الفهرس 
Types of diabetes mellitusOnly 14 pages are availabe for public view
 |  | from | 205 |  |  |
| | | from | 205 | | |
Abstract
In this study crude extracts of two microalgae Spirulina platensis (Cyanobacteria) and Chlorella vulgaris (Chlorophyta) as well as six different seaweeds: Turbinaria decurrens, Padina pavonica, Sargassum muticum and S. acinarium (Phaeophyta); Ulva lactuca (Chlorophyta); Pterocladia capillacea (Rhodophyta) were extracted using different organic solvents (acetone, methanol, ethanol) in addition to water. The extracts were then tested to identify the most active secondary metabolites through the phytochemical screening. The results revealed the presence of alkaloid, flavonoids and phenols in both extracts of S. platensis and C. vulgaris. While, the qualitative analysis of the seaweed extracts showed the presence of alkaloid, flavonoids, phenols, steroids and terpenoids. Different assays used to evaluate the antioxidant properties of the different algal extracts. The results revealed that, S. platensis methanolic extract (ME) exhibited higher scavenging activity against DPPH with an inhibition percentage of 59.4% with an IC50 of 27.39 mg/ml as compared with C. vulgaris acetone extract, as well as T. decurrens acetone extract (AE) displayed the highest DPPH scavenging activity of 62.1 % with and IC50 value recorded 40.66 mg/ml as compared with other studied seaweeds. Also, S. platensis ME exhibited the highest potent activity for both reducing power and the total antioxidant capacity with 2.85 and 3.85 mg AAE/g DW, respectively. In the same way, T. decurrens AE showed the most reducing activity with 2.72 AAE/g DW and presented the maximum antioxidant capacity of 4.3 mg AAE/g DW. In addition, the total phenolic content of the two microalgae was evaluated. S. platensis ME recorded higher phenolic content (5.86 mg GAE/g DW) than C. vulgaris. While, T. decurrens AE recorded the highest phenolic content (4.32 mg GAE/g DW) among other tested seaweeds. The obtained results showed a strong correlation between total phenolic content of different algal extracts and their antioxidant activities. In vitro, The antidiabetic potential, of the different algal extract on α- amylase and α-glucosidase starch hydrolyzing enzymes has been detected. The results illustrated that, of S. platensis ME exhibited the maximum α- amylase inhibition activity of 96.46 % with an IC50 value of 13.31 mg/ml and the same extract showed a strong -glucosidase inhibitory activity of 97.42% and with an IC50 value of 9.56 mg/ml. Similarly, among seaweed extracts, T. decurrens AE recorded the maximum α-amylase inhibition capacity recording 96.1% with an IC50 value of 4.37 mg/ml and showed the maximum - glucosidase inhibition of 97.4% with an IC50 value of 2.84 mg/ml. The cytotoxicity assay, in vitro, was conducted for both S. platensis ME and T. decurrens AE to assess their safety. Both extracts showed no toxicity on fibroblast normal cell lines as 100% of the cells were viable after 24 hours and 48 hours at 250 &500 μg/ml of S. platensis ME. Also, at a lower concentration of 250 μg/ml of T. decurrens AE, the cell viability was estimated to equal 97.62% and 96.18% at 24 and 48 hours of incubation, respectively. Gas chromatography-Mass Spectrum analysis (GC-MS) of S. platensis ME revealed the presence of diverse bioactive compounds mainly phytol 1- monolinoleoylglycerol trimethylsilyl ether and cholestan-3-ol, 2-methylene- (3β,5α) and T. decurrens AE showed the presence of different bioactive compounds mainly cyclotrisiloxane, hexamethyl and 3,7,11,15-tetramethyl- 2-hexadecen-1-ol. These compounds could be responsible for its antioxidant and antidiabetic activities. Also, they may be acted synergistically to exert their action. In vivo study, the effect of the oral administration of S. platensis ME (15 and10 mg/kg body weight (BW) dosages) and T. decurrens AE (300 and150 mg/kg body weight (BW) dosages) in the normal and diabetic rats injected with 150mg/kg of alloxan monohydrate. Seventy seven male albino rats were selected for this study and divided to 11 groups (7 rats in each group) as follows:- group 1: normal healthy control rats (NC), daily depends on tap water along the experiment. group 2: normal rats orally treated with 300 mg/Kg BW of T. decurrens acetone extract. group 3: normal rats orally treated with 150 mg/Kg BW of T. decurrens acetone extract. group 4: normal rats orally treated with 15 mg/Kg BW of S. platensis methanolic extract. Groups 5: normal rats orally treated with 10 mg/Kg BW of S. platensis methanolic extract. group 6: untreated alloxanized-diabetic control. group 7: diabetic rats orally treated with 300 mg/Kg BW of T. decurrens acetone extract. group 8: diabetic rats orally treated with 150 mg/Kg BW of T. decurrens acetone extract. group 9: diabetic rats orally treated with 15 mg/Kg BW of S. platensis methanolic extract. Groups 10: diabetic rats orally treated with 10 mg/Kg BW of S. platensis methanolic extract. group 11: diabetic rats orally administered diabenor 0.3 mg/Kg BW as an antidiabetic reference drug. Body weights and blood glucose levels were monitored weekly after treatments in all diabetic and normal animal sets. After 40 repeated days of treatment, various diabetic physiological and histological parameters were studied. According to the obtained results showed that diabetic rats treated with S. platensis ME and with T. decurrens AE generated a significant decrease in the elevated glucose level, liver functions, kidney functions, total bilirubin and lipid profile and caused increase in body weight, protein profile, albumin, hemoglobin and HDL as compared with diabetic rats group. Moreover, S. platensis ME at 15mg/Kg and T. decurrens AE 300mg/Kg caused a substantial improvement and restored the histological damage of the liver and pancreas tissues related to diabetes induction compared to the standard drug diabenor 0.3 mg/Kg. There was no obvious negative effect in the physiological and the histological parameters of the normal rats when treated with both algal extracts compared to the normal control one. Thus, indicating the safety of these extracts as already proved by the results obtained from the MTT assay. In conclusion, it could be revealed that S. platensis ME and T. decurrens AE derived compounds proved their potent activity as a natural antioxidant agent and their ability to control the postprandial blood glucose levels by inhibiting the diabetes linked enzymes. In addition, the extracts could improve the physiological parameters as well as reverse the histological damage related to the diabetes e Consequently, the study recommends S. platensis ME and T. decurrens AE as promising natural antioxidant agents and potent antidiabetic drugs to replace the synthetic one in the medicinal and pharmaceutical applications.