Osthole, 7-methoxy-8-(3-methyl-2-butenyl) - 2H-1-Benzopyran-2-one, is an active constituent of Cnidium
monnieri genus and apiaceae family. The anticancer effect of osthole has been reported due to osthole may inhibit the
growth, invasion and metastasis of cancer cells Aim: Preparation of osthole from different citrus fruit plant sources and
evaluates its cytotoxic effect on lung cancer. Methods: osthole from different cultivar of citrus fruits was extracted in
reflux by using petroleum ether and acetone, the solvent was evaporated and then precipitates and dried then crystallized.
Osthole structure was characterized by IR and GC-MS. Lung cancer cells A549was treated with different concentration of
osthole, cell proliferation was measured by MTT assay. Results: Osthole was extracted from lemon (citrus limon),
grapefruit (Citrus paradise) and orange (Citrus sinensis) plant sources The highest concentration of osthole exist in
grapefruit The IR spectrum grapefruit osthole with the peaks at 1747 cm-1 (coumarinic carbonyl), 1048cm-1 (C-O
streaching) and 1439 cm-1 (aromatic C=C) confirms the skeleton of osthole. The grapefruit osthole showed well separated peaks with retention times16.56 identical with the osthole standard solution. The IC50 value of grapefruit osthole was 46 μg/ ml against lung cancer cell line after 48 hrs treatment. Conclusion: our findings suggest the osthole exist in citrus fruit as lemon, grape fruit, orange practically free of osthole. Osthole has therapeutic application in human lung cancer.