Neerja Tiwari

Antitubercular diterpenoids from Vitex trifolia

A new halimane diterpenoid, 13-hydroxy-5(10),14-halimadien-6-one (1) and two new labdane diterpenoids, 6α,7α-diacetoxy-13-hydroxy-8(9),14-labdadien (2) and 9-hydroxy-13(14)-labden-15,16-olide (3), were isolated for the first time, along with fifteen known compounds, from the hexane soluble fraction of methanolic extract of Vitex trifolia leaves. The structures of these new diterpenoids were elucidated by spectral analysis. Their relative configurations were established using analysis of NOESY correlations and coupling constants observed in (1)H NMR. Compounds 2, 3 and another known diterpenoid, isoambreinolide (4) were evaluated for antitubercular activity. 3 and 4 exhibited antitubercular activity (MIC=100 and 25 μg/ml) against Mycobacterium tuberculosis H37Rv in BACTEC-460 assay.

Simultaneous quantification of diterpenoids in Premna integrifolia using a validated HPTLC method

A sensitive, selective and robust densitometric high-performance thin layer chromatographic method was developed and validated for the determination of diterpenoids in the root bark of Premna integrifolia. Diterpenoids 1β,3α,8β-trihydroxy-pimara-15-ene (A), 6α,11,12,16-tetrahydroxy-7-oxo-abieta-8,11,13-triene (B) and 2α,19-dihydroxy-pimara-7,15-diene (C) were used as chemical markers for the standardization of P. integrifolia plant extracts. The separation was performed on silica gel 60F(254) high-performance thin layer chromatography plates using hexane/acetone/ethylacetate (60:20:20 v/v) as mobile phase. The quantitation of diterpenoids was carried out using densitometric reflection/absorption mode at 475 nm after post-chromatographic derivatization using vanillin-sulfuric acid reagent. A precise and accurate quantification can be performed for compounds A, B and C in the linear working concentration range of 1-10 μg/spot with good correlations (r(2) =0.9985, 0.9996 and 0.9992, respectively). The method was validated for peak purity, precision, robustness, limit of detection (LOD) and quantitation (LOQ) etc., as per the International Conference on Harmonization (ICH) guidelines. Specificity of quantitation was confirmed using retention factor (R(f)) and spectra correlation of markers in standard and sample tracks. The method reported here is simple and reproducible which may be applied for quantitative analysis of above diterpenoids in the root bark of P. integrifolia.

Two new lignans from Phyllanthus amarus

Two new lignans, 3-(3,4-dimethoxy-benzyl)-4-(7-methoxy-benzo[1,3]dioxol-5-yl-methyl)-dihydrofuran-2-one (1) and 4-(3,4-dimethoxy-phenyl)-1-(7-methoxy-benzo[1,3]dioxol-5-yl)-2,3-bis-methoxymethyl-butan-1-ol (2), were isolated from the leaves of Phyllanthus amarus and their structures were established by spectral analysis. Additionally, eight known lignans were also isolated and characterized.

A MARKER-BASED STABILITY INDICATING HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHIC METHOD FOR VITEX TRIFOLIA

Casticin, chrysoplenol-D, p-hydroxy benzoic acid, and p-methoxy benzoic acid are representative flavonoids and benzoic acid derivatives in Vitex trifolia, a well-known traditional Chinese, as well as ayurvedic medicine, with a wide range of biological activities. In the present paper, the aforementioned four markers were isolated and simultaneously quantified by TLC densitometric method. In the present study, a novel stability-indicating high-performance thin-layer chromatography (HPTLC) method for quantitative determination of the aforementioned four markers has been developed and validated on silica using solvent dichloromethane–methanol–formic acid (9.6:0.4:0.06 v/v/v) in the absorbance mode at 254 nm. The method showed a good linear relationship (r2 = 0.999) in the concentration range 100–2400 ng per band. It was found to be linear, accurate, precise, specific, robust, and stability-indicating and can be applied for quality control and standardization of other multi-component formulations based on Vitex trifolia.

Validated HPTLC method for the simultaneous quantification of diterpenoids in Vitex trifolia L.

Vitex trifolia L. is an important Indian medicinal plant with diverse pharmacological properties. In a recent study, we reported the isolation and antitubercular activity evaluation of three new diterpenoids from its leaves; here we have developed a validated rapid, simple, precise, and accurate high-performance TLC method for the simultaneous quantification of isolated diterpenoids in V. trifolia. Diterpenoids, 6α,7α-diacetoxy-13-hydroxy-8(9),14-labdadien (A), 13-hydroxy-5(10),14-halimadien-6-one (B), and 9-hydroxy-13(14)-labden-16,15-olide (C) were separated on silica gel 60F254 high-performance TLC plates using chloroform/acetone (98:2, v/v) as mobile phase. The quantitation of diterpenoids was carried out using densitometric reflection/absorption mode at 610 nm after postchromatographic derivatization using a vanillin/sulfuric acid reagent. A precise and accurate quantification can be performed for compounds A and B in the linear working concentration range of 333-1000 ng/band and for C in the range of 670-2000 ng/band with good correlations (r = 0.9984, 0.9991, and 0.9994, respectively). The method was validated for peak purity, precision, accuracy, robustness, LOD, and LOQ, as per the ICH guidelines. The method reported here is simple, reproducible and may be applied for the quantitative analysis of the above diterpenoids in the leaves of V. trifolia.