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The bark of Himatanthus sucuuba was screened for pharmacological and anticancer activities. The lactone, fulvoplumierin (C14H12O4), was isolated from the n-hexane fraction. The identity was proven by elemental analysis and IR, mass spectral, and melting-point determinations. Reference samples were used for comparison.
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The high mortality caused by Crotalus durissus terrificus snake venom is mainly due to crotoxin, which acts on the neuromuscular junction inhibiting the mechanism mediating acetylcholine release, thus leading to motor and respiratory paralysis and subsequently to animal death. We recently demonstrated that the aqueous extract (AE) of Tabernaemontana catharinensis can inhibit the lethal activity of C. d. terrificus venom. Eight fractions, PI to PVIII, were obtained by gel filtration of the extract on Sephadex G-10, and assayed for lethality and cytotoxicity. Fraction PVII [2.0 mg/100 g rat/50 microl saline solution (ss)] injected intramuscularly (i.m.) 20 s after the venom (240 microg) or crotoxin (200 microg/50 microl ss) neutralized the lethal activity of 2 LD50 of both. Fractions PI, PVI and PVIII (5.0 mg/100 g rat/50 microl ss) presented potent antitumoral activity in vitro against cells from human breast carcinoma (SK-BR-3) after 24 h incubation, as measured by Mosmann colorimetric method. Fraction PVII contains 12-methoxy-4-methylvoachalotine as its major component. These results demonstrate that the antivenom and antitumoral activities of the AE of T. catharinensis are exerted by different substances present in fraction PVII and fractions PI, PVI and PVIII, respectively, whose characteristics are distinct in terms of staining and Rf when analyzed by thin layer chromatography. The results also show that a preliminary fractionation by Sephadex G-10 gel filtration is a good option as a first step for isolation of biologically active substances from T. catharinensis.
Partial neutralization of the myotoxic effect of Bothrops jararacussu venom (BV) and two of its myotoxins [bothropstoxin-I (BthTX-I), catalytically inactive, and II (BthTX-II), showing low PLA2 activity], by the lyophilized aqueous extract of Tabernaemontana catharinensis (AE), was studied in rat isolated soleus muscle preparations (in vitro) and through i.m. injection in the gastrocnemius muscle (in vivo) by determination of creatine kinase (CK) activity and histopathological analysis. Incubation of soleus muscle for 1 h with BV or toxins (20 microg/ml) plus AE (400 microg/ml) added immediately after BV, BthTX-I or BthTX-II reduced CK levels by 53%, 37% and 56%, respectively. The myonecrotic effects of BV (20 microg/ml) upon soleus muscle was reduced 24%, 35% and 36% when AE (400 microg/ml) was added 1 h after BV and CK was evaluated 30 min, 1 and 2 h later, respectively. For BthTX-I these values were 46%, 48% and 47%, while for BthTX-II no inhibitory effect was detected. Histological analysis of soleus muscle after incubation with AE (400 microg/ml, 1 h) did not reveal any change in muscle fibers, but severe necrosis induced by BV or toxins (20 microg/ml) was clearly in evidence, and decreased significantly when soleus muscle was protected by AE. This protection was also observed when AE was administered 1 h after BV or BthTX-I, but not after BthTX-II. AE did not inhibit the catalytic PLA2 activity of BthTX-II or BV and did not change the PAGE pattern of BV, BthTX-I or BthTX-II. In vivo assays were performed in 100-g rats and maximal CK release was attained at a dose of 100 microg of BV, 3 h after injection. AE was not effective when injected 20 s after BV or toxins. However, injecting BV or toxins (100 microg), which were pre-incubated with AE (2 mg) caused an inhibition of 57%, 59% and 51%, respectively, with zero time pre-incubation, but was less effective with 1 h pre-incubation. This plant represents a potential source of promising myotoxin inhibitors.
Four indole alkaloids, 12-methoxy-N(a)-methyl-vellosimine, demethoxypurpeline, 12-methoxyaffinisine, and 12-methoxy-vellosimine, in addition to picrinine, vinorine, raucaffrinoline, normacusine B, norseredamine, seredamine, 10-methoxynormacusine B, norpurpeline and purpeline, were isolated from the bark or leaf extracts of Rauvolfia bahiensis.
Leaf extracts of Schizozygia coffaeoides were investigated for antifungal activity using the disc diffusion assay technique. Petroleum ether 40-60 degrees C, dichloromethane-ethyl acetate (1:1) and methanol extracts were fungitoxic to Trichophyton mentagrophytes, Microsporum gypseum, Cladosporium cucumerinum and Candida albicans. The extracts were fungistatic in action.
Bioassay-guided fractionation of the aqueous extract of the leaves of Alstonia actinophylla with use of a coupled enzyme assay, CPU/hippuricase, to detect carboxypeptidase U inhibitors led to the isolation of a novel indole alkaloid, actinophyllic acid (1). The structure of 1 was determined from detailed 2D NMR studies. Actinophyllic acid was found to be a potent inhibitor of the coupled enzyme assay with an IC(50) of 0.84 microM. Actinophyllic acid possesses a unique 2,3,6,7,9,13c-hexahydro-1H-1,7,8-(methanetriyloxymethano)pyrrolo[1',2':1,2]azocino[4,3-b]indole-8(5H)-carboxylic acid skeleton.
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Flower structure, attractants, breeding system, and visitors were studied in Aspidosperma quebracho-blanco, a South American mass-flowering tree with simple moth-pollinated flowers and without floral reward. Flowers are protandrous, having an initial male phase for 2 d. The pendulous and horizontal flower position and protandry prevent self-pollination. Although an inconspicuous annular floral nectary is located at the ovary base, nectar is not secreted. Nonstructural, extrafloral nectaries have been found on the external surface of the calyx and corolla, the first report of the kind for the family. Ants, wasps, flies, and beetles collect the extrafloral exudate composed of fructose, glucose, and sucrose. Experiments indicate that natural selfing (autogamy) and agamospermy are unlikely to occur (0% success), but artificial selfing indicates self-compatibility (70% success). A very low natural fruit to flower ratio (0.03) was obtained. Floral features and nocturnal opening indicate that these flowers would be pollinated by moths that nocturnally visit the species (Noctuidae, Pyraloidea) finding no floral reward. We suggest a nonmodel deception mechanism: providing the same cues as most moth flowers, this tree seems to be dependent upon sympatric rewarding plants that share the same pollinators.
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Five flavonoids were isolated from the leaves of Vinca minor L. The structure of 4 glucosides was established as: kaempferol 3-rhamnogluco-7-glucoside (A), kaempferol 3-rhamnogluco-7-galactoside (B), quercetin 3-rutino-7-glucoside (D), quercetin 3-rhamnogluco-7-glucoside (E). One flavonoid isorhamnethin glucorhamnoside (C) was identified only partially. The occurance of flavonoids in the other organs of the plant was compared chromatographically.
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