Antimalarial potential of ethanol extract, and anti-inflammatory properties of flavonoid-, terpenoid-, and alkaloid-rich fractions of Sida linifolia L

Sida linifolia L. has been employed ethnomedicinally in the treatment of inflammatory diseases such as whitlow and malaria but is yet to be scientifically validated for use in the management of ailments. This investigation sought to assess the antimalarial potential of ethanol leaf extract as well as the in vitro anti-inflammatory qualities of flavonoid-, terpenoid- and alkaloid-rich leaf fractions of Sida linifolia L. The acute toxicity (LD50) study and the effect of the extract on parasitemia and hematological parameters were determined. In vitro, anti-inflammatory parameters were also determined. It was demonstrated that S. linifolia leaf extract was safe and significantly (p < 0.05) reduced parasitemia in malaria-infected mice. The extract also improved blood counts in mice infected with malaria. The activity of the alkaloid-rich fraction against hypotonicity-induced hemolysis was significantly (p < 0.05) higher than those of the terpenoid-rich and flavonoid-rich fractions. On protein denaturation, the activity of the flavonoid-rich fraction had significant (p < 0.05) improvement compared to those of the terpenoid-rich and alkaloid-rich fractions. The fraction with the best anti-proteinase activity was the flavonoid-rich which was better by a significant (p < 0.05) margin than those of alkaloid-rich and terpenoid-rich fractions. The terpenoid-rich fraction showed the highest inhibitory activity against PLA2 activity, followed by the flavonoid-rich and then the alkaloid-rich fractions. Crude leaf extract of S. linifolia proved potent against malaria, and the flavonoid-, terpenoid- and alkaloids-rich fractions exerted anti-inflammatory properties, justifying its use in traditional medicine in the treatment of malaria and other inflammatory diseases.