Subrata Pandit

Botanicals as medicinal food and their effects on drug metabolizing enzymes

Botanicals fall under different regulations in different countries and are mostly consumed without the consultation of the healthcare professional. Over the last decade, utilization of herbal therapies has been extensively documented. The findings indicate the possibility of potential herb-drug interactions due to the concomitant administration of herbal extracts and prescription/over-the-counter drugs. Simultaneously, with the increasing public awareness and search for safer herbal remedies, the study on herbal-drug interactions has gained momentum through the study of drug metabolizing enzymes. Cytochrome P450 (CYP) inhibition or induction is probably the most common mechanism for the pharmacokinetic interactions of herbs and drugs. Any inhibition of CYP enzymes by herbal extracts may result in enhanced plasma and tissue concentration of drugs, leading to toxicity, while induction results in reduced drug concentration leading to decreased drug efficacy and treatment failure. Considering the rapidly growing herbal markets, these types of clinical interactions remain under-reported and unclear. With the increasing consumption of herbal extracts along with prescription medicines, the safety of herbs has become a concern. This article reviews the potential for drug interactions by herbal extracts through drug metabolizing enzymes.

Metabolism mediated interaction of α-asarone and Acorus calamus with CYP3A4 and CYP2D6.

The present study was aimed to investigate the possible interaction of the standardized extract of Acorus calamus (AC) with Cytochrome P450 enzyme, quantitative determination of the α-asarone in the AC rhizome was performed by RP-HPLC method. In vitro interaction of the plant extract was evaluated by CYP450-carbon monoxide complex (CYP450-CO) assay. Effect on individual isoforms such as CYP3A4 and CYP2D6 isozymes were analyzed through fluorescence product formation and respective IC(50) values were determined. CYP450-CO assay showed moderate interaction potential. Extract showed higher IC(50) values (46.84±1.83-32.99±2.21 μg/ml) comparing to the standard inhibitors and lower IC(50) value than α-asarone (65.16±2.37-42.15±2.45 μg/ml).

Exploring the possible metabolism mediated interaction of Glycyrrhiza glabra extract with CYP3A4 and CYP2D6.

The rhizome of Glycyrrhiza glabra L. (licorice) is used very widely in Indian and Chinese traditional medicine, and it is a popular flavor ingredient of drinks, sweets and candies. Its medicinal uses include treating bronchitis, dry cough, respiratory infections, liver disorders and diabetes. Glycyrrhizin is normally considered to be its biologically active marker, so a rapid RP‐HPLC method was developed for the quantitative estimation of glycyrrhizin in the extract. The effect of the standardized extract and its marker on drug metabolizing enzymes was evaluated through CYP3A4 and CYP2D6 inhibition assays to evaluate the safety through its drug interaction potential. The inhibition of CYP3A4 and CYP2D6 isozymes was analysed by the fluorescent product formation method. In the CYP450‐CO assay, the interaction potential of the standardized extract and pooled microsomes (percentage inhibition 23.23 ± 1.84%), was found to be less than the standard inhibitor. In the fluorimetric assay, G. glabra extracts showed higher IC50 values than their positive inhibitors, ketoconazole and quinidine for CYP3A4 and CYP2D6, respectively. Furthermore, the interaction potential of the plant extract was greater than the pure compound. The results demonstrate that G. glabra and its principle bioactive compound, glycyrrhizin, when co‐administered with conventional medicines showed only a weak interaction potential with drug metabolizing enzymes. Copyright

Cytochrome P450 inhibition assay for standardized extract of Terminalia chebula Retz.

The hydroalcoholic extract of fruit pulp of Terminalia chebula Retz. was standardized and evaluated for its safety through cytochrome P450 (CYP 450) inhibition assay. Standardization was performed through high performance thin layer chromatography (HPTLC) using gallic acid (GA) standard. Cytochrome P450‐CO complex microplate assay was performed using rat liver microsomes. The effect of standardized extract, its fraction and bioactive marker compound were comparatively evaluated for its effect on CYP P450 enzymes. The extract of fruit pulp was used for HPTLC, where the Rf value of the marker was found to be 0.43. The calibration plot was linear in the range of 2–14 µg of GA and correlation co‐efficient of 0.99965. The mean quantity of GA was found to be 2.5% w/w. The CYP P450 concentration of the rat liver microsome sample used in the study was found to be 0.417 nmol/mg protein. The in vitro effect of various concentrations of extracts and fractions showed a linear concentration‐dependent inhibition of cytochrome P450 up to 60 µL. The study showed more inhibition of fraction when compared to the extract and GA. Still, the inhibition showed by fraction is less when compared with standard Ketoconazole. Thus, this study indicated the in vitro cytochrome P450 inhibition potential of T. Chebula.

RP-HPLC-DAD for simultaneous estimation of mahanine and mahanimbine in Murraya koenigii

Murraya koenigii leaves (Rutaceae) are widely used as food condiments in various food preparations in India. They possess a wide range of biological activities including antioxidant, antibacterial, anticancer, hypoglycemic and hypolipidemic activity. A rapid reverse-phase high-performance liquid chromatography (RP-HPLC) method has been developed for quantitative estimation of mahanine and mahanimbine, two major bioactive alkaloids in this plant. The amounts of mahanine and mahanimbine were detected as 9.56 ± 1.04 and 4.32 ± 0.81% w/w in the extract, with the retention times of 6.26 ± 0.66 and 10.40 ± 0.95 minutes. The limits of detection and quantification were estimated to be 29.30 and 81.12 µg/mL and 1.67 and 6.31 µg/mL, respectively. This specific and precise validated method can be useful for the routine analysis and quantitative determination of mahanine and mahanimbine in this therapeutically potent medicinal plant.

Quantification of α-Asarone in Acorus calamus by Validated HPTLC Densitometric Method

Acorus calamus L. (family Araceae), commonly known as “sweet flag” or “calamus”, is native to central Asia, North America, and Europe [1]. The rhizomes of the plants are used in Ayurveda and other Indian system of medicine (ISM) and Traditional Chinese Medicine (TCM) for its potential effect on memory disorder, lipid peroxide content, anti-aging and anti-cholinergic activity [2, 3]. Due to therapeutic and aromatic property, the plant is utilized both in phytotherapy and alimentary industry for preparation of food and beverages [4]. α-(1,2,4Trimethoxy-5-[(E)-prop-1-enyl]benzene) and β-asarone is the major bioactive component of A. calamus and it possesses wide range of pharmacological activity. α-Asarone (Figure 1) possesses sedative, neuroleptic, spasmolytic, anti-ulcerogenic, antiatherogenic, and anti-helminthic activity [1].

Evaluation of herb-drug interaction of a polyherbal Ayurvedic formulation through high throughput cytochrome P450 enzyme inhibition assay.

ETHNOPHARMACOLOGICAL RELEVANCE Arishtas are Ayurvedic formulation made with decoction of herbs. Arjunarishta formulation is being used in Ayurveda for cardio-protective activity. Ashwagandharishta formulation possesses antioxidant, anti-atherosclerotic and anti-stress properties. Ridayarishta, a novel empirical formulation was prepared using combination of selected ingredients from these two formulations to support healthy heart functions and to reduce stress. AIM OF THE STUDY Aim of the Study was to investigate herb-drug interaction (HDI) of Ridayarishta formulation through human hepatic cytochrome P450 (CYP450) enzyme inhibition assay. MATERIALS AND METHODS Ridayarishta formulation was phyto-chemically standardized against arjunolic acid, arjunetin, berberine, piperine, resveratrol and withaferin-A using high performance thin layer chromatography (HPTLC) analysis. The formulation was standardized with respect to ethanol by gas chromatographic (GC) analysis. HDI was evaluated with Ridayarishta formulation and amlodipine besilate, atenolol, atorvastatin, metformin, glipizide glimepiride cocktail using high throughput CYP450 enzyme inhibition assay; against CYP1A2, 2C19, 2D6 and 3A4 isozymes. RESULTS Contents of arjunolic acid, arjunetin, berberine, piperine, resveratrol and withaferin-A in Ridayarishta formulation were found to be 1.76±0.12, 1.51±0.09, 1.85±0.05, 3.2±0.12, 1.21±0.08, and 2.16±0.09ppm, respectively. Quantity of ethanol in Ridayarishta was found to be 7.95±0.023% (V/V). Ridayarishta showed significantly higher (P<0.001) IC50 value against CYP1A2 (IC50-13.80±1.96µg/mL), 2C19 (IC50-14.343±2.28µg/mL), 2D6 (IC50-0.897±0.28µg/mL) and 3A4 (IC50-32.057±2.51µg/mL) compared to positive controls such as furafylline, tranylcypromine, quinidine and ketoconazole respectively. Cocktail of herbal formulation and cardio protective, antihypertensive, anti-diabetic drugs showed significantly (P<0.001and P<0.01) less or negligible HDI. CONCLUSION Ridayarishta formulation alone and cocktail with amlodipine besilate, atenolol, atorvastatin, metformin, glipizide, glimepiride had negligible or insignificant effect on CYP450 inhibition. It may be concluded that consumption of Ridayarishta along with selective cardio protective, antihypertensive and anti-diabetic conventional medicine is safe with negligible or without any significant CYP450 (CYP1A2, 2C19, 2D6 and 3A4) inhibition mediated HDI.

Indian Medicinal Plants with Hypoglycemic Potential

India has a well-recorded and well-practiced knowledge of traditional herbal medicine for the treatment of chronic disease like diabetes. There is a growing demand for the leads with potential antidiabetic activity. Ethnomedical approach for diabetes is a practical, cost-effective, and a logical approach for its treatment and management. This chapter aims to provide a comprehensive review on the plant species and leads from Indian systems of medicine for the treatment of diabetes. Many of the species that contribute toward the antidiabetic activity are still unexplored and require further attention. Several potential medicinal plants have been explored from Indian biospheres which are being used for the treatment of diabetes and also several works on these plants have been reported.

Metabolism-mediated interaction potential of standardized extract of Tinospora cordifolia through rat and human liver microsomes.

Objective: Tinospora cordifolia is used for treatment of several diseases in Indian system of medicine. In the present study, the inhibition potential of T. cordifolia extracts and its constituent tinosporaside to cause herb-drug interactions through rat and human liver cytochrome enzymes was evaluated. Materials and Methods: Bioactive compound was quantified through reverse phase high-performance liquid chromatography, to standardize the plant extracts and interaction potential of standardized extract. Interaction potential of the test sample was evaluated through cytochrome P450-carbon monoxide complex (CYP450-CO) assay with pooled rat liver microsome. Influence on individual recombinant human liver microsomes such as CYP3A4, CYP2D6, CYP2C9, and CYP1A2 isozymes was analyzed through fluorescence microplate assay, and respective IC50 values were determined. Results: The content of tinosporaside was found to be 1.64% (w/w) in T. cordifolia extract. Concentration-dependent inhibition was observed through T. cordifolia extract. Observed IC50 (μg/ml) value was 136.45 (CYP3A4), 144.37 (CYP2D6), 127.55 (CYP2C9), and 141.82 (CYP1A2). Tinosporaside and extract showed higher IC50 (μg/ml) value than the known inhibitors. T. cordifolia extract showed significantly less interaction potential and indicates that the selected plant has not significant herb-drug interactions relating to the inhibition of major CYP450 isozymes. Conclusions: Plant extract showed significantly higher IC50 value than respective positive inhibitors against CYP3A4, 2D6, 2C9, and 1A2 isozymes. Consumption of T. cordifolia may not cause any adverse effects when consumed along with other xenobiotics.

Safety assessment of selected medicinal food plants used in Ayurveda through CYP450 enzyme inhibition study

BACKGROUND Andrographis paniculata, Bacopa monnieri and Centella asiatica are mentioned in Ayurveda for the management of neurodegenerative disorders. These plants and their phytomolecules, such as andrographolide, bacoside A and asiaticoside, were studied for their inhibition potential on pooled CYP450 as well as human CYP3A4, CYP2D6, CYP2C9 and CYP1A2 by CYP-CO complex assay and fluorogenic assay respectively followed by IC50 determination. Quantification of bioactive compounds present in the extracts was done by RP-HPLC. Heavy metal content in the selected medicinal plants was determined by atomic absorption spectroscopy. RESULT CYP-CO complex assay indicated significantly less inhibition potential than standard inhibitor (P < 0.05 and above). A. paniculata showed highest inhibitory activity against CYP3A4 and CYP2D6 (IC50 = 63.06 ± 1.35 µg mL-1 ; 88.80 ± 3.32 µg mL-1 ), whereas C. asiatica and B. monnieri showed least inhibitory activity against CYP1A2 (IC50 = 288.83 ± 1.61 µg mL-1 ) and CYP2C9 (184.68 ± 3.79 µg mL-1 ), respectively. In all cases the extract showed higher inhibition than the single bioactive compounds. The heavy metals content in the plant extracts were within the permissible limits. CONCLUSION The findings suggested that selected food plants and bioactive compounds contributed negligible interaction potential with CYP isozymes and may not possess any harmful effect with regard to their therapeutic application.