Chemometrics: a complementary tool to guide the isolation of pharmacologically active natural products.

Chemometrics offers an important complementary tool to enhance the searching and isolation of bioactive natural products from natural sources.

Antioxidant, anti-inflammatory and antinociceptive potential of Ternstroemia sylvatica Schltdl. & Cham.

OBJECTIVE: To evaluate the anti-inflammatory, analgesic, antioxidant and acute toxicity of extracts obtained from a successive extraction with solvents of ascending polarity [hexane, hex; chloroform, CHCl3 and ethanol (EtOH)] of Ternstroemia sylvatica Schltdl. & Cham. METHODS: The antioxidant potential was evaluated by 2,2 diphenyl-1-picrylhydrazyl, the ferric reducing/antioxidant power assays and by determining the total phenolic content. The anti-inflammatory and antinociceptive effects were evaluated using the in vivo croton oil-induced ear edema, phorbol 12-myristate 13-acetate induced ear edema, carrageenan-induced paw edema, acetic acid-induced writhing and formalin murine models. The acute toxicity was tested using the Lorke's method in mice. RESULTS: The EtOH extract was the most active for the antioxidant potential tests diphenyl-1-picrylhydrazyl (68.70% inhibition), ferric reducing/antioxidant power [(2431.30 ± 102.10) mmol Fe2+ and total polyphenols content (215.80 ± 8.50) meqAG/g]. The anti-inflammatory activity was evaluated by topical application of croton oil (2 mg/ear dose) where the EtOH extract showed the strongest activity compared to the control group (45.13% inhibition), whereas in the phorbol 12-myristate 13-acetate model, at the same dose, the CHCl3 extract showed the highest inhibition (42.88%). In the carrageenan induced edema model, the EtOH extract showed a stronger inhibition compared to indomethacin (56.34% and 50.70% at doses of 250 and 500 mg/kg of extract, respectively) during the first hour. Similarly, the same extract showed the highest analgesic activity (30.60% inhibition) in the acetic acid contortion assay, and in the formalin test it showed a greater effect with respect to the control group in both phases. CONCLUSIONS: Our work confirms the value of Ternstroemia sylvatica as an important anti-inflammatory and analgesic plant, whose mechanism seems to be associated to its antioxidant effects, and supports its uses in the Mexican traditional medicine.

Active and passive responses to catnip (Nepeta cataria) are affected by age, sex and early gonadectomy in male and female cats.

Catnip (Nepeta cataria) is a popular plant among cat owners because in about 60% of felids elicits active behaviors such as rolling over, grooming, motor activity and vocalizations. Herein, we assessed the display of active but also passive responses, such as time in sphinx-like position, and consequently hypothesized that 100% of cats respond to catnip. Accordingly, sixty domestic cats of different age (infant, juvenile, adults), sex (males, females) and gonadal status (early gonadectomized, gonadally intact) were placed in a cylindrical chamber (1.20×1.40m) during 5min and then exposed to 500mg of dehydrated catnip for another 5min. Behaviors were videorecorded and scored. Results indicated that about 20% of the cats (adults and juvenile only) displayed active behaviors (i.e. rolling over), whereas 80% displayed passive responses at any age (sphinx-like position, decreased frequency in vocalizations, and decreased motor activity). These results suggest that all cats respond to catnip but they express it actively, passively or with a combination of both types of responses, which mainly depends on age and sex, and early gonadectomy to a much less extent. We discuss the possible implications of brain maturation on this dichotomy and speculate on the role of opioidergic system on the catnip responses.

Anxiolytic-like effect of ethanolic extract of Argemone mexicana and its alkaloids in Wistar rats.

OBJECTIVE: Argemone mexicana is a Papaveracea plant; some reports have shown their antibacterial, anti-cancer, sedative and probably anti-anxiety properties. From their aerial parts, flavonoids and alkaloids have been isolated, which are intrinsically related to some actions on the central nervous system. The aim of this study was to evaluate the anxiolytic-like effects of the plant, using its ethanolic extract and alkaloid-enriched extract obtained from fresh leaves. MATERIAL AND METHODS: Phytochemical screening was carried out together with evaluation of antioxidant capacity and the enrichment of alkaloids present in the extract. Subsequently, 100 and 200 mg/kg doses of ethanolic extract and alkaloid-enriched extract (200 µg/kg) were intraperitoneally administered to female Wistar rats, which were exposed to elevated plus maze (EPM) test. Picrotoxin (1 mg/kg), a non-competitive gamma-aminobutyric acid A (GABAA) chloride channel antagonist, was used in experimental procedures to evaluate if this receptor is involved in the anxiolytic-like effects of A. mexicana. To discard motor effects associated with the treatments, the rats were evaluated by the locomotor activity test. RESULTS: Only the ethanolic extract at 200 mg/kg and alkaloid-enriched extract (200 µg/kg) produced anxiolytic-like effects similarly to diazepam 2 mg/kg on EPM test, without affecting locomotor activity. Meanwhile, the administration of picrotoxin blocked anti-anxiety effect of alkaloid-enriched extract of the plant. CONCLUSION: These results showed that A. mexicana is a potential anxiolytic agent and we suggest that this effect is mediated by the GABAA receptor. These effects are related to the presence of alkaloids.

Salvinorin A content in legal high products of Salvia divinorum sold in Mexico.

Salvia divinorum (Lamiaceae) is a herb native to Mexico where it is used by Mazatec shamans for spiritual and divination purposes. S. divinorum products are easily available to consumers and are used worldwide as legal highs because of the hallucinogenic effects caused mainly by salvinorin A. Highly popular videos and websites on the internet depicting the use of S. divinorum products have contributed to an increase in their consumption. Recent reports have highlighted the potential of these products to induce psychosis in consumers. In Mexico, dried leaf extracts of S. divinorum are sold in different strengths, claiming to correlate with increasing amounts of salvinorin A. In order to determine the variability of salvinorin A content between brands and to investigate possible correlation between brand strengths, this study sought to quantify salvinorin A in commercial products available in Mexico using an HPLC method. The HPLC analytical method showed a correlation coefficient R(2)>0.99, with LOD of 0.44 µg/mL and LOQ of 1.34 µg/mL. The retention time for salvinorin A was 23.09±0.95 min and the measured concentrations ranged between 8.32±0.65 and 56.52±3.77 mg/g dried leaf. The results for brand c did not show an agreement between the declared and the calculated amount of salvinorin A. Additionally, the emergence in Mexico of high strength salvia products (100×), the lack of regulation and the observed variability of salvinorin A content between brands of commercial legal highs products of S. divinorum could result in a health problem for consumers.

Cnidoscolus chayamansa Mc Vaugh, an important antioxidant, anti-inflammatory and cardioprotective plant used in Mexico.

ETHNOPHARMACOLOGICAL RELEVANCE: Cnidoscolus chayamansa Mc Vaugh (Euphorbiaceae) is commonly known as 'chaya' in Central America. In South East Mexico, because of its high nutritional values, is an important part of the diet of many indigenous communities. Chaya is also used as a traditional remedy for the treatment of diabetes, rheumatism, gastrointestinal disorders and inflammation-related diseases. Although Cnidoscolus chayamansa is one of most used and valued medicinal plants, only few studies on documenting its pharmacological properties can be found. MATERIALS AND METHODS: Dried leaves of Cnidoscolus chayamansa were subjected to a successive maceration using Hex, EtOAc and EtOH. The antioxidant activities of the extracts were tested using the DPPH radical scavenging, Ferric reducing/antioxidant power and total phenolic content assays. To determine the anti-inflammatory activity, the TPA-induced mouse ear edema and the carrageenan-induced mouse paw edema assays were used. The cardioprotective effects of the EtOH extract was determined using the ischemia/reperfusion (I/R) rat model. Finally, the acute toxicity was determined using Lorke's method. RESULTS: The results showed a similar anti-inflammatory activity (≈30%) for all extracts but only the EtOAc extract showed relevant activity when applied intraperitoneally. When tested for their antioxidant activity none of the extracts showed a significant activity suggesting that the antinflammatory activity is not related to a direct free radical scavenging of the extracts. Additionally, the EtOH extract showed a strong cardioprotective effect at 500mg/kg when given orally. Both the EtOAc and the EtOH extract have a LD50 >5g/kg, confirming their safety in acute oral administration. CONCLUSIONS: All these results are relevant for a better understanding of the therapeutic used of Cnidoscolus chayamansa in the Mexican traditional medicine and highlights its cardioprotective potential.

Salt effects on the conformational behavior of 5-carboxy- and 5-hydroxy-1,3-dioxane.

The varied and essential involvement of metal ions and inorganic salts in biological and chemical processes motivated the present study where 5-carboxy- and 5-hydroxy-1,3-dioxanes are used as model frameworks for the evaluation of the conformational behavior of oxygen-containing receptors in the presence of Li(+), Na(+), K(+), Ag(+), Mg(2+), Ca(2+), Ba(2+), and Zn(2+). Thus, the position of equilibria, established by means of BF(3), between diastereomeric cis- and trans-5-substituted-2-phenyl-1,3-dioxanes, in solvent THF and in the presence of 0, 1, and 5 equiv of salt, has been determined. The observed Delta G(o) degrees values for the conformational equilibria of 5-carboxy-1,3-dioxane show that Ag(+), Li(+), and Ca(2+) complexation leads to increased stability of the axial isomer. In the case of the 5-hydroxy-1,3-dioxane, Mg(2+), Ag(+), and Zn(2+) are the metal ions that stabilize the axial conformer of the heterocycle upon association. Interpretation of the experimental observations was based on DFT molecular modeling studies at the Becke3LYP/6-31G* and Becke3LYP/6-31+G** levels of theory. Although gas-phase calculations give Delta E values that are too large when modeling equilibria involving ionic species in polar solution, the computational results confirm the structural and energetic consequences of metal cation coordination to the oxygen atom in carbonyls or ethers. The results derived from the present study contribute to our understanding of the chemical processes involved in molecular recognition and physiological events.