Joydeb Chanda

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.

RP-HPLC simultaneous estimation of betulinic acid and ursolic acid in Carissa spinarum

Carissa spinarum is a well-known medicinal plant which has been reported for its anthelmintic, antipyretic, antiviral, antimicrobial and antitumour activities. In this study, a reverse-phase high-performance liquid chromatographic method was developed for the simultaneous estimation of betulinic acid (BA) and ursolic acid (UA) in the methanol extract of C. spinarum root. The method was further validated for linearity, limit of detection (LOD = 3.3σ/S), limit of quantification (LOQ = 10σ/S), precision, accuracy and ruggedness. The linear response was obtained using the equation, y = 511.5x+17603 (r2 = 0.9920) and y = 2886x+6821 (r2 = 0.9935) for BA and UA, respectively. The LOD and LOQ were found to be 0.268 ± 0.520 μg mL− 1, 0.878 ± 0.183 μg mL− 1 for BA (0.58% w/w) and 3.140 ± 0.36 μg mL− 1, 8.820 ± 0.85 μg mL− 1 for UA (1.09% w/w), respectively. The %RSD of precision and recovery of BA and UA was < 2.0%. The proposed method was simple, accurate, specific, precise and reproducible.

Evaluation of Bioactive Compounds as Acetylcholinesterase Inhibitors from Medicinal Plants

Abstract The predominant role of the central cholinergic pathway in learning and memory and the creation of severe cholinergic deficits with several neurodegenerative disorders and cognitive impairment contribute to the development of symptomatic cholinergic therapy. Inhibition of brain cholinesterase (ChE) serves as a strategy for the treatment of several cognitive diseases such as Alzheimer disease (AD), senile dementia, ataxia, myasthenia gravis, glaucoma, and Parkinson disease. ChE inhibitors are the drugs for the management of AD-type of dementia. The chapter highlights on acetylcholinesterase inhibitors from plants and the phytoconstituents derived from this.