Shaheed Ur Rehman

Review on a Traditional Herbal Medicine, Eurycoma longifolia Jack (Tongkat Ali): Its Traditional Uses, Chemistry, Evidence-Based Pharmacology and Toxicology

Eurycoma longifolia Jack (known as tongkat ali), a popular traditional herbal medicine, is a flowering plant of the family Simaroubaceae, native to Indonesia, Malaysia, Vietnam and also Cambodia, Myanmar, Laos and Thailand. E. longifolia, is one of the well-known folk medicines for aphrodisiac effects as well as intermittent fever (malaria) in Asia. Decoctions of E. longifolia leaves are used for washing itches, while its fruits are used in curing dysentery. Its bark is mostly used as a vermifuge, while the taproots are used to treat high blood pressure, and the root bark is used for the treatment of diarrhea and fever. Mostly, the roots extract of E. longifolia are used as folk medicine for sexual dysfunction, aging, malaria, cancer, diabetes, anxiety, aches, constipation, exercise recovery, fever, increased energy, increased strength, leukemia, osteoporosis, stress, syphilis and glandular swelling. The roots are also used as an aphrodisiac, antibiotic, appetite stimulant and health supplement. The plant is reported to be rich in various classes of bioactive compounds such as quassinoids, canthin-6-one alkaloids, β-carboline alkaloids, triterpene tirucallane type, squalene derivatives and biphenyl neolignan, eurycolactone, laurycolactone, and eurycomalactone, and bioactive steroids. Among these phytoconstituents, quassinoids account for a major portion of the E. longifolia root phytochemicals. An acute toxicity study has found that the oral Lethal Dose 50 (LD50) of the alcoholic extract of E. longifolia in mice is between 1500–2000 mg/kg, while the oral LD50 of the aqueous extract form is more than 3000 mg/kg. Liver and renal function tests showed no adverse changes at normal daily dose and chronic use of E. longifolia. Based on established literature on health benefits of E. longifolia, it is important to focus attention on its more active constituents and the constituents’ identification, determination, further development and most importantly, the standardization. Besides the available data, more evidence is required regarding its therapeutic efficacy and safety, so it can be considered a rich herbal source of new drug candidates. It is very important to conserve this valuable medicinal plant for the health benefit of future generations.

Interactions between herbs and antidiabetics: an overview of the mechanisms, evidence, importance, and management.

Complementary and alternative therapies are quickly gaining importance because they are perceived to be free of side effects due to their natural origin. However, herbal remedies are complex mixtures of bioactive entities, which may interact with prescription drugs through pharmacokinetic or pharmacodynamic mechanisms and sometimes result in life-threatening consequences. In particular, diabetes patients are often treated with multiple medications due to different comorbidities, and such patients use antidiabetic medications for their entire lives; thus, it is important to make the public aware of herb interactions with antidiabetic drugs. In this paper, we summarize the reports available on the interaction of herbal remedies with oral hypoglycemic agents and describe mechanisms, preclinical or clinical evidence, importance, and management strategies.

HPLC Determination of Bioactive Flavonoids in Hovenia dulcis Fruit Extracts

A simple, accurate and reproducible reversed-phase liquid chromatographic method was developed for qualitative and quantitative determination of four bioactive flavonoids (ampelopsin, taxifolin, myricetin and quercetin) from the fruit-stalk extract of Hovenia dulcis Thunb. Chromatographic separation was performed on a C18 column (4.6 × 150 mm, 3.5 µm) with mobile phase consisting of 0.1% acetic acid and 100% acetonitrile at a flow rate of 1.0 mL/min. The analysis was performed using a diode array detector at 365 nm. The method was validated in terms of selectivity, linearity, accuracy, precision and recovery. Good linearity was observed over the investigated concentration range (10-500 μg/mL), with correlation coefficient values greater than 0.99. The intra- and inter-day precisions over the concentration range were <3.91% (relative standard deviation), and the accuracy was between 91.57 and 106.66%. The mean recovery for all the analytes was 100.87%. This method was successfully applied in the quality assessment of bioactive flavonoids in the fruit-stalk extract of H. dulcis.

Development of a hydrophilic interaction liquid chromatography–tandem mass spectrometric method for the determination of kinsenoside, an antihyperlipidemic candidate, in rat plasma and its application to pharmacokinetic studies

Kinsenoside is a major bioactive constituent isolated from Anoectochilus formosanus and is investigated as an antihyperlipidemic candidate. In this study, a rapid, sensitive, and reliable bioanalytical method was developed for the determination of kinsenoside in rat plasma using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The plasma sample was pretreated with 1% acetic acid, followed by protein precipitation with acetonitrile:methanol (70:30). Chromatographic separation was performed on a HILIC silica column (2.1mm×100mm, 3μm). The mobile phases consisted of 0.1% acetic acid in distilled water (solvent A) and 0.1% acetic acid in acetonitrile (solvent B). A gradient program was used at a flow rate of 0.2mL/min. For mass spectrometric detection, the multiple reaction monitoring mode was used; the MRM transitions were m/z 265.2→m/z 102.9 for kinsenoside and m/z 163.3→m/z 132.1 for the internal standard (IS) nicotine in the positive ionization mode. A calibration curve was constructed in the range of 2-500ng/mL. The intra- and interday precision and accuracy were within 5%. The HILIC-MS/MS method was specific, accurate, and reproducible and was successfully applied in a pharmacokinetic study of kinsenoside in rats.

In Vitro Evaluation of the Effects of Eurycoma longifolia Extract on CYP-Mediated Drug Metabolism.

Eurycoma longifolia (Simaroubaceae) is a popular folk medicine that has traditionally been used in Southeast Asia as an antimalarial, aphrodisiac, antidiabetic, and antimicrobial and in antipyretic remedies. This study evaluates the effects of Eurycoma longifolia extract on cytochrome P450 (CYP) enzyme-mediated drug metabolism to predict the potential for herb-drug interactions. Methanolic extract of E. longifolia root was tested at concentrations of 1, 3, 10, 30, 100, 300, and 1000 µg/mL in human liver microsomes or individual recombinant CYP isozymes. The CYP inhibitory activity was measured using the cocktail probe assay based on liquid chromatography-tandem mass spectrometry. E. longifolia showed weak, concentration-dependent inhibition of CYP1A2, CYP2A6, and CYP2C19. The inhibitory effects on these CYP isozymes were further tested using individual recombinant CYP isozymes, showing IC50 values of 324.9, 797.1, and 562.9 μg/mL, respectively. In conclusion, E. longifolia slightly inhibited the metabolic activities of CYP1A2, CYP2A6, and CYP2C19 but this issue requires careful attention in taking herbal medicines or dietary supplements containing E. longifolia extracts.

Evaluation of Metabolic Stability of Kinsenoside, an Antidiabetic Candidate, in Rat and Human Liver Microsomes

Kinsenoside is a principle bioactive compound of Anoectochilus formosanus. It exhibits various pharmacological effects such as antihyperglycemic, antioxidant, anti-inflammatory, immunostimulating, and hepatoprotective activities and has recently been developed as an antidiabetic drug candidate. In this study, as part of an in vitro pharmacokinetic study, the stability of kinsenoside in rat and human liver microsomes was evaluated. Kinsenoside was found to have good metabolic stability in both rat and human liver microsomes. These results will provide useful information for further in vivo pharmacokinetic and metabolism studies.

Evaluation of herb–drug interactions of Hovenia dulcis fruit extracts

Background: Hovenia dulcis (Rhamnaceae) fruits are popularly used as herbal medicines or dietary supplements in Asian countries due to functions such as liver protection and detoxification from alcohol poisoning. Accordingly, it is very likely for dietary supplemental products, including H. dulcis fruit extracts, to be taken with prescription drugs. Objective: In this study, possible food–drug interactions involving H. dulcis fruit extracts were evaluated based on the inhibition of cytochrome P450 (CYP) enzyme activity. Material and Methods: The water extract of H. dulcis fruit extracts was incubated in human liver microsomes with CYP-specific substrates. The formation of the CYP-specific metabolites was measured using liquid chromatography-tandem mass spectrometry. Results: H. dulcis fruit extracts showed negligible effects on seven CYP isozyme activities at all concentrations tested. Conclusion: This result suggests that H. dulcis fruit extracts may have minimal pharmacokinetic interactions with coadministered drugs through the modulation of CYP enzymes. Abbreviations Used: CYP: cytochrome P450 enzymes, HPLC: High performance liquid chromatography, LC-MS/MS : liquid chromatography-tandem mass spectrometry, MRM: multiple-reaction monitoring

A Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Quantitation of 10 Bioactive Components in Rhus verniciflua Extracts.

The purpose of this study was to develop a simultaneous method to quantify 10 bioactive compounds in Rhus verniciflua extracts using high-performance liquid chromatography-tandem mass spectrometry. The chromatographic separation was performed using a C18 column under gradient elution with 0.1% formic acid and acetonitrile as the mobile phase solvents. The analytes were detected in the negative-ion mode using multiple-reaction monitoring detection with an electrospray ionization interface. The calibration curves for all the analytes showed good linearity (r(2) >0.997) over the concentration range of 1-1,000 ng/mL. The recovery values were within 89.53-110.14%, and the intra- and interday coefficients of variation were <4.86% for all the tested compounds. The developed method was successfully applied to a quality assessment of the R. verniciflua extract samples.

An ultra-high-performance liquid chromatography-tandem mass spectrometric method for the determination of hederacoside C, a drug candidate for respiratory disorder, in rat plasma.

Hederacoside C is a principal bioactive pharmaceutical ingredient of Hedera helix leaf extracts. H. helix extracts have long been used in folk medicine for the treatment of respiratory disorders. Currently, hederacoside C is investigated as a promising candidate for the treatment of respiratory diseases. In this study, an accurate, sensitive, rapid, and reliable bioanalytical method was developed for the determination of hederacoside C in rat plasma using ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). For sample preparation, plasma proteins were precipitated with 0.1% acetic acid in acetonitrile. Waters UPLC BEH C18 (2.1mm I.D.×100mm, 1.7μm) column was used for chromatographic separation. A gradient elution of mobile phases consisting of 0.02% acetic acid in distilled water (solvent A) and 0.02% acetic acid in acetonitrile (solvent B) was used at a flow rate of 0.3mL/min. The multiple reaction monitoring (MRM) mode was used for mass spectrometric detection; the MRM transitions were m/z 1219.7→m/z 469.2 for hederacoside C and m/z 1108.3→m/z 221.2 for ginsenoside Rb1 (internal standard) in the negative ionization mode. A calibration curve was constructed in the range of 10-1000ng/mL. The intra- and inter-day precision and accuracy were within 5%. The developed UPLC-MS/MS method was successfully applied in a pharmacokinetic study of hederacoside C in rats. Hederacoside C was quickly but inadequately absorbed from the gastrointestinal tract of rats resulting in extremely low bioavailability and relatively slow clearance.

Characterization of metabolites produced from the biotransformation of 6-shogaol formed by Aspergillus niger

Abstract6-Shogaol [(4E)-1-(4-Hydroxy-3-methoxyphenyl)-4-decen-3-one] is a pungent and bioactive ingredient of ginger. This study investigated the biotransformation of 6-shogaol by Aspergillus niger. 6-Shogaol was fermented by A. niger, and the resultant metabolites were structurally characterized by liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QTOF MS). As a result, 6-shogaol was biotransformed to yield metabolites: M1, M2 (6-paradol), M3, and M4. The major metabolic routes were reduction and hydroxylation; the carbonyl group and double bond of 6-shogaol were reduced to generate M1 and M2, respectively, which were further hydroxylated or reduced to M3 and M4. Among these metabolites, M1 was reported for the first time in this study.