Phytochemical study of Canavalia Rosea and Elateriospermum Tapos

Abstract

Phytochemical investigation of the chemical constituents of Canavalia rosea (Papilionaceae) aerial parts led to the isolation of six compounds including a new guanidine alkaloid, canarosine, a flavonoid glycoside, rutin, epi-inositol 6-O-methyl ether, β-sitosterol glucoside, and a 2:1 mixture of β-sitosterol and stigmasterol. Canarosine, at 100 μg/ml, caused 95% inhibition dopamine-1 receptor binding with the IC₅₀ value of 39.4 μM. The alkaloid was also active against Plasmodium falciparum K1 strain with IC₅₀ value of 4.48 μg/ml, was moderately active against Herpes simplex virus type 1. Study of chemical constituents of Elateriospermum tapos (Euphorbiaceae) led to the isolation of a total of twenty-five compounds from the stem, flowers and leaves of this plant. From the stem, fourteen compounds including four triterpenoids, lupeol, lupeol acetate, acetyl aleuritolic acid and germanicol palmitate, a new cleistanthane diterpenoid, 2,3-seco-sonderianol, two pimarane diterpenoids, yucalexin P-17 and yucalexin P-15, a beyerane diterpenoid, yucalexin B-22, a biflavonoid, amentoflavone, along with scopoletin, syringaldehyde, oleic acid and a β-sitosterol/stigmasterol (1:1) mixture were isolated. Isolation of its flowers yielded eight compounds including lupeol, lupeol acetate, a flavonoid, quercetin, two biflavonoids, amentoflavone and putraflavone, ellagic acid 3,3'-dimethyl ether and a β-sitosterol/stigmasterol (1:1) mixture. Thirteen compounds were isolated from the leaves of this plant, including two new taraxerane triterpenoids, 2,3-seco-taraxer-14-ene-2,3,28-trioic acid 2,3-dimethyl ester and 2,3-seco-taraxer-14-ene-2,3,28-trioic acid 3-methyl ester, two known triterpenoids, hopenol-B and aleuritolic acid, four biflavonoids, amentoflavone, sequoiaflavone, putraflavone and ginkgetin, a flavonoid, kaempferol, ellagic acid 3,3'-dimethyl ether, β-sitosterol glucoside and a β-sitosterol/stigmasterol mixture. Among the compounds isolated from E. tapos, 2,3-seco-taraxer-14-ene-2,3,28-trioic acid 2,3-dimethyl ester exhibited moderate cytotoxicity against BC cell line with IC₅₀ 7.08 μg/ml, strong cytotoxicity against NCI-H187 cell line with IC₅₀ value of 4.65 μg/ml, and anti-Mycobacterium tuberculosis with MIC value of 3.13 μg/ml. Lupeol was weakly cytotoxic against NCI-H187 cell line with IC₅₀ 18.4 μg/ml. Ginkgetin showed weak cytotoxic activity against KB and BC cell lines, with IC₅₀ values of 18.5 and 10.3 μg/ml, respectively. However, lupeol, ginkgetin and putraflavone were cytotoxic against Vero cells with IC₅₀ values of 13.4, 34.8 and 35.4 μg/ml, respectively. Both 2,3-seco-taraxer-14-ene 2,3,28-trioic acid 3-methyl ester and lupeol were active against M. tuberculosis with the same MIC value of 50 μg/ml. Among the biflavonoids, ginkgetin, putraflavone, amentoflavone and sequoiaflavone showed antituberculosis activity with MIC values of 25, 50, 100 and 200 μg/ml, respectively. Yucalexin P-17 displayed anti-Herpes simplex virus type 1 activity with IC₅₀ value of 3.60 μg/ml.