TABLE 1.
In vitro activities of crude extracts and alkaloids from some Strychnos species against two P. falciparum strainsa
| Compound N° | FCA 20 Ghana (chloroquine-sensitive strain)
|
W2 Indochina (chloroquine-resistant strain)
|
||||
|---|---|---|---|---|---|---|
| IC50 | IC90 | nb | IC50 | IC90 | nb | |
| Total extracts | ||||||
| S. usambarensis roots, EtOAc extract | (0.457 ± 0.005) | (2.345) | 2 | (0.039 ± 0.0029) | (0.597) | 3 |
| S. usambarensis leaves, EtOH extract | (0.287 ± 0.022) | (1.977) | 3 | (0.970 ± 0.141) | (4.853) | 2 |
| S. usambarensis bark liana variety, EtOAc extract | (0.766 ± 0.022) | (2.378) | 2 | (0.226 ± 0.039) | (2.897) | 2 |
| S. usambarensis bark tree variety, EtOH extract | (23.507) | (47.855) | 1 | (24.832) | (46.854) | 1 |
| S. scheffleri bark, EtOH extract | Inactive at (30) | 1 | NDc | |||
| S. mattogrossensis roots, EtOH extract | Inactive at (30) | 1 | ND | |||
| S. henningsii leaves, EtOH extract | (≅40) | (≅200) | 1 | ND | ||
| S. longicaudata roots, EtOH extract | Inactive at (50) | 1 | ND | |||
| S. variabilis bark, EtOH extract | (17.702) | (≅50) | 1 | ND | ||
| S. camptoneura roots, EtOH extract | (≅50) | 1 | ND | |||
| S. innocua roots, EtOH extract | Inactive at (40) | 1 | ND | |||
| S. angolensis leaves, EtOH extract | (29.935) | (≅80) | 1 | ND | ||
| S. angolensis roots, EtOH extract | (20.895) | (≅60) | 1 | ND | ||
| S. gossweileri roots, EtOH extract | (43.505) | (≅400) | 1 | ND | ||
| S. icaja leaves, EtOH extract | (40.421) | (94.159) | 1 | ND | ||
| S. icaja roots, EtOH extract | (1.433 ± 0.068) | (4.834) | 5 | (1.002 ± 0.054) | (4.628) | 2 |
| S. icaja roots, EtOAc extract | (0.286 ± 0.061) | (1.381) | 3 | (0.303 ± 0.022) | (1.998) | 2 |
| S. spinosa bark, EtOH extract | Inactive at (80) | 1 | ND | |||
| S. memecyloides leaves, EtOH extract | (13.489) | (48.75) | 1 | ND | ||
| Alkaloids | ||||||
| S. usambarensis | ||||||
| Dihydrousambarensine | 0.857 ± 0.061 (0.371) | 2.486 | 5 | 0.032 ± 0.002 (0.013) | 4.676 | 4 |
| Usambarensined | 1.516 ± 0.031 (0.655) | 4.412 | 6 | 0.594 ± 0.052 (0.257) | 4.831 | 3 |
| 10′-Hydroxyusambarensine | 1.071 ± 0.031 (0.480) | 3.619 | 3 | 0.357 ± 0.035 (0.160) | 6.851 | 3 |
| Nb-Methylusambarensined | 5.045 (2.436) | 9.835 | 1 | 3.919 ± 0.083 (1.893) | ≅20 | 2 |
| Strychnopentamined | 0.117 ± 0.033 (0.064) | 0.443 | 4 | 0.145 ± 0.020 (0.079) | 2.982 | 4 |
| Isostrychnopentamine | 0.120 ± 0.042 (0.066) | 0.450 | 2 | 0.152 ± 0.009 (0.070) | 0.628 | 2 |
| Usambarined | 2.501 (1.125) | 9.207 | 1 | 2.358 ± 0.015 (1.061) | 7.294 | 2 |
| Dihydrousambarined | 1.247 (0.673) | 6.051 | 1 | 1.408 ± 0.013 (0.636) | 5.515 | 2 |
| 11-Hydroxyusambarine | 0.487 ± 0.015 (0.227) | 1.770 | 5 | 1.538 ± 0.109 (0.716) | 4.535 | 3 |
| 10-Hydroxyusambarine | 1.134 ± 0.012 (0.528) | 3.384 | 2 | 1.958 ± 0.115 (0.912) | 5.803 | 2 |
| Strychnophylline | 1.009 ± 0.035 (0.570) | 4.491 | 2 | 2.523 ± 0.134 (1.425) | 9.310 | 2 |
| Isostrychnofoline | 5.657 ± 0.126 (3.2923) | 25.959 | 2 | 2.598 ± 0.420 (1.519) | 15.745 | 2 |
| 10-Hydroxydihydrousambarine | 0.937 ± 0.044 (0.438) | 5.522 | 3 | 4.699 ± 0.373 (2.199) | 35.687 | 3 |
| 11-Hydroxydihydrousambarine | 2.864 ± 0.046 (1.340) | 7.023 | 2 | 5.449 ± 0.019 (2.550) | 15.772 | 2 |
| Malindine | 162.63 (49.43) | ≅800 | 1 | Inactive at 60 (20) | 1 | |
| Tetradehydrolongicaudatine Y | 1.236 (0.823) | 7.970 | 1 | 0.958 ± 0.129 (0.543) | 12.087 | 2 |
| Strychnos icaja | ||||||
| Vomicine | Inactive at 30 (12) | 1 | ND | |||
| Novacine | Inactive at 90 (40) | 1 | ND | |||
| 14-Hydroxyepoxynovacine | Inactive at 50 (20) | 1 | ND | |||
| Epoxynovacine | Inactive at 50 (20) | 1 | ND | |||
| Icajine | Inactive at 80 (30) | 198.16 | 2 | 95 ± 5 (34.7) | ≅28 | 2 |
| Sungucine | 2.292 ± 0.049 (1.435) | 11.182 | 2 | 1.659 ± 0.089 (1.051) | 12.327 | 2 |
| Bisnordihydrotoxiferine | 3.826 (2.112) | 22.30 | 1 | 4.480 ± 0.092 (2.470) | 13.123 | 2 |
| Strychnine | Inactive at 20 (7) | 1 | 23 (8.5) | ≅50 | 1 | |
| Other Strychnos species | ||||||
| Holstiine | ≅80 (30) | 1 | 34 (12.9) | ≅100 | 1 | |
| Diaboline | Inactive at 33 (12) | 1 | ND | |||
| Strychnochromine | 40.046 (11.93) | ≅200 | 1 | 16 (4.82) | ≅70 | 1 |
| Guianensine | 5.920 (3.694) | ≅20 | 1 | 7309 ± 486 (4.561) | 24.765 | 2 |
| Reference compounds | ||||||
| Chloroquine | 0.020 ± 0.002 (0.006) | 0.119 | 9 | 0.284 ± 0.017 (0.091) | 1.745 | 6 |
| Quinine | 0.269 ± 0.006 (0.087) | 1.913 | 3 | 0.413 ± 0.011 (0.134) | 1.718 | 2 |
a
Data are expressed as mean micromolar concentrations ± standard deviations. Values in parentheses are given in micrograms per milliliter.
b
n, number of independent experiments. All experiments were realized in duplicate.
c
ND, not determined.
d
These six alkaloids were previously tested against P. falciparum with essentially the same IC50 as that for the W2 strain (17).