This study comprehensively analysed the chemical composition of the cuticle in pitaya fruits. The total coverage amount of the waxes versus cutin monomers accumulated at a ratio of 0.6, corresponding to masses per unit of 30.3 μg·cm−2and 50.8 μg·cm−2, respectively. The predominant wax mixtures weren-alkanes in homologous series of C20–C35, dominated by C31and C33; as well as triterpenoids with an abundant amount of uvaol, lupenon, β-amyrinon, and β-amyrin. The most prominent cutin compounds were C16- and C18-type monomers, in which 9(10),16-diOH-hexadecanoic acid and 9,10-epoxy-ω-OH-octadecanoic acid predominated, respectively. The average chain length (ACL) of aliphates in pitaya fruit cuticle (30.5) was similar to that estimated in leaf waxes, and higher than that in most of the fruit and petal waxes that have been reported. We propose that the relatively high ACL and wax/cutin ratio might enhance the cuticular barrier properties in pitaya fruit cuticle to withstand drought.Keywords:pitaya fruit;cuticle;wax;cutin;ACL
A sulfated polysaccharide (AG) was extracted and isolated from the sea cucumberH. fuscopunctata, consisting of GlcNAc, GalNAc, Gal, Fuc and lacking any uronic acid residues. Importantly, several chemical depolymerization methods were used to elucidate the structure of the AG through a bottom-up strategy. A highly sulfated galactose (oAG-1) and two disaccharides labeled with 2,5-anhydro-D-mannose (oAG-2, oAG-3) were obtained from the deaminative depolymerized product along with the structures of the disaccharide derivatives (oAG-4~oAG-6) identified from the free radical depolymerized product, suggesting that the repeating building blocks in a natural AG should comprise the disaccharide β-D-GalS-1,4-D-GlcNAc6S. The possible disaccharide side chains (bAG-1) were obtained with mild acid hydrolysis. Thus, a natural AG may consist of a keratan sulfate-like (KS-like) glycosaminoglycan with diverse modifications, including the sulfation types of the Gal residue and the possible disaccharide branches α-D-GalNAc4S6S-1,2-α/β-L-Fuc3Slinked to the KS-like chain. Additionally, the anticoagulant activities of the AG and its depolymerized products (dAG1-9) were evaluated in vitro using normal human plasma. The AG could prolong activated partial thromboplastin time (APTT) in a dose-dependent manner, and the activity potency was positively related to the chain length. The AG and dAG1-dAG3 could prolong thrombin time (TT), while they had little effect on prothrombin time (PT). The results indicate that the AG could inhibit the intrinsic and common coagulation pathways.Keywords:aminoglycan;structural features;keratan sulfate;depolymerization;oligosaccharides;anticoagulant activity
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