Antihyperglycemic activity of Porphyridium cruentum biomass and extra-cellular polysaccharide in streptozotocin-induced diabetic rats.

Porphyridium cruentum, known as red microalga, is able to produce extra-cellular polysaccharides (EPs) that have beneficial health effects. In this study, the effect of P. cruentum biomass and EPs with various doses was studied in streptozotocin (STZ)-induced diabetic rats to determine their antihyperglycemic activity and its potential mechanism. The doses of biomass were 600, 1200 and 1800 mg/kg body weight (BW) while the doses of EPs were 150, 300 and 450 mg/kg BW. P. cruentum biomass and EPs could slightly reduce food intake in STZ-diabetic rats as compared with diabetic group. After a 14-day treatment, P. cruentum EPs could decrease blood glucose levels of STZ-induced diabetic rats while P. cruentum biomass at all doses could not. P. cruentum EPs was as effective as glibenclamide in lowering blood glucose levels of diabetic rats. In addition, P. cruentum EPs could significantly increase (p < 0.05) Langerhans islets areas, the number of ß-cells and the height of intestinal villi. Treatment with 450 mg/kg BW of EPs resulted in the most effective antihyperglycemic activity. Thus, P. cruentum has the potential to resolve hyperglycemic and diabetic problems.

Evaluation of antiplasmodial properties of a cyanobacterium, Spirulina platensis and its mechanism of action.

The rapid emergence of antimalarial drug resistance necessitates a continual effort on novel drug discovery. A cyanobacterium, Spirulina platensis, is a potential antimalarial agent that has been widely consumed as food supplement in the form of crude extract. It is known to possess antiviral, antibacterial and antifungi activities. This study examined the antimalarial activities of several Spirulina formulas against Plasmodium falciparum 3D7, in vitro. The tested Spirulina formulas included commercially available capsule, crude extract and alkaloid fraction. Results showed that all tested formula possessed antimalarial activities with the Spirulina capsule exhibited the highest activities (IC50 = 2.16 µg/mL). Light and electron microscopies revealed interference of the Spirulina with the parasite hemozoin formation. In conclusion, all tested Spirulina formulas and fraction exhibited moderate to high antimalarial activities.