Antioxidative Potentials of Eleutherine bulbosa Bulb and Its Utilization in Topical Cosmetic Emulsion

The Eleutherine bulbosa bulb has been reported as a potent antioxidant in food. This work aims to extract the E. bulbosa bulb for use as an antioxidative agent in cosmetics. Water, 95% ethanol (EtOH), and propylene glycol (PG), which are normally used in cosmetic formulation, were employed as green and sustainable extraction solvents. EtOH and PG displayed better candidacy to extract active components from E. bulbosa bulbs than using water, and the mixture of EtOH and PG (EtOH/PG) resulted in the extract with higher bioactive compounds and biological activities compared with using EtOH or PG. The total phenolic content of the EtOH/PG extract was 87.60 ± 2.00 mgGAE/mL which was about an 18–23% increase from when using single EtOH or PG (70.91 ± 2.30, 74.05 ± 0.67 mgGAE/mL). UHPLC-ESI-QTOF-MS/MS analysis showed that the E. bulbosa bulb extracted in EtOH/PG was composed of naphthalenes, naphthoquinones, anthraquinones, myricetin, quercetin, epicatechin, catechin, epigallocatechin, and their derivatives. The ethanolic crude extract exhibited anti-elastase and anti-collagenase activity with the IC50 of 7.76 ± 0.35 and 0.53 ± 0.23 mg/mL, respectively, and was non-cytotoxic to human dermal fibroblast cells at 0.0001–1 mg/mL. The emulsion cream containing 2%(w/w) E. bulbosa bulb concentrated extract was found cosmetically stable after a one-month stability test under 4 °C, ambient temperature (30–35 °C), 45 °C, fluorescent light, and daylight. However, exposure to sunlight during daytime caused changes in the emulsion’s color with ΔE* of 3.85 ± 0.08, and at 45 °C caused the 12% decrease in DPPH activity of emulsion. The finding of this work heightens the antioxidative and safety potentials of the E. bulbosa bulb in cosmetic preparations.