Venkateswara Rao Janapala

Biophysicochemical evaluation of chitosan‐hydroxyapatite‐marine sponge collagen composite for bone tissue engineering

Tricomponent scaffold systems prepared by natural materials especially of marine origin are gaining much attention nowadays for the application in bone tissue engineering. A novel scaffold (Chi-HAp-MSCol) containing chitosan (Chi), hydroxyapatite (HAp) derived from Thunnus obesus bone and marine sponge (Ircinia fusca) collagen (MSCol) was prepared using freeze-drying and lyophilization method. This biomimetic scaffold, along with the Chi and Chi-HAp scaffolds were characterized biophysicochemically for their comparative significance in bone grafting applications. The structural composition of the chitosan, Chi-Hap, and Chi-HAp-MSCol scaffolds were characterized by Fourier Transform Infrared spectroscopy. The porosity, water uptake, and retention abilities of the composite scaffolds decreased, whereas Thermogravimetric and Differential Thermal Analyses results revealed the increase in thermal stability in the scaffold because of the highly stable HAp and MSCol. Homogeneous dispersion of HAp and MSCol in chitosan matrix with interconnected porosity of 60-180 μm (Chi-HAp) and 50-170 μm (Chi-HAp-MSCol) was observed by Scanning Electron Microscopy, X-ray diffraction, and optical microscopy. Cell proliferation in composite scaffolds was relatively higher than pure chitosan when observed by MTT assay and Hoechst staining in vitro using MG-63 cell line. These observations suggest that the novel Chi-HAp-MSCol composite scaffolds are promising biomaterials for matrix-based bone repair and bone augmentation.

Biochemical and biophysical characterization of collagens of marine sponge, Ircinia fusca (Porifera: Demospongiae: Irciniidae)

Collagens were isolated and partially characterized from the marine demosponge, Ircinia fusca from Gulf of Mannar (GoM), India, with an aim to develop potentially applicable collagens from unused and under-used resources. The yield of insoluble, salt soluble and acid soluble forms of collagens was 31.71 ± 1.59, 20.69 ± 1.03, and 17.38 ± 0.87 mg/g dry weight, respectively. Trichrome staining, Scanning & Transmission Electron microscopic (SEM & TEM) studies confirmed the presence of collagen in the isolated, terminally globular irciniid filaments. The partially purified (gel filtration chromatography), non-fibrillar collagens appeared as basement type collagenous sheets under light microscopy whereas the purified fibrillar collagens appeared as fibrils with a repeated band periodicity of 67 nm under Atomic Force Microscope (AFM). The non-fibrillar and fibrillar collagens were seen to have affinity for anti-collagen type IV and type I antibodies raised against human collagens, respectively. The macromolecules, i.e., total protein, carbohydrate and lipid contents within the tissues were also quantified. The present information on the three characteristic irciniid collagens (filamentous, fibrillar and non-fibrillar) could assist the future attempts to unravel the therapeutically important, safer collagens from marine sponges for their use in pharmaceutical and cosmeceutical industries.

Spatane diterpinoid from the brown algae, Stoechospermum marginatum induces apoptosis via ROS induced mitochondrial mediated caspase dependent pathway in murine B16F10 melanoma cells.

Spatane diterpinoids isolated from the brown marine algae Stoechospermum marginatum were known to have cytotoxic effects in human cancerous cell lines and murine melanoma cells; the underling apoptotic mechanism of diterpinoids still remains unclear so far. Thus, in the present study, the apoptotic mechanism of a spatane diterpinoid, 5(R), 19‐diacetoxy‐15,18(R and S), dihydro spata‐13, 16(E)‐diene (DDSD) was investigated mainly in B16F10 melanoma cells because they were most susceptible to DDSD than THP1, U937, COLO205, and HL60 cells. The treatment of B6F10 cells with DDSD resulted in morphological alterations, nuclear condensation, and DNA fragmentation, which leads to cell growth inhibition in a concentration‐dependent manner. Data indicate that DDSD induced the generation of ROS, consequentially caused alteration in Bax/Bcl‐2 ratio that disrupted the inner mitochondrial transmembrane potential (ΔΨm) resulting in cytochrome c redistribution to the cytoplasm and activation of caspase‐mediated apoptotic pathway. Flow cytometric analysis clearly indicated that the DDSD inducing phosphatidylserine externalization and mediated “S‐phase” arrest in cell cycle. In addition, results also found that DDSD induced apoptosis through deregulating PI3K/AKT signaling pathway. The anti‐tumor activity of DDSD was evaluated in C57BL/6 mice bearing B16F10 melanoma. It effectively inhibited tumor growth (volume and weight) in a dose dependent manner, yet without apparent toxic effects. Morphology and apoptotic status of tumor tissues in the treated mice were assessed by microscopy and TUNEL assay, respectively. Our study shows a therapeutic potential of DDSD for the treatment of malignant melanoma and a new source of anticancer drugs.

Comparative morphometry, biochemical and elemental composition of three marine sponges (Petrosiidae) from Gulf of Mannar, India

Abstract Three marine sponges Neopetrosia similis, Xestospongia testudinaria and Petrosia nigricans from the Gulf of Mannar, Southeast coast of India were compared based on their morphometric parameters and their biochemical and elemental composition. These sponges showed differences inspicule : protein (spongin) ratio of 5:1, 11:1 and 13:1, respectively. Xestospongia testudinaria possessed the longest oxeae, 3.05 times than P. nigricans and 1.47 times than N. similis. Spectral analysis revealed that the spicules of these sponges are mostly composed of O (>50%) and Si (29–45%), whereas Al and Ca (4–5%) were additionally detected only in the spicules of P. nigricans. In contrast, the percentage elemental composition in pinacodermal sections was significantly different as O and Si were the maximum (23–50%); followed by Cl and Al as moderate (1–17%); and Na, S, Fe and Ca in minor quantities (0.2–6%). Cluster analysis and traditional taxonomic arrangements show that X. testudinaria and N. similis have a close relationship whereas P. nigricans was hypothesized to be their sister group. The present findings could be the key for identifying sponges in situ as well as determining whether sponges could be used to assess pollution in the sea.

Potential anticancer activity of biogenic silver nanoparticles using leaf extract of Rhynchosia suaveolens: an insight into the mechanism

Abstract The present study reports a simple and eco-friendly synthesis of silver nanoparticles (AgNPs) using leaf extract of Rhynchosia suaveolens. UV-Vis analysis of R. suaveolens synthesized AgNPs (RS-AgNPs) showed surface plasmon resonance (SPR) peak at 426 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis revealed that RS-AgNPs were 10–30 nm in size with spherical shape. X-ray diffraction (XRD) analysis of RS-AgNPs confirmed the crystalline nature with face-centered cubic (FCC) lattice. Fourier transform infrared (FTIR) interprets that polyphenols and proteins take part in bioreduction and capping of RS-AgNPs. RS-AgNPs exhibited dose-dependent inhibition of proliferation of different cancer cells including DU145 and PC-3(human prostate carcinoma cell lines), SKOV3 (human ovarian carcinoma) and A549 (human lung adenocarcinoma)with IC50 values of 4.35, 7.72, 4.2 and 24.7 μg/mL, respectively. The plausible reasons behind anticancer activity of RS-AgNPs were explained using different assays on the most susceptible SKOV3 cells. RS-AgNPs induced oxidative stress in SKOV3 cells by generating reactive oxygen species (ROS), enhancing lipid peroxidation (LPO) levels and decreasing glutathione (GSH) levels. RS-AgNPs induced the apoptosis of SKOV3 cells by up regulating the caspase-3, caspase -8, caspase -9, p53 and BAX and down regulating the antiapoptotic protein Bcl-2. Further, RS-AgNPs showed elevation of caspase 3/7 activity and also exhibited antimigratory effect by inhibiting the migration of SKOV3 cells into the wounded area. The findings suggested that biogenic RS-AgNPs provide an alternative approach to overcome several limitations of chemotherapy.

Synthesis and biological evaluation of novel quinazoline-sulfonamides as anti-cancer agents

A robust economic approach to N-(quinazoline-4-yl)sulfonamides was developed and synthesized different aryl, hetero aryl, alkyl and cyclopropyl sulfonamides in excellent yields. All the compounds were evaluated for cytotoxic affinity to SKOV3, DU145, THP1, U937, and COLO205 cell lines. Interesting to find that the bulkiness of substituent at C-2 position of quinazoline forces the molecule to flip around in order to bind in the active site, when compared to the binding preference of previously known quinazoline compounds. Among the 21 compounds synthesized 2b, 2d, 2e, 2h, 2i, 3c, 3d, 3f, 3g and 3h found to be active on all the cell lines tested with IC50 values <10µg/mL. Performed docking simulations to understand the binding preference of various C-2 substituted quinazoline sulfonamides.

Morphometric, elemental and biochemical characterisation of three Haliclona species (Demospongiae) from the Gulf of Mannar, India

Abstract Marine sponges, in particular the Haliclona species (Demospongiae: Haplosclerida: Chalinidae) and/or their associated microorganisms, continue to yield an array of novel compounds. The aim of this work was the characterisation (morphometric, elemental and biochemical) of the three Haliclona species (Haliclona tenuiramosa, Haliclona cribricutis and Haliclona retiderma) from the Mandapam coast, Gulf of Mannar, India as an aid in the discrimination of the desired species for in vitro production of bioactive products and further ecobiotechnological applications. Diversity of the Haliclona species was analysed based on morphometric variables and elemental composition of the pinacoderm (outer epithelioid layer). Scanning electron microscope equipped with energy dispersive X-ray analysis did not reveal any change in elemental composition in spicules; however, the percentage of elemental composition in pinacoderm was significantly different among the species. The order and range of pinacoderm elemental composition were chlorine (36-51%), sodium (29-43%), silicon (0.72-2.2%), iron (0.46-0.73%). Aluminium (1.86-8.88%), calcium (0.92-16.19%) and sulfur (0.44-9.74%) varied greatly among the species. Total carbohydrate, protein and lipid contents also showed diversity among the species, i.e., carbohydrate content was high in H. tenuiramosa; proteins in H. cribricutis and lipids in H. retiderma, respectively. The order of ratio of spicule/protein content among the species were H. retiderma > H. cribricutis > H. tenuiramosa. The current approaches and results could direct an efficient application of discriminating sponge species in situ.

Vector and Agricultural Pest Control

Many of the small-scale farmers in developing countries continue to use high volumes of pesticides for crop protection due to their illiteracy, and lack of adequate information. Such practices have resulted in many environmental problems such as effect on nontarget species, pesticide residue accumulation, development of resistance to pests, ecological imbalance by elimination of natural predators as well as environment pollution. The current critical situation is that many of the previously used and economically affordable insecticides are no longer effective and are also banned in many countries. Therefore, there is an urgent need to develop newer, more effective, target specific and less persistent insecticides. In the search for developing newer insecticides, several researches had paid attention toward marine natural products. It is a well-known fact that the marine environment is an exceptional reservoir of bioactive natural products, which produce several novel structures with unique biological properties which may not be found in terrestrial natural products. In recent years, a number of studies have suggested that some of the bioactive compounds isolated from marine organisms exhibit pesticidal properties. Such bioactive metabolites from marine organisms may be an alternative source for vector and agricultural pest control agents. It is anticipated that these bioactive metabolites may potentially replace the existing and highly toxic synthetic insecticides and will play an important role in the future insecticide development program. This chapter provides an overview of recent trends in the exploration of marine secondary metabolites for pest management system.