Kothapalli Haribabu

Peptidomimetic organocatalysts: efficient Michael addition of ketones onto nitroolefins with very low catalyst loading

The syntheses of two novel peptidomimetic triazole-based organocatalysts that work for the asymmetric conjugate addition of cyclohexanone to nitroolefins are described. The catalysts worked with very low loading (0.5 mol%) in the absence of any additives to provide high diastereo- and enantio-selectivities.

Quantification of bergenin from Mallotus philippinensis by HPTLC-MS and study on different extraction methods

A simple and accurate high-performance thin-layer chromatographic (HPTLC) method has been established for the determination of bergenin in the roots and stem-bark powder of Mallotus phillippensis. It has been reported to have a wide array of biological activities like antioxidant, anti-HIV, antiarrhythmic, hepatoprotective, anti-inflammatory and anti-microbial. Methanolic extract of the stem-bark and root powder was used for the experimental work. Separation was performed on 20 × 10 silica gel 60 F254 using ethyl acetate-methanol-acetic acid-formic acid (8:1:0.5:0.5, v/v) as mobile phase and scanned using densitometry at 284 nm. Extracts were prepared by conventional soaking, and accelerated solvent extractor (ASE) was used for the analysis. The results indicate that bergenin was found to be maximum in root ASE extract (6.0% w/w), while the minimum concentration of bergenin was found in stembark cold extract (2.9% w/w).The determination was carried out using the densitometric absorbance mode at 284 nm. The method was validated in terms of selectivity, linearity, precision, accuracy, and robustness. Additionally, peak identity was confirmed by mass spectrometry. The electron spray ionization (ESI) mass spectra showed the [M + Na]+ ions for bergenin detected at m/z 351 being acquired directly from the sample bands by an elution-based interface. By considering the validation results, the method was found to be very simple, accurate, precise, fast, and economical and can be used for routine quality control.

Quantitative estimation of (-)-hinokinin, a trypanosomicidal marker in Piper cubeba, and some of its commercial formulations using HPLC-PDA

The fruits of Piper cubeba have been used in Ayurvedic system of medicine for pain, tastelessness, painful urination and mouth diseases. Among its various chemical constituents, (-)-hinokinin, a trypanosomicidal dibenzylbutyrolactone lignan, is found in significant quantities. For quality evaluation of P. cubeba fruit and its commercial formulations, there is an urgent need to develop an analytical method based on (-)-hinokinin. For this purpose, an HPLC method was developed using photo diode array detector and Waters HR C18 column with gradient elution consisting of water and acetonitrile. The developed method was validated as per ICH-Q2B guidelines and found to be accurate, precise and linear over a wide range of concentrations (5–300 µg/mL). (-)-Hinokinin contents were found to be in the range of 0.005–0.109% (m/m) in various P. cubeba samples. The developed method was extended to LC–MS for further identification and characterization of (-)-hinokinin in samples. The developed method is simple, rapid and specific, and can be used as a tool for quality control of P. cubeba fruits and its commercial formulations.

Simultaneous Determination of Asaranin and Sesamin in Piper chaba Fruit by using HPTLC-MS Method: Effect of Different Extraction Methods on the Yield of Marker Compounds

A simple, rapid and accurate HPTLC-MS method was developed for the simultaneous quantification of asaranin (AS) and sesamin (SM), the two epimeric furofuran lignans in Piper chaba (Piperaceae) fruit extracts obtained by cold percolation (PER), Soxhlet extraction (SOX), ultrasound assisted extraction (USAE), accelerated solvent extractor (ASE) and microwavexa0assisted extraction (MAE). Separation of AS and SM was achieved on 20×10 cm pre-coated silica gel 60 F254S HPTLC plates with ethyl acetate: hexane (30:70) as mobile phase. Detection and quantification were performed densitometrically at λmax 295 nm. The peak identity was confirmed by electron spray ionization (ESI) mass spectra, which showed the [M + Na]+ ions for both AS and SM at m/z 377. The method was validated according to the ICH guidelines in terms of limit of detection (LOD) and limit of quantification (LOQ), selectivity, linearity, precision, accuracy, and robustness. The results indicate that AS (2.108%) and SM (0.103%) found to present maximum in ASE extract and minimum in PER extract (AS 0.848%; SM 0.048%). By considering the validation results, the method was found to be reproducible and convenient for quantitative analysis of AS and SM in different P. chaba fruit extracts.