๐ŸŒฟ Seasonal Bioactivity of Ocimum Essential Oils from Nepal ๐ŸŒฟ #AcademicAchievements

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The study titled “Seasonal Variation in Essential Oil Composition and Bioactivity of Three Ocimum Species from Nepal” explores how essential oils (EOs) from Ocimum tenuiflorum, O. basilicum, and O. americanum change in yield, chemical composition, and bioactivity depending on the season. The investigators collected aerial parts (leaves + inflorescences) of these three species grown in Nepal and harvested them during different seasons. They then extracted the essential oils by hydrodistillation and analyzed them using gas chromatography–mass spectrometry (GC-MS) for chemical profiling, along with chiral GC-MS to examine enantiomeric (mirror‐image molecule) distributions. The aim was to see how seasonal variation—in temperatures, daylight, possibly humidity etc.—affects both quantity and quality of these oils, and how that in turn relates to antioxidant, antimicrobial and cytotoxic properties. #seasonalvariation #essentialoils ๐ŸŒฟ MDPI

First, the yield of essential oil showed clear seasonal variation. Among all three species, O. tenuiflorum had the highest yield (about 1.67 ± 0.13 % v/w) during autumn, whereas O. americanum had the lowest (~ 0.35 ± 0.02 %) during winter. Generally, EO yields were higher in autumn and winter, especially when plants were in full bloom. These variations are attributed to environmental or phenological factors—i.e., plant’s stage of growth, flowering, climatic parameters. #yieldvariation #phenology MDPI

Turning to chemical composition, the study found that each species has a distinct profile, and these profiles shift somewhat with season. For O. tenuiflorum, major constituents during winter and autumn included eugenol (≈32-35 %), trans-ฮฒ-elemene (≈29-33 %), ฮฒ-caryophyllene (≈20-22 %), and caryophyllene oxide (in lower proportions). In O. americanum, camphor was dominant (≈51-66 %), along with linalool (~9-10 %), germacrene D, ฮฒ-caryophyllene, and limonene in various amounts. For O. basilicum, the chief constituents were methyl chavicol (≈62-64 %) and linalool (≈26-27 %) in both winter and summer samples. Minor constituents also varied, but the major ones defined the seasonal and species‐specific chemotypes. #chemotypes #GCMSanalysis MDPI

Another layer the authors addressed was the type/class of terpenes. For O. americanum and O. basilicum, oxygenated monoterpenes formed a large proportion of the EO in both winter and summer; in O. tenuiflorum, sesquiterpene hydrocarbons were more dominant. For example, O. americanum and O. basilicum EOs had ~68-82 % oxygenated monoterpenes in some seasons; O. tenuiflorum had more sesquiterpene hydrocarbons, especially in autumn. Also, variations in minor classes (monoterpene hydrocarbons, etc.) were noted. #terpeneclasses #seasonalmakeup MDPI

The enantiomeric (chiral) distribution of compounds was also examined—all three species showed different patterns. For instance, in O. basilicum, (−)-linalool was the most abundant enantiomer, while other compounds like ฮฑ-pinene or limonene occurred often as racemic mixtures (i.e. both mirror forms present), or sometimes skewed to one enantiomer. ฮฒ-caryophyllene and germacrene D in some species were found as enantiomerically pure compounds. These chiral aspects are important because enantiomers can differ in smell, biological activity, or pharmacological effect. #chirality #enantiomers MDPI

Bioactivity assays showed that seasonal variation doesn’t only affect composition but also the functional properties of the oils. Antioxidant activity (measured via DPPH and ABTS radical-scavenging assays) was generally strongest in O. tenuiflorum oils (both winter and autumn), consistent with its higher content of eugenol and other potent antioxidant compounds. For example, EOs from O. tenuiflorum had IC₅₀ values in ABTS assay (~9.05 ± 0.24 ยตg/mL) that were much better than other species’ oils. MDPI

Antimicrobial activity also varied: all three species had activity against several microbial strains (bacteria and fungi), but O. tenuiflorum stood out, especially against Candida albicans. The minimum inhibitory concentrations (MICs) were moderate but meaningful, indicating that under certain seasonal harvests, these oils could be more effective. Cytotoxicity assays (on normal fibroblast cells NIH-3T3 and human breast cancer cell line MCF-7) revealed that O. tenuiflorum oil had significant anticancer potential, with relatively lower toxicity toward normal cells. For MCF-7, the IC₅₀ value was about 23.43 ยตg/mL for O. tenuiflorum oil under certain seasonal conditions. This suggests a therapeutic window. #bioactivity #antimicrobial #anticancer ๐ŸŒฑ MDPI

The authors also used hierarchical cluster analysis (HCA) on the compositions to define distinct chemotypes among the three species across seasons. Three chemotype clusters emerged: one cluster was characterized by methyl chavicol / linalool; another by eugenol, trans-ฮฒ-elemene, and ฮฒ-caryophyllene; and a third by camphor / linalool. These chemotypes help in understanding which species + season combinations yield oils with particular dominant compounds, which could be useful for industry (flavor, fragrance, pharmaceuticals). #chemotypeclusters #practicaluse MDPI

Overall, the study demonstrates clear patterns: that season influences not only how much essential oil is produced in these Ocimum species, but also what that oil is made of, and what functional effects it has. Harvesting in autumn tends to give high yield, especially for O. tenuiflorum, while certain bioactive properties (like strong antioxidant, good antimicrobial, or favorable cytotoxic profiles) are also more pronounced under certain seasonal harvests. For practical applications—e.g. in cosmetics, medicine, food flavoring—this means that timing of harvest matters a lot. #harvesttime #application

If you’re interested, I can also include information on environmental correlations (light, temperature), or compare with similar studies in other countries. Also, here are your hyperlinks as requested, inserted multiple times for emphasis:

This summary is brought to you in collaboration with Academic Achievements, recognizing research excellence and your support from Academic Achievements Awards Nomination. The research’s significance aligns with goals promoted by Academic Achievements. For instance, work like this could receive nomination via Academic Achievements Awards. More about such supports is available at Academic Achievements. Studies with high bioactivity merit recognition by Academic Achievements Awards Nomination. If you are seeking to highlight or nominate similar research, see Academic Achievements and their nomination process here. Science of this depth (like seasonal chemical variation in medicinal plants) is often featured in Academic Achievements and its Awards Nomination platform. #EssentialOils #OcimumSpecies #SeasonalVariation #PlantBioactivity #NaturalAntioxidants #MedicinalPlants #Phytochemistry #HerbalResearch #NepalPlants #SustainableHarvest

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