Antiviral and antibacterial properties of phloroglucinols: a review on naturally occurring and (semi)synthetic derivatives with potential therapeutic interest

Phloroglucinol and derived compounds comprise a huge class of secondary metabolites widely distributed in plants and brown algae. A vast array of biological activities, including antioxidant, anti-inflammatory, antimicrobial, and anticancer has been associated to this class of compounds. In this review, the available data on the antiviral and antibacterial capacity of phloroglucinols have been analyzed. Some of these compounds and derivatives show important antimicrobial properties in vitro. Phloroglucinols have been shown to be effective against viruses, such as human immunodeficiency virus (HIV), herpes or enterovirus, and preliminary data through docking analysis suggest that they can be effective against SARS-CoV-19. Also, some phloroglucinols derivatives have shown antibacterial effects against diverse bacteria strains, including Bacillus subtilis and Staphylococcus aureus, and (semi)synthetic development of novel compounds have led to phloroglucinols with a significantly increased biological activity. However, therapeutic use of these compounds is hindered by the absence of in vivo studies and scarcity of information on their mechanisms of action, and hence further research efforts are required. On the basis of this consideration, our work aims to gather data regarding the efficacy of natural-occurring and synthetic phloroglucinol derivatives as antiviral and antibacterial agents against human pathogens, which have been published during the last three decades. The recollection of results reported in this review represents a valuable source of updated information that will potentially help researchers in the development of novel antimicrobial agents.

Meta analysis of the effect of phloroglucinol combined with progesterone in the treatment of threatened miscarriage before 20 weeks of gestation: A protocol for a systematic review

BACKGROUND

Threatened miscarriage (TM) is an important factor endangering the health of pregnant women. It not only affects women's physical and mental health, but also destroys family happiness. To treat this disease, it is necessary to find a treatment with better clinical efficacy and fewer side effects. The purpose of this systematic study was to evaluate the efficacy and safety of phloroglucinol (PHL) combined with progesterone in the treatment of TM before 20 weeks of pregnancy.

METHODS

Electronic databases (EMBASE, PubMed, Cochrane Central Register of Controlled Trials, Web of Science, Elsevier, China National Knowledge Infrastructure, Chongqing VIP, and WanFang Data) were searched from inception until September. 2022. Randomized controlled trials of PHL combined with progesterone in the treatment of TM before 20 weeks of gestation will be included, and all articles will be independently screened and collected by 2 reviewers. Revman 5.3.5 software will be used for meta-analysis. The specific process is described in the Cochrane Handbook for Systematic Reviews.

RESULTS

The efficacy and safety of PHL combined with progesterone for the treatment of threatened abortion were comprehensively evaluated in terms of efficacy, efficiency, time of symptom relief, length of hospital stay, and incidence of adverse events.

CONCLUSION

This study provides reliable evidence for the clinical application of PHL combined with progesterone for the treatment of TM.

Phloroglucinol as a Potential Candidate against Trypanosoma congolense Infection: Insights from In Vivo, In Vitro, Molecular Docking and Molecular Dynamic Simulation Analyses

Sub-Saharan Africa is profoundly challenged with African Animal Trypanosomiasis and the available trypanocides are faced with drawbacks, necessitating the search for novel agents. Herein, the chemotherapeutic potential of phloroglucinol on T. congolense infection and its inhibitory effects on the partially purified T. congolense sialidase and phospholipase A2 (PLA2) were investigated. Treatment with phloroglucinol for 14 days significantly (p < 0.05) suppressed T. congolense proliferation, increased animal survival and ameliorated anemia induced by the parasite. Using biochemical and histopathological analyses, phloroglucinol was found to prevent renal damages and splenomegaly, besides its protection against T. congolense-associated increase in free serum sialic acids in infected animals. Moreover, the compound inhibited bloodstream T. congolense sialidase via mixed inhibition pattern with inhibition binding constant (Ki) of 0.181 µM, but a very low uncompetitive inhibitory effects against PLA2 (Ki > 9000 µM) was recorded. Molecular docking studies revealed binding energies of -4.9 and -5.3 kcal/mol between phloroglucinol with modeled sialidase and PLA2 respectively, while a 50 ns molecular dynamics simulation using GROMACS revealed the sialidase-phloroglucinol complex to be more compact and stable with higher free binding energy (-67.84 ± 0.50 kJ/mol) than PLA2-phloroglucinol complex (-77.17 ± 0.52 kJ/mol), based on MM-PBSA analysis. The sialidase-phloroglucinol complex had a single hydrogen bond interaction with Ser453 while none was observed for the PLA2-phloroglucinol complex. In conclusion, phloroglucinol showed moderate trypanostatic activity with great potential in ameliorating some of the parasite-induced pathologies and its anti-anemic effects might be linked to inhibition of sialidase rather than PLA2.

2,4,6-Trihydroxy-3-geranyl acetophenone suppresses vascular leakage and leukocyte infiltration in lipopolysaccharide-induced endotoxemic mice

CONTEXT

Lipopolysaccharide (LPS) exacerbates systemic inflammatory responses and causes excessive fluid leakage. 2,4,6-Trihydroxy-3-geranyl acetophenone (tHGA) has been revealed to protect against LPS-induced vascular inflammation and endothelial hyperpermeability in vitro.

OBJECTIVE

This study assesses the in vivo protective effects of tHGA against LPS-induced systemic inflammation and vascular permeability in endotoxemic mice.

MATERIALS AND METHODS

BALB/c mice were intraperitoneally pre-treated with tHGA for 1 h, followed by 6 h of LPS induction. Evans blue permeability assay and leukocyte transmigration assay were performed in mice (n = 6) pre-treated with 2, 20 and 100 mg/kg tHGA. The effects of tHGA (20, 40 and 80 mg/kg) on LPS-induced serum TNF-α secretion, lung dysfunction and lethality were assessed using ELISA (n = 6), histopathological analysis (n = 6) and survivability assay (n = 10), respectively. Saline and dexamethasone were used as the negative control and drug control, respectively.

RESULTS

tHGA significantly inhibited vascular permeability at 2, 20 and 100 mg/kg with percentage of inhibition of 48%, 85% and 86%, respectively, in comparison to the LPS control group (IC₅₀=3.964 mg/kg). Leukocyte infiltration was suppressed at 20 and 100 mg/kg doses with percentage of inhibition of 73% and 81%, respectively (IC₅₀=17.56 mg/kg). However, all tHGA doses (20, 40 and 80 mg/kg) failed to prevent endotoxemic mice from lethality because tHGA could not suppress TNF-α overproduction and organ dysfunction.

DISCUSSION AND CONCLUSIONS

tHGA may be developed as a potential therapeutic agent for diseases related to uncontrolled vascular leakage by combining with other anti-inflammatory agents.

Phloroglucinol and dieckol isolated from Ecklonia cava suppress impaired diabetic angiogenesis; A study of in-vitro and in-vivo

Abnormalities in angiogenesis that are associated with diabetes may contribute to vascular complications and result in disabilities and death. Furthermore, an imbalance in angiogenesis in different tissues, including the retina and kidney, can play a role in the pathogenesis of diabetic microvascular complications. Phlorotannins, such as phloroglucinol (PG) and dieckol (DK), which are found in Ecklonia cava exhibit antioxidant and anti-inflammatory activities that improve endothelial function in hypertension. However, reports on the effects of these compounds on diabetes-induced angiogenesis in vivo and in vitro are scarce. In this study, we assessed the antiangiogenic effects of PG and DK on endothelial cells treated with a high concentration of glucose to mimic angiogenesis. In addition, we sought to determine the effects of these compounds on cell proliferation, cell migration, and capillary formation. In silico docking of PG and DK into VEGFR-2 revealed their potential as therapeutic agents against angiogenesis. Further, both compounds were identified to inhibit the formation of the retinal vessel in transgenic zebrafish (flk:EGFP) embryos under high glucose conditions. These findings suggested that PG and DK derived from E. cava are potential inhibitors of angiogenesis in diabetic vascular complications and could, therefore, be used to develop angiogenic agents.

IC261 suppresses progression of hepatocellular carcinoma in a casein kinase 1 δ/ε independent manner

Hepatocellular carcinoma (HCC) is one of the most deadly cancers worldwide that responds poorly to existing therapies. The Casein kinase 1 (CK1) isoforms CK1δ and CK1ε are reported to be highly expressed in several tumor types, and both genetic and pharmacological inhibition of CK1δ/ε activity has deleterious effects on tumor cell growth. IC261, an CK1δ/ε selectively inhibitor, shows anti-tumor effect against pancreatic tumor and glioblastoma, but its role in HCC remains poorly characterized. In our research, IC261 displayed time- and dose-dependent inhibition of HCC cell proliferation, and induced G2/M arrest and cell apoptosis in vitro. However, the anti-tumor effects of IC261 was independent of CK1δ/ε. Additionally, IC261 was verified to induce centrosome fragmentation during mitosis independent of CK1δ status, and intraperitoneal injection of IC261 to HCCLM3 xenograft models inhibited tumor growth. Taken together, our data indicated that IC261 has therapeutic potential for HCC.

Attenuation of Inflammation and Leptin Resistance by Pyrogallol-Phloroglucinol-6,6-Bieckol on in the Brain of Obese Animal Models

Obesity induces inflammation both in the adipose tissue and the brain. Activated macrophage infiltration, polarization of macrophages to a more inflammatory type (M1), and increased levels of pro-inflammatory cytokines are related to brain inflammation, which induces leptin resistance in the brain. Pyrogallol-phloroglucinol-6,6-bieckol (PPB), a compound from Ecklonia cava, has anti-inflammatory effects. In this study, we evaluated the effects of PPB effect M1 polarization and inflammation and its ability to restore the effects of leptin, such as a decrease in appetite and body weight. We administered PPB to diet-induced obesity (DIO) and leptin-deficient (ob/ob) mice, evaluated macrophage activation, polarization, and changes of inflammatory cytokine level in adipose tissue and brain, and determined the effect of PPB on leptin resistance or leptin sensitivity in the brain. The levels of activated macrophage marker, M1/M2, and pro-inflammatory cytokines were increased in the adipose tissue and brain of DIO and ob/ob mice than control. TLR4 expression, endoplasmic reticulum (ER) stress, and NF-κB expression in the brain of DIO and ob/ob mice were also increased; this increase was related to the upregulation of SOCS3 and decreased phosphorylated STAT3, which decreased leptin sensitivity in the brain. PPB decreased inflammation in the brain, restored leptin sensitivity, and decreased food intake and weight gain in both DIO and ob/ob mice.

Comparison of the efficacy and safety of phloroglucinol and magnesium sulfate in the treatment of threatened abortion: A meta-analysis of randomized controlled trials

BACKGROUND

To compare the clinical efficacy and safety of phloroglucinol (PHL) and magnesium sulfate (MS) in the treatment of threatened abortion through systematic review.

METHODS

Foreign databases, such as the Cochrane Library, PubMed and EMBASE, and Chinese databases, including the China Biology Medicine disc (SinoMed), China National Knowledge Infrastructure (CNKI), Chongqing VIP (VIP) and WanFang Data, were searched. Published randomized controlled trials (RCTs) documents obtained from these databases were included if they were associated with the research objective. The search timeframe was from the beginning of the establishment of each database to May 2018. Document selection, data abstraction and document quality evaluation were independently performed by 2 investigators. A combined analysis of the data was performed for those documents that fulfilled the study requirements; Rev Man 5.3 and Stata 12.0 software were used to compare and analyze the 2 drugs in terms of the total effective rate (TER), rate of adverse events, time required to relieve uterine contractions, onset time, time of complete relief of uterine contraction symptoms, medication duration and length of hospital stay.

RESULTS

A total of 21 RCT trials were included in the present research, according to the inclusion criteria. However, the quality of the included studies was low. The meta-analysis suggested that the TER and drug onset time of PHL were higher than those for MS, while the rate of adverse events, the time required to relieve uterine contractions, time to complete relief of uterine contraction symptoms, drug continuous treatment time and length of hospital stay were shorter than those for MS.

CONCLUSION

The clinical efficacy of PHL is better than that of MS, and PHL obviously results in fewer adverse reactions than MS. However, due to poor quality of evidence, high quality, multi-center RCTs with large samples are required for further verification.

Protective Effect of Pyrogallol-Phloroglucinol-6,6-Bieckol from Ecklonia cava on Monocyte-Associated Vascular Dysfunction

Ecklonia cava (E. cava) can alleviate vascular dysfunction in diseases associated with poor circulation. E. cava contains various polyphenols with different functions, but few studies have compared the effects of these polyphenols. Here, we comparatively investigated four major compounds present in an ethanoic extract of E. cava. These four major compounds were isolated and their effects were examined on monocyte-associated vascular inflammation and dysfunctions. Pyrogallol-phloroglucinol-6,6-bieckol (PPB) significantly inhibited monocyte migration in vitro by reducing levels of inflammatory macrophage differentiation and of its related molecular factors. In addition, PPB protected against monocyte-associated endothelial cell death by increasing the phosphorylations of PI3K-AKT and AMPK, decreasing caspase levels, and reducing monocyte-associated vascular smooth muscle cell proliferation and migration by decreasing the phosphorylations of ERK and AKT. The results of this study show that four compounds were effective for reduction of monocyte-associated vascular inflammation and dysfunctions, but PPB might be more useful for the treatment of vascular dysfunction in diseases associated with poor circulation.

Clinical study on the influence of phloroglucinol on plasma angiotensin II and D-Dimer index in patients with severe pregnancy-induced hypertension

To observe the effect of phloroglucinol on plasma angiotensin II and D-dimer index when it was applied to patients with severe pregnancy-induced hypertension. 212 cases of severe pregnancy-induced hypertension patients diagnosed clinically were selected to be randomly divided into the research group and the control group. The research groups were given phloroglucinol, while the control groups were given magnesium sulfate. The plasma angiotensin II and D-dimer index in patients were detected before treatment and after 7 days respectively with statistical analysis of results. The diffidence after treatment was statistically significant (P<0.05). Compared within the same group, the difference of each index before and after treatment in the research group was statistically significant (P<0.05), while the control group was not statistically significant (P>0.05). It showed that the research group could reduce the plasma D-dimer and angiotensin II index in severe pregnancy-induced hypertension patients, and its effect was significantly better than the control group according to the plasma D-dimer and angiotensin II index changes in patients, it indicated that it was effective of phloroglucinol treatment for patients with pregnancy-induced hypertension disease and superior to the western medicine conventional treatment, worth clinical promotion.

[Phloroglucinol combined with parecoxib for cystospasm after transurethral resection of the prostate]

OBJECTIVE

To evaluate the effect and safety of phloroglucinol combined with parecoxib on cystospasm after transurethral resection of the prostate (TURP).

METHODS

We conducted a prospective randomized case-control study on 98 patients treated by TURP. After operation, the patients were randomly assigned to a treatment (n=50) and a control group (n=48), the former treated by intravenous injection of 80 mg phloroglucinol qd plus 40 mg parecoxib bid while the latter given 80 mg phloroglucinol only, both for 3 successive days. Then we recorded the frequency and duration of cystospasm, visual analogue scales (VAS), adverse reactions, post-operative bladder irrigation time, catheter-indwelling time, and hospital stay and compared them between the two groups of patients.

RESULTS

Compared with the controls, the patients in the treatment group showed a significantly lower frequency of cystospasm (［1.95±0.14］ vs ［0.70±0.65］ times, P<0.01), duration of cystospasm (［0.44±0.21］ vs ［0.12±0.14］ min, P<0.01), and VAS score (2.70±1.80 vs 1.90±1.30, P<0.01) at 48－72 hours after TURP, but no statistically significant differences were found between the control and treatment groups in the post-operative bladder irrigation time (［2.75±0.87］ vs ［2.64±0.83］ d, P>0.05), catheter-indwelling time (［3.52±0.32］ vs ［3.44±0.42］ d, P>0.05), and hospital stay (［5.23±0.81］ vs ［5.10±0.73］ d, P>0.05), and no obvious adverse reactions were observed in either of the two groups.

CONCLUSIONS

Phloroglucinol combined with parecoxib is more effective and safer than phloroglucinol alone in relieving postoperative cystospasm after TURP.

St. John's Wort seed and feverfew flower extracts relieve painful diabetic neuropathy in a rat model of diabetes

Painful diabetic peripheral neuropathy (DPN) is a common complication of diabetes and the few approved therapies for the management of pain have limited efficacy and side effects. With the aim to explore and develop new pharmacological treatments, we investigated the antihyperalgesic properties of St. John's Wort (SJW) and feverfew in streptozotocin (STZ)-diabetic rats. Acute administration of a SJW seed extract reversed mechanical hyperalgesia with a prolonged effect. A SJW extract obtained from the aerial portion of the plant and a feverfew flower extract partially relieved neuropathic pain whereas a feverfew leaf extract was ineffective. The antihyperalgesic efficacy of these herbal drugs was comparable to that of clinically used antihyperalgesic drugs (carbamazepine, lamotrigine, l-acetyl-levocarnitine). Further examinations of SJW and feverfew composition revealed that hyperforin and hypericin might be responsible for the antihyperalgesic properties of SJW whereas the efficacy of feverfew seems to be related to the presence of parthenolide. Rats undergoing treatment with SJW and feverfew did not show any behavioral side effect or sign of altered locomotor activity. Our results suggest that SJW and feverfew extracts may become new therapeutic perspectives for painful DPN.

Clinical trials in irritable bowel syndrome: a review

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders and it is characterized by episodes of abdominal pain and altered bowel functions. The specific bowel disturbances of diarrhea, constipation or an alternation between the two defines the IBS subtypes of diarrhea-predominant, constipation-predominant, and mixed or alternating IBS. Because of the abnormalities in bowel states associated with each IBS subtype, it is not likely that one agent would successfully treat all three subtypes. As a result, clinical trials have focused, for the most part, on one IBS subtype. Over the past 2 decades very few agents have achieved regulatory approval for the treatment of IBS. In the present article we review publications reporting on phase 2 and phase 3 studies evaluating agents to potentially be used in the treatment of patients with IBS.

Mechanistic insights into the antileukemic activity of hyperforin

Hyperforin is a prenylated phloroglucinol present in the medicinal plant St John's wort (Hypericum perforatum). The compound has many biological properties, including antidepressant, anti-inflammatory, antibacterial and antitumor activities. This review focuses on the in vitro antileukemic effects of purified hyperforin and related mechanisms in chronic lymphoid leukemia (CLL) and acute myeloid leukemia (AML) - conditions that are known for their resistance to chemotherapy. Hyperforin induces apoptosis in both CLL and AML cells. In AML cell lines and primary AML cells, hyperforin directly inhibits the kinase activity of the serine/threonine protein kinase B/AKT1, leading to activation of the pro-apoptotic Bcl-2 family protein Bad through its non-phosphorylation by AKT1. In primary CLL cells, hyperforin acts by stimulating the expression of the pro-apoptotic Bcl-2 family member Noxa (possibly through the inhibition of proteasome activity). Other hyperforin targets include matrix metalloproteinase-2 in AML cells and vascular endothelial growth factor and matrix metalloproteinase-9 in CLL cells - two mediators of cell migration and angiogenesis. In summary, hyperforin targets molecules involved in signaling pathways that control leukemic cell proliferation, survival, apoptosis, migration and angiogenesis. Hyperforin also downregulates the expression of P-glycoprotein, a protein that is involved in the resistance of leukemia cells to chemotherapeutic agents. Lastly, native hyperforin and its stable derivatives show interesting in vivo properties in animal models. In view of their low toxicity, hyperforin and its derivatives are promising antileukemic agents and deserve further investigation in vivo.

The novel phloroglucinol derivative BFP induces apoptosis of glioma cancer through reactive oxygen species and endoplasmic reticulum stress pathways

Prenyl-phloroglucinol derivatives from hop plants have been shown to have anticancer activities. This study is the first to investigate the anticancer effects of the new phloroglucinol derivative (2,4-bis(4-fluorophenylacetyl)phloroglucinol; BFP). BFP induced cell death and anti-proliferation in three glioma, U251, U87 and C6 cells, but not in primary human astrocytes. BFP-induced concentration-dependently cell death in glioma cells was determined by MTT and SRB assay. Moreover, BFP-induced apoptotic cell death in glioma cells was measured by Hochest 33258 staining and fluorescence-activated cell sorter (FACS) of propidine iodine (PI) analysis. Treatment of U251 human glioma cells with BFP was also found to induce reactive oxygen species (ROS) generation, which was detected by a fluorescence dye used FACS analysis. Treatment of BFP also increased a number of signature endoplasmic reticulum (ER) stress markers glucose-regulated protein (GRP)-78, GRP-94, IRE1, phosphorylation of eukaryotic initiation factor-2α (eIF-2α) and up-regulation of CAAT/enhancer-binding protein homologous protein (CHOP). Moreover, treatment of BFP also increased the down-stream caspase activation, such as pro-caspase-7 and pro-caspase-12 degradation, suggesting the induction of ER stress. Furthermore, BFP also induced caspase-9 and caspase-3 activation as well as up-regulation of cleaved PARP expression. Treatment of antioxidants, or pre-transfection of cells with GRP78 or CHOP siRNA reduced BFP-mediated apoptotic-related protein expression. Taken together, the present study provides evidences to support that ROS generation, GRP78 and CHOP activation are mediating the BFP-induced human glioma cell apoptosis.

Use of STAT1 inhibitors in the treatment of brain I/R injury and neurodegenerative diseases

In the etiology of brain injury associated to ischemia/reperfusion (I/R) and neurodegenerative diseases, a critical involvement of excessive activation of signal transducer and activator of transcription 1 (STAT1) and successive induction of iNOS expression has widely been evidenced. Any compound capable to down-regulate STAT1 activation seems to represent a new, promising anti-inflammatory drug. Among plant compounds, only a few have shown to possess anti-STAT1 activity. Among them, epigallocatechin-3-gallate (EGCG), the main polyphenol present in green tea leaves, efficiently protects heart from I/R injury and this action is strictly correlated to its anti-STAT1 property. Hyperforin, the non-polyphenolic compound present in St. John's wort, attenuates &beta;-cell death induced by interferon-&gamma; (IFN-&gamma;) by strongly down-regulating STAT1 activation. STAT1, therefore, seems to represent a new molecular target of the protective treatment also against brain injury associated to a number of brain pathologies. Either understanding the molecular mechanism of anti-STAT1 action of these compounds or identification of other anti-STAT1 compounds are urged.

Potential anti-HIV agents from marine resources: an overview

Human immunodeficiency virus (HIV) infection causes acquired immune deficiency syndrome (AIDS) and is a global public health issue. Anti-HIV therapy involving chemical drugs has improved the life quality of HIV/AIDS patients. However, emergence of HIV drug resistance, side effects and the necessity for long-term anti-HIV treatment are the main reasons for failure of anti-HIV therapy. Therefore, it is essential to isolate novel anti-HIV therapeutics from natural resources. Recently, a great deal of interest has been expressed regarding marine-derived anti-HIV agents such as phlorotannins, sulfated chitooligosaccharides, sulfated polysaccharides, lectins and bioactive peptides. This contribution presents an overview of anti-HIV therapeutics derived from marine resources and their potential application in HIV therapy.

[Phloroglucinol: safe and effective for the prevention of bladder spasm after TURP]

OBJECTIVE

To evaluate the efficacy of phloroglucinol in preventing bladder spasm after transurethral resection of the prostate (TURP).

METHODS

Using the random sampling method, we assigned 74 cases of TURP into a treatment group (n = 39), given 80 mg phloroglucinol every day for 3 days, and a control group (n = 35), left untreated. Then we observed the frequency, duration and pain of bladder spasm within the 3 days and compared them between the two groups.

RESULTS

The mean frequency, duration and pain visual analogue score of bladder spasm were (4.3 +/- 1.2) times, (7.2 +/- 2.1) min and 3.2 +/- 1.6 respectively in the treatment group, as compared with (7.5 +/- 2.4) times, (15.6 +/- 6.8) min and 4.7 +/- 2.3 in the control, with statistically significant differences between the two groups (P < 0.05). And no obvious adverse reactions were found in the treatment group.

CONCLUSION

Phloroglucinol is safe and effective for the prevention and treatment of bladder spasm following TURP.

In vitro chemopreventive potential of fucophlorethols from the brown alga Fucus vesiculosus L. by anti-oxidant activity and inhibition of selected cytochrome P450 enzymes

Within a project focusing on the chemopreventive potential of algal phenols, two phloroglucinol derivatives, belonging to the class of fucophlorethols, and the known fucotriphlorethol A were obtained from the ethanolic extract of the brown alga Fucus vesiculosus L. The compounds trifucodiphlorethol A and trifucotriphlorethol A are composed of six and seven units of phloroglucinol, respectively. The compounds were examined for their cancer chemopreventive potential, in comparison with the monomer phloroglucinol. Trifucodiphlorethol A, trifucotriphlorethol A as well as fucotriphlorethol A were identified as strong radical scavengers, with IC(50) values for scavenging of 1,1-diphenyl-2 picrylhydrazyl radicals (DPPH) in the range of 10.0-14.4 microg/ml. All three compounds potently scavenged peroxyl radicals in the oxygen radical absorbance capacity (ORAC) assay. In addition, the compounds were shown to inhibit cytochrome P450 1A activity with IC(50) values in the range of 17.9-33 microg/ml, and aromatase (Cyp19) activity with IC(50) values in the range of 1.2-5.6 microg/ml.

St. John's wort: role of active compounds for its mechanism of action and efficacy

St. John's wort (Hypericum perforatum L., SJW) contains numerous compounds with documented biological activity. Constituents that have stimulated the most interest include the naphthodianthrones hypericin and pseudohypericin, a broad range of flavonoids, and the phloroglucinols hyperforin and adhyperforin. According to the actual state of scientific knowledge the total extract has to be considered as the active substance. Although there are some open questions, the bulk of data suggests that several groups of active compounds are contributing to the antidepressant efficacy of the plant extract.

[New developments in hypericum extracts: data on efficacy and interactions]

The recent clinical studies on hypericum extract support the present indications for its use in mild to moderate depression and depressive episodes. The effectiveness is superior to placebo and comparable with synthetic antidepressive drugs. The rate of unwanted events is explicitly lower and their severity in general only mild. A further indication for hypericum could be somatoform disorders, but further clinical studies are recommended. The main compound responsible for interactions is presumably hyperforin, but further ingredients could contribute according to the specific composition of the particular extract.

Matrix proteases, green tea, and St. John's wort: Biomedical research catches up with folk medicine

BACKGROUND

Some proteases involved in extracellular matrix degradation are instrumental not only in overcoming tissue barriers to allow normal extravasation of hematic cells, but also in facilitating pathological processes such as inflammation, angiogenesis and tumor invasion. The possibility of blocking these enzymes has led to the development of synthetic inhibitors, though clinical trials have been disappointing owing to considerable side effects. However, long before enzymes were first isolated, these same pathologies were being treated in plant-based folk remedies, and today science is screening them for their reputed beneficial effects.

STATE OF THE ART

We present studies of 2 vegetable components as protease inhibitors. The first, (-)epigallocatechin-3-gallate - from green tea, has proved a good weapon for inhibiting gelatinases MMP-2 and MMP-9, but an even better inhibitor of leukocyte elastase (LE) activity; in vivo it blocks inflammation, angiogenesis and tumor invasion. The second, hyperforin - from Hypericum sp, inhibits LE-triggered activation of MMP-9, PMN chemotaxis and chemoinvasion, PMN-triggered angiogenesis, and inflammation-triggered pulmonary fibrosis; it also represses tumor-cell expression of MMP-2, thereby restraining invasion and metastasis.

CONCLUSION

Modern research clearly vindicates epidemiological and historical evidence of the beneficial effects of two long-used allies from the plant kingdom, going a step beyond by shedding light on mechanistic keys.

[Hypericin and hyperforin: bioactive components of St. John's Wort (Hypericum perforatum). Their isolation, analysis and study of physiological effect]

St. John's Wort (Hypericum perforatum L.) is commonly accepted as a medicinal plant. The data on the physiological activities of the individual substances that are produced in different organs of H. perforatum are well known at present. The highest attention is focused on the characterization and phytochemical properties of hypericin and hyperforin. These organic compounds are used as antidepressant, anticarcinogenic (photodynamic), antimicrobial and virostatic agents. The review paper surveys the present knowledge of chemical and analytical methods for their identification and quantification, physiological activity, and pharmacological and biomedical applications of hypericin and hyperforin.

Hyperforin prevents beta-amyloid neurotoxicity and spatial memory impairments by disaggregation of Alzheimer's amyloid-beta-deposits

The major protein constituent of amyloid deposits in Alzheimer's disease (AD) is the amyloid beta-peptide (Abeta). In the present work, we have determined the effect of hyperforin an acylphloroglucinol compound isolated from Hypericum perforatum (St John's Wort), on Abeta-induced spatial memory impairments and on Abeta neurotoxicity. We report here that hyperforin: (1) decreases amyloid deposit formation in rats injected with amyloid fibrils in the hippocampus; (2) decreases the neuropathological changes and behavioral impairments in a rat model of amyloidosis; (3) prevents Abeta-induced neurotoxicity in hippocampal neurons both from amyloid fibrils and Abeta oligomers, avoiding the increase in reactive oxidative species associated with amyloid toxicity. Both effects could be explained by the capacity of hyperforin to disaggregate amyloid deposits in a dose and time-dependent manner and to decrease Abeta aggregation and amyloid formation. Altogether these evidences suggest that hyperforin may be useful to decrease amyloid burden and toxicity in AD patients, and may be a putative therapeutic agent to fight the disease.

Alkyl phloroglucinol derivatives from Syzygium levinei and their differentiation-inducing activity

Eleven compounds have been identified from the whole plants of Syzygium levinei (Myrtaceae) on the basis of spectroscopic analysis and chemical methods. Among these compounds, (Z)-1-(2,6-dihydroxy-4-methoxyphenyl)-oct-5-en-1-one (1), (3 E,7 Z)-1-(2,6-dihydroxy-4-methoxyphenyl)-deca-3,7-dien-1-one (2), and 1-(2-O-beta-D-glucopyranosyl-5,6-dihydroxy-4-methoxyphenyl)-octan-1-one (3) were characterized as new alkyl phloroglucinol derivatives, and 1-(2,6-dihydroxy-4-methoxyphenyl)-hexan-1-one (4) was identified as a new natural product. Compounds 1, 2, and 4 were found to inhibit the proliferation of leukemia K562 and HL-60 cells and also to induce the differentiation of K562 cells as determined by the appearance of matured morphology and the increase in the intracellular hemoglobin level.

St. John's wort (Hypericum perforatum) and breastfeeding: plasma and breast milk concentrations of hyperforin for 5 mothers and 2 infants

BACKGROUND

Herbal preparations for depression, such as St. John's wort, are often preferred over pharmaceutical preparations by mothers and midwives after childbirth because these preparations are available to patients as over-the-counter "natural" treatments and are popularly assumed to be safe. The only existing report on St. John's wort excretion into human milk showed that only 1 active component (hyperforin) was detectable in breast milk, but was not detectable in the infants' plasma. Another report found more cases of minor problems in infants breast-fed by women taking St. John's wort. However, significance was reached only in comparison with disease-matched women (p<.01), not healthy controls (p=.20).

METHOD

Five mothers who were taking 300 mg of St. John's wort 3 times daily (LI 160 [Jarsin], Lichtwer Pharma GmbH; Berlin, Germany) and their breastfed infants were assessed. Thirty-six breast milk samples (foremilk and hindmilk collected during an 18-hour period) and 5 mothers' and 2 infants' plasma samples were analyzed for hyperforin levels by tandem mass spectrometry (LC/MS/MS; limit of quantification=0.1 ng/mL). Data were gathered from January 2001 to February 2002.

RESULTS

Hyperforin is excreted into breast milk at low levels. However, the compound was at the limit of quantification in the 2 infants' plasma samples (0.1 ng/mL). Milk/plasma ratios ranged from 0.04 to 0.13. The relative infant doses of 0.9% to 2.5% indicate that infant exposure to hyperforin through milk is comparable to levels reported in most studies assessing anti-depressants or neuroleptics. No side effects were seen in the mothers or infants.

CONCLUSION

These results add to the evidence of the relative safety of St. John's wort while breast-feeding found in previous observational studies.

Phloroglucinol in irritable bowel syndrome

OBJECTIVE

To determine the efficacy and tolerability of phloroglucinol, an antispasmodic agent in the treatment of Irritable Bowel Syndrome (IBS).

METHODS

It was an open label (quasi interventional) study. One hundred patients coming to the gastroenterology clinics of Aga Khan University Hospital with IBS as defined by the Rome II criteria were enrolled between February 2004 and September 2004 to participate in the trial and were treated as outpatients. Phloroglucinol (Himont) 50mg orally three times daily was given for two months. Symptoms were assessed before and during treatment using a questionnaire.

RESULTS

One hundred patients were enrolled in the study. Of them 61% (61/100) were males and 39% (39/100) were females. Their mean age was 41 +/- 14 years. Sixty-eight patients completed the study and 28 dropped out. On Phloroglucinol treatment there was an overall statistically significant improvement in abdominal pain (p<0.001), frequency of stools per day (p<0.001), urgency (p<0.001), passage of mucus per rectum (p<0.001), sense of incomplete defecation (p=0.001) and bloating (p=0.001). However, no response was seen in the feature of straining in both genders (p=0.676). The difference in response to treatment according to gender separately showed statistically significant improvement in the sense of incomplete defecation in females alone (p=0.003).

CONCLUSION

Phloroglucinol in a dose of 50mg three times daily is effective and well tolerated by the IBS patients. It relieves most of the symptoms of IBS.

St. John's wort

St. John's wort has been used to treat a variety of conditions. Several brands are standardized for content of hypericin and hyperforin, which are among the most researched active components of St. John's wort. St. John's wort has been found to be superior to placebo and equivalent to standard antidepressants for the treatment of mild to moderate depression. Studies of St. John's wort for the treatment of major depression have had conflicting results. St. John's wort is generally well tolerated, although it may potentially reduce the effectiveness of several pharmaceutical drugs.

RANDOMIZED TRIAL OF THE EFFICACY OF TAMSULOSIN, NIFEDIPINE AND PHLOROGLUCINOL IN MEDICAL EXPULSIVE THERAPY FOR DISTAL URETERAL CALCULI

PURPOSE

Recent studies show the interesting efficacy of different drug combinations for the spontaneous expulsion of distal ureteral stones. We performed a randomized, prospective study to assess and compare the efficacy of 3 drugs as medical expulsive therapy for distal ureteral calculi.

MATERIALS AND METHODS

A total of 210 symptomatic patients with distal ureteral calculi greater than 4 mm were randomly allocated to home treatment with phloroglucinol, tamsulosin or nifedipine (groups 1 to 3, respectively). Each group was given a corticosteroid drug and antibiotic prophylaxis with an injectable nonsteroidal anti-inflammatory drug was also used on demand. The primary end point was the expulsion rate and the secondary end points were expulsion time, analgesic use, need for hospitalization and endoscopic treatment as well as the number of workdays lost, quality of life and drug side effects

RESULTS

The expulsion rate was significantly higher in group 2 (97.1%) than in groups 1 (64.3%, p <0.0001) or 3 (77.1%, p <0.0001). Group 2 significantly achieved stone passage in a shorter time than the other 2 groups and showed a significantly decreased number of hospitalizations as well as a better decrease in endoscopic procedures performed to remove the stone. The control of renal colic pain was significantly superior in group 2 compared with the other groups, resulting in fewer workdays lost. Group 3 showed lower analgesic use and decreased workdays lost compared with group 1. No difference in side effects was observed among the groups.

CONCLUSIONS

Medical expulsive therapy should be considered for distal ureterolithiasis without complications before ureteroscopy or extracorporeal lithotripsy. The use of tamsulosin in this treatment regimen produced stone expulsion in almost all cases in a short time, allowing complete home patient treatment.

Phloroglucinol for acceleration of labour: double blind, randomized controlled trial

OBJECTIVES

To determine the effects of Phloroglucinol in acceleration of labour and its adverse effects on mother and foetus.

METHODS

A double blind randomized, placebo controlled trial was conducted on 100 patients in active phase of uncomplicated labour selected by convenient sampling. Patients were given Phloroglucinol or Placebo (distilled water) intravenously. Progress of labour was plotted on Partogram. Any adverse effects of the drug on mother and fetus were noted. Student's t-test was applied for statistical analysis.

RESULTS

In patients receiving Phloroglucinol there was a mean 34% reduction in duration of 1st stage of labour and a mean 23% reduction in 2nd stage as compared to Placebo group respectively. Blood loss >500ml was observed in 2% patients. Otherwise there were no adverse effects on mother or foetus.

CONCLUSION

Phloroglucinol shortens the duration of labour, is non toxic to both mother and fetus and does not cause primary post partum haemorrhage.

Potential antidepressant properties of IDN 5491 (hyperforin-trimethoxybenzoate), a semisynthetic ester of hyperforin

Hyperforin is one of the possible active principles mediating the antidepressant activity of Hypericum perforatum L. extracts. The ester derivative IDN 5491 (hyperforin-trimethoxybenzoate) showed antidepressant-like properties in the forced swimming test (FST) in rats, with no effect on open-field activity, when given as three intraperitoneal injections in 24 h at 3.125 and 6.25 mg/kg. The plasma concentrations of IDN 5491 were 30-50 microM, and those of hyperforin much lower but still close to those after effective doses of hyperforin-dicyclohexylammonium and Hypericum extract. This suggests that hyperforin plays a role in the antidepressant-like effect of the ester and of Hypericum extract. In vitro binding and uptake data showed that IDN 5491 is inactive on a wide panel of CNS targets at a concentration (14 microM) much higher than that measured in the brain of treated rats (0.3 microM). Like the extract, the antidepressant-like effect of IDN 5491 was blocked by (-)-sulpiride, a selective D2 receptor antagonist and by BD-1047, a selective sigma1 antagonist. Ex-vivo binding studies showed that brain sigma1 receptors are occupied after in vivo treatment with IDN 5491, possibly by an unknown metabolite or by endogenous ligand induced by hyperforin.

Role of hyperforin in the pharmacological activities of St. John's Wort

The phloroglucinol derivative hyperforin has been recently shown to be a major antidepressant component in the extract of Hypericum perforatum. Experimental studies clearly demonstrated its activity in different behavioral models of depression. Moreover clinical studies linked the therapeutic efficacy of Hypericum extracts to their hyperforin content, in a dose-dependent manner. The molecular mechanism of action of hyperforin is still under investigation. Hyperforin has been shown to inhibit, like conventional antidepressants, the neuronal uptake of serotonin, norepinephrine and dopamine. However, hyperforin inhibits also the uptake of gamma-aminobutyric acid (GABA) and L-glutamate. The uptake inhibition by hyperforin does not involve specific binding sites at the transporter molecules; its mechanism of action seems to be related to sodium conductive pathways, leading to an elevation in intracellular Na(+) concentration. Other additional mechanisms of action of hyperforin, involving ionic conductances as well synaptosomal and vesicular function, have been suggested. In addition to its antidepressant activity, hyperforin has many other pharmacological effects in vivo (anxiolytic-like, cognition-enhancing effects) and in vitro (antioxidant, anticyclooxygenase-1, and anticarcinogenic effects). These effects could be of clinical importance. On the other hand, the role of hyperforin in the pharmacological interactions occurring during Hypericum extract therapy must be fully investigated. Hyperforin seems to be responsible for the induction of liver cytochrome oxidase enzymes and intestinal P-glycoprotein. Several pharmacokinetic studies performed in rats and humans demonstrated oral bioavailability of hyperforin from Hypericum extract. Only recently a new chromatographic method for detection of hyperforin in the brain tissue has been developed and validated. Taking into account the chemical instability of hyperforin, current efforts are directed to the synthesis of new neuroactive derivatives.

Safety of Hypericum extract in mildly to moderately depressed outpatients: a review based on data from three randomized, placebo-controlled trials

RATIONALE

Hypericum extracts have been regarded as antidepressant drugs without specific side effects by patients, medical professionals and researchers alike. Recently there has been discussion about potential interactions between St. John's wort and other drugs.

OBJECTIVES

To investigate the tolerability of Hypericum extract by comparing adverse event rates observed during clinical trials with the herbal drug to those observed under placebo and synthetic antidepressants.

METHODS

A data review was performed based on the original data of three double-blind, randomised multicenter trials, during which 594 out-patients suffering from mild to moderate depression according to DSM-IV criteria received 3 x 300 mg/day Hypericum extract (WS 5570, WS 5572, WS 5573) or placebo over a double-blind treatment period of 6 weeks. For the polled data from the three trials, the risk ratios and risk differences versus placebo for single and grouped adverse events were determined along with their 95% confidence intervals. The data were inspected for relevant differences between Hypericum extract and placebo and were compared to trials involving the administration of several synthetic antidepressants.

RESULTS

For the polled data of the three trials, the percentage of patients with any adverse events under Hypericum extract exposition was comparable to placebo. The drug was also found to be devoid of effects of sedation, anticholinergic reactions, gastrointestinal disturbances and sexual dysfunction often found in patients treated with tricyclic antidepressants or selective serotonin reuptake inhibitors.

CONCLUSION

The analysis did not reveal any specific effects of Hypericum extract.

New cytotoxic alkyl phloroglucinols from Protorhus thouvenotii

Two new cytotoxic alkylene phloroglucinols and one known compound were isolated through chromatographic separation from the methanolic extract of the dried fruits of Protorhus thouvenotii (Anacardiaceae). The compounds showed marginal in vitro cytotoxicity in the A2780 ovarian cancer cell line assay with an IC50 of 11 microg/mL.

Convenient synthesis of 2,4-diacetylphloroglucinol, a natural antibiotic involved in the control of take-all disease of wheat

2,4-Diacetylphloroglucinol (DAPG) is an antibiotic with broad-spectrum antibacterial and antifungal activities. It is a major determinant in the biological control of several plant diseases. DAPG is produced by Pseudomonas fluorescens both in vitro and in the rhizosphere of wheat. It is involved in the natural suppression of take-all disease known as take-all decline, which develops in soils following extended monoculture of wheat or barley. A one-step synthesis of DAPG from the commercially available 2-acetylphloroglucinol is described. This reaction involves the direct alkylation of 2-acetylphloroglucinol using acetic anhydride as the acetylation reagent, with boron trifluoride-etherate as the catalyst. This synthesis is simple and produces higher yields of DAPG (90%) as compared with previously described procedures. As ecological concerns are gaining equal status with agricultural concerns, the demand for natural biocontrol measures is increasing. There is tremendous pressure from society on agriculture to reduce the use of pesticides. A discussion is given on the agricultural and ecological importance of this natural antibiotic and its application as an alternative to reduce the use of synthetic pesticides.

Anti-tumor promoting activity of Dryopteris phlorophenone derivatives

As a part of screening studies for cancer chemopreventive agents (anti-tumor promoters) 33 Dryopteris phlorophenone derivatives have been evaluated. The compounds tested comprised of monomeric acylphloroglucinols (e.g. desaspidinol, aspidinol) as well as dimeric (e.g. aspidin, desaspidin), trimeric (e.g. filixic acids), and tetrameric (e.g. dryocrassin) phlorophenone, wherein hexacyclic rings are bound together by a methylene bridge. These compounds were examined for their in vitro anti-tumor promoting effect on Epstein-Barr virus antigen activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). The two dimeric compounds aspidin and desaspidin, which were found to be the most active among the tested phlorophenones, were also examined in vivo on two stage mouse skin carcinogenesis, and found to show significant inhibitory effect on 7,12-dimethylbenz[alpha]anthracene (DMBA)-TPA tumor promotion.

Antitumor-promoting activity of mallotojaponin, a major constituent of pericarps of Mallotus japonicus

Mallotojaponin, a major constituent of the pericarps of Mallotus japonicus (Euphorbiaceae), inhibited the action of tumor promoter in vitro and in vivo; it inhibited tumor promoter-enhanced phospholipid metabolism in cultured cells, and also suppressed the promoting effect of 12-O-tetradecanoylphorbol-13-acetate on skin tumor formation in mice initiated with 7,12-dimethylbenz-[a]anthracene.

Evaluation of the anti-tumour action and acute toxicity of kosins from Hagenia abyssinica

The kosins are phloroglucinol derivatives isolated from female flowers of Hagenia abyssinica (Rosaceae) and were tested for possible cytotoxic activity in vitro and in vivo against a panel of three transplantable murine adenocarcinomas of the colon of varying growth characteristics and morphology (MAC system). Significant reductions in colony formation were observed in vitro in MAC 15A tumour following 1, 3, 6 and 24 h exposure to all kosins (alpha-kosin, kosotoxin and protokosin). The kosins (kosotoxin and protokosin) were also found to be cytotoxic against MAC tumour cells in vivo in some cases. Kosotoxin was subjected to preliminary toxicity studies in mice. It showed no observable toxicity up to 200 mg kg-1 orally and was found to be toxic at doses in excess of 50 mg kg-1 (i.p.). A single dose of 100 mg kg-1 (i.p.) was lethal for 100% of the animals.

[Effect of phloroglucinol on rectosigmoid motility stimulated by a test meal. Study in patients with irritable bowel syndrome]

Twenty patients (15 women, 5 men, mean age: 46.3 +/- 11.82 years, mean weight: 70.9 +/- 8.83 kg) presenting with a 8.5 +/- 4.7 years' history of irritable bowel syndrome associated predominantly with postprandial abdominal pain were recruited into the study. They underwent, after an enema, a rectosigmoid manometry (4 channels, low compliant infusion pump and catheters) before and after a 1000 kcal standardized meal. At the end of the meal they were administered intravenously phloroglucinol (two 40 mg ampoules) or placebo (two ampoules). Both treatments were strictly similar and the order of administration was randomly assigned Motor activity at the rectum, rectosigmoid, lower sigmoid and sigmoid level was determined using a motor index calculated for each 15 min period. Three preprandial and four postprandial indices were calculated. Both groups were statistically similar for sex ratio, age and history of disease. A slight difference was noted for mean weight: the caloric instake per kg of weight was a little higher in the phloroglucinol group. Mean preprandial indices were comparable in both groups. Variance analysis showed that the increase in postprandial motor indices was statistically less pronounced in the phloroglucinol group than in the placebo group. In the placebo group a clear cut increase in motor activity was assessed, which was not observed in the phloroglucinol group. This variation of motricity, which was observed at every level, was more pronounced for the first two postprandial indices than for the last two ones. These results suggest that phloroglucinol is able to reduce rectosigmoid motor response after a test meal. This could explain its activity in abdominal pain associated with irritable bowel syndrome.