Selected physical and chemical properties of commercial Hypericum perforatum extracts relevant for formulated product quality and performance

Identification of Major Constituents of Hypericum perforatum L. Extracts in Syria by Development of a Rapid, Simple, and Reproducible HPLC-ESI-Q-TOF MS Analysis and Their Antioxidant Activities

Hypericum perforatum Linn (St. John's wort) is a popular and widespread medicine in Syria, which is used for a wide range of conditions, including gastrointestinal diseases, heart disease, skin diseases, and psychological disorders. This widespread use prompted us to identify the main compounds of this plant from Syria that are responsible for its medicinal properties, especially since its components differ between countries according to the nature of the soil, climate, and altitude. This is, to the best of our knowledge, the first report in which St. John's wort, a plant native to Syria, is extracted using different solvents and its most important compounds are identified. In this study, the dried above-ground parts, i.e., leaves, stem, petals, and flowers, were extracted using different solvents (water, ethanol, methanol, and acetone) and extraction protocols. By increasing the polarity of the solvent, higher yields were obtained, indicating that mainly hydrophobic compounds were extracted. Therefore, we conclude that extraction using the tea method or using a mixture of water and organic solvents resulted in higher yields compared with pure organic solvents or continuous boiling with water for long periods. The obtained extracts were analyzed using high-performance liquid chromatography equipped with a diode array detector (HPLC-DAD), coupled with UV-visible spectrophotometry at a full spectrum (200-800 nm). The HPLC spectra of the extracts were almost identical at three wavelengths (260 nm for phloroglucinols (hyperforin and derivates), 590 nm for naphthodianthrones (hypericins), and 350 nm for other flavonols, flavones, and caffeoylquinic acids), with differences observed only in the intensity of the peaks. This indicates that the same compounds were obtained using different solvents, but in different amounts. Five standards (chlorogenic acid, quercetin, quercitrin hydrate, hyperoside, and hypericin) were used, and a comparison with retention times and ultraviolet (UV) spectra reported in the literature was performed to identify 10 compounds in these extracts: hyperforin, adhyperforin, hypericin, rutin, quercetin, quercitrin, quercitrin hydrate, hyperoside, biapigenin, and chlorogenic acid. Although the European Pharmacopoeia still describes ultraviolet spectroscopy as a method for determining the quantity of Hyperici herba, interference from other metabolites can occur. Combined HPLC-DAD and electrospray ionization-mass spectrometry (LC-ESI-MS) in the positive mode have therefore also been used to confirm the presence of these compounds in the extracts by correlating known masses with the identified masses or through characteristic fragmentation patterns. Total phenolic contents of the extracts were determined by the Folin-Ciocalteu assay, and antioxidant activity was evaluated as free radical scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The results indicate that the aqueous extracts prepared by the tea method gave the highest total phenols, while the pure organic solvents gave very low phenols. Also, the extracts that contain the largest amount of phenols gave lower IC₅₀ values or higher antioxidant activity than that of others.

Investigation of impact of storage conditions on Hypericum perforatum L. dried total extract

Hypericum perforatum L. (Hypericaceae) has been widely prescribed for mild to moderate depression following the release of promising results in clinical trials. However, it is known that its constituents may be affected by milieu. The stability complexities of the constituents of H. perforatum have gained interest in recent years. The aim of the present study was to examine the impact of storage conditions on H. perforatum total extract simultaneously under different storage conditions. Temperature, humidity, and light conditions were evaluated. Comparative analyses of methanol extracts were conducted using high performance liquid chromatographydiode array detection for chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin, quercetin, amentoflavone, pseudohypericin, hyperforin, and hypericin. Analysis and extraction were performed using a validated method. The fluctuation of the constituents of the plant extract has been demonstrated. Among these components, chlorogenic acid was the most stable. Hyperforin, hypericin, and pseudohypericin were more stable than the flavonoids at −20°C, in the 6^th month. As estimated, decay was lowest at −20°C and highest at 40°C–75% relative humidity for the analyzed constituents. Except for hyperforin, light protection decreased the breakdown of components within 4 months. However, at the 6^th month, equivalent changes were seen for all constituents. Degradation of the constituents at −20°C indicates the importance of stability tests in analysis studies covering time and storage conditions.

Effects of polysaccharide elicitors on secondary metabolite production and antioxidant response in Hypericum perforatum L. shoot cultures

The effects of polysaccharide elicitors such as chitin, pectin, and dextran on the production of phenylpropanoids (phenolics and flavonoids) and naphtodianthrones (hypericin and pseudohypericin) in Hypericum perforatum shoot cultures were studied. Nonenzymatic antioxidant properties (NEAOP) and peroxidase (POD) activity were also observed in shoot extracts. The activities of phenylalanine ammonia lyase (PAL) and chalcone-flavanone isomerase (CHFI) were monitored to estimate channeling in phenylpropanoid/flavonoid pathways of elicited shoot cultures. A significant suppression of the production of total phenolics and flavonoids was observed in elicited shoots from day 14 to day 21 of postelicitation. This inhibition of phenylpropanoid production was probably due to the decrease in CHFI activity in elicited shoots. Pectin and dextran promoted accumulation of naphtodianthrones, particularly pseudohypericin, within 21 days of postelicitation. The enhanced accumulation of naphtodianthrones was positively correlated with an increase of PAL activity in elicited shoots. All tested elicitors induced NEAOP at day 7, while chitin and pectin showed increase in POD activity within the entire period of postelicitation. The POD activity was in significantly positive correlation with flavonoid and hypericin contents, suggesting a strong perturbation of the cell redox system and activation of defense responses in polysaccharide-elicited H. perforatum shoot cultures.

The filling of powdered herbs into two-piece hard capsules using hydrogenated cotton seed oil as lubricant

The aim of this work was to investigate the plug formation and filling properties of powdered herbal leaves using hydrogenated cotton seed oil as an alternative lubricant. In a first step, unlubricated and lubricated herbal powders were studied on a small scale using a plug simulator, and low-force compression physics and parameterization techniques were used to narrow down the range in which the optimum amount of lubricant required would be found. In a second step these results were complemented with investigations into the flow properties of the powders based on packing (tapping) experiments to establish the final optimum lubricant concentration. Finally, capsule filling of the optimum formulations was undertaken using an instrumented tamp filling machine. This work has shown that hydrogenated cotton seed oil can be used advantageously for the lubrication of herbal leaf powders. Stickiness as observed with magnesium stearate did not occur, and the optimum lubricant concentration was found to be less than that required for magnesium stearate. In this work, lubricant concentrations of 1% or less hydrogenated cotton seed oil were required to fill herbal powders into capsules on the instrumented tamp-filling machine. It was found that in principle all powders could be filled successfully, but that for some powders the use of higher compression settings was disadvantageous. Relationships between the particle size distributions of the powders, their flow and consolidation as well as their filling properties could be identified by multivariate statistical analysis. The work has demonstrated that a combination of the identification of plug formation and powder flow properties is helpful in establishing the optimum lubricant concentration required using a small quantity of powder and a powder plug simulator. On an automated tamp-filling machine, these optimum formulations produced satisfactory capsules in terms of coefficient of fill weight variability and capsule weight.

Toxicity and drug interactions associated with herbal products: ephedra and St. John's Wort

Health care providers are being increasingly confronted with the use of herbal medications by their patients. It is imperative that patients be questioned regarding herbal preparation use and that health care providers become familiar with these agents. Research into the active components and mechanisms of action of various herbals is ongoing [350]. Long-range studies need to be performed to follow patients for efficacy or toxicity in chronic use [351,352]. Adverse reactions to herbal remedies should be reported to the FDA MedWatch at http://www.fda.gov/medwatch. As withany therapeutic agent, risk of use must always be weighed against potential benefits.

Usefulness of studies on the molecular mechanism of action of herbals/botanicals: The case of St. John's wort

The use of herbals/botanicals has been gaining wide popularity in recent years in the United States as well as in other parts of the world. The mechanism of action of most of these herbals/botanicals has not been subjected to thorough scientific investigations. St. John's wort (Hypericum perforatum) represents a useful case study in this sense. Traditionally, it is used as a natural treatment for depression; however, in recent years its molecular mechanism of action has been elucidated by a number of laboratories across the world. Such studies have helped understand potential interactions of St. John's wort with drugs and other xenobiotics. St. John's wort activates a nuclear receptor called pregnane X receptor (PXR). PXR is a ligand-activated transcription factor that induces a number of xenobiotic-metabolizing enzymes and transporters including cytochrome P4503A4 (CYP3A4) in humans. Because CYP3A4 alone metabolizes about 60% of all clinically relevant drugs, induction of CYP3A4 may result in the rapid elimination of these drugs and a consequent reduction in drug efficacy. Ironically, such enzyme-inducing effects may not produce any immediate adverse symptomatology in the person taking St. John's wort. Therefore, the case of St. John's wort should serve as a good example of the usefulness and importance of studies on the mechanism of action of the herbals/botanicals, particularly those with widespread use. Scientists, physicians, and other health professionals can make use of the knowledge from such studies as an additional risk management tool.

Influence of the punch diameter and curvature on the yield pressure of MCC-compacts during Heckel analysis

The volume reduction behaviour of powders has been quantified by means of the 'in-die' yield pressure (YP) using Heckel analysis. However, because different YPs are reported for the same material, the experimental conditions influencing this material-constant were investigated. Silicified microcrystalline cellulose was compressed into flat-faced and convex tablets using a compaction simulator instrumented with load and displacement transducers. During compression, upper and lower punch force and displacement data were recorded and corrected for punch deformation. A symmetrical triangle wave compression profile was used and the instantaneous punch velocity was kept constant (5mm/s). Individual tablet height and weight were used for Heckel analysis. The influence of the 'effective compression pressure' (P(EFF)) (ranging from 10 to 350 MPa), punch diameter (PD) (4, 9.5 and 12 mm) and filling depth (FD) (4.5, 7.5 and 10.5mm) on YP was statistically evaluated using Response Surface Modelling software. A quadratic surface response equation, describing the relationship between P(EFF), PD, FD and YP, was proposed for concave (Adj R(2): 0.8424; S.D.: 14.60 MPa) and flat-faced (Adj R(2): 0.8409; S.D.: 4.49 MPa) punches. YP and tensile strength were mainly determined by P(EFF), irrespective of punch curvature. FD and PD had only a minor influence on the YP, although more pronounced for the concave punches. The method used resulted in reproducible P(EFF) and tensile strength values and the flat-faced tablets showed less weight variation. Flat-faced punches are preferred over punches with a concave surface when investigating the volume reduction behaviour of a powder by means of Heckel analysis and the experimental parameters should be reported.

Simultaneous determination of protopseudohypericin, pseudohypericin, protohypericin, and hypericin without light exposure

St. John's wort products are commonly standardized to total naphthodianthrones and hyperforin. Determination of these marker compounds is complicated because of the photochemistry of the naphthodianthrones pseudohypericin and hypericin and the instability of hyperforin in solution. Protopseudohypericin and protohypericin have been identified as naturally occurring naphthodianthrones and, when exposed to light, they are converted into pseudohypericin and hypericin, respectively. However, exposure to light and the resulting naphthodianthrone free-radical reactions oxidize hyperforin. A mathematical relationship between the response of the proto compound and the resulting naphthodianthrone can be established by comparing the analytical response of the proto compound in a solution protected from light with the increase in the analytical response of naphthodianthrone in the same solution after exposure to light. By mathematically converting the proto compounds to their respective products, exposure to light can be avoided while still including proto compounds in a single assay. The method presented here details the reporting of all significant naphthodianthrones, including protopseudohypericin and protohypericin, without exposure to light. This approach includes the benefits of improved naphthodianthrone precision and protection of hyperforin from oxidation.

Excipient compatibility study of Hypericum perforatum extract (St. John's wort) using similarity metrics to track phytochemical profile changes

The formulation of botanical dietary supplements is challenging due to their complex activity-composition relationship, as well as physical and chemical stability issues. As excipient compatibility testing is a major component of sound formulation development, the objectives of this work were: (1) explore excipient compatibility storage paradigms; (2) determine interactions between phytochemicals of interest in Saint John's Wort (SJW) with several excipients; and (3) explore the application of similarity metrics to the data. Modifications to conventional isothermal stress testing paradigms included additional storage conditions of heat and moisture (5, 50 degrees C, 5 and 0% added water), as well as more rigorous controls. Binary blends of SJW and ten commonly used excipients were prepared and neat SJW was used as control. After 3 weeks, the percentage remaining of each phytochemical was determined by HPLC. Several similarity metrics were applied to the data. Common storage paradigms were suitable for excipient compatibility testing when controls of neat material are stored under similar conditions and the percentage of phytochemicals remaining in excipient:SJW blends and neat SJW are compared. Excipient incompatibilities were determined for SJW phytochemicals of interest. Similarity metrics applied to the phytochemical profiles conveniently summarized the data. This work allows logical decisions to be made regarding the formulation of SJW.