Optimisation of enzyme-assisted extraction of camptothecin from Nothapodytes nimmoniana and its characterisation.

INTRODUCTION: Efficient extraction of camptothecin (CPT), an anticancer agent from the commercial source Nothapodytes nimmoniana (J. Graham) Mabb in India, is of paramount importance. CPT is present in the highest concentration in the stem portion, and the stem can be readily harvested without uprooting the plant. The fluorescence microscopy mapping of the bark matrix for CPT revealed its presence in a free form within both the outer (epidermal and cortical tissues) and inner (xylem and phloem tissues) sections. The bark matrix primarily consists of cellulose, hemicellulose, and lignin, rendering it woody, rigid, and resistant to efficient solvent penetration for CPT extraction. We proposed a hypothesis that subjecting it to disruption through treatment with hydrolytic enzymes like cellulase and xylanase could enhance solvent diffusion, thereby enabling a swift and effective extraction of CPT. OBJECTIVE: The present study was aimed at enzyme-assisted extraction, using cellulase and xylanase for hydrolytic disruption of the cells to readily access CPT from the stem of the plant N. nimmoniana (J. Graham) Mabb. METHODOLOGY: The hydrolytic cell disruption of ground powder from the stem bark was studied using cellulase and xylanase enzymes. The enzymatically pretreated stem bark powder was subsequently recovered by filtration, dried, and subjected to extraction with methanol to isolate CPT. This process was optimised through a Box-Behnken design, employing a one-factor-at-a-time approach to assess parameters such as enzyme concentration (2-10% w/w), pH (3-7), incubation time (6-24 h), and solid-to-solvent ratio (1:30-1:70 g/mL). CPT was characterised using proton nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FTIR) spectra, and a high-performance liquid chromatography (HPLC) method was developed for quantification. RESULTS: The cellulase and xylanase treatment resulted in the highest yields of 0.285% w/w and 0.343% w/w, with efficiencies of 67% and 81%, respectively, achieved in a significantly shorter time compared to the untreated material, which yielded 0.18% with an efficiency of only 42%. Extraction by utilising the predicted optimised process parameters, a nearly two-fold increase in the yield, was observed for xylanase, with incubation and solvent extraction times set at 16 and 2 h, respectively. Scanning electron microscopy (SEM) images of the spent material indicated perforations attributed to enzymatic action, suggesting that this could be a primary factor contributing to the enhanced extraction. CONCLUSION: Enzyme-mediated hydrolytic cell disruption could be a potential approach for efficient and rapid isolation of CPT from the bark of N. nimmoniana.

Simulation of high-Mach-number inviscid flows using a third-order Runge-Kutta and fifth-order WENO-based finite-difference lattice Boltzmann method.

A discrete-velocity Boltzmann equation (DVBE) with Bhatnagar-Gross-Krook (BGK) approximation is discretized in time and space using a third-order Runge-Kutta (RK3) and fifth-order weighted essentially nonoscillatory (WENO) finite-difference scheme to simulate benchmark inviscid compressible flows. The implementation of the WENO ensures that solutions behave with minimal or no oscillations, narrowing the gap between the exact and the numerical results. Discrete-velocity sets given by Kataoka and Tsutahara [Phys. Rev. E 69, 056702 (2004)10.1103/PhysRevE.69.056702] are used. The additional dissipation terms as well as artificial viscosity are incorporated in the formulation to solve the compressible flows at high Mach number. Further, the flows which are subjected initially to a high density ratio are effectively simulated. In this article, one-dimensional benchmarks are simulated at initial Mach number up to 30 and density ratio up to 1000, whereas, the benchmarks in two dimensions are simulated with a Mach number up to 10. The algorithm is assessed by simulating numerous benchmarks, namely, (i) one-dimensional Riemann problem for various shock waves combinations [namely (a) shock-shock waves in the case of different Mach numbers, (b) rarefaction-shock waves for various density ratios, (c) sudden contact shock discontinuity, and (d) shock-rarefaction waves for density ratio 5], (ii) isentropic vortex convection test, (iii) regular shock reflection (RR) for Mach numbers 2.9 and 10, (iv) double Mach reflection (DMR) for inflow Mach numbers as 6 and 10, and (v) forward-facing step for inflow Mach numbers 2 to 5. Further, the effect of change in Mach numbers and wedge angles on the flow structures in the case of DMR are detailed. In the case of a forward-facing step, the variations of flow structure (e.g., the Mach stem height, triple points location, and shock standoff distance) are detailed with respect to Mach number, step height, and specific-heat ratios. Finally, the numerical stability of the proposed formulation is carried out to assess the behavior of the free parameters.

An Examination of the Low Strain Rate Sensitivity of Additively Manufactured Polymer, Composite and Metallic Honeycomb Structures.

The characterization of additively manufactured cellular materials, such as honeycombs and lattices, is crucial to enabling their implementation in functional parts. One of the characterization methods commonly employed is mechanical testing under compression. This work focuses specifically on the dependence of these tests to the applied strain rate during the test over low strain rate regimes (considered here as 10-6 to 10-1 s-1). The paper is limited to the study of strain the rate dependence of hexagonal honeycomb structures manufactured with four different additive manufacturing processes: one polymer (fused deposition modeling, or material extrusion with ABS), one composite (nylon and continuous carbon fiber extrusion) and two metallic (laser powder bed fusion of Inconel 718 and electron beam melting of Ti6Al4V). The strain rate sensitivities of the effective elastic moduli, and the peak loads for all four processes were compared. Results show significant sensitivity to strain rate in the polymer and composite process for both these metrics, and mild sensitivity for the metallic honeycombs for the peak load. This study has implications for the characterization and modeling of all mechanical cellular materials and makes the case for evaluation and if appropriate, inclusion, of strain rate effects in all cellular material modeling.

Ultrasound-assisted rapid extraction and kinetic modelling of influential factors: Extraction of camptothecin from Nothapodytes nimmoniana plant.

Ultrasound-assisted extraction (UAE) of commercially important natural product camptothecin (CPT) from Nothapodytes nimmoniana plant has been investigated. The influences of process factors such as electric acoustic intensity, solid to liquid ratio, duty cycle, temperature and particle size on the maximum extraction yield and kinetic mechanisms of the entire extraction process have been investigated. The kinetics results showed that increasing the intensity, duty cycle, solid to liquid ratio and decreasing the particle size lead to substantial increase in extraction yields compared to classical stirring extraction. Different kinetic models were applied to fit the experimental data. The second order rate model appears to be the best. The extraction rate constant, initial extraction rate and the equilibrium concentration for all experimental conditions have been calculated. SEM analysis of spent plant material clearly showed hollow openings on cell structure, which could be directly correlated to explosive disruption by the action of ultrasound waves. Overall 1.7-fold increase in extraction yields of CPT (0.32% w/w) and decrease in time from 6h to 18min was observed over the stirring method.

Implication of novel thiazolo-thiophene derivative (MCD-KV-10) for management of asthma.

CONTEXT: Asthma is multifaceted disease where many targets contribute towards its development and progression. Among these, adenosine receptor subtypes play a major role. OBJECTIVE: MCD-KV-10, a novel thiazolo-thiophene was designed and evaluated pre-clinically for its implication in management of asthma. MATERIALS AND METHODS: This compound showed good affinity and selectivity towards A(2A)/A3 adenosine receptor (AR) subtypes. Furthermore, MCD-KV-10 was evaluated for in vitro lipoxygenase inhibition activity; in vivo mast cell stabilization potential and in vivo anti-asthmatic activity was done in ovalbumin-induced airway inflammation model in guinea pigs. RESULTS: The compound showed good (>57%) inhibition of lipoxygenase enzyme and also effectively protected mast cell degranulation (>63%). The compound showed good anti-asthmatic activity as inferred from the in vivo studies. DISCUSSION: These results indicate that MCD-KV-10 has an inhibitory effect on airway inflammation. CONCLUSION: Though, we have identified a potential candidate for management of asthma, further mechanistic studies are needed.