Seasonal Variation of Triterpenes and Phenolic Compounds in Australian Centella asiatica (L.) Urb.

INTRODUCTION: Specific triterpenes, phenolic acids and flavonoids in Centella asiatica have been found to be bioactive. Harvesting the plant when these putative bioactive compounds are at their highest concentrations would provide consistency in their chemical profile, thus ensuring the quality and efficacy of derived medicinal products. OBJECTIVE: The aim of the study was to determine the impact of harvesting time on the contents of major triterpenoid and phenolic compounds in C. asiatica. METHODOLOGY: Australian C. asiatica was collected from a designated area in different months. The principal triterpenes (asiaticoside, madecassoside, asiatic acid and madecassic acid), flavonoid compounds (rutin, quercetin and kaempferol) and chlorogenic acid were quantitatively determined by HPLC-DAD analysis. RESULTS: Triterpenoid, kaempferol and chlorogenic acid content showed significant variation (p < 0.05) in different collecting months. The total content of the four triterpenes reached its highest levels in January and February (83.15 ± 0.16 mg/g and 78.41 ± 0.16 mg/g, respectively), the summer season of the southern hemisphere, and their lowest values in winter (June) and spring (October) seasons (35.65 ± 0.20 and 35.50 ± 0.55 mg/g, respectively). Similarly, the contents of chlorogenic acid and kaempferol were the highest in December and January (1.62 ± 0.01 and 0.33 ± 0.01 mg/g, respectively), and the lowest in June (0.06 ± 0.01 and 0.09 ± 0.01 mg/g, respectively). CONCLUSION: The results indicate that harvesting C. asiatica in summer returns the highest yield of the target triterpenoids, kaempferol and chlorogenic acid.