Effect of seasonal variation on phenolics, flavonoids and terpenoids in Mesosphaerum suaveolens (L.) Kuntze., and Ocimum basilicum L. using GC-MS and LC-MS/MS

Mesosphaerum suaveolens (L.) Kuntze. and Ocimum basilicum L., species belonging to Lamiaceae, are used in cosmetics and folk medicine. Most of the available studies focus on the phytochemical profile of these plants. The present study was aimed at understanding the metabolic content of both plants collected in summer, winter and rainy season. The plants were collected in all three seasons and analysed using gas chromatography -mass spectrometry (GC MS) and liquid chromatography using Agilent Jet Stream and Electrospray Ionization Quadrupole time of flight mass spectrometric detection. The total phenolics were found to be highest in the monsoon samples for M. suaveolens at 5.3 mg/mL ± 0.124 and in the summer samples for O. basilicum at 7.46 mg/mL ± 0.23. Total flavonoids were to be highest in summer samples in both M. suaveolens and O. basilicum with 3302 mg/mL ± 112.6 and 5210 mg/mL ± 74.57 respectively. Total terpenoids were found to be highest in the summer samples in both plants with 72 mg/mL ± 1.55 and 58 mg/mL± 1.413 in M. suaveolens and O. basilicum respectively. In total, more than 950 compounds were identified, with majority of the compounds identified being phenolics, flavonoids and terpenoids. Metabolic profiling revealed the presence of compounds such as ethers, esters, steroids, catechins, imidazoles, retinols, ketones, amino acids, alcohols and aldehydes. The comparative analysis also revealed that M. suaveolens showed more accumulation of compounds compared to Ocimum. This study led to an in-depth understanding of the metabolite content in Mesosphaerum, which is a less studied wild plant. It also helped in understanding how seasons influence the metabolite content of both plants which has also not been studied at length.