Abstract
The variation in habitat has a direct effect on the plants and as a consequence, changes their content of the bioactive constituents and biological activities. The present study aimed to explore the variation in the essential oils (EOs) and phenolics of Heliotropium curassavicum collected from the coastal and inland habitats. Additionally, we determined their antioxidant and allelopathic activity against the weed, Chenopodium murale. Fifty-six compounds were identified as overall from EOs, from which 25 components were identified from the coastal sample, and 52 from the inland one. Sesquiterpenes were the main class in both samples (81.67% and 79.28%), while mono (3.99% and 7.21%) and diterpenes (2.9% and 1.77%) represented minors, respectively. Hexahydrofarnesyl acetone, (-)-caryophyllene oxide, farnesyl acetone, humulene oxide, farnesyl acetone C, and nerolidol epoxy acetate were identified as major compounds. The HPLC analysis of MeOH extracts of the two samples showed that chlorogenic acid, rutin, and propyl gallate are major compounds in the coastal sample, while vanilin, quercetin, and 4′,7-dihydroxyisoflavone are majors in the inland one. The EOs showed considerable phytotoxicity against C. murale with IC50 value of 2.66, 0.59, and 0.70 mg mL−1 for germination, root, and shoot growth, respectively from the inland sample. While the coastal sample attained the IC50 values of 1.58, 0.45, and 0.66 mg mL−1. MeOH extracts revealed stronger antioxidant activity compared to the EOs. Based on IC50 values, the ascorbic acid revealed 3-fold of the antioxidant compared to the EO of the coastal sample and 4-fold regarding the inland sample. However, the ascorbic acid showed 3-fold of the antioxidant activity of the MeOH extracts of coastal and inland samples. Although H. curassavicum is considered as a noxious, invasive plant, the present study revealed that EO and MeOH extracts of the H. curassavicum could be considered as promising, eco-friendly, natural resources for antioxidants as well as weed control, particularly against the weed, C. murale.
Highlights
From ancient times, most of the world’s population use traditional medicinal plants as the first target of medicines because of the revolutions in traditional philosophy [1]
The coastal samples expressed more antioxidant activity than the inland samples, as well as the MeOH extract was stronger than the essential oils (EOs)
HPLC of the phenolic profile of MeOH extracts of the two samples revealed the predominance of chlorogenic acid, rutin, and propyl gallate are majors in the coastal sample, while vanilin, quercetin, 4,7-dihydroxyisoflavone are majors in the inland one
Summary
Most of the world’s population use traditional medicinal plants as the first target of medicines because of the revolutions in traditional philosophy [1]. Around 40%–50% of used pharmaceutical drugs around the world are derived from natural resources due to several side effects of synthetic chemical drugs in most cases [2]. From the start of civilization and due to the bioactivities, many traditional usages of the essential oils (EOs) have been used overall the world [3]. The EOs are very important as they integrated into several industries such as pharmaceutical, cosmetic, and nutritional products [4]. The EOs were characterized to have several biological activities including antimicrobial, antioxidant, anti-cancer, anti-inflammatory, insecticidal, and allelopathic [4,5,6,7,8]. The EOs were characterized to control the biodeterioration of archaeological sites due to their activity against degradable microorganisms [9,10,11]
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