## 3 Encapsulation Techniques for Improving Phenolic Compounds Functionality
### Encapsulated Phenolic Compounds as Antidiabetic Agents
\begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Compound** & **Encapsulating Material/Technique** & **Type of Study/ Dose** & **Biological Parameters/Activities** & **Positive Effects** & **Refs** \\ \hline Proantoc-yanidin-rich extract & Gum Arabic, maltodextrin, gelatin microcapsules/Freeze-drying & In vitro assays/1 & \(\alpha\)-Amilase and 1-4 mg/mL & Inhibitory activity above \(\alpha\)-glucosidase & [82; 102] \\ \hline Quercitin & Alginate and succinyl chitosan core-shell-corona structured nanoparticles/ Ionic cross-linking for 28 days & _In vivo_ using streptozotocinoactin-induced diabetic rats/100 mg/kg of either encapsulated or free quceritin for 28 days & Fasting blood glucose and glucose & Hypoglycaemic effect and efficient maintenance of glucose homeostasis compared to free oral quercetin & [103] \\ \hline Poly(lactic-co-glycolic acid) nanoparticles/ & _In vivo_ using streptoactin-induced diabetic rats/100 mg/kg of either free (daily) or encapsulated (every fifth day) quercetin & Blood glucose & Enhanced quercetin oral & [104] \\ \hline Poly(lactic-co-glycolic acid) nanoparticles/ Emulsion-diffusion-evaporation method & _In vivo_ using strepto2000-steprophotometrica & Catalase and SOD levels in pancreas and kidneys (daily or free compound) or & Enhanced quercetin oral & [104] \\ \hline Quercitin nanorods/ Thermomagnetic treatment & _In vivo_ & Blood glucose & Reduction in fasting blood glucose, oxidative stress, lipid 20 mg/kg for four weeks & [105] \\ \hline \multirow{4}{*}{Resveratrol} & \multirow{4}{*}{Multilayered resveratrol} & \multirow{4}{*}{In vitro using \(\beta\)-CC cells/30 \(\mu\)g/mL to glucose and 1-4 mg/mL to glucose and 1-4 mg/mL} & \multirow{4}{*}{Biocompatibility and cellular uptake} & \multirow{4}{*}{[106]} \\  & & & & & \\ \cline{1-1} \cline{4-5}  & & & & & \\ \cline{1-1} \cline{4-5}  & & & & & \\ \cline{1-1} \cline{4-5}  & & & & & \\ \hline Poly(lactic-co-glycolic acid) nanoparticles/ Evasion-diffusion-evaporation method & _In vivo_ using metabolic syndrome-induced mice & Blood glucose, weight, insulin, and lipid profile & Regulation of insulin and glucose levels & [43] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._apeutic profile of quercetin as an anti-diabetic drug, quercetin was effectively encapsulated in succinyl-chitosan core-shell-corona nanoparticles produced by ionic cross-linking [103]. Results obtained with these biocompatible and biodegradable nanoparticles showed that the nanoformulation enabled pH-sensitive controlled release of quercetin with no detected toxicity [103]. Furthermore, in diabetic rat models, after oral administration of free quercetin and these quercetin nanoparticles, encapsulated quercetin was found to have a significantly stronger hypoglycaemic effect and effective maintenance of glucose homeostasis compared to free quercetin [103]. In a similar study, PLGA nanoparticles loaded with quercetin were prepared by the emulsion-diffusion-evaporation method and characterised with a drug entrapment efficiency higher than 86% [104]. This report showed that encapsulation in PLGA nanocapsules improved the oral bioavailability of quercetin (523% increase) compared to a free quercetin suspension, allowing diabetic rats to be dosed every five days instead of daily to achieve a similar effect [104]. In a different approach, quercetin nanorods reduced protein oxidation, lipid peroxidation, and hexokinase activity in aloxan-induced diabetic mice. The liver function and kidney function of the mice improved. The authors found increased levels of antioxidant enzymes (SOD, GSH, and catalase) in the groups treated with quercetin nanorods. A comet assay showed a reduction in DNA damage, suggesting that quercetin nanorods have great potential in treating diabetes and its associated complications [105].