Green-chemistry of by-products from Sai-Nam-Phueng orange in Thailand (1): Recovering a valuable source of bioactive compounds using response surface methodology, antioxidant, and cytotoxicity

What if orange peels and seeds—usually tossed aside—hold a treasure trove of health-boosting compounds? A new study shows how to unlock them with green chemistry.

Citrus waste is no longer just trash. In Thailand, researchers turned to the Sai-Nam-Phueng orange, a variety of Citrus reticulata Blanco, and found its seeds and peels rich in phytochemicals like limonoids and flavonoids. These compounds are known for their antioxidant power, making the by-products a potential goldmine for nutraceuticals and pharmaceuticals.

To extract these valuable molecules efficiently, the team used response surface methodology (RSM), a statistical tool that optimizes multiple factors at once. They tested how ethanol concentration, solvent-to-solid ratio, and temperature affected yield. The sweet spot: 70.50% ethanol, 28.11 mL/g solvent-to-solid ratio, and 69.99°C—conditions that produced results matching predictions.

The extracted compounds were then characterized using advanced techniques like HPLC, mass spectrometry, and NMR. This confirmed that the method is both cost-effective and reliable, turning what was once waste into a sustainable source of bioactive ingredients. The study also hints at future cytotoxicity testing, opening doors for safer, greener health products.

Key Points

• Seeds and peels of Sai-Nam-Phueng orange contain limonoids and flavonoids.
• Optimized extraction: 70.5% ethanol, 28.11 mL/g, 69.99°C.
• Green method confirmed by HPLC, mass spec, and NMR.