Immunomodulatory constituents from Annona squamosa twigs provoke differential immune response in BALB/c mice

Annona squamosa (AS) has traditionally been used as ethnomedicine and various parts of the plant have been used to combat several disorders including dysentery, cancer and hyperthyroidism. Since the twig of this plant is reported to contain a large number of alkaloids, we chose to study its medicinal properties on the immune response of BALB/c mice. The present study, thus, aims at evaluation of immunomodulatory activity in the crude ethanolic extract and its four fractions, viz. hexane (F1), chloroform (F2), n-butanol (F3) and aqueous (F4) prepared from the twigs of AS to locate the active constituents in the fractions. The extract and fractions were fed orally at 3, 10 and 30 mg/kg for 14 consecutive days and mice were euthanized to assess various immune parameters. The ethanolic extract and its three fractions F2, F3 and F4 were found active since they increased splenic T and B cellular proliferation with a significant accentuation in peritoneal macrophage function, differentially increased the CD4+, CD8+ T lymphocytes and CD19+ B lymphocytes. The extract and its active fractions also demonstrated significant Th1 or Th2 mixed cytokine response at almost all doses tried in a dose-dependent manner. Its hexane fraction, however, could only induce reactive oxygen species production in peritoneal macrophages and could not induce lymphocytes; thus, it remained inactive. Thus, the activity could be localized distributed in its three fractions (chloroform, n-butanol and aqueous). Further purification and evaluation of the active molecule/s is underway in our laboratory.