Crabapple fruit extracts lower hypercholesterolaemia in high-fat diet-induced obese mice

Nine New Glycosylated Compounds from the Leaves of the Medicinal Plant Malus hupehensis

Nine new compounds (1-9), including four dihydrochalcone glycosides, two dibenzofuran glycosides, and two biphenyl glycosides, were isolated from the leaves of the medicinal plant Malus hupehensis collected in Shennongjia Forestry District (Hubei, China). Their structures were elucidated by comprehensive spectroscopic techniques, including HRESIMS and NMR spectra. All compounds were tested by preliminary biological evaluation for their α-glucosidase inhibitory and NO production activities. Compound 4 was found to show significant inhibitory activity against NO production in LPS-activated RAW 264.7 macrophage cells with an IC50 value of 29.60 μM, and compounds 3 and 4 were found to exhibit potent α-glucosidase inhibition with IC50 values of 44.17 and 60.15 μM, respectively. This work represents the first report of the diverse glycosides from the plant Malus hupehensis. It expands our understanding of the secondary metabolites of this medicinal plant and lays the foundation for the study of the bioactive principles of the ethnic hypoglycemic medicinal plant.

Bioassay-guided preparation of antioxidant, anti-inflammatory active fraction from crabapples (Malus prunifolia (Willd.) Borkh.)

The aim of current study was to optimize the extraction process and purification of main components (MC) to obtain high antioxidant, anti-inflammatory effective fractions from crabapple (Malus prunifolia (Willd.) Borkh.). The effects of three variables including ethanol concentration A₁, solid-liquid ratio A₂, extraction temperature A₃ were investigated and optimized by response surface methodology (RSM) coupled with Box-Behnken design (BBD). The adsorption/desorption characteristics of MC on the five types of macroporous resins were investigated. According to batch adsorption test, HPD-300 resins were selected for kinetics. The adsorption mechanism showed that the process was appropriate by pseudo-second-order kinetics model, and purification parameters of MC were optimized through adsorption/desorption experiments with the column packed by HPD-300 resin. The effective fractions were obviously superior to other fractions according to DPPH, ABTS, COX-2 and 15-LOX radical scavenging. This work implies that the purified active fraction with high contents of antioxidants and anti-inflammatory compounds from crabapple might be potential source for natural products and food industries.

α-Glucosidase inhibitory phenylpropanoid-dihydrochalcone hybrids from the leaves of medicinal plant Malus hupehensis (Pamp.) Rehder

Eight undescribed phenylpropanoid-dihydrochalcone hybrids, namely (+)- and (-)-malahupin A, (+)- and (-)-malahupin B, (±)-malahupin C, malahupinosides A and B, 7‴-epi-malahupinoside B, together with two known compounds, phloretin and phlorizin, were isolated from the leaves of the folk medicinal plant Malus hupehensis. Their structures were elucidated by extensive NMR and MS spectroscopic methods, chiral-phase analysis, and ECD calculations. Compounds (+)-malahupin B and malahupinoside B showed weak inhibition activities against the nitric oxide production in liposaccharide-induced murine RAW264.7 macrophages with IC50 values of 36.7 and 27.0 μM, respectively. Compounds (+)- and (-)-malahupin A, (+)- and (-)-malahupin B exhibited significant α-glucosidase inhibitory activity, with IC50 values of 22.5, 19.1, 19.2, and 17.4 μM, respectively. The postulated biosynthetic pathways to these hybrid compounds were proposed. This work represents the first report of the natural phenylpropanoid-dihydrochalcone hybrid compound, and lays foundation for the study on the bioactive principles of the ethnic hypoglycemic medicinal plant.

Phytochemical compositions, health-promoting properties and food applications of crabapples: A review

Crabapples belong to the genus Malus (Rosaceae), which are small sized edible fruits with unique aroma and taste. According to previous studies, crabapples are rich in bioactive compounds and possess a series of health-promoting properties. Various crabapple-based food products and additives have also been developed by different research groups in recent years. In this paper, we aim to summarize the current knowledge about the phytochemical compositions, health-promoting properties and food applications of crabapples for the first time. It is shown that crabapples are good sources of polyphenols, terpenoids, vitamins, lipids, fibers, soluble sugars, microelements, organic acids and amino acids, which exhibit antioxidant, anticancer, lipid-lowering, anti-diabetic and anti-inflammatory activities in vitro and/or in vivo. Nowadays, the crabapple fruits have been successfully utilized to produce vinegar, jam, mixed beverage, fruit bar/gelatinized layers and lipophilic antioxidant. In a word, crabapples may have great potential in the development of new functional food and drinks.

How does Malus crabapple resist ozone? Transcriptomics and metabolomics analyses

Ozone (O₃), an oxidizing toxic air pollutant, is ubiquitous in industrialized and developing countries. To understand the effects of O₃ exposure on apple (Malus) and to explore its defense mechanisms, we exposed 'Hongjiu' crabapple to O₃ and monitored its responses using physiological, transcriptomics, and metabolomics analyses. Exposure to 300 nL L^-1 O₃ for 3 h caused obvious damage to the leaves of Malus crabapple, affected chlorophyll and anthocyanin contents, and activated antioxidant enzymes. The gene encoding phospholipase A was highly responsive to O₃ in Malus crabapple. McWRKY75 is a key transcription factor in the response to O₃ stress, and its transcript levels were positively correlated with those of flavonoid-related structural genes (McC4H, McDFR, and McANR). The ethylene response factors McERF019 and McERF109-like were also up-regulated by O₃. Exogenous methyl jasmonate (MeJA) decreased the damaging effects of O₃ on crabapple and was most effective at 200 μmol L ^-1. Treatments with MeJA altered the metabolic pathways of crabapple under O₃ stress. In particular, MeJA activated the flavonoid metabolic pathway in Malus, which improved its resistance to O₃ stress.

Targeted isolation and identification of bioactive compounds lowering cholesterol in the crude extracts of crabapples using UPLC-DAD-MS-SPE/NMR based on pharmacology-guided PLS-DA

The anti-hyperlipidemic effects of crude crabapple extracts derived from Malus 'Red jade', Malus hupehensis (Pamp.) Rehd. and Malus prunifolia (Willd.) Borkh. were evaluated on high-fat diet induced obese (HF DIO) mice. The results revealed that some of these extracts could lower serum cholesterol levels in HF DIO mice. The same extracts were also parallelly analyzed by LC-MS in both positive and negative ionization modes. Based on the pharmacological results, 22 LC-MS variables were identified to be correlated with the anti-hyperlipidemic effects using partial least square discriminant analysis (PLS-DA) and independent samples t-test. Further, under the guidance of the bioactivity-correlated LC-MS signals, 10 compounds were targetedly isolated and enriched using UPLC-DAD-MS-SPE and identified/elucidated by NMR together with MS/MS as citric acid(1), p-coumaric acid(2), hyperoside(3), myricetin(4), naringenin(5), quercetin(6), kaempferol(7), gentiopicroside(8), ursolic acid(9) and 8-epiloganic acid(10). Among these 10 compounds, 6 compounds, hyperoside(3), myricetin(4), naringenin(5), quercetin(6), kaempferol(7) and ursolic acid(9), were individually studied and reported to indeed have effects on lowering the serum lipid levels. These results demonstrated the efficiency of this strategy for drug discovery. In contrast to traditional routes to discover bioactive compounds in the plant extracts, targeted isolation and identification of bioactive compounds in the crude plant extracts using UPLC-DAD-MS-SPE/NMR based on pharmacology-guided PLS-DA of LC-MS data brings forward a new efficient dereplicated approach to natural products research for drug discovery.

Ethyl acetate extract of crabapple fruit is the cholesterol-lowering fraction

Hypercholesterolemia is highly associated with cardiovascular diseases (CVDs) such as atherosclerosis.