## 2 Bioactive Compounds
### Betaine  
Betaine was first identified in beets and is a nontoxic and stable natural compound. It is primarily found in plants, animals, and microorganisms at higher concentrations [76]. Consumption of dietary betaine plays a crucial role in raising betaine content in the kidneys, liver, and brain [77]. Betaine is a modified amino acid consisting of glycine with three additional methyl groups [78]. Thus, it frequently serves as a methyl donor for several metabolic pathways. Studies of human diseases have shown involvement in cardiovascular disease, metabolic syndrome, Alzheimer's disease [79, 80, 81, 82], and cancer. In breast cancer cells, betaine inhibits alcohol-induced transcription of Pol III both in vitro and in vivo. One study showed that betaine inhibited cell growth and colony formation via the down-regulation of Brfl and Pol III [83]. Betaine enhanced the expression of antioxidants such as GSH, SOD, CAT, and TAS, and reduced the expression of pro-inflammatory cytokines such as TNF-\(\alpha\) and IL-6 in the prostate cancer cell line DU-145. Additionally, it induced morphological changes, DNA fragmentation, and apoptosis in a dose-dependent manner [84]. Betaine was also found to enhance the proliferation of HeLa cells, while inhibiting cell growth and migration by promoting activity of the pro-apoptotic genes p53, Bax, and caspase-3 [85]. It was also shown to directly target mitochondria. A study demonstrated that betaine treatment led to increasing mitochondrial respiration and cytochrome c oxidase activity which were reduced in human pathological diseases including cancer, consequentially producing ATP, cellular energy, and reversal of the Warburg effect in cancer cells [86]. In an AOM/DSS-induced colon cancer model, betaine administration significantly reduced ROS generation and GSSG concentration by down-regulating inflammatory cytokines such as TNF-\(\alpha\), IL-6, iNOS, and COX-2 [87]. It also attenuated cisplatin-induced hepatic injury in rats through regulation of NF-\(\kappa\)B and caspase-3-dependent apoptosis [88]. Among the betaines, \(\delta\)-valerobetaine inhibited the growth of human oral squamous cell carcinoma, Cal 27 cells, and ROS accumulation. SIRT1 up-regulation and apoptosis were found to be responsible for the observations [89]. The study showed that SIRT1 silencing using small interfering RNA reduced apoptosis induced by the combination of \(\delta\)-valerobetaine with \(\delta\)-buttyrobetiaine by modulating proaspase-3 and cyclin B1. Betaine also regulates angiogenesis, the formation of new vessels surrounding the tumor, in vitro and in vivo, and suppressed tube formation, invasion, and migration in HUVECs (human umbilical vein endothelial cells) in a mouse matrigel plug assay [90]. The study demonstrated that following betaine treatment, the mRNA expression of basic fibroblast growth factor, matrix metalloproteinase-2, and matrix metalloproteinase-9 was down-regulated via the suppression of NF-\(\kappa\)B and Akt activation. Betaine supplementation in rats bearing diethylinitosamine-induced liver cancer increased p16 while blocking c-myc expression. Furthermore, in the model, it was observed that increased levels of malondialdehydedehyde and glutathione S-transferase resulted in enhanced antioxidative capacity [91].