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.

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.