# An Updated Review: _Opuntia focus indica_ (OFI) Chemistry and Its Diverse Applications
## 2 Nutritional and Phytochemicals
### Phytochemicals
#### 2.2.2 Betalains  
The presence of betalains is restricted to a limited number of plant species; beets, and cacti are the primary sources of this type of pigment. They are recognized for their cheerful and bright hues. Recent analyses have shown that OFI betalains have various  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Compounds** & **Contents** & **Sources** & **References** \\ \hline Gallic acid & 0.64–2.37 & \\
3,4-dihydroxybenzoic & 0.06–5.02 & \\
4-hydroxybenzoic & 0.5–4.72 & \\ Coumaric & 14.08–16.18 & \\ Narcissin & 14.69–137.1 & \\ Rutin & 2.36–26.17 & Cladode & [55; 58; 59; 60] \\ Nicotiiflorin & 2.89–146.5 & \\ Isohamnetin-3-O-glucose & 4.59–32.21 & \\ Isoquercetin & 2.29–39.67 & \\ Salicylicacid & 0.58–3.54 & \\ Ferulicacid & 0.56–34.77 & \\ \hline Total phenolic acid & 48–89 & \\ Total Flavonoids & 1.5–2.6 & \\ Sinapoyl-diglucoside & 12.6–23.4 & \\ Total Tannins & 4.1–6.6 & \\ Feruloyl-Saccharose 1 & 7.36–17.62 & \\ Feruloyl-Saccharose 2 & 2.9–17.1 & \\ \hline Gallic acid & 1630–4900 & \\ Kaempfer-3-O-Rutinoside & 400 & \\ Isoquercitin & 447 & \\ Isorhamnetin-3-O-Robinobiology & 4269 & Flower & [48; 49; 50; 61] \\ Isorhamnetin-3-O-b-d- & 979 & \\ glucopyranoside & 723 & \\ Isoharmonic-3-O-Glucoside & 324 & \\ Kaempfer-3-O-Rutinoside & 709 & \\ \hline Total Flavonoid & 6.95 & \\ Total phenolic acid & 45,700 & \\ Isorhamnetin & 2.41–91 & Skin & [7; 53; 57] \\ Quercetin & 4.32 & \\ Kaempfer & 0.22 & \\ \hline All phenolic acid & 218.8 & \\ Enisorhamnetin glycosides & 50.6 & \\ Kaempfer & 2.7 & \\ Quercitin & 9 & Pulp & [37; 51; 52; 54; 55; 62] \\ Isorhamnetin & 4.94 & \\ Luteolin & 0.84 & \\ \hline \hline \end{tabular}
\end{table}
Table 6: Polyphenolic contents (mg/100 g) of the seed, skin, pulp, flower, and cladode of OFIinteresting properties that are valuable for human health. Indeed, potentially, betalains are used as antimicrobials, they have cardiovascular benefits (they improve cholesterol levels and reduce blood pressure), they have anti-cancer benefits (especially against colon cancer cells), they act as antioxidants (they protect cells from damage), and they have been found to improve insulin sensitivity in the human body [63]. The core structure of betalain is made of nitrogen and betalamic acid, as reported in Figure 5. The derivates of amino acids and imino compounds react with betalamic acid to make betaxanthins and betacyanins pigments, which are yellow and violet, respectively. Amazingly, a large number of betalains are present in the skin and pulp of OFI. The color variation of the fruit depends on the concentration of betaxanthins, betacyanins, and their derivatives. Furthermore, indicaxanthin, betanin, betanidin, neobetanin, and isobetanin are also produced by OFI fruit pulp [64; 65]. Betanin and indicaxanthin are also identified in the skin [66]. The presence of Vulgaxanthin IV, (\(S\))-serine-betaxanthin, Vulgaxanthin II, Vulgaxanthin I, Miraxanthin II, Portulacaxanthin III, Portulacaxanthin I, mustcaaurin, (\(S\))-valine-betaxanthin's, (\(S\))-isoleucine and (\(S\))-Phenylalanine betaxanthin, and gombrinen I has also been reported [66; 67; 68; 69].  
At low concentrations, betacyanin-derived pigments including betanin, phyllocactin, and betanidin exhibited antioxidant activity, manifesting as yellow and red colors The presence of catechol groups in betanidin structures involved in free radical nitrogen scavenging activity has significant antioxidant capacity. The natural pigment betacyanins are useful for maintaining physiological ability under oxidative stress [70]. Additionally, indicaxanthin was presented as less active with respect to betanin in the free radical scavenging reactions [71].