## 3 Results and Discussion
### In Vivo Study  
The effect of the phlorotannin extracts on the differently treated groups' serum glucose and insulin levels was evaluated. The results in Table 2 show a significant increase of serum glucose in the diabetic rats (596 mg/dl) compared to the normal control group (130.75 mg/dL), where _S. linfolium_ phlorotannin extract lowered the level of glucose (111.25 mg/dL) below the normal control. Meanwhile, a significant decrease in serum glucose levels in the diabetic rats was observed after administration (60 mg/kg) of phlorotannins extracts of _S. linfolium_; the glucose levels of diabetic rats that were administered phlorotannin extracts of _S. linfolium_ were 159.25 \({}^{\text{b}}\)\(\pm\) 20.22. In addition, the results in Table 3 demonstrate the rise in serum insulin in the rats treated with _S. linfolium_ phlorotannins above the normal control. There was no significant change in the serum insulin levels in diabetic rats treated with _S. linfolium_ phlorotannins (5.03 \({}^{\text{a}}\)\(\pm\) 1.43 \(\upmu\)LU/mL) and the normal controls (5.302 \({}^{\text{a}}\)\(\pm\) 1.336 \(\upmu\)LU/mL). These results indicated that the _S. linfolium_ phlorotannins promoted the \(\beta\)-Cell in the pancreas to secret insulin, which can be used to treat diabetes. The primary enzyme in saliva and pancreatic juice, \(\alpha\)-amylase, is responsible for releasing the bonds that allow carbs to break down into glucose and maltose. The enzyme glucosidase, which is present in the brush border of the small intestine and is responsible for cleaving 1-4 linkages and releasing glucose for enterocyte absorption, works in tandem with it to break down carbohydrates [51]. The procedure for lowering blood glucose levels involves blocking the active sites of \(\alpha\)-glucosidase and -amylase, which prevents the breakdown of carbs and delays glucose absorption [52]. Phlorotannins, which can be isolated from a wide range of brown algae, can prevent glucose absorption and impede the digestion of carbohydrates [53]. Brown algae _Ecklonia cava_ and _Ecklonia bicyclis_ phlorotannin extracts demonstrated \(\alpha\)-glucosidase inhibition [54; 55]. Phlorotannin extract of _Sargassum patens_ caused \(\alpha\)-glucosidase and \(\alpha\)-amylase inhibition [56]. Phlorotannins isolated from _Cystoseira compressa_ brown alga improved serum insulin in diabetic rats [57]. Figure 5: Cytotoxicity of phlorotannins extracted from _S. linfolium_ brown alga on the WPMY1 normal cell line. The results tabulated in Table 4 show the influence of the phlorotannins isolated from _S. linifolium_ on the untreated rats and diabetic rates compared to the normal control and diabetic control, concerning glucosidase, alpha-amylase, catalase, and glutathione. The results showed that the phlorotannin extract of _S. linifolium_ reduced glucosidase, alpha-amylase, and catalase levels but elevated glutathione in the untreated and diabetic rats. The methanol extracts of _Iyengaria stellata_ and _Colpomenia sinuosa_ had a more substantial inhibitory impact on \(\alpha\)-glucosidase. In addition, _Sirophysalis trinodis_ methanol extracts reduced the postprandial blood glucose levels in the diabetic rats in comparison to the untreated group [58]. Phlorotannins extracted from Phaeophyceae have shown a variety of anti-diabetic activities, such as inhibiting glucosidase and amylase, glucose uptake in muscle, inhibiting the protein tyrosine phosphatase enzyme, development of insulin sensitivity in type 2 diabetic mice, and prevention of complications from diabetes [59]. The ability of phlorotannins sequestered from _Ecklonia stolonifera_ and _Eisenia bicyclis_ to inhibit-glucosidase may improve the effectiveness of medicines for regulating blood sugar levels and preventing diabetic complications [60]. The results in Table 5 detail the kidney function tests, serum urea, and creatinine levels in the rat groups treated with phlorotannins extracted from brown alga _S. linifolium_, in comparison to the normal controls and diabetic controls.