Development and validation of an HPLC-DAD method for determination of oleuropein and other bioactive compounds in olive leaf by-products

BACKGROUND

Oil mills could benefit by preparing their own aqueous extracts from olive leaves. Accordingly, the present study aimed to measure the bioactive compounds richness of such extracts, especially oleuropein. A water-based microwave extraction procedure was developed and a selective and precise high-performance liquid chromatography with diode array detection (HPLC-DAD) method was validated for the determination of oleuropein and others bioactive compounds from olive leaves.

RESULTS

The water solubility of oleuropein was determined to be 9.5 g L^-1 . The extraction procedure was optimized in terms of power, olive leaf weight/water volume ratio and time of extraction, and the results revealed that 2 mg mL^-1 and a microwave irradiation at 800 W for 30 s resulted in the greatest efficiency. Oleuropein was determined by the new validation method, which showed good linearity (r² = 0.996), precision (% relative standard deviation < 10%), recovery (118.6%), and limits of detection (17.48 mg L^-1 ) and quantification (21.54 mg L^-1 ). Good correlation (r² = 0.979) was obtained between oleuropein of the olive leaf extracts determined by HPLC-DAD and by UV-visible spectrophotometry.

CONCLUSION

A simple extraction method was developed and validated to obtain aqueous extract from olive leaves by microwave extraction, determining for the first time oleuropein water solubility. Validation of the method showed that oleuropein in olive leaves could be quantified when it is at least 1% of dry weight by means of HPLC-DAD. UV-visible spectrophotometry can be useful in oil mills because it enables the content of oleuropein and other bioactive compounds content to be determined in situ in such leaf aqueous extracts. © 2020 Society of Chemical Industry.

Epidermal growth factor receptor (EGFR) mutations in a series of non-small-cell lung cancer (NSCLC) patients and response rate to EGFR-specific tyrosine kinase inhibitors (TKIs)

INTRODUCTION Epidermal growth factor receptor (EGFR) mutation related to tyrosine kinase inhibitors' (TKIs) responsiveness in non-small cell lung cancer (NSCLC) has become an important issue for therapeutic decision-making in NSCLC patients. MATERIAL AND METHODS Sixty-nine Caucasian NSCLC patients were screened for mutations in the tyrosine kinase (TK) domain of EGFR by direct sequencing from December 2005 to September 2010. RESULTS Activating mutations in the EGFR TK domain were found in 8 of 69 (11.6%) (7 deletions in exon 19 and one L858R mutation in exon 21). Seven of those mutations were found in adenocarcinoma and one mutation in bronchiolo-alveolar carcinoma; five of them in females (one smoker) and three of them in males (one smoker). All patients carrying activating mutations in the TK domain of EGFR were treated with TKIs. Ten patients not carrying an activating mutation in EGFR, who progressed after chemotherapy, were also treated with compassionate use of EGFR-specific TKIs (gefitinib or erlotinib). An objective response (partial response) was observed in all patients carrying an activating mutation in EGFR that received TKIs. Median overall survival for these patients has not been reached, however mean survival has been estimated at 39.5 months (95% CI, 22-57). CONCLUSIONS As previously reported, EGFR TK mutational analysis was a predictive test for response to targeted therapy with EGFR TKIs. The early identification of these patients consistently attains disease response and clearly improves outcomes.