Alibertia edulis (L.C. Rich.) A.C. Rich - A potent diuretic arising from Brazilian indigenous species

ETHNOPHARMACOLOGICAL RELEVANCE

Although Alibertia edulis (L.C. Rich.) A.C. Rich decoction is used in Brazilian folk medicine due to its possible antihypertensive effect, this species has never been critically investigated as a hypotensive drug. So, the aim of this study was to evaluate the possible hypotensive and antihypertensive effects of the oral administration of Alibertia edulis aqueous extract (AEAE) in normotensive and hypertensive rats, and evaluate its inter-relation with a possible diuretic activity.

MATERIAL AND METHODS

Different doses of AEAE (20, 65 and 200mg/kg) were tested on the mean arterial pressure (MAP) of normotensive Wistar rats and after induction of renovascular hypertension (two-kidney, one-clip Goldblatt model). In addition, the diuretic effects of AEAE were compared with hydrochlorothiazide (HCTZ) in an acute and repeated-dose treatment for 7 days. Volume, sodium, potassium, chloride, calcium contents, pH and density were estimated in urine samples collected after 8 or 24h. Plasma sodium, potassium, total protein, urea, creatinine, AST and ALT concentrations were measured in samples collected at the end of the experimental period (seventh day). Finally, the antioxidant activity of the AEAE was assessed using the DPPH radical scavenging and ferric ions reducing power assay.

RESULTS

The intraduodenal administration of the HCTZ and AEAE significantly reduced, in a dose-dependent manner, the MAP in both normotensive and hypertensive rats. Otherwise, the heart rate was not affected by any treatment. Acute and prolonged oral administration of AEAE (200mg/kg) and HCTZ caused a significant increase in volume and urinary concentrations of sodium, potassium and chloride. Moreover, urinary calcium concentration was significantly increased after administration of AEAE (200mg/kg). Finally, AEAE was able to present important in vitro antioxidant properties.

CONCLUSION

The results obtained have shown that AEAE presents potent diuretic activity and significant hypotensive and antihypertensive effect. In addition, this study may confirm part of the pharmacological activity popularly attributed to this species and opens perspective for the future use in various renal and cardiovascular diseases.

[Steroidal saponins from the plant Agave brittoniana with activity against the parasite Trichomona vaginalis]

The genus Agave (Agavaceae), includes more than 300 species; around 16 of them show an homogeneous distribution throughout Cuba. Agave brittoniana (ssp. brachypus), is an endemic subspecies that grows in the central region of the country and its leaves are traditionally used in the treatment of parasitic diseases. The parasite Trichomonas vaginalis causes the disease known as trichomoniasis, that infects the genital tract. To test in vitro the plant against Trichomona vaginalis, the dried and powdered leaves were extracted three times with ethanol-water (7:3) by maceration at room temperature. The solvent was removed under reduced pressure and the extract was suspended in distilled water, defatted with n-hexane, and extracted with water-saturated n-butanol. After solvent removal, a portion of the n-butanol extract was hydrolyzed. After extraction with ethyl acetate the hydrolysis products were compared with authentic sapogenins samples using thin layer chromatography (TLC). Most of the sapogenins (yuccagenin and diosgenin) were isolated and their structures were confirmed. using nuclear magnetic resonance (NMR) experiments. The n-butanol extract was subjected to a separation process through column chromatography to obtain five fractions. After multiple separation processes by reversed phase high performance liquid chromatography (HPLC), the most active one produced one refined fraction that contained two saponins with the same aglycone (diosgenin) and one yuccagenin based saponin. Best results of the activity were obtained with the yuccagenin derived glycoside.

Potential allelochemicals from Sambucus nigra

Twenty-four aromatic metabolites belonging to cyanogenins, lignans, flavonoids, and phenolic glycosides were obtained from Sambucus nigra. Structures were determined on the basis of their spectroscopic features. Two compounds have been isolated and identified as (2S)-2-O-beta-D-glucopyranosyl-2-hydroxyphenylacetic acid and benzyl 2-O-beta-D-glucopyranosyl-2,6-dihydroxybenzoate. All the compounds have been assayed on dicotyledons Lactuca sativa (lettuce) and Raphanus sativus (radish) and monocotyledon Allium cepa (onion) to test their stimulatory or inhibitory effects on seed germination and radicle elongation. Cyanogenins have a mainly inhibiting effect while lignans stimulate the growth. Some compounds show different effects on dicotyledons and monocotyledons.

Alfalfa (Medicago sativa L.) flavonoids. 2. Tricin and chrysoeriol glycosides from aerial parts

Ten flavone glycosides have been isolated and identified in aerial parts of alfalfa. These included six tricin, one 3'-O-methyltricetin, and three chrysoeriol glycosides. Most of these compounds were acylated with ferulic, coumaric, or sinapic acids, and acylation occurred on the terminal glucuronic acid. Eight of these compounds, including 7-O-beta-D-glucuronopyranosyl-3'-O-methyltricetin, 7-O-beta-D-glucuronopyranosyl-4'-O-beta-D-glucuronopyranosidechrysoeriol, 7-O-[2'-O-feruloyl-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]chrysoeriol, 7-O-[2'-O-feruloyl-[beta-D-glucuronopyranosyl(1-->3)]-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]chrysoeriol, 7-O-[2'-O-sinapoyl-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]tricin, 7-O-[2'-O- feruloyl-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]tricin, 7-O-[2'-O-p-coumaroyl-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]tricin, and 7-O-[2'-O-feruloyl-[beta-D-glucuronopyranosyl(1-->3)]-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]tricin, have not been reported previously in the plant kingdom. Two previously identified alfalfa flavones, 7-O-beta-D-glucuronopyranosidetricin and 7-O-[beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]tricin, were also isolated.

Acylated apigenin glycosides from alfalfa (Medicago sativa L.) var. Artal

Three flavones, including 4'-O-[2'-O-E-feruloyl-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]apigenin, 7-O-beta-D-glucuronopyranosyl-4'-O-[2'-O-E-feruloyl-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]apigenin and 7-O-beta-D-glucuronopyranosyl-4'-O-[2'-O-p-E-coumaroyl-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside]apigenin have been identified in alfalfa var. Artal. The known flavone 7-O-[2-O-E-feruloyl-[beta-D-glucuronopyranosyl(1-->3)]-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucurono-pyranoside] apigenin was also isolated. The structures of these compounds were deduced on the basis of their spectral data.

Novel bioactive breviane spiroditerpenoids from Penicillium brevicompactum Dierckx

The structures of four new, naturally occurring bioactive spiroditerpenoids, (+)-breviones B, C, D, and E, potential allelopathic agents, have been determined from extracts of semisolid fermented Penicillium brevicompactum Dierckx. The structures display the novel breviane spiroditerpenoid skeleton. Structure elucidation was performed by chemical transformations and by homo- and heteronuclear 2D-NMR spectral data. On the basis of combined studies of the theoretical conformations and NOEDIFF data, their relative stereochemistry is proposed. A mixed biogenesis for this novel family of spiroditerpenoids is tendered. The levels of activity shown by breviones B, C, and E in the etiolated wheat coleoptiles bioassay, especially breviones E (100% inhibition) and C (80% inhibition) both at 10(-4) M, suggest them as lead compounds for new agrochemicals.

Bioactive carotanes from Trichoderma virens

Four new metabolites with carotane skeletons, trichocaranes A (1), B (2), C (3), and D (4), were isolated from Trichoderma virens and their structures established by the interpretation of NMR and mass spectroscopic data. The trichocaranes significantly inhibited the growth of etiolated wheat coleoptiles: 40% at 10(-4) M with 1 and 2 and 86% at 10(-3) M with 3.

Natural and synthetic podolactones with potential use as natural herbicide models

A collection of 11 natural and synthetic podolactones have been tested as allelochemicals in a range between 10(-4) and 10(-9) M, and their potential use as natural herbicide models is discussed. Their effects on the germination and growth of the dicots Lactuca sativa (cv. Nigra and cv. Roman), Lepidium sativum, and Lycopersicon esculentum and the monocots Allium cepa, Hordeum vulgare, and Triticum aestivum as standard target species have been studied. An important inhibitory effect on the germination and growth of all tested species (average = 90%) was produced by compounds 9-11 at 10(-4) M. The specific structural requirements related to their activities are studied. On the basis of these results, their use as potential natural herbicide models is proposed.