Kinetics Study of Protein Hydrolysis and Inhibition of Angiotensin Converting Enzyme by Peptides Hydrolysate Extracted from Walnut

Screening the elite chemotypes of Gloriosa superba L. in India for the production of anticancer colchicine: simultaneous microwave-assisted extraction and HPTLC studies

BACKGROUND

Gloriosa superba L. (Colchicaceae) is a high-value medicinal plant indigenous to Africa and Southeast Asia. Its therapeutic benefits are well-established in traditional medicines including Ayurveda. It is well known for its natural bioactive compound colchicine which exhibits a wide range of pharmacological activities i.e. rheumatism, gout and was also introduced into clinical practices. The increasing demand as well as its illegal harvesting has brought this valuable plant under threatened category.

METHODS

The present investigation describes a microwave assisted extraction (MAE) strategy coupled with a densitometric-high performance thin layer chromatographic (HPTLC) methodology for the analysis of colchicine from 32 different populations of G. superba. A Box-Behnken statistical design (3 level factor) has been employed to optimize MAE, in which power of microwave, time of irradiation, aqueous ethanol and pH were used as independent variables whereas colchicine was used as the dependent variables. Chromatography was carried out on Silica gel 60 F₂₅₄ TLC plates with toluene: methanol, 85:15 (v/v) being used as solvent system. Densitometric measurement was performed at λ=254 nm following post-derivatization (10% methanolic sulphuric acid).

RESULTS

Optimal conditions for extraction to obtain the maximum colchicine yield was found to be 7.51 mg g^- 1 which was very close to be predicted response 7.48 mg g^- 1 by maintaining microwave power (460 W), irradiation time (6.4 min), aqueous ethanol-30, pH -3. Colchicine content ranged between 2.12-7.58 mg g^- 1 among 32 G. superba populations in which only three chemotypes viz. GS- 1, GS- 3, and GS- 2 collected from West Bengal and Sikkim, respectively exhibited maximum yield of colchicine.

CONCLUSION

Therefore, this newly developed optimized MAE coupled with HPTLC densitometry methodology not only quantifies colchicine in order to identify elite chemotypes of G. superba, but it also encourages in selecting high yielding populations of the plants for industrial use and economic boost for the farmers. This validated, simple and reproducible HPTLC protocol is being used for the first time to estimate colchicine from natural populations of G. superba obtained from 32 different geographical regions of India.

Enzymolysis of walnut (Juglans regia L.) meal protein: Ultrasonication-assisted alkaline pretreatment impact on kinetics and thermodynamics

To improve the utility of walnut meal protein, influences of ultrasonication on the kinetic and thermodynamic constraints of enzyme (trypsin) hydrolysis were assessed using a multi-frequency counter current S-type ultrasound machine. Results revealed that both the ultrasonication treatment and control hydrolysis obeyed the first-order kinetics within the study constraints. After 90 min hydrolysis time, the uppermost percentage conversion rate (57.5%) of substrate to product and the percentage increase (25.42%) in hydrolyzed protein concentration were obtained at 323 K and 10% substrate concentration, respectively. The Michaelis constant (K_M ) in ultrasonic enzymolysis declined by 58.66% over the control. The reaction rate coefficient (k) for the proteolysis improved by 84.75%, 52.43%, 48.25%, and 37.79% at 219, 303, 313, and 323 K, correspondingly. Generally, the bond energy (E_a ), enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy (ΔG) were reduced by the ultrasound pretreatment with 36.61%, 28.05%, 18.22%, and 5.24%, respectively. PRACTICAL APPLICATIONS: Walnut meal protein has a well-balanced amino acid profile and its economic utilization could be increased practicably as a food ingredient via production of hydrolysates/peptides for the production of improved food ingredients instead of being cast off as animal feed. This study demonstrated a positive bearing of ultrasonication-assisted alkaline pretreatment on proteolytic reaction characteristics and its energy efficiency for walnut meal protein, which makes this technique applicable to the enhancement of plant proteins for inclusion in food products, especially tree nut and oil seed waste products from the oil industry.