In-vitro screening of selected traditional medicinal plants for their anti-obesity and anti-oxidant activities

Obesity is a multifactorial problem that leads to several life-threatening diseases and is becoming one of the most important public health problems with huge social costs. The incidence of obesity is increasing at an alarming rate, so the discovery of natural products that counteracts obesity with the least side effects has become of extreme importance nowadays. Inhibition of digestive enzymes is one of the most widely studied mechanisms used to determine the potential efficacy of anti-obesity agents. To that effect, the total methanolic and aqueous extracts of five plants [viz: Caralluma quadrangula, Caralluma tuberculata, Hibiscus shizopetalous, Hibiscus subdariffa (white variety) and Solenostemma argel] were tested for their inhibitory activity against pancreatic lipase, α-amylase and α-glucosidase, along with their anti-oxidant potential via two different complementary methods; DPPH (1, 1-Diphenyl-2-picrylhydrazyl) radical scavenging activity and iron reducing power assays. The plants' extracts were also estimated quantitatively for their total phenolic, flavonoid, tannin and steroidal contents. The results showed that Solenostemma argel was the most active among the selected plants. An optimized extraction method was developed for S. argel based on its enzyme inhibitory activity to ensure maximum biological activity. The methylene chloride and n-butanol fractions in addition to seven isolated compounds viz: sterols, pregnane glycoside and flavonoid aglycones and glycosides from S. argel were further evaluated. Consequently, the present study suggests that S. argel could be of therapeutic interest for the control of obesity.