Seasonal variation in chemical composition and biological activities of essential oils from Artemisia annua L.
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Date
2021-10
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The objectives of the present research study were to investigate the seasonal variation in phytochemical analysis and biological activites of Artemisia annua essential oils. The plants were collected from Tarai region of Uttarakhand, Pantnagar in the month of September, 2020 and January 2021 respectively .The essential oils of fresh aerial part of the collected plant materials were extracted by hydrodistillation using Clevenger apparatus and were studied by GC/MS for its phytochemical study and various biological activities. The essential oils isolated in rainy and winter season were designated as AAREO & AAWEO respectively. The phytochemical analysis of AAREO revealed the identification of 75 constituents which contributed 91.7% of the total essential oil. The major components of AAREO were camphor (14.1%) followed by germacrene –D (9.0%), trans-β-caryophyllene (8.7%), eucalyptol (4.2%), cis-cadin-4en-7-ol (3.9%), isoborneol (3.2%), p-cymene (2.9%) etc. Similarly, in AAWEO 59 constituents were identified which contributed 94.1% of the total essential oil. The major components of AAWEO were camphor (17.9%) followed by eucalyptol (14.6%), (E,E)-2,6-dimethyl-3,5,7-octatrien-2-ol (6.3%), (5E)-2,6-dimethyl-1,5,7-octatrien-3-ol (5.2%), artemisia alcohol (3.5%), isoborneol (3.2%), caryophyllene oxide (3.1%), artemisia ketone (2.5%) etc besides other minor and trace constituents. Both AAREO & AAWEO showed qualitative and quantitative differences in their phytochemical makeup. Both AAREO and AAWEO exhibited dose dependent in-vitro anti-oxidant activity, evaluated by , DPPH scavenging, metal chelating assay and H2O2 radical scavenging as indicated by different IC50 values. IC50 =77.87±0.528 to IC50=45.588±0.334 μl/mL for DPPH radical scavenging activity similarly IC50 =51.40±0.158 to IC50=49.50±0.234 for metal chelating activity and IC50 = 44.83±1.304 to IC50 =34.79±0.419 for H2O2 radical scavenging activity with respect to various standards like, BHT and Na2EDTA respectively. With respect to diclofenac sodium, the standard anti-inflammatory drug both AAREO and AAWEO exhibited anti-inflammatory activity with IC50= AAWEO (IC50=66.90±0.040) > AAREO (IC50=76.55±0.218) μl/mL respectively. Similarly, significant anti-diabetic activity was observed in both AAREO and AAWEO with IC50= 74.26±3.706μl/mL to IC50= 47.45±0.195μl/mL, respectively compared to standard acarbose (IC50= 38.21±0.03μl/mL). Both AAREO and AAWEO were observed to exhibit strong anti-feedant activity respectively against Spodoptera litura (90.85% & 87.92%) .Like wise AAREO & AAWEO were subjected to nematicidal activity against root knot nematode, Meloidogyne incognita. It was observed that AAREO exhibited more mortality over AAWEO at different concentration ( 1-5 μl/mL) , where as in the case of egg inhibition process AAWEO was found to be more effective (5.38% egg hatching) than AAREO (11.41% egg hatching)at a concentration of 10 μl/mL respectively. Based on observations of above mentioned study, it can be inferred that Artemisia annua can be a good natural resource of camphor and 1,8 cineole and the essential oils can be good source of antioxidant, anti-inflammatory, anti-diabetic, anti-feedant and nematicidal activities after proper clinical trials.