Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

Piper Species: A Comprehensive Review on Their Phytochemistry, Biological Activities and Applications.

The biological activities of natural lignans from olives and virgin olive oils: A review

Antibacterial activity and mechanism of pinoresinol from Cinnamomum Camphora leaves against food-related bacteria

Hawthorn is a well-known functional food; at present, increasing attention has been given to hawthorn leaf due to its numerous functional and nutritional properties. In this study, the antithrombotic properties of hawthorn leaves were evaluated using the activity-guided isolation process and high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). A crude extract prepared in 75% ethanol was fractionated using macroporous resin D101 and polyamide chromatography to obtain three active fractions (Fr.C, Fr.C-1 and Fr.C-2). Thereafter, the inhibitory activities of these fractions were examined by platelet aggregation and antithrombus assays using a zebrafish model. Using the HPLC-QTOF-MS technique, we identified 25 compounds in the active fraction (Fr.C). The structures of these compounds were identified by comparing the retention time (tR) and mass spectral data from the previous reports and 19 reference compounds. Based on the analysis, 21 peaks were detected in the mass spectrum of Fr.C-1 and 8 peaks were detected in Fr.C-2, we found that 11 compounds in Fr.C-1 exhibited potent inhibitory effects on platelet aggregation, including nine monoterpenoids, one diterpenoid and one flavanone. Accordingly, monoterpenoids are suggested as the main anti-platelet aggregation constituents from hawthorn leaves. Particularly, compounds 10 and 24 inhibited ADP-induced platelet aggregation and delayed FeCl3-induced thrombus in zebrafish. Furthermore, interactions between compounds 10 and 24 with two ADP receptors P2Y1 and P2Y12, serving as the target for key regulators of antiplatelet aggregative activity, were investigated via molecular modeling. In addition, five flavones were obtained from the active fraction (Fr.C-2). These results indicated that monoterpenoid glycosides and some flavones were responsible for the antithrombotic activity of hawthorn leaves. Moreover, this study shows that the activity-guided isolation is a fast, efficient and systematic separation method for the identification of active compounds in natural products.

Antiplatelet aggregation and antithrombotic benefits of terpenes and flavones from hawthorn leaf extract isolated using the activity-guided method

Carbohydrates are synthetically challenging molecules with vital biological roles in all living systems. Selective synthesis and functionalization of carbohydrates provide tremendous opportunities to improve our understanding on the biological functions of this fundamentally important class of molecules. However, selective functionalization of seemingly identical hydroxyl groups in carbohydrates remains a long-standing challenge in chemical synthesis. We herein describe a practical and predictable method for the site-selective and stereoselective alkylation of carbohydrate hydroxyl groups via Rh(II)-catalyzed insertion of metal carbenoid intermediates. This represents one of the mildest alkylation methods for the systematic modification of carbohydrates. Density functional theory (DFT) calculations suggest that the site selectivity is determined in the Rh(II)-carbenoid insertion step, which prefers insertion into hydroxyl groups with an adjacent axial substituent. The subsequent intramolecular enolate protonation determines the unexpected high stereoselectivity. The most prevalent trans-1,2-diols in various pyranoses can be systematically and predictably differentiated based on the model derived from DFT calculations. We also demonstrated that the selective O-alkylation method could significantly improve the efficiency and stereoselectivity of glycosylation reactions. The alkyl groups introduced to carbohydrates by OH insertion reaction can serve as functional groups, protecting groups, and directing groups.

Lian Yang

Papers

Lignans and aromatic glycosides from Piper wallichii and their antithrombotic activities

Chemical constituents from Piper wallichii