In vitro screening for the anti-anaphylactic agent in Thonningia sanguinea

Dihydrochalcone Glucosides from the Subaerial Parts of Thonningia sanguinea and Their in Vitro PTP1B Inhibitory Activities

Six new and four known dihydrochalcone glucoside derivatives (1-10), the phenylpropanoid coniferin (11), and the lignans (+)-pinoresinol (12) and lariciresinol (13) were isolated from the subaerial plant parts of Thonningia sanguinea in the course of a screening campaign for new antidiabetic lead compounds. The structures of the new substances were elucidated by HRESIMS, NMR, GC-MS, and ECD data evaluation. 2'- O-(3-Galloyl-4,6- O- S_a-hexahydroxydiphenoyl-β-d-glucopyranosyl)-3-hydroxyphloretin (4), 2'- O-(4,6- O- S_a-hexahydroxydiphenoyl-β-d-glucopyranosyl)phloretin (5), 2'- O-(3- O-galloyl-4,6- O- S_a-hexahydroxydiphenoyl-β-d-glucopyranosyl)phloretin (6), and thonningianin B (9) showed moderate protein tyrosine phosphatase-1B inhibition in an enzyme assay (IC₅₀ values ranging from 19 to 25 μM), whereas thonningianin A (10) was identified as a more potent inhibitor (IC₅₀ = 4.4 μM). The observed activity differences could be explained by molecular docking experiments. The activity of 10 could further be confirmed in HEPG2 liver carcinoma cells, where the compound was able to increase the level of phosphorylated insulin receptors in a concentration-dependent manner.

Medicinal plants of northern Angola and their anti-inflammatory properties

ETHNOPHARMACOLOGICAL RELEVANCE

32 plants, from which 30 are used in local traditional medicine - identified by interviews with the resident population - in the province of Uíge in northern Angola for the treatment of inflammation related disorders, were screened on different anti-inflammatory parameters. Three extracts were selected for a detailed ethnobotanical, pharmacological and phytochemical investigation based on their in vitro activity.

AIM OF THE STUDY

We aimed to assess the in vitro anti-inflammatory activity of these plants and highlight the active principles of the three most promising candidates.

MATERIALS AND METHODS

Plant material was collected in northern Angola during eight field trips from 2013 to 2015 based on data documented in 61 interviews with 142 local informants. 36 methanol (MeOH) extracts were prepared and tested at different concentrations (100, 50, 10µg/mL) to evaluate their inhibition on cyclooxygenase (COX)-2 expression and on nitric oxide (NO) release in lipopolysaccharide (LPS)-stimulated J774A.1 macrophages. Five selected extracts were additionally tested at the lower concentrations of 5, 2.5, and 1.25µg/mL and for their potential on inhibition of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) release. The major compounds of three of those five extracts were either identified by HPLC coupled with (tandem) mass spectrometry and comparison with data from literature or isolated from the respective extracts and confirmed by NMR experiments (one and two dimensional).

RESULTS

30 plant species with in total 161 citations were mentioned by the informants to have anti-inflammatory properties. The predominantly used plant part is the leaf (39%), followed by underground organs like roots and rhizomes (25%), bark (18%) as well as fruits and seeds with 15%. With 47%, decoction is the most frequent preparation form. A large number of the MeOH extracts showed promising activities in our preliminary screening for the inhibition of COX-2 expression and NO release. Five extracts with high activities in both assays showed also concentration dependent inhibition at lower concentrations and a decreased release of two additional pro-inflammatory mediators (IL-6 and TNF-α) vs. LPS. Three leaf extracts where chosen for a detailed investigation, which lead to the identification of several constituents: verbascoside and isoverbascoside (Acanthus montanus), geraniin, chebulagic acid and a large flavonoid fraction (Alchornea cordifolia) as well as the four flavonoids astilbin, isovitexin, isoorientin and swertisin (Chaetocarpus africanus). Their implication in the observed biological activity was proved by comparison with published data of these compounds in identical or similar pharmacological models.

CONCLUSIONS

The indigenous use of these plants against inflammation related ailments could be - at least partly - verified by our in vitro models for many of the investigated extracts. Acanthus montanus and Alchornea cordifolia particularly stood out with their high activity in all four performed assays, which was in accordance with pharmacological studies of their major constituents in literature. In addition, this study was the first phytochemical investigation of Chaetocarpus africanus and first description of the occurrence of the ellagitannins geraniin and chebulagic acid in Alchornea cordifolia. These results support the traditional use and should encourage further investigations of medicinal plants of northern Angola.

Chemical studies on the parasitic plant Thonningia sanguinea Vahl

A detailed first-time report on plant sterols and one flavanone characterized from Thonningia sanguinea provides significant evidence for its ethnomedicinal usage.

Aqueous ethanol extract of the fruit of Xylopia aethiopica (Annonaceae) exhibits anti-anaphylactic and anti-inflammatory actions in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xylopia aethiopica has been traditionally used in the form of the dried fruit decoction to treat bronchitis, asthma, arthritis and rheumatism in Ghana, Nigeria and Cameroon. Aim of the study is to evaluate the anti-anaphylactic and anti-inflammatory effects of a 70% aqueous ethanol extract of the fruits of Xylopia aethiopica.

MATERIALS AND METHODS

Systemic anaphylaxis was induced by the injection of either compound 48/80 or lipopolysaccharide, LPS and survival rates of mice monitored for 1 h or 7 days respectively while IgE-mediated anaphylaxis in a local allergic reaction was studied in the pinnal inflammation model in mice. Clonidine-induced catalepsy in mice was used to evaluate the indirect antihistamine effect of Xylopia aethiopica, XAE. The effects of XAE assessed on the maximal and total oedema responses in the carrageenan-induced paw oedema in mice was used to evaluate the anti-inflammatory action of the extract.

RESULTS

Administered at 30, 100, 300 and 1000 mg kg(-1) p.o., XAE dose dependently suppressed compound 48/80-induced mouse systemic anaphylactic shock and offered 63% protection to mice against LPS-induced endotoxic shock at a dose of 300 mg kg(-1). In addition, the extract (30-300 mg kg(-1)) in a dose dependent manner significantly inhibited by 23-62% the mouse pinnal inflammation. Clonidine-induced catalepsy in mice was significantly suppressed in a dose and time dependent manner when administered both prophylactically and therapeutically. In the same doses, when administered before the induction of the mouse carrageenan-induced paw oedema, the mean maximal swelling attained during 6 h was reduced to 41.02±6.94%, 35.61±4.30%, and 29.09±4.90% of the inflamed control response respectively and total paw swellings induced over the 6 h were also dose-dependently and significantly suppressed to 74.84±14.84%, 63.95±9.37%, and 48.13±10.90% of the inflamed control response respectively. Administered after the induction of the carrageenan paw oedema the mean maximal swelling attained during 6 h was suppressed to 49.84±3.95%, 43.62±1.01%, and 35.97±1.34% of the inflamed control response respectively while the total paw swellings induced over the 6 h were also dose-dependently and significantly suppressed at 100 and 300 mg kg(-1) to 72.39±4.38% and 60.81±3.25% of the inflamed control response respectively.

CONCLUSION

These findings suggest that XAE inhibits mast cell-dependent immediate allergic reactions and exhibit anti-inflammatory actions through the inhibition of histamine release from mast cells via stabilizing the cell membrane. Our results contribute towards validation of the traditional use of Xylopia aethiopica in the treatment of bronchitis, asthma, arthritis and rheumatism.

Selective suppression of cytochrome P450 gene expression by the medicinal herb, Thonningia sanguinea in rat liver

The effect of the administration of Thonningia sanguinea (T. S.) on the abundance of individual components of the cytochrome P450 monooxygenase enzyme was examined using Western blotting and competitive reverse-transcriptase-polymerase chain reaction (RT-PCR). We also investigated the time-course of inhibition of T. S. on drug metabolizing enzymes. A single intraperitoneal dose of T. S. extract (5 ml/kg) suppressed CYP, cytochrome b5 and NADPH-CYP reductase activity by 45%, 34% and 22% respectively 24 h after T. S. administration. While T. S. did not have any significant effect on microsomal glutathione S-transferase activity, it inhibited p-nitrophenol hydroxylase (PNPH, CYP2E1) and 7-methoxyresorufin O-demethylase (MROD, CYP 1A2) activities by 37% and 32% respectively at 12 h post-T. S. administration. PNPH, erythromycin N-demethylase (ERDM, CYP 3A1/2) and MROD activities were inhibited by 28-36% 24 h after T. S. injection. Consistent with these observations, the levels of CYP2E1, CYP1A2 and CYP3A2 proteins were also suppressed 24 h post-T. S. administration. While CYP2E1 mRNA was unaffected by T. S. administration, CYP1A2 and CYP3A2 mRNAs were decreased by T. S. Cytosolic glutathione S-transferase activity was increased by 30%, 6 h after T. S injection. These data demonstrate that administration of T. S. differentially affect CYP isoforms in the liver of rats and that T. S. selectively suppresses CYP3A2 and CYP1A2 gene expression.

Antioxidant properties of Thonningianin A, isolated from the African medicinal herb, Thonningia sanguinea

The antioxidant properties of Thonningianin A (Th A), an ellagitannin, isolated from the methanolic extract of the African medicinal herb, Thonningia sanguinea were studied using the NADPH and Fe2+/ascorbate-induced lipid peroxidation (LPO), electron spin resonance spectrometer and the deoxyribose assay. Th A at 10 microM inhibited both the NADPH and Fe2+/ascorbate-induced LPO in rat liver microsomes by 60% without inhibitory effects on cytochrome P450 activity. Th A was similar to the synthetic antioxidant, tannic acid, as an inhibitor of both the NADPH and Fe2+/ascorbate-induced LPO but potent than gallic acid, vitamin C and vitamin E. While Th A poorly scavenged the hydroxyl radical generated by the Fenton reaction it dose-dependently scavenged 1,1-diphenyl-2-picrylhydrazyl, superoxide anion and peroxyl radicals with IC50 of 7.5, 10 and 30 microM, respectively. Furthermore, Th A showed inhibitory effects on the activity of xanthine oxidase with an IC50 of 30 microM. In the deoxyribose assay both T. sanguinea and its methanolic component Th A showed only site-specific (Fe3+ + H2O2) but not non-site-specific (Fe3+ + EDTA + H2O2) hydroxyl radical scavenging suggesting chelating ability for iron ions. Spectroscopic studies showed that Th A enhanced absorbance in the visible region in the presence of Fe2+ ions. These results indicate that the antioxidant properties of Th A involve radical scavenging, anti-superoxide formation and metal chelation.

Inhibitory effects of the medicinal herb, Thonningia sanguinea, on liver drug metabolizing enzymes of rats

In this study we examined the effect of the aqueous extract of Thonningia sanguinea (T.S.) on 7-ethoxyresorufin O-deethylase (EROD, CYP1A1), 7-pentoxyresorufin O-dealkylase (PROD, CYP2B1/2), 7-methoxyresorufin O-demethylase (MROD, CYP1A2), aniline hydroxylase (aniline, CYP2E1), p-nitrophenol hydroxylase (PNPH, CYP2E1) and erythromycin N-demethylase (ERDM, CYP3A1) in rat liver in vitro and in vivo. Although T.S. extract increased ERDM activity in induced rat liver microsomes, it showed a dose-dependent inhibitory effect in vitro on other P450 monooxygenase activities particularly EROD and PROD, which are mediated primarily by CYP1A1 and CYP2B1/2, respectively. PROD, EROD and MROD activities were also decreased by 18%, 19% and 40%, respectively, in hepatic microsomes prepared from rats treated with T.S. extract for 3 days. Kinetic analysis of CYP activity of 3-methylchloranthrene-induced microsomes demonstrated that T.S. inhibited EROD and MROD activities by a noncompetitive and competitive mechanism, respectively. The analysis of alterations produced by T.S. on PROD kinetic parameters in phenobarbital-induced microsomes suggested that the inhibition is noncompetitive. Pretreatment of rats with T.S. prolonged pentobarbital and phenobarbital sleeping time; however, plasma phenobarbital concentration determined on awakening showed no significant difference between control and T.S.-treated rats. T.S. was also found to be a potent inhibitor of the liver cytosolic glutathione S-transferase. These data suggest that selective modulation of CYP isoenzymes by T.S. might contribute to protection of the liver from xenobiotic-induced intoxication or to alteration of the action of drug(s) concomitantly administered besides its antioxidative properties.

Thonningianins A and B, new antioxidants from the African medicinal herb Thonningia sanguinea

Two new ellagitannins, thonningianins A (1) and B (2), have been isolated from the African medicinal herb Thonningia sanguinea and their structures elucidated by interpretation of spectroscopic data. Both 1 and 2 showed strong free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) as shown by ESR analysis.

Antimicrobial properties of Thonningia sanguinea root extracts

The aqueous and methanolic extracts of Thonningia sanguinea root, as well as seven fractions obtained by PTLC from the methanol extract, have been shown to possess varying degrees of antimicrobial activity.

Free-radical scavenging action of medicinal herbs from Ghana: Thonningia sanguinea on experimentally-induced liver injuries

The antioxidant action of medicinal herbs used in Ghana for treating various ailments was evaluated in vitro and in vivo. Five plants, Desmodium adscendens, Indigofera arrecta, Trema occidentalis, Caparis erythrocarpus, and Thonningia sanguinea were tested for their free radical scavenging action by their interaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH). Of these five plants, only Thonningia sanguinea was found to scavenge the DPPH radical. Lipid peroxidation in liver microsomes induced by H2O2 was also inhibited by T. sanguinea. The hepatoprotective effect of T. sanguinea was studied on acute hepatitis induced in rats by a single dose of galactosamine (GalN, 400 mg/kg, IP) and in mice by carbon tetrachloride (CCl4, 25 microl/kg, IP). GalN induced hepatotoxicity in rats as evidenced by an increase in alanine aminotransferase (ALT) and glutathione (GSH) S-transferase activities in serum was significantly inhibited when T. sanguinea extract (5 ml/kg, IP) was given to rats 12 hr and 1 hr before GalN treatment. The activity of liver microsomal GSH S-transferase, which is known to be activated by oxidative stress, was increased by the GaIN treatment and this increase was blocked by T. sanguinea pretreatment. Similarly, T. sanguinea pretreatment also inhibited CCl4-induced hepatotoxicity in mice. These data indicate that T. sanguinea is a potent antioxidant and can offer protection against GalN- or CCl4-induced hepatotoxicity.

Medicinal herb, Thonningia sanguinea protects against aflatoxin B1 acute hepatotoxicity in Fischer 344 rats

1. Thonningia sanguinea, a plant used prophylactically against bronchial asthma in Ghana was recently found to have antioxidative and hepatoprotective actions in our laboratory. 2. In this study, the effect of T. sanguinea extract on certain biochemical indices in serum and liver of Fischer 344 rats given a single intraperitoneal (i.p.) dose (1 mg/kg) of aflatoxin B1 (AFB1) was investigated. 3. Administration of AFB1 resulted in significant increases in serum alanine aminotransferase (ALT) and glutathione S-transferase (GST) levels and a significant decrease in aniline hydroxylase activity in liver microsomes. When T. sanguinea (5 ml/kg) was intraperitoneally administered to rats 12 h and 1 h before AFB1, liver injury was significantly reduced as seen in the decreased levels of serum ALT and serum GST. However, the decrease in aniline hydroxylase activity by AFB1 was not recovered but enhanced by T. sanguinea pre-treatment. 4. Kinetic analysis of cytochrome P450 activity of rat liver microsomes in vitro demonstrated that T. sanguinea inhibited aniline hydroxylase non-competitively suggesting depression of biotransformation of AFB1 to toxic metabolites. 5. The data indicate a hepatoprotective action of T. sanguinea against AFB1-induced liver injury.