Valorization of tuberose flower waste through development of therapeutic products using supercritical carbon dioxide...

Tuberose flowers (Calcutta Single variety) valued as ornamentals globally, have short shelf-lives of 8 days at 4 ± 1 °C and are therefore discarded post senescence. Previous investigations from our laboratory have established that a combination treatment using GRAS preservatives [(sucrose (4%) and CaCl₂ (0.02%)]-cum-gamma-irradiation (0.02 kGy) could extend its shelf-life to 24 days, when stored at 4 ± 1 °C with concomitant enhancement in the content of its bioactive principle, viz. methyl eugenol. Supercritical carbon dioxide (SC-CO₂) extract of the tuberose flower wastes post combination treatment therefore had a higher methyl eugenol content (4.11 ± 0.05 µg/g), vis-à-vis its non-treated counterpart (2.03 ± 0.03 µg/g), and thus significantly higher antioxidant and antimicrobial potencies (MIC values of 1.83 ± 0.02 mg/ml and 1.98 ± 0.03 mg/ml against S. aureus ATCC 25923 strain and MDR strain, respectively). The microencapsulated powder of the extract (ME_p) obtained by spray drying was applied for healing of epidermal wounds created on New Zealand white rabbits, post skin irritancy test (wherein no clinical sign of toxicity, redness or swelling was observed). When ME_p was applied, accelerated healing occurred which commenced on day 2 and was completed by day 6 vis-à-vis that of the control powder set (without extract) which showed no signs of wound healing. Therefore, the sensorially compromised-senesced tuberose flowers, a rich source of methyl eugenol, has been successfully valorized through utilization of the same in developing a novel topical antibiotic powder against potent skin pathogens.