Isolation and Optical Properties of Natural Pigments from Purple Mangosteen Peels

Purple mangosteen (Garcinia mangostana) has several biological applications such as anticancer, antitubercular and antioxidant agents. In this work, we isolated and studied the optical properties of the natural pigments from the purple mangosteen peels. To isolate the natural pigments, the mangosteen peels were macerated using distilled water, ethanol, or acetone for 24 h. The extracts were filtrated and characterized using spectrophotometers of Fourier transform infrared (FTIR), ultraviolet-visible (UV-Vis), and spectrofluorometer. The extracts gave the FTIR vibration peaks of O-H, C-H sp(3), C=O, C=C, and C-O functional groups, while absorption peaks at 210.374 nm were observed in the UV-Vis spectra of the extracts due to the presence of mangostins, anthocyanins, and phenolic acids. The three-dimensional fluorescence spectra showed that the excitation and emission peaks of the mangosteen peels extracted with ethanol were found at 444 and 498 nm, respectively, while that extracted with distilled water gave no significant fluorescence peaks. On the other hand, the mangosteen peels extracted with acetone gave the strongest emission intensity at 472 and 502 nm due to the most intense color intensity. This study provided useful information about the optical properties of natural pigments extracted from purple mangosteen peels through a simple isolation technique.