Mrinalini C. Damle

HPTLC Quantitation of 2-Hydroxy-4-methoxybenzaldehyde in Hemidesmus indicus R.Br. Root Powder and Extract

Literature survey revealed one HPLC method for quantification of 2-hydroxy-4-methoxybenzaldehyde in the root of Hemidesmus indicus [13], another for simultaneous analysis of 2-hydroxy-4-methoxybenzaldehyde and 2-hydroxy-4-methoxybenzoic acid in root tissues of the same plant [14], and a GC–MS method for determination of the chemical composition of volatile oil of H. indicus [15]. Gas chromatographic assay of 2hydroxy-4-methoxybenzaldehyde in dry and fresh root of Decalepis hamiltonii and H. indicus has also been reported [16]. No suitable HPTLC method is available. HPTLC has been widely used as quality-control tool for phytochemical evaluation of herbal drugs. In this work a precise and accurate HPTLC method has been established for rapid and accurate analysis of 2-hydroxy-4-methoxybenzaldehyde in H. indicus dried root powder and its extract. One important reason for selection of this marker was its absence from the plants commonly used as substitutes for H. indicus. It has been reported [17] that the roots of Ichnocarpus frutescens (Linn.) R.Br. (Apocyanaceae), Decalepis hamiltonii Wight and Arn. (Asclepiadaceae), and Cryptolepis buchnani Roem. & Schult. (Asclepiadaceae) are used as substitutes for H. indicus. Because there are no reports of the presence of this marker in the roots of I. frutescens and C. buchnani, substitution by the roots of these plants can be easily revealed by use of this HPTLC method. A study [18] of the essential oil (0.33%) of D. hamiltonii discovered the 2-hydroxy-4-methoxybenzaldehyde content of the oil was 37.45%. The amount of this marker in H. indicus is much higher. Sircar et al. [14] have reported the content to be 3.2 ± 0.2 mg g –1 of the mature roots of H. indicus and 2.6 ± 0.3 mg g –1 of the young roots. Thus even in this case, substitution of H. indicus by D. hamiltonii can be detected easily. Thus quantification of this marker will aid the detection of adulteration or substitution by common substituents because they either lack this marker or the content is less than in H. indicus.

Development and validation of a stability-indicating HPTLC method for the determination of mirtazapine as bulk drug and in pharmaceutical formulation

Asensitive, selective, precise, and stability-indicating (in accordance with ICH guidelines) high-performance thin-layer chromatography (HPTLC) method of analysis for mirtazapine was developed to resolve the drug response from that of its degradation products. TLC aluminum plates precoated with silica gel 60 F254 were used as the stationary phase. The solvent system consisted of methanol-chloroform, 9:1 (v/v). This system was found to give a compact spot for mirtazapine (RF value 0.56 ± 0.03). Mirtazapine was subjected to stress test conditions such as acid, alkali, neutral hydrolysis, oxidation, dry heat, and photodegradation. The spots for the product of degradation were well resolved from those of the drug. Densitometric analysis of drug was carried out in the absorbance mode at 294 nm. The linear regression data for the calibration plots showed good linear relationship with an r2 value of 0.994 in the concentration range 400–2000 ng/band. The result indicates that the drug was susceptible to degradation but to different extents under different conditions.