Differential Expression of Oman’s Wild Lavender, Lavandula subnuda for Chemical Composition towards Medicinal and Aromatic Application

Abstract

Plants have been used directly or indirectly as medicines for over 5000 years as a source of antibiotics, antineoplastics, analgesics, and cardio-protective, among others. Approximately 70–90% of the population in developing countries continue to use ancient medicines based on plant extracts for treatment. Recently, the isolation and identification of biologically active compounds and molecules from nature have led to the discovery of new therapeutics, prompting the improvement of the health and pharmaceutical sectors. Phytochemicals revolve around the pharmaceutical industry's research and development (R&D) sector as a source of new molecules leading to the development of new novel drugs. Given the above, the present investigation addresses the differential nature of wild lavender (Lavandula subnuda Benth) plants of diverse locations in Oman with respect to their chemical composition of the essential oil in addition to morphological characters and chlorophyll contents of leaves to explore the possibility of isolating its prime chemical compounds on a commercial scale in perfumery industry. There are no previous studies so far who have reported on essential oil recovery and chemical composition exclusively in respect of Lavandula subnuda. Composite samples of ten randomly selected plants were collected from wadi habitats of four diversified locations. Edaphic features of managed sites were recorded, and their soil chemical contents were determined following instructions using S1 Titan/Tracer 5/CTX equipment of Bruker developed based on energy dispersive X-ray fluorescence (EDXRF). Morphological traits were measured using a ruler, and chlorophyll contents were recorded using the atLEAF CHL Plus chlorophyll meter as atLEAF values. The essential oil was extracted using ETHO X's advanced microwave extraction system and analyzed for chemical compounds using GC-MS analysis on Shimadzu GC-2010 Plus gas chromatograph. The experimental data were analyzed statistically, wherever required, by applying basic statistics of the EXCEL -16 version. The results indicated that in general, the Lavandula subnuda plants of locations of high altitudes had higher expressivity in all the morphological traits and chlorophyll contents than those of low altitudes. The essential oil recovery, however, was found to be higher from the plant samples of lower altitudes (0.70 to 0.79% (w/w)) than from those of higher mountains/ altitudes (0.15 to 0.18% (w/w)). The pattern of values of commonly occurring chemical contents of essential oils was different. Each essential oil's top ten chemical compounds contributed about 80% of the total in four locations. Of the ten top chemical compounds, eight compounds, namely D-Germacrene (42.67%) from Wadi Al-Khod, Estragole (32%) and Linalool (23.89%) from Wadi Halban), trans-Borneol (23.46%) and 4-Terpineol (18.73%) from Wadi Najd Al-Waqba and Kessane (18.60%), beta-cis-Caryophyllene (13.68%) and beta-Elemene (10.618%) from Wadi Al-Hayul, were found highest in quantity and had huge potential for further application. It is concluded that there exists a higher possibility of adapting Good Agriculture Practice (GAP) to produce the highest herbage yield of vegetative parts of Lavandula subnuda plants based on morphological features under wild conditions to extract these compounds on a commercial scale in both the pharmaceutical and perfumery industries. Keywords: Morphology, Chlorophyll, Chemical compounds, Differential Expression, Lavandula subnuda,, Lamiaceae