ABSTRACT
The report features the first isolation of paclitaxel from wood of conservated Taxus sumatrana. The T. sumatrana is a nationally protected endemic plant that has been successfully cultivated outside its natural habitat at the Singgalang Conservation Centre in West Sumatra. The paclitaxel was utilised as a reference standard for evaluating its presence in different parts of T. sumatrana. This analysis exhibits that the acetone extract from T. sumatrana bark contained the highest paclitaxel concentration, measuring about 0.473 ± 0.031 ppm. The isolated paclitaxel demonstrated potent cytotoxic activity against A549, HeLa, and MCF7 cancer cells, by IC50 values of 3.26 ± 0.334, 2.85 ± 0.257, and 3.81 ± 0.013 µM, respectively. This outcome provides scientific support for conservation programs and campaigns for the community to engage in conservation efforts.
ABSTRACT
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 (V max), 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, V max=10.90 µmolemL-1min-1, 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, V max=3.37 µmolemL-1min-1, 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.
ABSTRACT
The stability of the α-amylase enzyme has been improved from Aspergillus fumigatus using the immobilization method on a bentonite matrix. Therefore, this study aims to obtain the higher stability of α-amylase enzyme from A. fumigatus; hence, it is used repeatedly to reduce industrial costs. The procedures involved enzyme production, isolation, partial purification, immobilization, and characterization. Furthermore, the soluble enzyme was immobilized using 0.1 M phosphate buffer of pH 7.5 on a bentonite matrix, after which it was characterized with the following parameters such as optimum temperature, Michaelis constant (K M ), maximum velocity (V max), thermal inactivation rate constant (k i), half-life (t 1/2), and the change of energy due to denaturation (ΔG i ). The results showed that the soluble enzyme has an optimum temperature of 55°C, K M of 3.04 mg mL-1 substrate, V max of 10.90 µmole mL-1 min-1, k i of 0.0171 min-1, t1/2 of 40.53 min, and ΔG i of 104.47 kJ mole-1, while the immobilized enzyme has an optimum temperature of 70°C, K M of 8.31 mg mL-1 substrate, V max of 1.44 µmole mL-1 min-1, k i of 0.0060 min-1, t 1/2 of 115.50 min, and ΔG i of 107.37 kJ mole-1. Considering the results, the immobilized enzyme retained 42% of its residual activity after six reuse cycles. Additionally, the stability improvement of the α-amylase enzyme by immobilization on a bentonite matrix, based on the increase in half-life, was three times greater than the soluble enzyme.
ABSTRACT
Native to tropical Asia, Sesbania grandiflora (L.), Pers is a member of the Fabaceae family of flowering plants. All parts of S. grandiflora are used in traditional medicine and phytochemical investigations have been conducted on extracts of the leaves, seeds and roots of S. grandiflora to provide scientific validation of its properties. However, to date, no study has determined the phytochemical constituents of S. grandiflora stem bark. The stem bark powdered of S. grandiflora was extracted exhaustively with n-hexane, EtOAc and 90% aqueous MeOH sequentially. In this study, we successfully isolated two new 2-arylbenzofurans, sesbagrandiflorain A and B, from the EtOAc stem bark of S. grandiflora. The structure elucidation of these compounds was determined by using one- and two-dimensional nuclear magnetic resonance, ultraviolet and infrared spectroscopy and electrospray ionisation time-of-flight mass spectrometry. The finding expands the understanding of the natural constituents of the Fabaceae and, in particular, the Papilionoideae genera.
