Four new resin glycosides from Ipomoea muricata seeds: muricatins XIV-XVII.

Ipomoea muricata (L.) Jacq. seeds (Convolvulaceae) are used as a traditional laxative and carminative medicine. Muricatins XIV (1), XV (2), XVI (3), and XVII (4), were isolated from I. muricata seeds as four new resin glycosides, along with seven known compounds, three of which were isolated for the first time as natural products; their structures were determined using MS and NMR spectroscopy. Compounds 1-4 are macrolactones (jalapins); the sugar moieties of 1, 2, and 4 are partially acylated with 2S-methylbutyric acid, while that of 3 is esterified with 2S-methylbutyric and 2S-methyl-3S-hydroxybutyric acids. In addition, the antiviral activities of the seven compounds obtained in this study, together with five known compounds obtained in our previous study into resin glycosides from I. muricata seeds, were evaluated against herpes simplex virus type 1 (HSV-1); their cytotoxicities against HL-60 human promyelocytic leukemia cells were also investigated. All examined jalapins exhibited similar or slightly weaker anti-HSV-1 activities than acyclovir, the positive control; however, the glycosidic acid of 4 was inactive, while its methyl ester was weakly active. On the other hand, cytotoxicity testing against HL-60 cells showed similar results to those observed during anti-HSV-1 activity testing, with the exception that one jalapin was less active.

Five new resin glycosides, calyhedins XI-XV, from Calystegia hederacea.

Calystegia hederacea Wall. (Convolvulaceae) is a perennial herbaceous vine that grows widely in India and East Asia. All parts of this plant are used to treat various disorders such as menoxenia and gonorrhea. Four new resin glycosides, calyhedins XI (1)-XIV (4), were isolated from the rhizomes of C. hederacea. A new glycoside, calyhedin XV (5), was isolated from its leaves and stems. Alkaline hydrolysis of 1 and 2 furnished a new glycosidic acid, calyhedic acid G (1a), from 1 and a new acid, calyhedic acid H (2a), from 2 along with 2S-methylbutyric acid and 2R-methyl-3R-hydroxybutyric (2R,3R-nilic) acid. The structures of 1-5, 1a, and 2a were determined using MS and NMR spectral analyses. Compounds 1a and 2a had the same sugar moiety, ß-D-glucopyranosyl-(1 → 6)-O-ß-D-glucopyranosyl-(1 → 6)-O-ß-D-glucopyranosyl-(1 → 3)-[O-ß-D-glucopyranosyl-(1 → 3)-O-α-L-rhamnopyranosyl-(1 → 2)]-O-ß-D-glucopyranosyl-(1 → 2)-ß-D-fucopyranose, while their aglycones were 11S-dihydroxyhexadecanoic acid and 12S-dihydroxyhexadecanoic acid, respectively. These compounds are the first glycosidic acids, with fucose as the monosaccharide component obtained from the resin glycosides of C. hederacea. Compounds 1-5, comprising either 1a or 2a, were heptaglycosides with macrolactone structures, and their sugar moieties were partially acylated with 5 mol of organic acids comprising 2S-methylbutyric, (E)-2-methylbut-2-enoic, and 2R,3R-nilic acids. Compounds 1 and 5 had 22-membered rings, while 2-4 had 28-membered rings. In addition, 1 and 5 exhibited cytotoxic activity against HL-60 human promyelocytic leukemia cells, comparable to that of the positive control cisplatin.

Screening of promising chemotherapeutic candidates from plants against human adult T-cell leukemia/lymphoma (VIII): six new withanolides from Physalis philadelphica.

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature peripheral T-lymphocytes caused by human T-cell leukemia virus type I (HTLV-I). There are an estimated 5-20 million HTLV-1-infected individuals worldwide. Conventional chemotherapeutic regimens used against other malignant lymphomas have been administered to patients with ATL, but the therapeutic outcomes of acute and lymphoma-type ATL remain extremely poor. In the course of our screening program for novel chemotherapeutic candidate compounds from plants against two human T-cell leukemia virus I-infected T-cell lines (MT-1 and MT-2), we screened 16 extracts obtained from different parts of 7 Solanaceae plants. We identified that the extracts of Physalis pruinosa and P. philadelphica showed potent anti-proliferative activity in MT-1 and MT-2 cells. In our previous study, we have isolated withanolides from extract of aerial parts of P. pruinosa and examined their structure-activity relationships. In addition, we are also investigating further structure-activity relationships about other withanolides from Solanaceae plants (Withania somnifera, Withania coagulans, Physalis angulate, Nicandra physalodes, Petunia hybrida, and Solanum cilistum). In this study, we attempted to isolate their active compounds against MT-1 and MT-2 from extracts of P. philadelphica. We identified 13 withanolides, including six newly isolated compounds [24R, 25S-4ß, 16ß, 20R-trihydroxy-1-oxowitha-2-en-5ß, 6 ß -epoxy-22,26-olide (1), 4ß, 7ß,20R-trihydroxy-1-oxowitha-2-en-5ß, 6ß -epoxy-22,26-olide (2), 17ß,20 S-dihydroxywithanone (3), 2,3-dihydro-3ß-methoxy-23ß-hydroxywithaphysacarpin (4), 3-O-(4-rhamnosyl)glucosyl-physalolactone B (5), and 17R, 20R, 22S, 23S, 24R, 25R-4ß, 5α, 6ß, 20ß, 22α -tetrahydroxy-16ß, 23-diepoxy-1-oxowitha-2-en-26, 23-olide (6)], from the extract and examined the structure-activity relationships. The 50% effective concentration of withaphysacarpin (compound 7) [MT-1: 0.10 µM and MT-2: 0.04 µM] was comparable to that of etoposide [MT-1: 0.08 µM and MT-2: 0.07 µM]. Therefore, withanolides might be promising candidates for the treatment of ATL.

Identification and characterization of organic and glycosidic acids in the crude resin glycoside fraction from the leaves and stems of Calystegia japonica.

The alkaline hydrolysis of the crude resin glycoside fraction from the leaves and stems of the plant Calystegia japonica Choisy (Convolvulaceae) yielded organic acid and glycosidic acid fractions. The organic acid fraction was esterified with p-bromophenacyl bromide to obtain p-bromophenacyl 2R-methyl-3R-hydroxybutyrate (1) and p-bromophenacyl (E)-2-methylbut-2-enoate (2). By treating the glycosidic acid fraction with trimethylsilyldiazomethane-hexane, seven new methyl esters of glycosidic acids, namely calyjaponic acid A methyl ester (3) calyjaponic acid B methyl ester (5), calyjaponic acid C methyl ester (6), calyjaponic acid D methyl ester (7), calyjaponic acid E methyl ester (8), calyjaponic acid F methyl ester (9), and calyjaponic acid G methyl ester (10), were isolated along with one known ester (4). Their structures were characterized based on spectroscopic and chemical analyses. Compounds 3-8 had the same sugar moiety, α-L-rhamnopyranosyl-(1 → 2)-O-ß-D-glucopyranosyl-(1 → 2)-[O-α-L-rhamnopyranosyl-(1 → 6)]-O-ß-D-glucopyranose, and the aglycones of 3-8 were methyl 3S,11S-dihydroxyhexadecanoate, methyl 3S,12S-dihydroxyhexadecanoate, methyl 11S-hydroxyhexadecanoate, methyl 11S-hydroxypentadecanoate, methyl 3S,11S-dihydroxypentadecanoate, and methyl 3S,12S-dihydroxypentadecanoate, respectively. Compounds 9 and 10 were derivatives of 3 and 4, respectively, in which the C-6 of the second glucosyl residue was methylated. Compounds 6-8 contained methyl esters of unusual odd-carbon fatty acids as aglycones. The cytotoxicity of the crude resin glycoside fraction and 3 against HL-60 human promyelocytic leukemia cells was evaluated further; both were either weakly active or inactive compared to the positive control, cisplatin.

A new steroidal glycoside from the fruits of Solanum myriacanthum.

A new cholestane-type steroidal glycoside, solamyriaside A (1), was isolated from the fruits of Solanum myriacanthum Dunal (Solanaceae), along with two known steroidal glycosides, namely, solaviaside A (2) and aculeatiside A (3), and three known steroidal alkaloid glycosides, namely, solamargine (4), khasianine (5) and solasonine (6), which were isolated for the first time from this plant. Based on spectroscopic data as well as chemical evidence, 1 was determined to be 3-O-α-L-rhamnopyranosyl-(1→2)-O-[α-L-rhamnopyranosyl-(1→4)]-ß-D-glucopyranosyl-22R,25R-cholest-5-ene-3ß,16α,22,26-tetraol 26-O-ß-D-glucopyranoside. The cytotoxic activity of 1-6 against HL-60 human promyelocytic leukaemia cells was examined. Compounds 4-6 showed cytotoxic activity. Among them, 4 exhibited the strongest activity with an IC50 value of 4.64 ± 0.17 µM, similar to the activity of cisplatin, a positive control.

A New Glycosidic Acid, Muricatic Acid D, and Resin Glycosides, Muricatins X and XI, from the Crude Resin Glycoside Fraction of the Seeds of Ipomoea muricata.

Alkaline hydrolysis of crude resin glycoside fraction of the seeds of Ipomoea muricata (L.) Jacq. (Convolvulaceae) yielded a new glycosidic acid, muricatic acid D; three known glycosidic acids, namely, muricatic acids A, B, and C; and three known organic acids, namely, isobutyric, 2S-methylbutyric, and 2S-methyl-3S-hydroxybutyric acid. Two new genuine resin glycosides with macrolactone structures (jalapins), muricatins X and XI, were also isolated from the fraction. Their structures were determined using spectroscopic data and chemical evidence.

Screening of Promising Chemotherapeutic Candidates from Plants against Human Adult T-Cell Leukemia/Lymphoma (VI): Cardenolides from Asclepias curassavica.

In the course of our screening program for novel chemotherapeutic candidates from plants against adult T-cell leukemia/lymphoma, the extracts of Asclepias curassavica L. showed potent activity against MT-1 and MT-2 cells. Therefore, we attempted to isolate their active components. We identified a new cardenolide, 19-dihydrocalactinic acid methyl ester (1), along with 16 known cardenolides (2-17). Their structures were determined on the basis of spectroscopic data. Almost all of the isolated cardenolides inhibited the growth of both tumor cell lines. All the doubly linked cardenolides (11-17) except for 14 showed more potent activity than the other cardenolides. A comparison of the activities of 11, 14 and 16 revealed that the presence of hydroxy or acetoxy functional groups at C-16 led to a decrease in the activity. The 50% effective concentration (EC50) value of calotropin (11) against MT-2 cells was comparable to the potency of the clinical antineoplastic drug doxorubicin. The cytotoxic effect of 11 toward normal mononuclear cells obtained from the peripheral blood (PB-MNCs) was observed at a concentration 6 to 12 times higher than that used to induce growth inhibition against MT-1 and MT-2 cells. The proportions of annexin V-positive cells after 72 h of treatment with 11 were increased, indicating that it significantly induced apoptosis in MT-1 and MT-2 cells in a concentration-dependent manner. Cell cycle experiments demonstrated that 11 arrested MT-1 and MT-2 cells at the G2/M phase. Therefore, compound 11 may be a promising candidate for the treatment of adult T-cell leukemia/lymphoma.

Identification and characterization of organic and glycosidic acids in crude resin glycoside fraction from Calystegia hederacea.

Resin glycosides are well known as the purgative ingredients, which are characteristic of convolvulaceous plants. Calystegia hederacea Wall. is a perennial herbaceous vine that is widespread throughout India and East Asia. All parts of this plant are used for the treatment of menoxenia, gonorrhea, etc. Alkaline hydrolysis of the crude resin glycoside fraction of the whole plants of C. hederacea yielded four new glycosidic acids, calyhedic acids A, B, C, and D, along with two known glycosidic acids, calysolic acids A and C, and three known organic acids, 2S-methylbutyric, tiglic, and 2R,3R-nilic acids. Their structures were characterized on the basis of spectroscopic data and chemical evidence. Calyhedic acids A, B, and D were penta-, hexa-, and hepta-glycosides of 12S-hydroxyhexadecanoic acid, respectively, and cayhedic acid C was an isomer of calyhedic acid D, in which the 12S-hydroxyhexadecanoyl residue of calyhedic acid D was replaced by a 11S-hydroxyhexadecanoyl residue. Additionally, cytotoxic activity toward HL-60 human promyelocytic leukemia cells of the crude resin glycoside fraction, the glycosidic acid fraction, calyhedic acid A, and calysolic acid A from C. hederacea was evaluated. Furthermore, to clarify the structure-activity relationship of resin glycosides, the activities of six genuine resin glycosides with calysolic acid A or calysolic acid C as the glycosidic acid, which were isolated from C. soldanella, were examined. Among them, the crude resin glycoside fraction and five genuine resin glycosides with macrolactone structures demonstrated clear cytotoxic activities, while the glycosidic acid fraction, calyhedric acid A, calysolic acid A, and a genuine non-macrolactone-type resin glycoside were either inactive or exhibited weaker activity than the tested macrolactone-type resin glycosides.

Two New Triterpene Glycosides in the Roots of Uraria crinita.

Two new triterpene glycosides, 24-deoxyoxytrogenin 3-O-α-L-rhamnopyranosyl (1→2)[ß-D-glucopyranosyl]-ß-D-galactopyranosyl (1→2)-ß-D-glucuronopyranoside and sophoradiol 3-O-α-L-rhamnopyranosyl (1→2)-ß-D-glucuronopyranosyl (1→2)-ß-D-glucuronopyranoside with four known glycosides were isolated from a Chinese natural medicine, the roots of Uraria crinita (L.) DESV. Their structures were determined by chemical and spectral methods.

Seven new resin glycosides from the seeds of Quamoclit × multifida.

Seven new resin glycosides, multifidins III (1)-IX (7), were isolated from the seeds of Quamoclit × multifida (syn. Q. sloteri House) (Convolvulaceae), along with five known glycosides, quamoclinic acid B methyl ester (8), operculin XIII (9), quamoclin I (10), QM-10 (11), and QM-12 (12). Their structures were determined on the basis of spectroscopic data and chemical evidence. These compounds were of two different types, i.e., those with macrolactone structures and those with non-macrolactone structures. Additionally, cytotoxic activity towards HL-60 human leukemia cells of 1, 2, 5, 8, 9, 11, and 12 was evaluated. Among them, macrolactone-type resin glycosides (jalapins), 1, 2, and 9, specifically demonstrated clear cytotoxic activity with IC50 values of 3.46, 14.7, and 10.9 µM, respectively.

Four new resin glycosides, murasakimasarins I-IV, from the tuber of Ipomoea batatas.

Four new resin glycosides having macrolactone structures (jalapins), murasakimasarins I-IV, were isolated from the tubers of Ipomoea batatas (L.) Lam. ('Murasakimasari', Convolvulaceae), along with three known glycosides. Their structures were determined on the basis of spectroscopic data as well as chemical evidence. Murasakimasarin III is the first representative of a resin glycoside with 10-methylundecanoic acid as the component organic acid.

A new resin glycoside from Calystegia soldanella and its antiviral activity towards herpes.

A new resin glycoside, named calysolin XVIII (1), was isolated from the leaves, stems and roots of Calystegia soldanella Roem. et Schult. (Convolvulaceae). The structure of 1 was defined as 11S-jalapinolic acid 11-O-ß-d-glucopyranosyl-(1 → 3)-O-(2-O-2S-methylbutyryl,4-O-3-hydroxy-2-methylenebutyryl)-α-l-rhamnopyranosyl-(1 → 2)-[O-ß-d-glucopyranosyl-(1 → 6)-O-(34-di-O-2S-methylbutyryl)-ß-d-glucopyranosyl-(1 → 3)]-O-ß-d-glucopyranosyl-(1 → 2)-ß-d-quinovopyranoside, intramolecular 1,2″'″'-ester on the basis of spectroscopic data. Compound 1 is the first known resin glycoside to feature 3-hydroxy-2-methylenebutyric acid as a component organic acid. In addition, 1 demonstrated an antiviral activity against herpes simplex virus type 1, with an IC50 value 2.3 µM.

Screening of promising chemotherapeutic candidates from plants against human adult T-cell leukemia/lymphoma (V): coumarins and alkaloids from Boenninghausenia japonica and Ruta graveolens.

During the course of our studies towards the identification of promising chemotherapeutic candidates from plants against two human T-cell lymphotropic virus type I-infected T-cell lines (MT-1 and MT-2), we screened 17 extracts from 9 rutaceous plants against MT-1 and MT-2 cells. The extracts from the aerial parts and roots of Boenninghausenia japonica, as well as the leaves and roots of Ruta graveolens showed potent antiproliferative effects. After activity-guided fractionation, we isolated 44 compounds from two rutaceous plants, including three new compounds (1-3), which were classified into 26 coumarin analogs (13 coumarins, 8 furanocoumarins, 4 dihydrofuranocoumarins and one dihydropyranocoumarin), 15 alkaloid analogs (7 quinolone alkaloids, 4 acridone alkaloids, 3 furanoquinoline alkaloids and one tetrahydroacridone alkaloid) and 3 flavonoid glycosides. Structure-activity relationship studies were also evaluated. The coumarin compounds (2, 3 and 7-9) bearing a 3-dimethylallyl moiety showed potent activity. Similarly, of all the furanocoumarins evaluated in the current study, compound 17 bearing a 3-dimethylallyl group also showed potent activity. A dihydrofuranocoumarin (27) bearing a 3-dimethylallyl moiety showed the most potent activity. Following 27, compound 28 showed potent activity. These results therefore suggested that the presence of a 3-dimethylallyl moiety was important to the antiproliferative activity of these coumarin analogs.

Two new triterpenoids from the seeds of blackberry (Rubus fructicosus).

Two new ursane-type triterpenoids (1, 2) attached to isopropylidenedioxy group were isolated from the seeds of blackberry (Rubus fructicosus L., Rosaceae) along with two known ursane-type triterpenoids, 2,3-O-isopropylidenyl-2α,3α,19α-trihydroxyurs-12-en-28-oic acid (3) and 1ß-hydroxyeuscaphic acid (4). The chemical structures of 1 and 2 were determined to be 2,3-O-isopropylidene-1ß,2ß,3ß,19α-tetrahydroxyurs-12-en-28-oic acid and 1,2-O-isopropylidene-1ß,2α,3α,19α-tetrahydroxyurs-12-en-28-oic acid, respectively, based on spectroscopic data. Additionally, their cytotoxic activity towards HL-60 human leukaemia cells was evaluated. Among them, 3 demonstrated a clear cytotoxic activity with 72.8 µM of IC50 value.

Screening of promising chemotherapeutic candidates from plants against human adult T-cell leukemia/lymphoma (IV): phenanthroindolizidine alkaloids from Tylophora tanakae leaves.

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature peripheral T lymphocytes caused by human T-cell lymphotropic virus type 1 (HTLV-1). There are an estimated 5 million to 20 million HTLV-1-infected individuals worldwide; their lifetime risk of developing ATL is 3-5 %, and high HTLV-1 proviral loads have been shown to be an independent risk factor. Although conventional chemotherapeutic regimens used against other malignant lymphomas have been administered to ATL patients, the prognosis is often poor. In previous studies, we screened 459 extracts from 344 plants to isolate components exhibiting antiproliferative activity against HTLV-1-infected T-cell lines (MT-1 and MT-2). In our continuing search for potential anti-HTLV-1 natural products, 15 extracts of Asclepiadaceae plants were further tested against MT-1 and MT-2 cells. The MeOH extract of aerial parts of Tylophora tanakae showed antiproliferative activity. Activity-guided fractionation resulted in the isolation of 6 phenanthroindolizidine alkaloids (including a new compound), and we examined their antiproliferative activity against MT-1 and MT-2 cells. The EC50 value of some of the alkaloids was in the low nanomolar range, comparable to that of the clinically used antineoplastic drug doxorubicin. Structure-activity relationship analyses suggested that a 14ß-hydroxy moiety is essential for activity against HTLV-1-infected T cells. In contrast, the presence of a 2-methoxy moiety, a 7-methoxy moiety, or an N-oxide moiety appears to reduce the potency of the antiproliferative activity against HTLV-1-infected T cells.

Screening of promising chemotherapeutic candidates from plants against human adult T-cell leukemia/lymphoma (III).

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature peripheral T lymphocytes caused by human T-cell lymphotropic virus type I (HTLV-I). In our previous paper, 214 extracts from 162 plants were screened to elucidate the anti-proliferative principles against HTLV-I-infected T-cell lines. In this study, 245 extracts from 182 plants belonging to 61 families were further tested against two HTLV-I-infected T-cell lines (MT-1 and MT-2). Potent anti-proliferative effects were exhibited against MT-1 and MT-2 cells by 52 and 60 of the 245 extracts tested, respectively. Of these, two extracts showed strong inhibitory activity (EC50 values 0.1-1 µg/mL; +++) against both cells, 7 extracts showed moderate inhibitory activity (EC550 values 1-10 µg/mL; ++), and 43 extracts showed weak inhibitory activity (EC50 values 10-100 µg/mL; +), whereas the remaining extracts did not show any activity (EC50 values >100 µg/mL; -) against MT-1 cells. On the other hand, 10 extracts showed moderate inhibitory activit and, 48 extracts showed weak inhibitory activity, whereas the remaining extracts did not show any activity against MT-2 cells. Extracts from the aerial parts of Annona reticulata and A. squamosa showed the most potent inhibitory activity and three aporphine alkaloids were isolated from their extracts as the active principles by activity-guided fractionation.

Two new glycosidic acids, multifidinic acids F and G, of the ether-insoluble resin glycoside (convolvulin) from the seeds of Quamoclit × multifida.

Two new glycosidic acids, multifidinic acids F and G, were isolated from the glycosidic acid fraction afforded by alkaline hydrolysis of the ether-insoluble resin glycoside (convolvulin) fraction from the seeds of Quamoclit × multifida (syn. Q. sloteri House, Convolvulaceae), a hybrid between Q. pennata and Q. coccinea. The two compounds are the third and fourth examples of bisdesmosides of glycosidic acids having sugar linkages at C-3 of 3,11-dihydroxytetradecanoic acid (ipurolic acid) as well as at C-11.

A new diterpenoid from the leaves of Clerodendron trichotomum.

A new diterpenoid was isolated from the leaves of Clerodendron trichotomumThunb. (Verbenaceae) along with one each of a known diterpenoid, phenylethanoid glycoside, and sterol and two known flavonoids. Their chemical structures were characterized on the basis of spectroscopic data and X-ray analysis. In addition, their antioxidant activities were evaluated using four different analyses.

Screening of promising chemotherapeutic candidates from plants against human adult T-cell leukemia/lymphoma (II): apoptosis of antiproliferactive principle (24,25-dihydrowithanolide D) against ATL cell lines and structure-activity relationships with withanolides isolated from solanaceous plants.

Adult T-cell leukemia/lymphoma (ATL) is an incurable peripheral T-cell malignancy caused by human T-cell lymphotropic virus type I. In our preceding paper, 214 extracts from 162 plants were screened to elucidate the antiproliferative principles against ATL cell lines. Several withanolides were isolated and the structure-activity relationships (SAR) examined. To extend the search for SAR, 31 further withanolides, previously isolated from solanaceous plants, were tested against ATL cell lines. The presence of a 4ß-hydroxy group as well as a 5ß,6ß-epoxy group appeared to be essential for the activity. In contrast, the presence of a sugar moiety at either the 3- or the 27-position led to a reduction in the activity. Furthermore, 24,25-dihydrowithanolide D (13) was identified as the most potent inhibitor, showing selective toxicity against ATL cell lines by inducing apoptotic cell death.

Garlicnin A from the fraction regulating macrophage activation of Allium sativum.

Garlicnin A (1), a new stable, sulfur-containing compound isolated from a fraction of the acetone extracts of Allium sativum L. garlic bulbs, showed the potential to suppress tumor cell proliferation by inhibiting the polarization of M2 alternatively activated macrophages, and its structure was characterized as 3,4-dimethyl-5-(4,5-dithia-1E,7-octadiene)-tetrahydrothiophene-2-sulfoxide-S-oxide, on the basis of the results of spectroscopic analysis results.