Research On The Chemical Constituents And Anticancer Activities Of Actinostemma Lobatum MAXIM.

Actinostemma lobatum MAXIM., a kind of wild growing annual herb of Cucurbitaceae family, is widely distributed in China and other Southeast Asian countries, such as Japan, India and Korea. In China, this herb has been traditionally used as a diuretic for treating ascites swelling and nephrotic edema, as a medicine for expelling pathogenic cold and dampness and as an antidote to poisonous snake bites for thousands years.Pharmacological investigation demonstrated that extracts of this plant exhibited a variety of biological effects, such as anticancer, anti-inflammatory and cadiovascular effects. In our serious of studies on the anticancer natural medicines, we have found some active compounds. As a continuation of our work for discovering more effective components, we have now investigated A. lobatum. Based on the review on the chemical constituents and pharmacological research of A.lobatum, the chemical constituents were studied and their antitumor activities were tested.By means of many different chromatographic methods such as silica gel, sephadex LH-20,reversed phase ODS column and P-HPLC chromatography, 40 compounds were isolated from the 75% ethanol extract of the herbs of A. lobatum. On the basis of spectroscopic analysis (UV,IR, NMR, MS) and physicochemical characters,their chemical structures were identified as lobatoside L (1),lobatoside M (2),lobatoside N (3),lobatoside O (4),lobatoside B (5),lobatoside C (6), lobatoside D (7), lobatoside E (8), lobatoside G (9), tubeimoside ? (10),tubeimoside ? (11), dexylosytubeimoside ? (12), tubeimoside V (13), actinostemmoside ? (14),actinostemmoside J (15), actinostemmoside A (16), actinostemmoside C (17), actinostemmoside D (18), actinostemmoside E (19), cucurbitacin E (20), quercetin (21), kaempferol (22), rutin (23),quercitrin (24), kaempferol-3-O-?-L-rhamnopyranosyl (1 ?6)-?-D-glucoypyranoside (25),isoquercitrin (26), garlic acid (27), methyl gallate (28), protocatechuic acid (29), protocatechuic acid methyl ester (30), 4-hydroxyacetophenone (31), p-hydroxybenzoic acid (32),p-hydroxybenzaldehyde (33), ?-sitosterol (34), daucosterol (35), a-spinasterol (36),a-spinasterol-3-O-?-D-glucopyranoside (37), 22, 23-dehydroxychondrillasterone (38),5-(hydroxymethyl)-2-furaldehyde (39), 1-(5-(hydroxymethyl)furan-2-yl) ethanone (40).Among them, 1-4, 14 and 15 were new compounds; 10-13, 20, 27-37, 39-40 were firstly isolated from this genus.In the course of our search for triterpene saponins with antitumor activity, by MTT methods, the in vitro cytotoxicity activities against cancer cell lines of some compounds isolated were assayed. The effects of the compounds on human cancer cells growth, expressed as the IC50 value. For MCF-7 cells line, compounds 1-5, 8-10, 12 and 13 were the most potents with the IC50 value less than 10 ?mol/L. For A549 cell line, compounds 6, 8 and 10-13 showed strong activities with IC50 value less than 10 pmol/L,especially compounds 8, 10 and 13 with IC50 value of 0.07, 0.98 and 0.96 ?mol/L. For HCT-116 cell line, compounds 1-8 and 10-13 showed strong activities with IC50 value less than 10 pmol/L. For HT-29 cell line,compounds 5 and 8-10 showed strong activities with IC50 value less than 10 ?mol/L, especially compound 8 and 10 with IC50 value of 0.06 and 0.88 ?mol/L. For BCG-823 cell line, compounds 1-8, 10, 12 and 13 showed strong activities with IC50 value less than 10 ?mol/L, especially compounds 1, 8 and 10 with IC50 value of 0.001, 0.03 and 0.03 ?mol/L.