Embelin is a naturally occurring para-benzoquinone isolated from Embelia ribes (Burm. f.) of the Myrsinaceae family, and contains two carbonyl groups, a methine group and two hydroxyl groups. With embelin as the lead compound, more than one hundred derivatives have been reported. Embelin is well known for its ability to antagonize the X-linked inhibitor of apoptosis protein (XIAP) with an IC50 value of 4.1 μM. The potential of embelin and its derivatives in the treatment of various cancers has been extensively studied. In addition, these compounds display a variety of other biological effects: antimicrobial, antioxidant, analgesic, anti-inflammatory, anxiolytic and antifertility activity. This paper reviews the recent progress in the synthesis and biological activity of embelin and its derivatives. Their cellular mechanisms of action and prospects in the research and development of new drugs are also discussed.

Embelin is a naturally occurring para-benzoquinone isolated from Embelia ribes (Burm. f.) of the Myrsinaceae family. It was first discovered to have potent inhibitory activity (IC 50 ¼ 4.2 lM) against a-glucosidase in this study. Then, four series of novel embelin derivatives were designed, prepared and evaluated in a-glucosidase inhibition assays. The results show that most of the embelin derivatives synthesised are effective a-glucosidase inhibitors, with IC 50 values at the micromolar level, especially 10d, 12d, and 15d, the IC 50 values of which are 1.8, 3.3, and 3.6 lM, respectively. Structure-activity relationship (SAR) studies suggest that hydroxyl groups in the 2/5-position of para-benzoquinone are very important, and long-chain substituents in the 3-position are highly preferred. Moreover, the inhibition mechanism and kinetics studies reveal that all of 10d, 12d, 15d, and embelin are reversible and mixed-type inhibitors. Furthermore, docking experiments were carried out to study the interactions between 10d and 15d with a-glucosidase.

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Two essential oils were isolated from discarded perfume lemon and leaves (Citrus limon (L.) Burm. F.) by hydro-distillation with good yield (0.044% for perfume lemon and 0.338% for leaves). Their biological activities were evaluated against five selected bacterial strains and Aedes albopictus (Ae. albopictus, Diptera: Culicidae). Chemical composition indicated that both essential oils were rich in essential phytochemicals including hydrocarbons, monoterpenes and sesquiterpene. These constituents revealed some variability among the oils displaying interesting chemotypes (R)-(+)-limonene (12.29–49.63%), citronellal (5.37–78.70%) and citronellol (2.98–7.18%). The biological assessments proved that the two essential oils had similar effect against bacterial (inhibition zones diameter ranging from 7.27 ± 0.06 to 10.37 ± 0.15 mm; MICs and MBCs ranging from 1.6 to 6.4 mg/mL); against Ae. albopictus larvae (LC50 ranging from 384.81 to 395.09 ppm) and adult mosquito (LD50 ranging from 133.059 to 218.962 μg/cm2); the activity of the two chemotypes ((R)-(+)-limonene and citronellal): larvae (LC50 ranging from 267.08 to 295.28 ppm), which were all presented in dose-dependent manners. Through this work, we have showcased that recycling and reusing of agriculture by-products, such as discarded perfume lemon and leaves can produce eco-friendly alternatives in bacterial disinfectants and mosquito control product.

In this study, the microwave‐assisted sodium hexametaphosphate (SHMP) method was applied for soluble dietary fiber (SDF) extraction from potato pulp; the extraction conditions were optimized by response surface methodology (RSM). The water holding capacity (WHC), swelling capacity (SC), oil binding capacity (OBC), adsorption capacity for cholesterol (ACC), and DPPH and ABTS free radical scavenging capacities of potato pulp SDF were then evaluated. The optimal extraction conditions were 1.0% SHMP, liquid to solid (L:S) ratio; 40:1, and microwave time; 1.26 min. The WHC and SC were 2.66 g/g and 4.47 ml/g, respectively. Adsorption capacities for unsaturated fatty acid (UFA) and saturated fatty acid (SFA) were 1.405 and 1.302 g/g, respectively. At pH 2 and 7, the ACC was 1.87 and 1.33 mg/g, respectively. The free radical scavenging assays show that potato pulp SDF has moderate antioxidative activity. This study serves as a reference for the full processing of potatoes and the comprehensive utilization of potato pulp. Practical applications Potato pulp is often thrown away in starch manufacture, which not only causes waste of resources but also environmental pollution. Extracting functional components such as SDF is one direction for the comprehensive utilization of potato pulp. Compared to traditional methods, microwave‐assisted technology is more efficient and environment‐friendly. In this study, the optimal microwave‐assisted extraction conditions were obtained by single‐factor experiments and RSM, which provides a reference for the application of microwave‐assisted technology in the potato‐processing industry. Moreover, compared with other sources of SDF, the property assays reveal that SDF from potato pulp has good SC, as well as moderate WHC, OBC, and antioxidative activity, which suggest that it has potential for applications in the functional food industry.