Savitribai Phule Pune University

The present study attempted to analyze the bioactive phytochemicals present in chloroform, methanol, and aqueous leaf extracts of Caesalpinia crista (CC). Initially, the leaf extraction was done with a more efficient Soxhlet extraction method to increase yield. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed that the chloroform crude extract contained 43 distinct phytochemicals, whereas the methanol and aqueous extracts comprised 57 and 71 phytochemicals, respectively. According to RT, peak height, and peak width of the chromatograms, 16 notable phytochemicals were detected in the chloroform extract, while the methanol and aqueous extracts contained 20 and 12 notable phytochemicals, respectively. Moreover, the chromatogram of the chloroform extract displayed the most prominent peak at a RT of 4.984967 minutes, with a peak height of 182243.8 and a peak width of 761051.0625, signifying the presence of 2-[(2-hydroxy-3-methylbutanoyl)amino]-4-methylpentanoic acid as the predominant phytochemical. The chromatogram of the methanol extract also displayed three prominent peaks at RT 2.1156, 4.45125, and 7.187783 minutes, separated by their maximum peak height and width, indicating the presence of cycloserine, juglone, and dihydrojasmonic acid as major phytochemicals. Likewise, the aqueous extract exhibited three significant peak at RT 5.159, 9.64825, and 15.87752 minutes, linked with the phytochemicals caryophyllene oxide, meglutol, and 3,7-epoxycaryophyllan-6-one.

The ability of an indigenous marine actinomycete, Nocardiopsis dassonvillei NCIM 5124, to remove hexavalent chromium [Cr (VI)] in the free and calcium alginate immobilized form was evaluated. While field emission scanning electron microscope (FESEM) studies revealed the mycelial and porous nature of the free and immobilized biosorbents, respectively, thermogravimetric analysis indicated their thermal stability. In the free form, the biomass removed 76.98 ± 1.77% Cr (VI), while lesser quantities of immobilized N. dassonvillei (0.12 g) mediated the removal of 84.55 ± 1.92% of Cr (VI) under optimized conditions. FESEM-energy dispersive X-ray (FESEM-EDX) revealed the presence of chromium on the biosorbents, and Fourier transform infrared analysis suggested that amide, amino, carbonyl, hydroxyl, and phosphate groups were involved. Brunauer-Emmett-Teller (BET) analysis confirmed the mesoporous nature of the beads. For the free and immobilized biosorbents, the biosorption occurred onto monolayers and multilayers, respectively via chemisorption. The negative values of ΔG observed during the thermodynamic studies revealed the spontaneous and endothermic nature of the biosorption process. This is the first study to show that alginate immobilized N. dassonvillei biomass can act as an effective biosorbent for eliminating potentially harmful Cr (VI) ions in an environmentally acceptable manner.