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Rapid extraction, isolation, and quantification of oleanolic acid from Lantana camara L. Roots using microwave and HPLC-PDA techniques

Verma S. C., Jain C. L., Nigam S., Padhi M. M.

Acta Chromatographica

2013

Vol. 25, no. 1

181--199

An ecofriendly solvent polarity based microwave-assisted extraction (MAE) technique was developed for the rapid extraction and isolation of bioactive oleanolic acid from roots of Lantana camara L. Several different influential extraction parameters such as microwave power, extraction time, solvent type, and volume were studied in a systematic fashion for the determination of optimum extraction conditions. Simply modified and rapid high-performance liquid chromatography-diode array detector (HPLC-DAD) method was also developed and validated for quantitative determination of oleanolic acid from roots of L. camara. Under optimum conditions, using a mixture of CHCl3:MeOH (60:40, v/v, 15 mL) as a solvent, 600 W microwave powers, and 50 °C temperature for 6 min of MAE produced a maximum yield of 1.23% (dry weight of roots). No degradation of the target analyte was observed at the optimum conditions as evidenced from the recovery studies performed with standard oleanolic acid. The proposed method also showed high degree of reproducibility; hence, it may be useful for maximum extraction and isolation of biologically active oleanolic acid.

Flexural and extensional waves propagation in transversely isotropic plates in generalized thermoelasticity

Verma K. L., Verma S. C., Hasebe N.

International Journal of Applied Mechanics and Engineering

2004

Vol. 9, no 3

587-606

In this paper, the boundary value problem concerning the propagation of plane harmonic thermoelastic waves in flat infinite homogeneous transversely isotropic plate of finite thickness in the generalized theory of thermoelasticity with two thermal relaxation times is studied. The frequency equations for a heat conducting thermoelastic plate corresponding to the extensional (symmetric) and flexural (antisymmetric) thermoelastic modes of vibration are obtained and discussed. Special cases of the frequency equations are also discussed. The horizontally polarized SH wave gets decoupled from the rest of motion and propagates without dispersion or damping, and is not affected by thermal variations on the same plate. A numerical solution to the frequency equations for an aluminum plate (isotropic) and zinc plate (transversely isotropic) is given, and the dispersion curves are presented. The three motions namely, longitudinal, transverse and thermal of the medium are found dispersive and coupled with each other due to the thermal and anisotropic effects. The phase velocity of the waves is modified due to the thermal and anisotropic effects and is also influenced by the thermal relaxation time. Relevant results of previous investigations are deduced as special cases.