Biotransformation of ent-kaur-16-en-19-oic acid by Absidia blakesleeana and Rhizopus oligosporus.

Biotransformation of ent-kaur-16-en-19-oic acid was carried out with Absidia blakesleeana and Rhizopus oligosporus. Absidia blakesleeana produced two novel metabolites, ent-(7alpha, 9alpha)-dihydroxy-kaur-16-en-19-oic acid and ent-(1beta, 7alpha)-dihydroxy-kaur-16-en-19-oic acid, together with three known compounds: ent-7alpha-hydroxy-kaur-16-en-19-oic acid, ent-(7alpha, 11beta)-dihydroxy-kaur-16-en-19-oic acid and ent-(7alpha, 13)-dihydroxy-kaur-16-en-19-oic acid. The ent-7alpha-hydroxy-kaur-16-en-19-oic acid and ent-(7alpha, 9alpha)-dihydroxy-kaur-16-en-19-oic acid were obtained from R. oligosporus. The structures were established by spectroscopic techniques and X-ray crystallography.

A new sesquiterpenoid metabolite from Psilocybe samuiensis.

A novel 2,3-secoaromadendrane-type sesquiterpenoid metabolite, psilosamuiensin A (1), was isolated from the broth of Psilocybe samuiensis. The structure of psilosamuiensin A was established by spectroscopic data and its configurations were confirmed by single crystal X-ray crystallographic analysis. This is the first report of psilosamuiensin A found in the genus Psilocybes.

Antimalarial benzoquinones from an endophytic fungus, Xylaria sp.

Two novel benzoquinone metabolites, 2-chloro-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione ( 1) and xylariaquinone A ( 2) together with two known compounds were isolated from an endophytic fungus, Xylaria sp. Their structures were assigned by analysis of spectroscopic data, and the structures of 1 and 3 were also confirmed by single-crystal X-ray data. Compounds 1 and 2 showed in vitro activity against Plasmodium falciparum, K1 strain, with IC 50 values of 1.84 and 6.68 microM and cytotoxicity against African green monkey kidney fibroblasts (Vero cells) with IC 50 values of 1.35 and >184 microM, respectively.

Furanocembranoids from the stem bark of Croton oblongifolius.

Four novel furanocembranoids (1-4) were isolated from the stem bark of Croton oblongifolius. Their structures were elucidated on the basis of spectroscopic analysis, mainly NMR and MS. Compounds 1, 3, and 4 exhibited good cytotoxicity against several human tumor cell lines.

Cytotoxic constituents from Butea superba Roxb.

A carpin (3-hydroxy-9-methoxypterocarpan) (Medicarpin) (1) and four isoflavones, 7-hydroxy-4'-methoxy-isoflavone (Formononetin) (2); 7,4'-dimethoxyisoflavone (3); 5,4'-dihydroxy-7-methoxy-isoflavone (Prunetin) (4) and 7-hydroxy-6,4'-dimethoxyisoflavone (5) were isolated from the tuber roots of Butea superba Roxb. Compounds 2 and 4 showed moderate cytotoxic activity on KB cell lines with IC(50) (microM) values of 37.3+/-2.5 and 71.1+/-0.8 and on BC cell lines with IC(50) (microM) values of 32.7+/-1.5 and 47.3+/-0.3, respectively.

Slow acting protein extract from fruit pulp of Momordica charantia with insulin secretagogue and insulinomimetic activities.

The protein from Thai bitter gourd (Momordica charantia) fruit pulp was extracted and studied for its hypoglycemic effect. Subcutaneous administration of the protein extract (5, 10 mg/kg) significantly and markedly decreased plasma glucose concentrations in both normal and streptozotocin-induced diabetic rats in a dose-dependent manner. The onset of the protein extract-induced antihyperglycemia/hypoglycemia was observed at 4 and 6 h in diabetic and normal rats, respectively. This protein extract also raised plasma insulin concentrations by 2 fold 4 h following subcutaneous administration. In perfused rat pancreas, the protein extract (10 microg/ml) increased insulin secretion, but not glucagon secretion. The increase in insulin secretion was apparent within 5 min of administration and was persistent during 30 min of administration. Furthermore, the protein extract enhanced glucose uptake into C2C12 myocytes and 3T3-L1 adipocytes. Time course experiments performed in rat adipocytes revealed that M. charantia protein extract significantly increased glucose uptake after 4 and 6 h of incubation. Thus, the M. charantia protein extract, a slow acting chemical, exerted both insulin secretagogue and insulinomimetic activities to lower blood glucose concentrations in vivo.

Cytotoxic activity of four xanthones from Emericella variecolor, an endophytic fungus isolated from Croton oblongifolius.

Four xanthones were isolated from mycelia of Emericella variecolor, an endophytic fungus isolated from the leaves of Croton oblongifolius. Their structures were elucidated by spectroscopic analysis to be shamixanthone, 14-methoxytajixanthone-25-acetate, tajixanthone methanoate, and tajixanthone hydrate. All compounds were tested for cytotoxic activity against various human tumor cell lines including gastric carcinoma, colon carcinoma, breast carcinoma, human hepatocarcinoma, and lung carcinoma. The antitumor activities of these xanthones were compared with that of doxorubicin hydrochloride, a chemotherapeutic substance. All of them showed moderate activities and were selective against gastric carcinoma, colon carcinoma, and breast carcinoma. Only tajixanthone hydrate exhibited moderate activity against all cancer cell lines. Furthermore, under the test conditions it was found that 14-methoxytajixanthone-25-acetate and tajixanthone hydrate are almost as active as doxorubicin hydrochloride against gastric carcinoma (KATO3) and breast carcinoma (BT474).

Inhibitory activity of cyanidin-3-rutinoside on alpha-glucosidase.

Cyanidin-3-rutinoside, a natural anthocyanin, inhibited alpha-glucosidase from baker's yeast in dose-responsive manner. The IC50 value was 19.7 microM +/- 0.24 microM, compared with the IC50 value of voglibose (IC50 = 23.4 +/- 0.30 microM). Cyanidin-3-rutinoside was found to be a non-competitive inhibitor for yeast alpha-glucosidase with a Ki value in the range of 1.31-1.56 x 10(-5)M. These results indicated that cyanidin-3-rutinoside could be classed as a new alpha-glucosidase inhibitor.

Structure-activity relationships of trans-cinnamic acid derivatives on alpha-glucosidase inhibition.

trans-Cinnamic acid and its derivatives were investigated for the alpha-glucosidase inhibitory activity. 4-Methoxy-trans-cinnamic acid and 4-methoxy-trans-cinnamic acid ethyl ester showed the highest potent inhibitory activity among those of trans-cinnamic acid derivatives. The presence of substituents at 4-position in trans-cinnamic acid altered the alpha-glucosidase inhibitory activity. Increasing of bulkiness and the chain length of 4-alkoxy substituents as well as the increasing of the electron withdrawing group have been shown to decrease the inhibitory activity. 4-Methoxy-trans-cinnamic acid was a noncompetitive inhibitor for alpha-glucosidase, whereas, 4-methoxy-trans-cinnamic acid ethyl ester was a competitive inhibitor. These results indicated that trans-cinnamic acid derivatives could be classified as a new group of alpha-glucosidase inhibitors.

New halimane diterpenoids from Croton oblongifolius.

Three new halimane-type diterpenoids, crotohalimaneic acid ( 1), crotohalimoneic acid ( 2) and 12-benzoyloxycrotohalimaneic acid ( 3), were isolated from the stem bark of Croton oblongifolius Roxb. Their structures were established on the basis of spectroscopic and X-ray analysis. Compounds 1 and 2 showed non-specific strong cytotoxicity against a panel of human tumor cell lines; whereas 3 was inactive.

Diterpenoids from the stem barks of Croton robustus.

Three compounds were isolated from the stem barks of Croton robustus. Their structures were elucidated as trachyloban-19-oic acid, trachyloban-19-ol and poilaneic acid by spectroscopic analysis. Among them, trachyloban-19-ol and methyl trachyloban-19-oate exhibited weak cytotoxic activity against gastric carcinoma and colon carcinoma with ED50 of 9.2, 9.6 and 8.3, 9.1 microg/mL, respectively.

Inhibition of Na+,K+-ATPase activity by (-)-ent-Kaur-16-en-19-oic acid and its derivatives.

The diterpene, (-)- ent-kaur-16-en-19-oic acid, from Croton oblongifolius was identified as an Na +,K +-ATPase inhibitor. This compound exhibits an IC 50 of 2.2 x 10( -5 )M against crude enzyme Na +,K +-ATPase from rat brain. The semi-synthetic derivatives, (-)-methyl kaur-16-en-19-oate, (-)-kaur-16-en-19-ol, (-)-16beta,17-epoxykauran-19-oic acid and (-)-17-hydroxykaur-15-en-19-oic acid were also tested and their IC 50 were 5.5 x 10 (-4), 5.0 x 10( -4), 4.8 x 10( -4) and 6.0 x 10 (-4) M, respectively.

Cytotoxic activity of natural labdanes and their semi-synthetic modified derivatives from Croton oblongifolius.

Labda-7,12( E),14-triene-17-oic acid, previously isolated from Croton oblongifolius, and its derivatives were investigated for cytotoxicity against five human tumor cell lines. Six of these compounds, labda-7,12( E),14-triene-17-al, 17-hydroxylabda-7,12( E),14-triene, 17-acetoxylabda-7,12( E),14-triene, 15-hydroxylabda-7,13( E)-diene-17,12-olide, labda-7,13( E)-diene-17,12-olide, and 12,17-dihydroxylabda-7,13( E)-diene showed non-specific, moderate, cytotoxicity against all cell lines, whereas the other compounds were inactive.

Croblongifolin, a new anticancer clerodane from Croton oblongifolius.

A new furoclerodane, croblongifolin, together with one known clerodane, crovatin and one known labdane, nidorellol, were isolated from the stem bark of Croton oblongifolius. Structures were established based on spectroscopic and X-ray analysis. Croblongifolin showed a significant cytotoxicity against various human tumor cell lines including HEP-G2, SW620, CHAGO, KATO3 and BT474.