Chemopreventive and biological activities of Helicteres isora L. fruit extracts

Helicteres isora L. (H. isora) has been used in traditional medicine in Asia. This study was aimed to determine biological activities of H. isora fruit extracts. Chemopreventive effect was examined by cell proliferation assay and differentiation-inducing effect. Anti-inflammatory activity of extracts was studied on the levels of nitric oxide (NO), tumor necrosis factor alpha (TNF-α), production of prostaglandin E2 (PGE-2), and cyclooxygenas-2 (COX-2). Cell proliferation assay revealed that H. isora extracts and its major compound, rosmarinic acid, showed no cytotoxicity in THP-1 and RCM-1 cells. Methylthio acetic acid from Cucumis melo var.conomon used as a positive control and 80% ethanol extracts demonstrated significant cell differentiation induction. Hexane extract of H. isora could lower the levels of TNF-α, PGE-2, and NO in THP-1 cells with 51.61 ± 0.79%, 69.68 ± 0.017%, and 69.93 ± 9.41% inhibition, respectively. The highest inhibitory effect on COX-2 was obtained from dichloromethane extract. Dexamethasone inhibited the secretion of TNF-α with 95.82 ± 0.50% while celecoxib showed the inhibitory effect on COX-2 and PGE-2 with 100% and 99.86%, respectively. The ethanol extract showed the best antioxidant activity by DPPH and FRAP assays at IC₅₀ of 5.43 ± 1.01 μg/mL and 22.83 ± 0.13 mmol FeSO₄/g sample, respectively, while the positive control, trolox, showed the antioxidant activity with IC₅₀ and FRAP values at 4.08 ± 0.85 μg/mL and 10.84 ± 0.04 mmol FeSO₄/g sample, respectively. Taken together, H. isora possess chemopreventive and antioxidant activity. Further studies on in vivo activities of this plant are suggested.