Seasonal Variation in Wild Rosmarinus officinalis L.: Phytochemicals and Their Multifunctional Potential Against Metabolic Disorders

TL;DR

This study shows that the chemical content and health benefits of rosemary vary by season, with autumn and spring being the best times to harvest for medicinal and cosmetic use.

Contribution

The study reveals how seasonal changes affect the phytochemical profile and bioactivities of Rosmarinus officinalis, identifying optimal harvesting periods.

Findings

Autumn extract had the highest phenolic and flavonoid content and strongest antioxidant activity.

Spring extract showed the best reducing power, urease inhibition, and analgesic activity without toxicity.

Seasonal variation significantly influenced the plant's chemical profile and biological activities.

Abstract

This investigation explored how seasonal variation affects the phytochemical composition and biological potential of Rosmarinus officinalis L., a widely used aromatic and medicinal plant. Aerial parts collected during spring, summer, autumn, and winter were extracted with ethanol and analyzed using LC-ESI-MS/MS, while total phenolic (TPC) and flavonoid (TFC) contents were determined spectrophotometrically. The extracts were evaluated for antioxidant, anti-inflammatory, enzyme inhibitory, analgesic, antimicrobial, cytotoxic, and photoprotective properties. Major constituents identified in all seasons included luteolin, kaempferol, rutin, and biochanin A. The autumn extract contained the highest phenolic (353.21 ± 4.05 µg GAE/mg) and flavonoid (190.11 ± 5.65 µg QE/mg) levels. Antioxidant assays revealed that the autumn extract had the strongest DPPH radical scavenging activity (IC50 = 24.72 ± 0.16 µg/mL), while the spring extract exhibited the greatest reducing power (A0.5 = 7.62 ± 0.30 µg/mL). The winter extract demonstrated superior anti-inflammatory activity (IC50 = 28.60 ± 2.84 µg/mL), exceeding the reference drug diclofenac. Only the spring extract inhibited urease (IC50 = 62.26 ± 0.58 µg/mL) and moderately inhibited α-amylase. All seasonal extracts showed notable photoprotective potential, with SPF values between 25.18 and 32.46, well above the recommended minimum. The spring extract also presented strong analgesic activity and no acute toxicity up to 2000 mg/kg. Antimicrobial effects were weak, limited to slight inhibition of Staphylococcus aureus, while moderate cytotoxicity was observed against MCF-7 and MDA-MB-231 breast cancer cells. Overall, seasonal variation significantly influenced the chemical profile and bioactivities of R. officinalis, with autumn and spring identified as the most suitable harvesting periods for pharmaceutical and cosmetic applications.

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