No abstract

Food is one of the three basic requirements of mankind, supplying six kinds of nutrients including water, carbohydrate, protein, lipid, vitamins, and minerals. Alkaloid-containing foods are an intrinsic part of the human diet, such as tea, coffee, and tomato. These food-oriented alkaloid constituents possess diverse effects on the human body, either wanted or unwanted. A large variety of food-produced alkaloids exhibit potent bioactivities, such as caffeine, atropine, and cocaine, whereas, lots of other alkaloids are toxic to human, such as pyrrolizidine alkaloids. This chapter focuses on the alkaloids in human diet and their mode of action and possible toxic effects. To organize this chapter, the alkaloids were categorized into nine groups based on their structures: pyrrolizidine alkaloids, tropane alkaloids, quinolizidine alkaloids, isoquinoline alkaloids, quinoline alkaloids, glycoalkaloids, purine alkaloids, pyridine alkaloids, and amide alkaloids. The structures of food-derived alkaloids are described, and their pharmacological activities, bioavailability, metabolism, and toxicological effects are discussed. Moreover, the application of alkaloids in medicines and food supplement, patents, as well as a conclusion about their current impact on food safety are reviewed. The main purpose of this chapter is to provide a comprehensive and up-to-date state of knowledge from phytochemical, pharmacological, and toxicological studies performed on alkaloids in human food.

Background and Purpose: Pharmacological intervention to induce white adipose tissue browning provides a promising anti-obese therapy. The fruits of Garcinia cambogia (Clusiaceae) have been widely applied to manage body weight. The current study aims to uncover the chemical principles responsible for the anti-obese property of the fruits of G. cambogia and investigate the underlying mechanisms. Experimental Approach: The bioactivity-based molecular networking and Oil-red O staining on 3T3-L1 and C3H10T1/2 adipocytes were applied for guided isolation. High-fat diet-induced obese mice were recruited to evaluate the anti-obese activity. Key Results: Guided by the bioactivity-based molecular networking, several polycyclic polyprenylated acylphloroglucinols were targetedly isolated from the fruits of G. cambogia with lipid lowering effect on adipocytes, including guttiferone J (GOJ), garcinol and 14-deoxygarcinol. As the most potent one, GOJ (10 µM) reduced lipid accumulation by 70% and 76% in 3T3-L1 and C3H10T1/2 adipocytes, respectively. Furthermore, GOJ (2.5‒10 µM) activated the deacetylase Sirtuin 3 (SIRT3), which, in turn, reduced the acetylation level of PPARγ coactivator-1α to boost mitochondrial biogenesis, and promoted uncoupling protein 1 expression and function to enhance thermogenesis, resulting in browning of adipocytes. In high-fat diet-induced-obese mice, GOJ (10 and 20 mg∙Kg-1) protected against adiposity, hyperlipidemia, insulin resistance and liver lipotoxicity, through boosting SIRT3-mediated browning of inguinal white adipose tissue. Conclusions and Implications: The bioactivity-based molecular networking is a promising strategy for guided isolation of bioactive molecules, and GOJ represents a new scaffold of thermogenic inducer, which might be responsible for the anti-obese property of G. cambogia.