Isolation and anti-HIV-1 activity of a new sesquiterpene lactone from Calocephalus brownii F. Muell.

As part of our ongoing collaborative effort to discover potential anti-HIV-1 agents from plants, the CH2Cl2 extract of Calocephalus brownii F. Muell. was phytochemically investigated, which resulted in the isolation of two sesquiterpene lactones of the cis-fused guaianolides type, one new identified as 1α-hydroxy-3ßH-3α,4α-epoxy-4,10-dimethyl-5αH,7αH,8ßH,10αH-guai-11(13)-ene-7,8-olide (1) and one known identified 1αH-4α-hydroxy-4,10-dimethyl-5αH,7αH,8ßH,10αH-guai-11(13)-ene-7,8-olide (2). Their structures were elucidated on the bases of IR, UV, 1D-NMR, 2D-NMR, DIFNOE and high-resolution ESI-TOF-MS. The anti-HIV-1 activity was evaluated and revealed that STLs (1 and 2) caused a reduction for the viability of mock-infected MT-4 cells by CC50 = 29.1 and 0.5 µg/mL, respectively, and caused 50% protection of MT-4 cells against HIV-1 induced cytopathogeneticy by EC50 = 29.1 and 0.5 µg/mL, respectively, as compared with Efavirenz (EFV) as positive control that showed a CC50 = 11.6 and EC50 = 0.0006 µg/mL, using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method.

Anti-HIV-1 and cytotoxicity of the alkaloids of Erythrina abyssinica Lam. growing in Sudan.

Erythrina abyssinica Lam. is an important medicinal plant growing in Sudan; its seeds were investigated for the first time for their alkaloidal constituents and biological activity. The in vitro cytotoxicity of the crude alkaloidal fraction (CAF) against the cell lines HeLa, Hep-G2, HEP-2, HCT116, MCF-7 and HFB4 showed promising activity, with IC50 values of 13.8, 10.1, 8.16, 13.9, 11.4 and 12.2 µg mL⁻¹, respectively. Doxorubicin (positive control) showed in vitro cytotoxic activity with IC50 values 3.64, 4.57, 4.89, 3.74, 2.97 and 3.96 µg mL⁻¹, respectively. Bioassay-guided fractionation and isolation of the CAF led to the isolation of five Erythrina alkaloids, identified as erythraline, erysodine, erysotrine, 8-oxoerythraline and 11-methoxyerysodine. These were evaluated for their in vitro cytotoxic activity against Hep-G2 which resulted in IC50 values 17.60, 11.80, 15.80, 3.89 and 11.40 µg mL⁻¹, respectively. Furthermore, in vitro cytotoxic activity against HEP-2 was evaluated, which resulted in IC50 values 15.90, 19.90, 21.60, 18.50 and 11.50 µg mL⁻¹, respectively. The CAF caused a reduction in the viability of mock-infected MT-4 cells with a CC50 of 53 µM and a 50% protection of MT-4 cells against HIV-1 induced cytopathogeneticy with a EC50 of >53 µM, compared with EFV as a positive control, which had a CC50 of 45 µM and an EC50 of 0.003 µM. We concluded that the isolated alkaloids were responsible for the anti-carcinogenic [corrected] actions of the plant extract previously reported in the literature.