Suman Bala

Schiff Bases: A Versatile Pharmacophore

Schiff bases are condensation products of primary amines with carbonyl compounds gaining importance day by day in present scenario. Schiff bases are the compounds carrying imine or azomethine (–C=N–) functional group and are found to be a versatile pharmacophore for design and development of various bioactive lead compounds. Schiff bases exhibit useful biological activities such anti-inflammatory, analgesic, antimicrobial, anticonvulsant, antitubercular, anticancer, antioxidant, anthelmintic, antiglycation, and antidepressant activities. Schiff bases are also used as catalysts, pigments and dyes, intermediates in organic synthesis, polymer stabilizers, and corrosion inhibitors. The present review summarizes information on the diverse biological activities and also highlights the recently synthesized numerous Schiff bases as potential bioactive core.

Formulation and Characterization of Drug Loaded Nonionic Surfactant Vesicles (Niosomes) for Oral Bioavailability Enhancement

Nonionic surfactant vesicles (niosomes) were formulated with an aim of enhancing the oral bioavailability of tenofovir disoproxil fumarate (TDF), an anti-HIV drug. Niosomes were formulated by conventional thin film hydration technique with different molar ratios of surfactant, cholesterol, and dicetyl phosphate. The formulated niosomes were found spherical in shape, ranging from 2.95 μm to 10.91 μm in size. Vesicles with 1 : 1 : 0.1 ratios of surfactant : cholesterol : dicetyl phosphate with each grade of span were found to have higher entrapment efficiencies, which were further selected for in vitro and in vivo studies. Vesicles formulated with sorbitan monostearate were found to have maximum drug release (99.091%) at the end of 24 hours and followed zero order release kinetics. The results of in vivo study revealed that the niosomes significantly enhanced the oral bioavailability of TDF in rats after a dose of 95 mg/kg. The average relative bioavailability of niosomes in relation to plane drug solution was found to be 2.58, indicating more than twofold increase in oral bioavailability of TDF. Significant increase in mean residential time (MRT) was also found, reflecting release retarding efficacy of the vesicles. In conclusion, niosomes could be a promising delivery for TDF with improved oral bioavailability and prolonged release profiles.

Mannich bases: an important pharmacophore in present scenario.

Mannich bases are the end products of Mannich reaction and are known as beta-amino ketone carrying compounds. Mannich reaction is a carbon-carbon bond forming nucleophilic addition reaction and is a key step in synthesis of a wide variety of natural products, pharmaceuticals, and so forth. Mannich reaction is important for the construction of nitrogen containing compounds. There is a number of aminoalkyl chain bearing Mannich bases like fluoxetine, atropine, ethacrynic acid, trihexyphenidyl, and so forth with high curative value. The literature studies enlighten the fact that Mannich bases are very reactive and recognized to possess potent diverse activities like anti-inflammatory, anticancer, antifilarial, antibacterial, antifungal, anticonvulsant, anthelmintic, antitubercular, analgesic, anti-HIV, antimalarial, antipsychotic, antiviral activities and so forth. The biological activity of Mannich bases is mainly attributed to α, β-unsaturated ketone which can be generated by deamination of hydrogen atom of the amine group.

Therapeutic potential of hydrazones as anti-inflammatory agents.

Hydrazones are a special class of organic compounds in the Schiff base family. Hydrazones constitute a versatile compound of organic class having basic structure (R1R2C=NNR3R4). The active centers of hydrazone, that is, carbon and nitrogen, are mainly responsible for the physical and chemical properties of the hydrazones and, due to the reactivity toward electrophiles and nucleophiles, hydrazones are used for the synthesis of organic compound such as heterocyclic compounds with a variety of biological activities. Hydrazones and their derivatives are known to exhibit a wide range of interesting biological activities like antioxidant, anti-inflammatory, anticonvulsant, analgesic, antimicrobial, anticancer, antiprotozoal, antioxidant, antiparasitic, antiplatelet, cardioprotective, anthelmintic, antidiabetic, antitubercular, trypanocidal, anti-HIV, and so forth. The present review summarizes the efficiency of hydrazones as potent anti-inflammatory agents.

Design, characterization, computational studies, and pharmacological evaluation of substituted-N′-[(1E) substituted-phenylmethylidene]benzohydrazide analogs

A series of substituted-N′-[(1E)-substituted-phenylmethylidene]benzohydrazide analogs were synthesized and authenticated by TLC, UV–Visible, FTIR, and NMR spectroscopic techniques. The physicochemical similarity of the new analogs with standard drugs was assessed by calculating from a set of ten physicochemical properties using software programs. The information so obtained can be related to prediction of biological activity for important targets. All the target compounds 4a–n were evaluated for their antioxidant, anti-inflammatory, and antimicrobial activity using different in vitro models. The test compounds demonstrated good similarity values with respect to the standard drugs. The compounds 4c, 4d, and 4e have emerged as important lead compounds showing potential anti-inflammatory; and 4b, 4f, and 4c having antioxidant profile. While studying MIC against bacterial strains 4c, 4f, 4i, 4k, and 4m were most active among all the target compounds. All compounds were found to have very good antifungal activity. The compounds having nitro substitution at the arylidene moiety i.e., 4c and 4f showed the most potent antifungal as well as antibacterial activities. While studying total antioxidant activity, all target compounds were found to have good antioxidant activity.

Security in Wireless Sensor Networks using Frequency Hopping

Sensor Network (WSN) is a collection of thousands of tiny sensor nodes having the capability of wireless communication, limited computation and sensing. These networks are vulnerable to internal and external attacks due to the lack of tamper-resistant packaging and the insecure nature of wireless communication channels. Since most of the existing routing protocols are application specific and hence do not satisfy the security constraints of wireless sensor networks. Whenever any device comes within the frequency range can get the access to the transmitting data and may affect the transmission. In this paper, we simulated the concept of frequency hopping and proved it a better approach to provide security in WSN..

Comparison of Flooding and Directed Diffusion for Wireless Sensor Network

A Wireless Sensor Network (WSN) is a collection of thousands of tiny sensor nodes having the capability of wireless communication, limited computation and sensing. In this paper, all the components of a sensor node are discussed in brief. Also, a comparison of two routing protocols Flooding and Directed Dif- fusion on the basis of throughput, energy consumption and net- work lifetime is presented. Keywords-component; Wireless Sensor Networks; flooding; directed diffusion

An Improved Forward Secure Elliptic Curve Signcryption Key Management Scheme for Wireless Sensor Networks

The concept of forward secrecy is extended to wireless sensor networks where it is frequent that nodes run out of energy and new nodes join the network. However it should not be able to retrieve the previous session key or some crucial information. In 2011 Hagras et al. proposed a key management scheme for heterogeneous wireless sensor networks, which satisfies confidentiality, authentication, integrity and unforgetability but lacks forward secrecy. In this paper, the shortcomings of the victim scheme has been extricated and repaired with the help of Elliptic Curve Discrete logarithm problem (ECDLP). An elliptic curve based signcryption key management scheme has been proposed which includes forward secrecy.

Pharmacology and Phytochemistry of Oleo-Gum Resin of Commiphora wightii (Guggulu)

Guggulu is an oleo-gum resin which exudes out as a result of injury from the bark of Commiphora wightii (Arnott) Bhandari [syn.  Commiphora mukul (Hook. Ex Stocks) Engl; Balsamodendron mukul (Hook. Ex Stocks); Family, Burseraceae]. It has been used in the Ayurveda since time immemorial for the treatment of variety of disorders such as inflammation, gout, rheumatism, obesity, and disorders of lipids metabolism. It is a mixture of phytoconstituents like volatile oil which contains terpenoidal constituents such as monoterpenoids, sesquiterpenoids, diterpenoids, and triterpenoids; steroids; flavonoids; guggultetrols; lignans; sugars; and amino acids. This review is an effort to compile all the information available on all of its chemical constituents which are responsible for its therapeutic potential. The wild occurrence of this species is restricted mainly to the dry regions of Rajasthan and Gujarat States of India, and the bordering regions of Pakistan. Oleo-gum resin, guggulu, tapped from the stems of this species, is consumed in high volumes by the Indian herbal industries. There has been a decline in its wild population over the last several decades, as a result of habitat loss and degradation, coupled with unregulated harvesting and tapping of oleo-gum resin. This species is consequently assessed as Critically Endangered and enlisted in the IUCN red list of threatened species.

On the Security of Certificateless Signature Schemes

Wireless Sensor Network (WSN) has proved its presence in various real time applications and hence the security of such embedded devices is a vital issue. Certificateless cryptography is one of the recent paradigms to provide security. Certificateless public key cryptography (CL-PKC) deals effectively with the twin issues of certificate management in traditional public key cryptography and key escrow problem in identity-based cryptography. CL-PKC has attracted special attention in the field of information security as it has opened new avenues for improvement in the present security architecture. Recently, Tsai et al. proposed an improved certificateless signature scheme without pairing and claimed that their new construction is secure against different kinds of attacks. In this paper, we present a security analysis of their scheme and our results show that scheme does not have resistance against malicious-KGC attack. In addition, we have found some security flaws in the certificateless signature scheme of Fan et al. and proved the scheme vulnerable to Strong Type I attack.