María Isabel Aguilar

Ethnobotanical survey and antibacterial activity of plants used in the Altiplane region of Mexico for the treatment of oral cavity infections.

ETHNOPHARMACOLOGICAL RELEVANCE The ethnobotanical survey conducted in this study showed 47 plant species used in the Altiplane region of Mexico for the treatment of dental diseases such as toothache, dental caries, periodontal disease and gingivitis. MATERIALS AND METHODS Information was collected by performing interviews. The following data were recorded: name of the patients or herbalists with their age, sex; date and place of gathering information; pathology of persons interviewed; name of the drug (vernacular name); parts used (leaves, bark, fruits, seeds, aerial parts), mode of preparation and administration, and possible combinations. The inhibitory effects of the aqueous and ethanolic extracts of the medicinal plants detected during the survey the on the growth of Streptococcus mutans and Phrophyromonas gingivalis were determined using microdilution method. The minimum bactericidal concentrations (MBC) were determined from the wells of microplate with no visible bacterial growth. RESULTS In total, tree places of the Altiplane region of Mexico were visited and five healers and 100 patients were questioned. 47 wild and cultivated species were recorded. The most frequent uses were to treat tooth pain, gum diseases, bad breath and cavities. Infusions were the most frequently prepared formulation. Other applied preparations mentioned with decreasing frequency were decocts, syrups, tinctures, direct application of the plant material without prior preparation and finally macerations. The ethanolic extracts of Haematoxylon brasiletto, Punica granatum, Iostephane heterophyla, Bursera simaruba, Cedrela odorata and Rhus standleyi (12.5-65.0 μg/mL) as well as water extracts of Haematoxylon brasiletto, Punica granatum, Iostephane heterophyla, Amphipterygium adstringens, Argemone mexicana, Cedrela odorata, Eysenhardtia polystachya, Persea americana, Syzygium aromaticum, Cinnamomun zeylanicum, Cnidoscolus multilobus and Rhus standleyi (10.5-78.0 μg/mL) showed the highest inhibitory effect against Streptococcus mutans and Porphyromonas gingivalis. CONCLUSIONS Many plants are used in the Mexican traditional medicine to treat oral bacterial diseases by the healers or patients. Our study demonstrated that most of the medicinal plants showed an antibacterial effect in vitro, and justified at least in part their use in traditional medicine. These results encourage further investigations to extract and identify the active chemical compounds responsible for the antibacterial effect observed.

Inhibition of photosystem II in spinach chloroplasts by trachyloban-19-oic acid

Abstract The effect of trachyloban-19-oic acid isolated from Iostephane heterophylla (Asteraceae), was investigated on several photosynthetic activities in spinach thylakoids. The results indicated that this compound inhibited ATP synthesis and uncoupled electron transport, as well as basal and phosphorylating electron flow. Therefore, trachyloban-19-oic acid acts as Hill reaction inhibitor. This compound did not affect photosystem I activity but inhibited uncoupled photosystem II electron flow from H 2 O to DCPIP, and has not effect on electron flow from H 2 O to SiMo, indicating that the site of inhibition of this compound is at the level of Q A –Q B . Chlorophyll a fluorescence measurements confirm the behavior of this diterpene as Q A –Q B inhibitor, and in the other hand, this results indicate that a perturbation in the thylakoid membranes at the level of LHC II occurs.

Alkaloids from the flowers of Erythrina americana

Abstract The two alkaloids, α- and β-erythroidine have been identified in 0.034 and 0.11 % yield in flowers of Erythrina americana and could be responsible for the hypnotic activity of flower extracts.

Biflavonoids Isolated from Selaginella lepidophylla Inhibit Photosynthesis in Spinach Chloroplasts

Through bioactivity-guided chemical analysis of Selaginella lepidophylla, biflavonoids robustaflavone (1), 2,3-dihydrorobustaflavone (2), and 2,3-dihydrorobustaflavone-5-methyl ether (3) were isolated and their structures confirmed by spectroscopic and spectrometric analyses. Their NMR resonances were unambiguously assigned from HMBC, NOESY, and NOESY-1D experiments, and absolute configurations of 2 and 3 were established. Compound 3 has not been reported, and although structure of 2 was described before, the (13)C NMR assignment does not correlate with the structure reported. Therefore, this is the first report of 2. All compounds inhibited ATP production. Compounds 1 and 2 behaved as Hill reaction inhibitors. 1 interacted with photosystem II, transforming the reaction centers to silent centers at 300 and 600 microM. The interaction and inhibition target of 2 was located on Cyt b6f to PC. The three compounds also behaved as energy transfer inhibitors, 3 being the most active.

The sesquiterpenes β-caryophyllene and caryophyllene oxide isolated from Senecio salignus act as phytogrowth and photosynthesis inhibitors.

The n-hexane extract of S. salignus plants inhibited ATP synthesis and two sesquiterpenes, the β-caryophyllene (1) and caryophyllene oxide (2) were isolated from this nonpolar fraction. Compound 1 inhibited by 42% the root elongation of Physalis ixocarpa seedlings at 50 µg/mL and by 53% at 150 µg/mL, whereas at 150 µg/mL this compound only inhibited root elongation of Echinochloa crus-galli by 30%. On the other hand, compound 2 had no effect on either germination or root and stem growth of E. cruss galli and P. ixocarpa. However, 1 and 2 inhibited the dry biomass of P. ixocarpa plants grown for 18 days previous to treatment and it was found that 1 was the most active biomass inhibitor. The Chl a fluorescence transient in vivo experiment indicates that 1 (100 µg/mL) has a major effect at 72 h after treatment on leaves of P. ixocarpa plants by inhibiting photosystem II (PS II) transforming active reaction centers to “heat sinks” or the formation of silent reaction centers unable to reduce QA. β-Caryophyllene also induces chlorosis on treated leaves.

Bioactive Compounds from Iostephane heterophylla (Asteraceae)

Abstract The novel bisabolene sesquiterpenes 3-6, were isolated from Iostephane heterophylla, using bioguided fractionation. The new compounds were determined to be (12R/12S)-12,13-epoxy-xanthorrhizols (3,4) and (12R/12S)-12,13-dihydro-12,13-dihydroxy-xanthorrizols (5,6) and their structures were characterized by analysis of spectroscopic data and by chemical correlation from xanthorrhizol (2). The stereochemistry at C-12 of 5 was deduced using the modified Mosher experiment. Some of the isolated compounds elicited activity against gram positive and gram negative bacteria, levadura and dermatophytes.

Bisabolenes, polycyclic diterpenoids and other constituents from the roots of Iostephane heterophylla☆

Abstract From the roots of the medicinal plant Iostephane heterophylla , two new bisabolenes and a new ent -kaurenoid diterpene, along with xanthorrhizol, eight polycyclic diterpenes, scopoletin and 8-hydroxy-6-acetyl-2,2-dimethyl-chromene were isolated. Some compounds displayed toxicity in the Artemia salina bioassay.

Natural diterpenes from Croton ciliatoglanduliferus as photosystem II and photosystem I inhibitors in spinach chloroplasts

In our search for new natural photosynthetic inhibitors that could lead to the development of “green herbicides” less toxic to environment, the diterpene labdane-8α,15-diol (1) and its acetyl derivative (2) were isolated for the first time from Croton ciliatoglanduliferus Ort. They inhibited photophosphorylation, electron transport (basal, phosphorylating and uncoupled) and the partial reactions of both photosystems in spinach thylakoids. Compound 1 inhibits the photosystem II (PS II) partial reaction from water to Na+ Silicomolibdate (SiMo) and has no effect on partial reaction from diphenylcarbazide (DPC) to 2,6-dichlorophenol indophenol (DCPIP), therefore 1 inhibits at the water splitting enzyme and also inhibits PS I partial reaction from reduced phenylmetasulfate (PMS) to methylviologen (MV). Thus, it also inhibits in the span of P700 to Iron sulfur center X (FX). Compound 2 inhibits both, the PS II partial reactions from water to SiMo and from DPC to DCPIP; besides this, it inhibits the photosystem I (PS I) partial reaction from reduced PMS to MV. With these results, we concluded that the targets of the natural product 2 are located at the water splitting enzyme, and at P680 in PS II and at the span of P700 to FX in PS I. The results of compounds 1 and 2 on PS II were corroborated by chlorophyll a fluorescence.

Novel Bisabolene Glycoside and Other Constituents from the Roots of the Medicinal Plant Iostephane heterophylla (Asteraceae)

Abstract The novel sesquiterpene glycoside 1-O-[12-O-(12S)- dihydro-12,13-dihydroxyxanthorrizol]-β-L-arabinopyranosyl-(1rarr;2)-β-D-glucopyranoside 1 was identified as a constituent of the ethanol extract of the roots of Iostephane heterophylla, a species used in Mexican traditional medicine, and characterized as the heptaacetyl derivative 2. β-D-glucopyranose, β sitosteryl β-D-glucopyranoside, and stigmasterol were also found as constituents of this extract.

Interference of methyl trachyloban-19-oate ester with CF0 of spinach chloroplast H+-ATPase

In isolated spinach chloroplasts, low concentrations (I(50)=14 microM) of methyl trachyloban-19-oate ester inhibited ATP synthesis and coupled electron transport as well as light-activated membrane-bound Mg(2+)-ATPase activity. Basal (-Pi) and uncoupled electron transport and heat-activated Ca(2+)-dependent ATPase activity of isolated coupling factor proteins were unaffected by methyl trachyloban-19-oate. Thylakoids partially stripped of coupled factor by EDTA were unable to accumulate protons in the light. However, increasing concentrations of methyl trachyloban-19-oate ester restored this ability. It is concluded that the methyl trachyloban-19-oate ester effects result from blocking proton transport through the CF(0) channel. Methyl trachyloban-19-oate ester exhibited non-competitive kinetics with DCCD and triphenyltin. These results suggest that the natural products, DCCD and triphenyltin, access inhibition sites in CF(0). The K(i) is 75 microM.