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A stability-indicating UV/Vis spectrophotometric method was developed and validated for estimation of diazepam in tablet dosage form. The proposed method utilized a Specord 250 plus PC double beam spectrophotometer using 1.0 cm quartz cells and all determinations were made at a wavelength of 231 nm in methanol:distilled water (1:1). Experiments were designed for determining linearity, limit of detection and quantitation, accuracy, precision and specificity of this analytical method as per the International Organization for Standardization guidelines. The drug substance and the drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed using the proposed method to demonstrate the specificity of the method. The proposed method was found to be linear in the concentration ranges from 3.096-15.480 µg/ml with the linear correlation coefficient of R 2 = 0.999 and the mean recoveries were 98.36 to 100.72 %. Although the degradation products of stressed condition had not been identified, the method had been able to detect the changes due to stress condition. The stated method can be used as stability indicating method with high degree of linearity, accuracy and precision for assay of diazepam in routine pharmaceutical analysis of tablets.

Commelina diffusa Burm. F. is a herbaceous tropical plant with different traditional medicinal uses. Present study is aimed to isolate the bioactive compounds from DCM-Methanol extract of the powdered whole plant of Commelina diffusa and to investigate the cytotoxic, antimicrobial and antioxidant activities of the crude extract and its twelve vacuum liquid chromatographic fraction (CD 1-12 ). Vacuum Liquid Chromatography (VLC) was employed to isolate bioactive metabolites. The physicochemical properties of the isolated compound were examined and the molecular structure was elucidated by NMR spectroscopy. Cytotoxic, antibacterial, antioxidant activities were evaluated following brine shrimp lethality bioassay, disc diffusion method and DPPH free radical scavenging assay respectively. The isolated compound was identified as steroid (stigmasterol) which had significant cytotoxic effect on vero cell line. The crude extract and its fractions (CD8-CD12) exhibited strong cytotoxicity in brine shrimp lethality bioassay having LC 50 values 3. 79, 9.19, 29.49, 16.60, 19.36, 44.58 μg/mL respectively. The crude extract showed mild to strong antibacterial activity. Fractions (CD5-CD12) showed mild to strong antibacterial activity against Escherichia coli in comparison with Kanamycin (standard). Strong antioxidant activities were found in crude extract (IC 50 value 30.52 μg/ml), CD11 (IC 50 value 39.27 μg/ml) and CD12 (IC 50 value 19.50 μg/ml). The study suggests Commelina diffusa plant extract to have strong antioxidant and cytotoxic activity which is indicative of presence of compounds with broad spectrum of curative applications. One compound namely stigmasterol has been isolated from the plant.

Background Thysanolaena maxima (Roxb.) Kuntze, a perennial grass plant, is usually distributed in hilly regions of the Indian Subcontinent. Different parts of T. maxima have been used as herbal medicine by traditional healers of this region. In this present study, T. maxima plant extract has been screened for examination of its secondary metabolite content with their probable cytotoxic activity. Methods Secondary metabolites of the crude T. maxima plant extract were isolated by different chromatographic methods. The structures were elucidated by spectroscopic data (1H NMR, 13C NMR) as well as comparison with available literature sources. Antiradical activity by DPPH radical scavenging assay and antimicrobial activity by disc diffusion method of the fractions and cytotoxic activity by trypan blue exclusion method of the isolated compounds were also evaluated. Results Three phenolic compounds 4-hydroxybenzaldehyde (1), 4-hydroxycinnamic acid (2), 4-hydroxybenzoic acid (3) and two steroids stigmast-4-en-3-one (4) and β-stigmasterol (5) were isolated from the aerial part of T. maxima. Among the compounds 4-hydroxycinnamic acid, 4-hydroxybenzoic acid and stigmast-4-en-3-one exhibited notable cytotoxic activity against African Green Monkey Kidney Cell line (Vero cell). Conclusion Bioassay investigation of the isolated compounds and fractions suggested that T. maxima could be a potential source of bioactive secondary metabolites. Graphical abstract

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In the pharmaceutical world the majority of the active pharmaceutical ingredients (API) have been obtained from the natural products. Piperine is such naturally occurring alkaloid which can be considered as major bioactive phytochemical having broad spectrum of pharmacological activities. It is obtained from the most valuable ethnomedicinal spices peppercorns i.e. black pepper and white pepper, which are the fruits of the Asian vine Piper nigrum L. Because of the widespread traditional uses of this medicinal compound, present article reveals a simple and effective isolation method of bulk piperine. The novelty of this investigation is to provide an idea for utilizing such natural method of large scale commercial piperine production as API drug in spite of chemical synthesis. Piperine was isolated in a pure crystal form and characterized by its melting point, X-Ray diffraction (XRD) studies and spectral data, including two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Chromatographic techniques like Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC) were applied to determine the purity of the yielded piperine. It was found that piperine yield from black pepper was within 2.5%-3.0% and from white pepper within 4.0%-4.5% and the purity of the yielded piperine was found to be up to 98.5% for black pepper and 98.2% for white pepper. Considering this yield value and purity it is indicated that, such effective isolation method can be successfully utilized for industrial large-scale production commercially. According to the result, it can be claimed that, as a natural product the isolated piperine can also be utilized as API drug like other expensive chemically synthesized piperine in different drug formulation.