[Studies on the anti-ulcer effects of isoprenyl flavonoids (1). The anti-ulcer effects of isoprenyl chalcone extracted from Sophora subprostrata (author's transl)]

Significance of Chalcone Scaffolds in Medicinal Chemistry

Chalcone is a simple naturally occurring α,β-unsaturated ketone with biological importance, which can also be easily synthesized in laboratories by reaction between two aromatic scaffolds. In plants, chalcones occur as polyphenolic compounds of different frameworks which are bioactive molecules that have been in traditional medicinal practice for many years. Chalcone-based lead molecules have been developed, possessing varied potentials such as antimicrobial, antiviral, anti-inflammatory, anticancer, anti-oxidant, antidiabetic, antihyperurecemic, and anti-ulcer effects. Chalcones contribute considerable fragments to give important heterocyclic molecules with therapeutic utilities targeting various diseases. These characteristic features have made chalcone a topic of interest among researchers and have attracted investigations into this widely applicable structure. This review highlights the extensive exploration carried out on the synthesis, biotransformations, chemical reactions, hybridization, and pharmacological potentials of chalcones, and aims to provide an extensive, thorough, and critical review of their importance, with emphasis on their properties, chemistry, and biomedical applications to boost future investigations into this potential scaffold in medicinal chemistry.

From lab to nature: Recent advancements in the journey of gastroprotective agents from medicinal chemistry to phytotherapy

Peptic ulcer, affecting 10 % of the global population, results from imbalances in gastric juice pH and diminished mucosal defences. Key underlying factors are non-steroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori infection, undermining mucosal resistance. Traditional treatments like proton pump inhibitors (PPIs) and histamine-2 (H2) receptor antagonists exhibit drawbacks such as adverse effects, relapses, and drug interactions. This review extensively explores the ethnomedicinal, synthetic and pharmacological facets of various potential peptic ulcer treatments. Rigorous methodologies involving electronic databases, and chemical structure verification via 'PubChem' and 'SciFinder' enhance the review's credibility. The provided information, spanning medicinal insights to intricate pharmacological mechanisms, establishes a robust groundwork for future research and the development of plant-derived or synthetic molecules for peptic ulcers, offering a promising alternative to conventional therapies.

Systematic analysis of chemical profiles of Sophorae tonkinensis Radix et Rhizoma in vitro and in vivo by UPLC-Q-TOF-MSE

Sophorae tonkinensis Radix et Rhizoma (S. tonkinensis) has been recorded as a "poisonous" Chinese herbal medicine in Chinese Pharmacopoeia 2020. The clinical reaction reports of S. tonkinensis indicated its neurotoxicity, there exists still dispute about its toxic substances. At present, there is no report on the blood and brain prototype research of S. tonkinensis. Most studies focused on alkaloids, and less on other compounds. Moreover, the constituents absorbed into the blood and brain were rarely investigated so far. In this study, a rapid and efficient qualitative analysis method was established by UPLC-Q-TOF-MS^E to characterize S. tonkinensis ingredients and those entering into the rat body after oral administration. A total of 91 compounds were identified in S. tonkinensis, of which 28 were confirmed by the standards. 30 and 19 prototypes were also firstly identified in rat blood and brain, respectively. It was found that except for alkaloids, most flavonoids were detected in the rat body and distributed in the cerebrospinal fluid, suggesting that flavonoids may be one of the important toxic or effective substances of S. tonkinensis, which provides new clues and data for clarifying its toxicity or efficacy of the medical plant.

UPLC-MS identification and anticomplement activity of the metabolites of Sophora tonkinensis flavonoids treated with human intestinal bacteria

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Total flavonoids of S. tonkinensis showed obvious anticomplement activity after incubated with human intestinal bacteria.

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Eighteen flavonoids were identified from TFST and its metabolites by UPLC-ESI- LTQ/MS.

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Five glycosides were metabolized into three aglycones with more potent anticomplement activity.

Anticomplement activity played an important role in anti-inflammatory effects of traditional Chinese herbs. The total flavonoids of Sophora tonkinensis (TFST) were inactive on the complement system but showed obvious anticomplement activity after incubated with human intestinal bacteria in vitro. In order to discover the metabolic activation of TFST by intestinal flora, the constituents of TFST and its metabolites were identified by UPLC-ESI-LTQ/MS. Their anticomplement activities were evaluated through the classical and alternative pathway. As a result, eighteen flavonoids were identified, including seven flavonoid glycosides, five aglycones and six isoprenylated flavonoids. All the glycosides (daidzein-4′-glucoside-rhamnoside, sophorabioside, rutin, isoquercitrin, quercitrin, ononin, trifolirhizin) were metabolized into their corresponding aglycones in different extent by human intestinal bacteria, resulting in the contents of the five aglycones were highly increased in 24 h. However, no changes have occurred on the six isoprenylated flavonoids. Interestingly, three aglycones (quercetin, formononetin and maackiain) had significantly more potent anticomplement activities than their prototype glycosides. The results indicated that the enhancement of TFST anticomplement activity was attributed to the active aglycones, especially formononetin and quercetin, produced by human intestinal bacteria. These aglycones are likely to be among the potential active components of S. tonkinensis for its inhibiting inflammation effects.

Secondary metabolites for antiulcer activity

Peptic ulcers are open sores or erosions in the lining of either the duodenum (duodenal ulcers) or the stomach (gastric ulcers). Peptic ulcer, which is mainly caused by bacterial attack or excess of acid secretion, can be cured effectively by these isolated plant compounds. In this present scenario, demand for herbal medicines are increasing due to easy availability in surrounding place at low cost. This review article is all about such isolated plant compounds such as alkaloids, flavonoids and terpenoids. Various plants have been used as folk medicine by the people of rural area, which shows significant effect against peptic ulcer. Further study should be conducted upon these herbal plants because there is possibility for minimising the adverse effect caused by the present antiulcer drugs.

Flavonoids with gastroprotective activity

Peptic ulcers are a common disorder of the entire gastrointestinal tract that occurs mainly in the stomach and the proximal duodenum. This disease is multifactorial and its treatment faces great difficulties due to the limited effectiveness and severe side effects of the currently available drugs. The use of natural products for the prevention and treatment of different pathologies is continuously expanding throughout the world. This is particularly true with regards to flavonoids, which represent a highly diverse class of secondary metabolites with potentially beneficial human health effects that is widely distributed in the plant kingdom and currently consumed in large amounts in the diet. They display several pharmacological properties in the gastroprotective area, acting as anti-secretory, cytoprotective and antioxidant agents. Besides their action as gastroprotectives, flavonoids also act in healing of gastric ulcers and additionally these polyphenolic compounds can be new alternatives for suppression or modulation of peptic ulcers associated with H. pylori. In this review, we have summarized the literature on ninety-five flavonoids with varying degrees of antiulcerogenic activity, confirming that flavonoids have a therapeutic potential for the more effective treatment of peptic ulcers.

Anti-ulcerogenic properties of the aqueous and methanol extracts from the leaves of Solanum torvum Swartz (Solanaceae) in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Solanum torvum (Solanaceae) is a plant currently used in Cameroon ethnomedicine for the treatment of stomach ailments.

AIM OF THE STUDY

The present study was undertaken to determine the anti-ulcer potential of the aqueous and methanol extracts from the leaves of Solanum torvum.

MATERIALS AND METHODS

The aqueous and methanol extracts from the leaves of Solanum torvum were tested orally at the doses of 250, 500 and 750 mg/kg, on gastric ulcerations experimentally induced by HCl/ethanol, indomethacin, pylorus ligation and stress. The fractionation of the methanol extract through silica gel column chromatography produced seven different fractions (A-G) which were tested orally at the dose of 100mg/kg against HCl/ethanol-induced ulceration.

RESULTS

The methanol extract at the dose of 750 mg/kg produced 98.12, 99.16, 98.70 and 96.03% inhibition when gastric ulcerations were induced by HCl/ethanol, indomethacin, pylorus ligation and stress, respectively. The aqueous extract at the same dose produced 96.55, 96.86, 98.63 and 98.63% inhibition on ulcerations induced respectively by HCl/ethanol, indomethacin, pylorus ligation and stress. All the fractions of the methanol extract significantly inhibited ulcer formation. Fraction F which contains flavonoids and triterpens was the most active and exhibited an inhibitory percentage of 84.74. Both extracts significantly increased mucus production and reduced gastric acid secretion.

CONCLUSIONS

The aqueous and methanol extracts of the leaves of Solanum turvum possess anti-ulcerogenic properties that may be due to cytoprotective mechanism. These results support the ethnomedical uses of the plant in the treatment of gastric ulcer.

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.

Biotransformations in the regioselective deacetylation of polyphenolic peracetates in organic solvents

Regioselectivity has been observed in the deacetylation of peracetates of polyphenolic aromatic ketones by lipases from porcine pancreas (PPL) and Candida cyclindracea (CCL) suspended in organic solvents. The deacetylation of acetoxyl groups at positions para and meta to the carbonyl (ketonic) group is favoured over the one at the ortho position.

Effects of KW-5805, a new antiulcer agent, on experimental gastric and duodenal ulcers, gastric mucosal lesions by necrotizing agents and gastric acid secretion

Effects of KW-5805, a new antiulcer agent, on various experimental ulcers, necrotizing agent-induced gastric lesions and gastric acid secretion in rats were compared with those of pirenzepine and cimetidine. KW-5805 showed antiulcer activities against experimental gastric and duodenal ulcers (ED50 = 1.2-10.0 mg/kg, p.o.). KW-5805 effectively inhibited gastric lesions induced by various necrotizing agents (ED50 = 4.5-39.8 mg/kg, p.o.). In addition, the cytoprotective effect of KW-5805 was not affected by indomethacin, but reserved by N-ethylmaleimide. These antiulcer and cytoprotective effects of KW-5805 were more potent than those of pirenzepine and cimetidine. In pylorus-ligated rats, intraduodenal KW-5805 administration at 30 mg/kg showed a weak antisecretory effect, which was 3-10 times less potent than those of pirenzepine and cimetidine. In rats with acute gastric fistula, intravenous injection of KW-5805 reduced methacholine-stimulated gastric acid secretion at doses of 10 and 30 mg/kg and inhibited tetragastrin-induced acid secretion at 30 mg/kg. These results indicate that KW-5805 has potent and broad antiulcer properties, which are probably exerted by its potent cytoprotective effect in addition to its antisecretory effect.

Inhibition of gastric H+,K(+)-ATPase by the anti-ulcer agent, sofalcone

Effects of the anti-ulcer agent, sofalcone, on gastric H+,K(+)-ATPase were studied as well as those of other chalcone derivatives, chalcone and sophoradin. These drugs inhibited pig gastric H+,K(+)-ATPase in a dose-dependent manner. They were 5-10-fold less inhibitory toward Na+,K(+)-ATPase than H+,K(+)-ATPase. The potencies of these drugs on the inhibition of enzymes were as follows: sophoradin greater than sofalcone greater than chalcone. Kinetic studies showed that the inhibition of H+,K(+)-ATPase by sofalcone was competitive with respect to ATP and was non-competitive with respect to K+. Sofalcone also inhibited H+,K(+)-ATPase mediated proton transport and reduced the phosphoenzyme level. These results suggest that sofalcone inhibits gastric H+,K(+)-ATPase competitively with ATP at the ATP site and thereby blocks the phosphorylation of the enzyme. This may be the cause of the anti-secretory activity of sofalcone.

Effect of 2'-carboxymethoxy-4,4'-bis(3-methyl-2-butenyloxy)chalcone (SU-88) on prostaglandin metabolism in hog gastric mucosa

SU-88 [2'-carboxymethoxy-4,4'-bis(3-methyl-2-butenyloxy)chalcone] inhibited the activity of the prostaglandin (PG)-metabolizing enzyme, 15-hydroxy-PG-dehydrogenase (15-OH-PG-DH), in a cytoplasmic fraction of gastric mucosa. This compound had no effect on the PG synthetase of bovine seminal vesicle microsomes and lactate dehydrogenase in rat liver. The 15-OH-PG-DH activity of gastric mucosa was not influenced by a specific inhibitor of alcohol dehydrogenase, 4-methylpyrazole. Carbenoxolone (CBX) also inhibited 15-OH-PG-DH activity. The IC50 values for SU-88 and CBX were approximately 20 and 40 microM respectively. SU-88 inhibited 15-OH-PG-DH activity uncompetitively or competitively according to whether PGE1 or NAD was used as substrate. CBX inhibited competitively the activity of this enzyme for both substrates. After the addition of SU-88 or CBX to the incubation medium of gastric mucosa, the PGE2 level of the medium was increased significantly while that of the tissue remained unchanged. These results indicate that SU-88 specifically inhibited 15-OH-PG-DH activity and suggest that 15-OH-PG-DH activity regulates the level of PGs in gastric mucosa and may have an anti-ulcer influence.

Flavonoids, a class of natural products of high pharmacological potency

A review has been presented of the biochemistry and pharmacology of a class of natural products, the flavonoids. These substances which are widely distributed in the plant kingdom and present in considerable quantities in common food products, spices and beverages have in a concentrated form (Propolis) been used since ancient times by physicians and laymen to treat a great variety of human diseases but they have yet to pass the tests of modern, controlled, clinical experimentation. An attempt has been made to present the fundamental evidence from the basic biological sciences which is required to stimulate the interest of the clinicians in this new field. The few existing reports on the careful pharmacodynamic, pharmacokinetic and clinical studies which have been made have been summarized to provide a basis for a full-scale investigation of the therapeutic potential of flavonoids.