Circadian-dependent phytochemical variation of and antihypertensive effects of Canarium schweinfurthii Engl. (Burseraceae) in Wistar rats

Circadian-driven metabolic variation can significantly influence bioactivity. Consequently, pharmaceutical and biotechnology industry are increasingly interested in manipulating plant circadian clocks in order to identify the optimal time of the day for harvesting, when secondary metabolites are present at their highest levels. This study aimed to establish the circadian phytochemical profile of different parts of Canarium schweinfurthii and to evaluate antihypertensive potential of extracts from these parts in Wistar rats. Plant material consisted of the leaves, roots and stem bark of C. schweinfurthhi. Harvesting was conducted three times a day (at 6 a.m., 12 pm. and 6 pm.) to assess the effect of circadian rhythm on phytochemical composition. The antihypertensive activity of extracts from all the plant parts was evaluated on hypertensive Wistar rats induced by daily oral administration of N(ω)-Nitro-l-Arginine Methyl Ester (L-NAME, 25 mg/kg) for 7 days. Hemodynamic parameters, including systolic blood pressure, diastolic blood pressure, and mean arterial pressure, were measured using the CODA system (Emka Scientific), and Biochemical parameters were also analyzed to assess antihypertensive effect. 6 a.m. was identified as the optimal harvesting time for this plant, as plant material collected at this time contained higher levels of secondary metabolites. stem bark extract of C. schweinfurthii harvested at 6 a.m. exhibited the most pronounced antihypertensive effects (p < 0.0001) at 200 mg/kg, compared with extracts from other plant parts at the different harvesting times. These findings suggest that Canarium schweinfurthii, particularly the stem bark may represent a promising natural source for the management of hypertension, with its most effective antihypertensive constituents obtained when the plant is harvested at 6 a.m.