Preliminary study of the potential vasodilator effects on rat aorta of centaurein and centaureidin, two flavonoids from Centaurea corcubionensis

New flavonoid-based compound synthesis strategy for antihypertensive drug development

Hypertension is one of the leading causes of mortality in relation to the cardiovascular conditions and easily the most overlooked and poorly managed disease in mankind. With well over 200 drugs available in the market globally, there is still an urgency to search for antihypertensive alternatives due to the subpar efficacy and unwarranted side effects of the current choices. Present studies reported over 250 types of plant-derived compounds were being investigated for potential pharmacological effects on the vasculature in the last 3 decades. There were numerous literatures that claimed various compounds exhibiting vasorelaxant properties to a certain extent with low numbers of these compounds being successfully adapted into the current medicinal practice for treatment of hypertension. The issue is the scarcity of reviews that summarizes the discovery of this field and the lack of thorough comparison of these compounds to identify which of these vasodilators should be the next face of hypertension management. Thus, this review is aiming towards identifying the relationship between a major class of plant-derived compounds, flavonoid's activity as a vasodilator with their signalling pathways and their structural characteristics according to their vasorelaxant properties. Interestingly, we found that both nitric oxide and voltage-operated calcium channels pathways, and two of the flavonoid's structural characteristics play crucial roles in eliciting strong vasorelaxant effects. We have faith that the insights of this review will serve as a reference for those researching similar topics in the future and potentially lead to the development of more promising antihypertensive alternative.

Identification of the main active antidepressant constituents in a traditional Turkish medicinal plant, Centaurea kurdica Reichardt

ETHNOPHARMACOLOGICAL RELEVANCE

In Turkish folk medicine, infusions and decoctions prepared from the flowers, fruits and aerial parts of Centaurea kurdica Reichardt (Asteraceae) are used as sedative and antidepressant-like effects of various sedative plants have been identified in many studies. The present study was designed to evaluate the antidepressant activity of this plant.

MATERIALS AND METHODS

n-Hexane, ethyl acetate (EtOAc), and methanol (MeOH) extracts were prepared from the branches with leaves and also flowers of the plant. Antidepressant potentials of these extracts were researched by using the forced swimming test, tail suspension test, and antagonism of tetrabenazine-induced ptosis, hypothermia, and suppression of locomotor activity.

RESULTS

After determination of high antidepressant potentials of MeOH extract prepared from flowers and n-hexane extract prepared from branches with leaves, isolation studies were carried out on these two extracts and the main active components were determined as β-amyrin, mixture of β-sitosterol and stigmasterol and costunolide for the branches with leaves and quercitrin, isoquercetin and naringenin-7-O-glucopyranoside for the flowers.

CONCLUSIONS

As a result of the mechanistic and toxicity studies planned on this plant, it is thought that C. kurdica may be a glimmer of hope for depressed patients.

Evaluation of cell protection by Psephellus pyrrhoblepharus (Boiss.) Wagenitz extracts in MPP+-induced dopaminergic cell damage

Neurodegenerative diseases affect millions of people. Major reasons behind the onset and progression of these diseases are still under investigation. Therefore, any approach that would treat/prevent progression is important. In this study, we aimed to investigate the potential protective effects of Psephellus pyrrhoblepharus (Boiss.) Wagenitz extracts in MPP⁺-induced dopaminergic cell damage and compare the effectiveness of different extracts (methanol:water (1:1), chloroform and n-hexane). The cells were pretreated with four different concentrations (10, 50, 100, and 200 µg/ml) of methanol:water (1:1), chloroform and n-hexane extracts of P. pyrrhoblepharus following MPP⁺ treatment for 12 or 24 h. The changes in cell viability were determined using the MTT assay. Additionally, antioxidant activities and total phenolic/flavonoid contents of the extracts were determined with radical scavenging capacity, Folin-Ciocalteu and aluminum chloride assays, respectively. The extracts at selected concentrations were found to be protective in a dose-dependent manner at 12 and 24 h. Nevertheless, the methanol extract of the plant showed the highest protection both at 100 and 200 µg/ml (115.13%±3.98, 121.87%±1.66; p < 0.05) against dopaminergic damage at 24 h. The results showed that selected concentrations were not toxic and did not affect cell proliferation rate. Besides, the chloroform extract was found to have higher antioxidant activity than the other extracts (p < 0.05). The total phenolic and total flavonoid contents were found consistent with antioxidant activities. Our findings support the neuroprotective and antioxidant potential of P. pyrrhoblepharus. However, further studies on identifying the presence of chemicals in P. pyrrhoblepharus extracts which are responsible for protection should be carried out to confirm their therapeutic potential.

Some popular medicinal plants and diseases of the Upper Palaeolithic in Western Georgia

ETHNOPHARMACOLOGICAL RELEVANCE

Palynological studies of cultural layers of cave sediments have been used in order to better understand traditional practices. The Upper Palaeolithic in Georgia (36,000-11,000 cal. BP) provides a rich source of such material. However, up to day from such sediments the identification of medicinal plants has hardly been achieved. Large quantities of pollen most notably from entomophilous taxa in fossil spectra can serve as a tool to identify traditionally important species. As these plants are used in modern popular medicine on the territory of Georgia (like Achillea millefolium L., Artemisia annua L., Artemisia absinthium L., Centaurea jacea L., Urtica dioica L.) can be served as an indirect evidence for their medicinal relevance from the Palaeolithic Period up to days. Their modern uses may point that the main diseases during the Upper Palaeolithic were the same as today.

MATERIALS AND METHODS

The Upper Palaeolithic sediments were studied palynologically come from four caves: Dzudzuana, Satsurblia, Kotias Klde and Bondi. Modern sediments were investigated from 6 caves. Fossil and modern samples were taken according to the standard procedure in palynology. The laboratory treatment was carried out as follows: first, 50g of the sample was boiled in 10% KOH. At the second stage, centrifuging of the material in cadmium liquid was performed. At the final stage, acetolysis treatment was used.

RESULTS

Pollen of A. absinthium L. (Asteraceae), A. annua L. (Asteraceae), A. millefolium L. (Asteraceae), C. jacea L. (Asteraceae), and U. dioica L. (Urticaceae) are identified to species level. This species are not edible and are popular in present-day folk medicine. In the Upper Palaeolithic layers, significant amounts of studies species pollen were recorded in the cave, likely due to their flowering branches being brought in by humans for use. Detailed consideration of the pharmacological characteristics of the examined species showed that almost all of them have anti-inflammatory, antibacterial, antimicrobial and antipyretic activity.

CONCLUSION

The fossil pollen complex of medicinal herbs, dominated by A. millefolium and Artemisia (A. annua and A. absinthium), suggests that the ancient population living in the studied caves could have been prone to malaria, rheumatism and gastrointestinal diseases. In the Upper Palaeolithic, the population inhabiting cave sites might have suffered from gout and callouses.

Vasodilator compounds derived from plants and their mechanisms of action

The present paper reviews vasodilator compounds isolated from plants that were reported in the past 22 years (1990 to 2012) and the different mechanisms of action involved in their vasodilator effects. The search for reports was conducted in a comprehensive manner, intending to encompass those metabolites with a vasodilator effect whose mechanism of action involved both vascular endothelium and arterial smooth muscle. The results obtained from our bibliographic search showed that over half of the isolated compounds have a mechanism of action involving the endothelium. Most of these bioactive metabolites cause vasodilation either by activating the nitric oxide/cGMP pathway or by blocking voltage-dependent calcium channels. Moreover, it was found that many compounds induced vasodilation by more than one mechanism. This review confirms that secondary metabolites, which include a significant group of compounds with extensive chemical diversity, are a valuable source of new pharmaceuticals useful for the treatment and prevention of cardiovascular diseases.

Flavonoids in subtribe Centaureinae (Cass.) Dumort. (tribe Cardueae, Asteraceae): distribution and (13)C-NMR spectral data

This review reports the occurrence of flavonoids in subtribe Centaureinae of Asteraceae family. It extensively covers the literature up to 2010 and collects all available (13)C-NMR data.

Pharmacological and histological effects of Centaurea bruguierana ssp. belangerana on indomethacin-induced peptic ulcer in rats

The species Centaurea bruguierana (DC.) Hand.-Mazz. ssp. belangerana (DC.) Bornm. (CBB) (Asteraceae), known as "Baad-Avard" in Borazjan, Bushehr Province, southern Iran, is used in folk medicine as a hypoglycemic herb in diabetes and as a remedy for peptic ulcer disorders. Total 80% EtOH extract and petroleum ether, CHCl(3), EtOAc, n-BuOH, and remaining fractions obtained by solvent-solvent fractionation of dried aerial flowering parts of the plant were investigated for anti-ulcer activity against indomethacin-induced ulcerogenesis in rats. Anti-ulcer activity was evaluated by measuring the ulcer index (UI) and ulcer inhibition. The UI was significantly reduced in all treated animals. A dramatic decrease in the UI was observed following the administration of total extract (100 mg/kg, p < 0.001) and CHCl(3) fraction (42 mg/kg, ***p < 0.001) in comparison with the control group. The percentage ulcer inhibition with total extract at a dose of 100 mg/kg (97.66%) and CHCl(3) fraction at a dose of 42 mg/kg (96.96%) was found to be higher (p < 0.001) than the reference group (cimetidine 100 mg/kg) (87.08%). The pharmacological and histological results of the present study proved that the aerial flowering parts of CBB possess preventive activity against peptic ulcer, supporting the traditional assertion in southern Iranian folk medicine.

In vivo anti-inflammatory and wound healing activities of Centaurea iberica Trev. ex Spreng

AIM OF THE STUDY

Several Centaurea species (Asteraceae) are used in Turkish folk medicine to alleviate pain and inflammatory symptoms in rheumatoid arthritis, high fever, head ache and for wound healing. Particularly, the aerial part of Centaurea iberica Trev. ex Spreng. has been practiced on wounds for healing. In order to evaluate the anti-inflammatory and wound healing activities of the plant, extracts were prepared with variety of solvents: hexane, chloroform, ethyl acetate and aqueous methanol (85%) from the aerial parts of Centaurea iberica.

MATERIALS AND METHODS

The incision by using tensiometer and excision models were used in order to assess the effect of the plant extracts on wound healing in mice and rats. Results were also evaluated histopathologically. In vivo inhibitory effect of the extracts on acetic acid-induced increase in capillary permeability was studied for the assessment of anti-inflammatory activity.

RESULTS

The wound healing effect was comparatively evaluated with a reference ointment Madecassol. Noteworthy wound healing activity was observed for the ointment formulation prepared with 1% methanol extract. The results of histopathological evaluation supported the outcome of both incision and excision wound models. Moreover, the methanol extract exerted remarkable wound healing activity and also demonstrated a significant and dose-dependent anti-inflammatory activity.

CONCLUSION

The experimental study revealed that Centaurea iberica displays remarkable wound healing and anti-inflammatory activity.

Sesquiterpene lactones with antinociceptive and antipyretic activity from two Centaurea species

ETHNOPHARMACOLOGICAL RELEVANCE

Several Centaurea species are used to alleviate pain and inflammatory symptoms in rheumatoid arthritis, high fever, and head ache in Turkish folk medicine.

AIM OF THE STUDY

The effectiveness of extracts, fractions and subfractions from dried Centaurea solstitialis L. subsp. solstitialis (CSS) (Asteraceae) roots and aerial parts were studied on mice.

MATERIALS AND METHODS

The antinociceptive and antipyretic effects of Centaurea solstitialis L. subsp. solstitialis have been investigated by using p-benzoquinone-induced writhing reflex for antinociceptive activity and Freund's Complete Adjuvant-induced pyrexia model for antipyretic activity assessment in mice.

RESULTS

The ethanolic extract from the aerial parts of the plant was shown to possess significant antinociceptive (p < 0.01) and antipyretic activities (p < 0.01). The extract was then submitted to subsequent solvent extractions and chromatographic processes. Through bioassay-guided fractionation and isolation procedures two sesquiterpene lactones, solstitialin A and acetyl solstitialin, were isolated and defined as the active components of CSS. On the other hand, a comparative study was conducted on another species, Centaurea depressa Bieb., which has no similar folkloric utilization. Following the same fractionation chart same compounds were defined as the active ingredients.

CONCLUSION

Results of the present study proved that aerial part of CSS possesses antinociceptive and antipyretic activities supporting the folkloric assertion in Turkish folk medicine. However, these effects seem not limited to CSS, some other Centaurea species, in fact, having no folkloric use might be equally active.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

The possible implication of trans-Resveratrol in the cardioprotective effects of long-term moderate wine consumption

trans-Resveratrol (t-RESV; 1-10 microM), a phenolic component of wines, had no effect on phenylephrine-(PE; 1 microM) and high KCl-(60 mM) induced contractions in endothelium-denuded rat aortic rings. However, it relaxed the contractile response produced by these vasoconstrictor agents in intact rat aorta. The vasorelaxing effects of t-RESV were completely inhibited by N(G)-nitro-L-arginine (L-NOARG; 0.1 mM) and methylene blue (10 microM), but they were unaffected by atropine (10 microM) and yohimbine (1 microM). The reversal effect produced by L-NOARG was antagonized by L-arginine but not by D-arginine (0.1 mM). t-RESV (1-10 microM) did not significantly modify rat aorta constitutive nitric-oxide synthase activity. However, this natural compound decreased NADH/NADPH oxidase activity in rat aortic homogenates. In addition, t-RESV (1-10 microM) was ineffective in scavenging superoxide anions (O(2)*) generated enzymatically by a hypoxanthine/xanthine oxidase (HX/XO) system and/or to inhibit XO. The above data demonstrate that the characteristic endothelium-dependent vasorelaxant effect of t-RESV in rat aorta seems to be caused by the inhibition of vascular NADH/NADPH oxidase and the subsequent decrease of basal cellular O(2)* generation and, therefore, of NO biotransformation. Under the assumption that t-RESV exhibits a similar behavior in human blood vessels and bearing in mind that an overactivity of NADH/NADPH oxidase has been found in a number of cardiovascular pathologies, the results obtained in this work suggest that t-RESV could play an important role in the cardioprotective effects induced by the long-term moderate wine consumption.