Isolation And Bioactivities Of The Natural Products From Several Plants

In an ongoing discovery of the bioactive agents from natural products, three tranditional Chinese medicinal plants (Leonurus japonicus Houtt, Hedyotis chrysotricha (Palib.) Merr., and Erycibe obtusifolia Benth) as well as three plants(Viburnum formosanum Hayata ssp. leiogynum Hsu, Potamogeton crispus L., and Penstemon centranthifolius Benth) have been systematically investigated for their chemical constituents and their bioactivities. A total of79compounds were obtained and structurally elucidated on the basis of spectroscopic means, especially (1D,2D-NMR and MS) as well as chemical transformations. These79compounds can be classified as eleven28-noroleanane-derived spirocyclic triterpenoids, three oleanane triterpenoids, seven ursane triterpenoids, four steroid-2’-acetylamido-2’-deoxy-β-D-glucosides, ten steroids, an isopimarane type diterpenoid, a sesquiterpenoid, a sesquiterpenoid glycoside, two iridoids, eighteen iridoid glycosides, seven phenylethanoid glycosides, four coumarins, three phenylpropionic acids, three cerebrosides, and four acylglycerols. There were13new compounds, including six28-noroleanane-derived spirocyclic triterpenoids, four steroid-2’-acetylamido-2’-deoxy-β-D-glucosides, an isopimarane type diterpenoid as well as two3,8-epoxy-iridoids. Moreover, the structures of28-noroleanane-derived spirocyclic triterpenoids and3,8-epoxy-iridoids are quite rare. Thus, these discoveries enriched the natural products library. And it was the first time to systematically investigate the constituents of P. crispus, V. formosanum and P. centranthifolius. Some of the isolates were proved to possess cytotoxicities, antiproliferative and inhibitory activities of the migration of the tested tumor cell lines, as well as anti-inflammatory, antioxidative, and antibiofilm activities, providing basis for the research and development of new antitumor, anti-inflammatory, antioxidation and antibiofilm agents.Details were as follows:1). Twenty compounds, including eleven28-noroleanane-derived spirocyclic triterpenoids (1.1-1.11), four steroid-2’-acetylamido-2’-deoxy-β-D-glucosides (1.12-1.15), two oleanane triterpenoids (1.16,1.17), a phenylpropionic acid (1.18), an acylglycerol (1.19) along with a cerebroside (1.20) were isolated from the fruits of L.japonicus (Labiatae), ten of which were new compounds. Leonurusoleanolides E-J (1.1-1.6) were new28-noroleanane-derived spirocyclic triterpenoids; and leonurosides A-D (1.12-1.15) were new steroid2’-acetylamido-2’-deoxy-glucosides. Among the known compounds,1.16,1.18,1.19, and1.20were isolated from this plant for the first time. Compounds1.1-1.11exhibited cytotoxicities against eight human tumor cell lines (BGC-823, HUH-7, KE97, Jurcat,293T, A549, MCF-7, and BEL-7402). And the cytotoxicities of compounds1.5and1.6were significant, with IC50values of2.0-13.0μM. Moreover, compounds1.5,1.6,1.11and1.17demonstrated moderate anti-inflammatory activity on IL-1β-exposed HT-29human colon carcinoma cells. Among them, compound1.5reduced81.6%of IL-8’s secretion. And1.11presented inhibitory activity of the migration of the SK-HEP-1human hepatocellular carcinoma cells, and anti-proliferative activity of this cell line.2). Purification of the methanol extract of the whole plant of H. chrysotricha (Rubiaceae) led to sixteen known compounds (2.1-2.16), which were classified as four steroids (2.1-2.4), five ursane triterpenoids (2.5-2.9) as well as seven iridoid glycosides (2.10-2.16). Compounds2.1-2.4,2.6-2.9, and2.14-2.16were isolated from Hedyotis genus for the first time. Compound2.1significantly inhibited the migration of the SK-HEP-1human hepatocellular carcinoma cells by transwell migration assay in vitro.3). Eight compounds (3.1-3.8) were purified from the methanol extract of stern of the E. obtusifolia (Convolvulaceae). These compounds were two coumarins (3.1,3.2), five phenylpropionic acids (3.3-3.7), and an acylglycerol (3.8). Among them, compounds3.3-3.8were gained from E. obtusifolia for the first time.4). Two new iridoids (4.1,4.2), two ursane triterpenoids (4.3,4.4) and one oleanane triterpenoid (4.5) were isolated from the leaves of V. formosanum (Caprifoliaceae). Isolation for the chemical constituents from this plant was still in process. 5). The EtOAc extract (100mg/mL) of the whole plant of P. crispus was determined to enhance the expression of NAD(P)H:quinone oxidoreductase1(NQO1) by Western Blot. Bioassay-guided purification led to the isolation of thirteen compounds (5.1-5.13) from this extract, including a new isopimarane type diterpenoid [17-hydroxyl-8aH-isopimara-9(11),15-diene](5.1), a sesquiterpenoid (5.2), a sesquiterpenoid glycoside (5.3), two cerebrosides (5.4,5.5), two acylglycerols (5.6,5.7), as well as six steroids (5.8-5.13). All these compounds were isolated from this plant for the first time. Compound5.2was proved to be the representive principal, which enhanced the expression of NQO1at100μM.6). The EtOAc/EtOH (50:50, v/v) extract of the whole plant of P. centranthifolius (Scrophulariaceae) showed primary antibiofilm activity against Escherichia. coli UTI89. Bioassay-guided isolation of the extract led to seventeen compounds (6.1-6.17), including six phenylethanoid glycosides (6.1-6.6), and eleven iridoid glycosides (6.7-6.17). Compounds6.1-6.6and6.13-6.17were obtained from this plant for the first time, moreover,6.1,6.3and6.6were from Penstemon genus for the first time. Compound6.1showed77%inhibition at2.5μg/mL and6.2showed60%at5.0μg/mL.