## 3 _Nelumbo nucifera_
### Antioxidant Health Promoting Effect of Nelumbo uncifera Bioactives and Extracts
#### 3.2.1 In Vitro Antioxidant Effects of Nelumbo uncifera's Bioactives and Extracts
The results indicated that both lotus plumule and blossom extracts displayed antioxidant properties. However, lotus plumule exhibited greater antioxidant effects than lotus blossom, particularly in scavenging hydroxyl radicals and ferrous ion chelation. Lotus blossom showed slightly higher scavenging activity of hydroxyl radicals at lower concentrations, while lotus plumule demonstrated higher activity at higher concentrations. Plus, only the methanol extract of lotus plumule exhibited ferrous ion chelating capabilities [41]. These studies also employed methods like the Folin-Ciocalteu assay to assess total phenol content, consistently showing that the presence of phenolics contributes to higher antioxidant activity [38; 39; 42] or the reducing power assay [40; 41; 42]; these findings align with those of DPPH. Finally, [PERSON] et al. examined various parts of the lotus plant, such as leaves, flowers, stamens, stems, seedpods, seeds, plumules and rhizomes, using ether as an extraction solvent and evaluated lipid peroxidation, SOD activity, catalase activity, peroxidase activity and glutathione levels. The findings indicated that each part tended to exhibit either the highest or lowest activities in the various methods used, with no single part consistently showing the highest or lowest activity across all assays. This suggests that the choice of method employed plays a crucial role in determining the activity levels observed for each part. Rhizomes were noted for their high vitamin C content [43]. [PERSON] et al. studied lotus extract for potential hepatotoxicity and free radical-scavenging properties using purchased drug-free hepatocytes as a control. More specifically, an ethanol extract from seeds of _N. nucifera_ (ENN) was assayed with DPPH for potential antioxidant effects to scavenge free radicals, as well as with carbon tetrachloride (CCI4) and aflatoxin B1 (AFB1)-induced hepatocyte toxicity models for potential hepatotoxicity effect. The reduction of DPPH via spectrophotometric monitoring allowed for the determination of the extract free radical scavenging effect. Hepatocytes treated with ENN reduced CCl4 cytotoxicity and serum enzyme production. Moreover, ENN suppressed AFB1's cytotoxic and genotoxic effects in a dose-dependent manner [44]. Antioxidant activity was also observed in dried stamens of _N. nucifera_, which were mixed with ethanol, and the flavonoids were extracted. The lotus stamen extract (LSE) was analyzed by high-performance liquid chromatography (HPLC) and assayed for its potential in vitro cell free antioxidant activity, evaluation of chronological aging, estimation of nicotinamide adenine dinucleotide hydrogen (NADH), NAD+, adenosine triphosphate (ATP) contents, etc. The results of LSE analysis revealed a rich antioxidant flavonoid resource with the ability to slow down the aging process of yeast. Interestingly, LSE can be considered an alternative plant source for the development of anti-aging products [45]. The in vitro antioxidant activity of flavonoids from aquatic plants like _N. nucifera_ plays a crucial role in combating oxidative stress and safeguarding against various diseases. The structural characteristics of these bioactive compounds justify their antioxidant properties. Phenolic compounds such as chlorogenic acid, ferulic acid and coumarin, along with flavonoids like kaempfer, baicalein, quercetin and rutin, are renowned for their antioxidant effects due to the presence of phenolic hydroxyl groups in their structures. These hydroxyl groups, along with the conjugated double bonds in the molecules, enable them to function as potent free radical scavengers, effectively neutralizing ROS and preventing oxidative damage. The multiple phenolic hydroxyl groups can donate hydrogen atoms or electrons, forming stable phenoxyl radicals through resonance structures, thereby neutralizing free radicals. Additionally, these compounds can chelate metal ions like Fe\({}^{2+}\) and Cu\({}^{2+}\), which catalyze free radical formation, further reducing their generation.