Amit Kar

Enhancement of photoprotection potential of catechin loaded nanoemulsion gel against UVA induced oxidative stress.

The present study was aimed to develop a catechin (CA) loaded nanoemulsion based nano-gel for the protection of skin against ultraviolet radiation (UV) induced photo-damage and to ensure its enhanced skin permeability as well as bioavailability through transdermal route. The optimized nanoemulsion (CA-NE4) was prepared by spontaneous nano-emulsification method. It was composed of oil (ethyl oleate), Smix [surfactant (span 80) and co-surfactant (transcutol CG)] and aqueous system in an appropriate ratio of 15:62:23% w/w respectively. The CA-NE4 was characterized through assessment of droplet size, zeta potential, refractive index, transmission electron microscopy (TEM), UV, high performance thin layer chromatography (HPTLC) and Fourier transform infrared spectroscopy (FTIR) analysis. The average droplet size and zeta potential of CA-NE4 were found to be 98.6±1.01nm and -27.3±0.20mV respectively. The enhanced skin permeability was better with CA-NE4 based nano-gel (CA-NG4) [96.62%] compared to conventional gel (CA-CG) [53.01%] for a period of 24h. The enhanced % relative bioavailability (F) of CA (894.73), Cmax (93.79±6.19ngmL(-1)), AUC0-t∞ (2653.99±515.02nghmL(-1)) and Tmax (12.05±0.02h) was significantly obtained with CA-NG4 as compared to oral suspension for extended periods (72h). CA-NG4 could improve the level of cutaneous antioxidant enzymes like superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) and reduce the level of thiobarbituric acid reactive substances (TBRAS) against oxidative stress induced by UVA. Nano-gel formulation of CA showed sustained release profile and enhanced photoprotection potential due to its improved permeability as well as bioavailability (P<0.05) compared to the conventional gel. Therefore, transdermal administration of nano-gel (CA-NG4) of CA offers a better way to develop the endogenous cutaneous protection system and thus could be an effective strategy for decreasing UV-induced oxidative damage in the skin tissues.

Tyrosinase inhibitory mechanism of betulinic acid from Dillenia indica

The fruit of Dillenia indica L. is extensively used as a food additive. Betulinic acid (BA) is the most prominent secondary metabolite present in D. indica. This study screened the bioassay guided isolation of BA from D. indica and explored its tyrosinase inhibitory mechanism. Half maximal inhibitory concentration (IC50) of BA were calculated as 13.93µM and 25.66µM for diphenolase and monophenolase. Enzyme kinetic analysis revealed that BA inhibited tyrosinase activity non-competitively. Further, conformational analysis of tyrosinase with BA was measured by fluorescence and circular dichroism spectroscopy. These results implied that diminish rigidity of enzyme might disturb the catalytic conformation of tyrosinase. Moreover, In-silico analysis confirmed probable binding polar and non-polar region on the active site of tyrosinase. Based on these findings, we suggest that BA from D. indica may be useful in preventing enzymatic browning reactions in food products.

Quality Related Safety Issue-Evidence-Based Validation of Herbal Medicine Farm to Pharma

Evidence-Based Validation of Herbal Medicines brings together current thinking and practice in the areas of characterization and validation of natural products. This book reviews all aspects of evaluation and development of medicines from plant sources, including their cultivation, collection, phytochemical and phyto-pharmacological evaluation, and therapeutic potential. Emphasis is placed on describing the full range of evidence-based analytical and bio-analytical techniques used to characterize natural products, including ?omic technologies, phyto-chemical analysis, hyphenated techniques, and many more.Includes state-of-the-art methods for detecting, isolating, and performing structure elucidation by degradation and spectroscopic techniquesCovers biosynthesis, synthesis, and biological activity related to natural productsConsolidates information to save time and money in researchIncreases confidence levels in quality and validity of natural products

CYP450 mediated inhibition potential of Swertia chirata: An herb from Indian traditional medicine.

ETHNOPHARMACOLOGICAL RELEVANCE An Ayurvedic herb, Swertia chirata (SC) have been used in treating various ailments such as hyperglycemia, leishmania, liver infections, inflammation, abdominal pain, bacterial infection, malaria etc. in Indian Systems of Medicine (ISM). AIM OF THE STUDY Study was designed to investigate the inhibition potential of the standardized SC extract along with its bioactive molecule ursolic acid on hepatic drug metabolizing isozymes (CYP3A4 and CYP2D6) and further some heavy metals were also analysed of the plant material. MATERIALS AND METHODS The hydro-alcoholic extract was standardized with standard ursolic acid by reverse phase-high performance liquid chromatography (RP-HPLC) method and the heavy metals content were analyzed through atomic absorption spectroscopy (AAS). The effect of extract on rat liver microsome (RLM) and individual CYP isozymes (CYP3A4 and CYP2D6) was investigated through CYP450-CO complex assay and fluorescence microplate assay respectively. RESULTS The content of ursolic acid was found to be 2.66% (w/w) in the SC extract and heavy metal contents along with trace elements were within the prescribed limits as per WHO guidelines. The inhibitory potential of SC extract on RLM was found to be 23.64±1.80%. CYP3A4 and CYP2D6 inhibitory effect of SC and ursolic acid (IC50: 197.49±2.68, 211.45±3.54 and IC50: 229.25±2.52, 212.66±1.26 µg/mL) was less as compared to that known inhibitors, ketoconazole and quinidine respectively. CONCLUSIONS The current study revealed that S. chirata has less inhibition potential with two major drug metabolizing isozymes CYP3A4 and CYP2D6. SC extract and ursolic acid showed significantly (P<0.001) less inhibitory potential on RLM. The Ayurvedic herb (SC) has shown less inhibitory activity in a concentration dependent manner against the tested two CYP450 enzymes. The tested heavy metals and trace elements present SC was within limit. Therefore, the traditional use of S. chirata may be safe in respect of both tested isozymes.

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.

Interaction potential of Trigonella foenum graceum through cytochrome P450 mediated inhibition.

Objective: The seeds of Trigonella foenum-graecum (TFG) (family: Leguminosae) are widely consumed both as a spice in food and Traditional Medicine in India. The present study was undertaken to evaluate the inhibitory effect of standardized extract of TFG and its major constituent trigonelline (TG) on rat liver microsome (RLM) and cytochrome P450 (CYP450) drug metabolizing isozymes (CYP3A4 and CYP2D6), which may indicate the possibility of a probable unwanted interaction. Materials and Methods: Reverse phase-high performance liquid chromatography method was developed to standardize the hydroalcoholic seed extract with standard TG. The inhibitory potential of the extract and TG was evaluated on RLM and CYP isozymes using CYP450-carbon monoxide (CYP450-CO) complex assay and fluorescence assay, respectively. Results: The content of TG in TFG was found to be 3.38% (w/w). The CYP-CO complex assay showed 23.32% inhibition on RLM. Fluorescence study revealed that the extract and the biomarker had some inhibition on CYP450 isozymes e.g. CYP3A4 and CYP2D6 (IC50 values of the extract: 102.65 ± 2.63–142.23 ± 2.61 µg/ml and TG: 168.73 ± 4.03–180.90 ± 2.49 µg/ml) which was very less compared to positive controls ketoconazole and quinidine. Inhibition potential of TFG was little higher than TG but very less compared to positive controls. Conclusions: From the present study, we may conclude that the TFG or TG has very less potential to inhibit the CYP isozymes (CYP3A4, CYP2D6), so administration of this plant extract or its biomarker TG may be safe.

Boswellia serrata oleo-gum-resin and β-boswellic acid inhibits HSV-1 infection in vitro through modulation of NF-кB and p38 MAP kinase signaling

BACKGROUND Herpes Simplex Virus (HSV), a highly contagious pathogen, is responsible for causing lifelong oral to genital infection in human. Boswellia serrata oleo-gum-resin possesses a strong traditional background of treating diverse skin ailments including infection but its effect on HSV-1 has not been examined yet. PURPOSE To exploit its potential, we aimed to explore the antiviral activity of methanol extract of B. serrata oleo-gum-resin (BSE) and one of its major constituent β-boswellic acid (BA) against HSV-1 along with the underlying mechanism of action involved. METHODS BSE was subjected to RP-HPLC analysis to quantify the active constituent. Cytotoxicity (CC50) and antiviral activity were evaluated by MTT and plaque reduction assay, followed by the determination of median effective concentration (EC50). The mode of antiviral activity was assessed by time-of-addition assay and confirmed by reverse transcriptase-PCR (RT-PCR). Further, the expressions of various cytokines were measured by RT-PCR, while the proteins by Western blot. RESULTS BSE and BA potently inhibited wild-type and a clinical isolate of HSV-1 (EC50 5.2-6.2 and 12.1-14.63 μg/ml), with nearly-complete inhibition (EC99) at 10 and 30 μg/ml, respectively. The inhibitory effect was significant at 1 h post-infection and effective up to 4 h. Based on target analysis we examined the inhibition of NF-κB, essential for virus replication, and observed significant down-regulation of NF-κB, and p38 MAP-kinase activation, with reduced expression of tumor necrosis factor (TNF)-α, Interleukin (IL)-1β and IL-6, involved in scheming NF-κB signaling. CONCLUSION Thus, our results support the ethnomedicinal use of BSE in skin infection by inhibiting HSV-1 through the modulation of NF-κB and p38 MAPK pathway.

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.