Eucheuma cottonii waste seaweed has high cellulose content. Therefore, it could be potentially used as a raw material for biodegradable films to replace plastic. A plastic film is its moisture resistance, and this property allows plastic films to be used as packaging materials and biodegraded by microbes. This research aims to obtain a concentration of glycerol and Carboxy Methyl Cellulose (CMC) to obtain the best biodegradable film characteristics from E. cottonii seaweed waste. This study was conducted in factorial by using a complete randomized block design with two factors: glycerol concentration and CMC concentration. Each treatment has three levels and three replications (3 × 3). The first factor was glycerol concentration: 0.25% (G1), 0.5% (G2), and 0.75% (G3). The second factor included concentrations of 1% CMC (C1), 2% CMC (C2), and 3% CMC (C3). Then, Tensile Strength (TS), thickness, solubility, and elongation were observed. Functional group analysis was conducted by Fourier-transform infrared spectroscopy and biodegradability test. The results showed that the addition of glycerol concentrations of 0.5 and 0.7% and CMC from 1 to 3% produced tensile strengths of 23–39 MPa. These values are proportional to the tensile strength of Poly Tetra Fluoro ethyne (PTFE) and Poly Propylene (PP) synthetic plastics released by Dotmar Engineering Plastics. The biodegradability test showed that the produced biodegradable films decomposed after 14 days.

Enzyme immobilization is a powerful method to improve the stability, reuse, and enzymatic properties of enzymes. The immobilization of the α-amylase enzyme from Aspergillus fumigatus on a chitin-bentonite (CB) hybrid has been studied to improve its stability. Therefore, this study aims to obtain the higher stability of α-amylase enzyme to reduce industrial costs. The procedures were performed as follows: production, isolation, partial purification, immobilization, and characterization of the free and immobilized enzymes. The CB hybrid was synthesized by bentonite, chitin, and glutaraldehyde as a cross-linker. The free enzyme was immobilized onto CB hybrid using 0.1 M phosphate buffer pH 7.5. The free and immobilized enzymes were characterized by optimum temperature, Michaelis constant (K_M), maximum velocity , thermal inactivation rate constant (k_i), half-life (t_1/2), and transformation of free energy because of denaturation (ΔG_i). The free enzyme has optimum temperature of 55°C, K_M = 3.04 mg mL⁻¹ substrate, , k_i = 0.0171 min⁻¹, t_1/2 = 40.53 min, and ΔG_i = 104.47 kJ mole⁻¹. Meanwhile, the immobilized enzyme has optimum temperature of 60°C, K_M = 11.57 mg mL⁻¹ substrate, , k_i = 0.0045 min⁻¹, t_1/2 = 154.00 min, and ΔG_i = 108.17 kJ mole⁻¹. After sixth cycle of reuse, the residual activity of the immobilized enzyme was 38%. The improvement in the stability of α-amylase immobilized on the CB hybrid based on the increase in half-life was four times of the free enzyme.

Antimalarial activity study of organotin(IV) derivatives with nitrobenzoic acid derivatives used as ligands has been performed. The targeted compounds were prepared from their organotin(IV) chlorides via dibutyltin(IV) oxide, diphenyltin(IV) dihydroxide, and triphenyltin(IV) hydroxide intermediate products, followed by reacting the intermediate products with 2-nitrobenzoic acid. The antimalarial activity was performed against P. falciparum. The results showed that the IC50values of dibutyiltin(IV) di-2-nitrobenzoate, diphenyltin(IV) di-2-nitrobenzoate, and triphenyltin(IV) 2-nitrobenzoate were in 8.4 × 10‑3, 5.3 × 10–2, and 9.1 × 10–3 µg/ml, respectively. The IC50 values were slightly higher than the value for chloroquine (2 × 10–3 µg/ml) used as the positive control; however, one advantage is that all prepared organotin(IV) compounds were not resistant to Plasmodium, making the use of organotin(IV) as an antimalarial is possible. The results indicated that the derivative of triphenyltin(IV) was more potent when used as an antimalarial, as expected, and has potential to be developed as an antimalarial drug in the future.

The synthesis and comparative study on the antibacterial activity of three organotin(IV) compounds, namely dibutyltin(IV) bis-(3-hydroxybenzoate), [Bu₂Sn(3-HBz)₂] (7), diphenyltin(IV) bis-(3-hydroxybenzoate), [Ph₂Sn(3-HBz)₂] (8), and triphenyltin(IV) 3-hydroxybenzoate, [Ph₃Sn(3-HBz)] (9) which were prepared by the reaction of dibutyltin(IV) oxide, [Bu₂SnO] (4), diphenyltin(IV) dihydroxide, [Ph₂Sn(OH)₂] (5), and triphenyltin(IV) hydroxide, [Ph₃SnOH] (6) with 3-hydroxybenzoic acid (3-HBz) has successfully been performed. The characterization of these compounds were done using ¹H and ¹³C NMR, IR, UV spectroscopies and their compositions were determined based on microanalytical data. Antibacterial activity of these compounds was demonstrated at concentrations of 1.89 × 10⁻⁴, 1.81 × 10⁻⁴, and 1.72 × 10⁻⁴ M, respectively by dilution method against Pseudomonas aeruginosa. Similarly, the compounds were active at concentration of 1.87 × 10⁻⁴, 1.79 × 10⁻⁴, and 1.71 × 10⁻⁴ M, respectively, against Bacillus subtilis. These activities are comparable to that of streptomycin at a concentration of 1.70 × 10⁻⁴ M as a positive control, but the halozone of compounds 7, 8, and 9 were slightly lower than that of streptomycin’s halozone. The results obtained suggest that the compounds synthesized have potential as antibacterial agents.

IN VITRO ACTIVITY AND COMPARATIVE STUDIES OF SOME ORGANOTIN(IV) BENZOATE DERIVATIVES AGAINST LEUKEMIA CANCER CELL, L-1210