of the acetone, methanol and water extracts of hot-air dried lychee (Litchi chinenesis Sonn.) flowers were estimated with Trolox equivalent antioxidant capacity (TEAC) assay, reducing power and 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical-scavenging assay. The contents of antioxidant components in these extracts were also determined. Results showed that the highest and lowest contents of these components including phenols, flavonoids and condensed tannins were found in acetone and water extracts, respectively. The antioxidant activities of the lychee flower extracts for all assays were in the order: acetone extract>methanol extract>water extract. The contents of antioxidant components in these extracts were correlated with antioxidant activities. [Copyright &y& Elsevier]

Abstract: The main oligomeric procyanidins from litchi pericarp (Litchi chinensis) were isolated and identified. Complete assignment of epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin structure was obtained using CD, NMR and ESI-MS techniques. The known (−)-epicatechin and procyanidin A2 were also isolated from litchi pericarp. The effects of oligomeric procyanidins, A2 and epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin from litchi pericarp on free radical-scavenging were determined by using a chemiluminescent method. The results showed that all of them had a strong scavenging effect on OH, and the IC50 values were 2.60μg/ml, 1.75μg/ml and 1.65μg/ml for oligomeric procyanidins, A2 and the trimeric procyanidins, respectively. The antioxidant activities of A-type dimeric and trimeric procyanidins seemed to be related to the number of hydroxyls in their molecular structures. [Copyright &y& Elsevier]

Abstract: To evaluate the possibility of using high pressure as an alternative to canning for lychee preservation, fresh lychees and samples preserved in syrup were subjected to various pressures (200–600 MPa), temperatures (20–60 °C) and times (10 or 20 min) and subsequently analysed for physical attributes, peroxidase (POD) and polyphenol oxidase (PPO) activities. Pressure treatment caused less loss of visual quality in both fresh and syrup processed lychee than thermal processing. The optimal pH for lychee POD and PPO were 5.0–8.0 and 7.0, respectively. Pressure treatment at 200 MPa caused a marked increase of POD activity and this effect was greater at 40 °C than at 20 and 60 °C. Pressure treatment at 400 and 600 MPa, and temperatures of 20–40 °C, did not affect the activity of POD, but some inactivation at 60 °C was observed. The combined effect of pressure and temperature on PPO activity were more marked at the longer treatment time (20 min) and under the more severe treatments. A pressure 600 MPa, at 60 °C for 20 min caused extensive inactivation of POD and PPO in fresh lychee, over 50% and 90% respectively but for those processed in syrup, the effects were less marked, presumably due to baroprotection by the syrup. Overall lychee POD was more pressure resistant than PPO. [Copyright &y& Elsevier]

Litchi (Litchi chinensis Sonn.) is a subtropical to tropical fruit of high commercial value in international trade. However, harvested litchi fruit rapidly lose their bright red skin colour. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments. This process is associated with enzymatic oxidation of phenolics by polyphenol oxidase (PPO) and/or peroxidase (POD). PPO and POD from litchi pericarp cannot directly oxidize anthocyanins. Moreover, PPO substrates in the pericarp are not well characterised. Consequently, the roles of PPO and POD in litchi browning require further investigation. Recently, an anthocyanase catalysing the hydrolysis of sugar moieties from anthocyanin to anthocyanidin has been identified in litchi peel for the first time. Thus, litchi enzymatic browning may involve an anthocyanase–anthocyanin–phenolic–PPO reaction. Current research focus is on characterising the properties of the anthocyanase involved in anthocyanin degradation. Associated emphasis is on maintenance of membrane functions in relation to loss of compartmentation between litchi peel oxidase enzymes and their substrates. [Copyright &y& Elsevier]

Free and glycosidically-bound volatile compounds were isolated and separated from fresh clear lychee juice using an Amberlite XAD-2 column. The volatile compounds from the bound fraction were released by hydrolysis with almond β-glucosidase. Volatile components of both free and bound fractions were then determined by GC and GC–MS, and they showed similar volatile profiles. Totally, 25 compounds were identified in both fractions, including one ester, 14 alcohols, two aldehydes, four acids, two ketones and two terpenes. In the free fraction (2907 mg kg−1), the major volatile compounds found were acetoin (30.1%), geraniol (15.6%), 3-methyl-2-buten-1-ol (15.3%), octanoic acid (7.28%), 2-phenylethanol (4.91%), cis-ocimene (4.32%), and butyric acid (3.40%). In the bound fraction (1576 mg kg−1), the latent major volatile compounds found were geraniol (73.7%) and geranial (7.95%). In aroma evaluation, the free volatile fraction showed a fresh-fruity, lychee-like aroma whereas the bound fraction was odourless. The characteristic lychee-like aroma was noted in the bound fraction after enzymatic hydrolysis. On combination of the free and hydrolysed bound fractions, a strongly fruity, lychee-like aroma was perceived. [Copyright &y& Elsevier]