Phytochemical screening, phenolic compounds determination, and antioxidant activity of Thymus satureioides from two regions of southern Morocco
EL OUAHMANI Nadia1*, EL GHAZOUANI Fatima1, ALEM Chakib2, ZEKHNINI Abderrahmane1, YACOUBI Bouchra1
1 Laboratory of Aquatic Systems, Faculty of Sciences, Agadir, Morocco.
2 Laboratory of Biochemistry of Natural Products, FST, Errachidia, Morocco
INTRODUCTION
Thymus saturieioides is an endemic plant of Morocco andAlgeria, belonging to the family of lamiaceae. This plant is verywell known in Morocco by its therapeutic virtues, hence itswide use in traditional medicine, it is also used as a condimentin culinary preparations. Several studies have shown thatThymus saturieioides is endowed with several biologicalactivities, such as antibacterial, antifungal and antioxidantactivity, due to the many secondary metabolites it contains,namely flavonoids and tannins etc...The objective of this study is to compare the phytochemicalcomposition and the antioxidant activity of Thymussaturieioides from two regions of south east Morocco.
The plant material used is collected from two areas at different altitudes 1800 m for Rheriss and 1300 m for Er-rich. Both localities belong to the province of Errachidia known by a dry continental climate.
ExtractionThe hydroalcoholic extraction was carried out by ethanol at 80% according to the following process :
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Systematic• Kingdom : Plantae• Subdomain : Tracheobionta• Division : Magnoliophyta• Class : Magnoliopsida• Subclass : Asteridae• Order : Lamiales• Family : Lamiaceae• Genus : Thymus• Species : Thymus saturieioides
Photochemical screening
The main families of secondary metabolites weredetermined by the qualitative method. The free quinoneswere determined with NaOH (DOHOU et al., 2003). Sterolswere revealed by the Liebermann Buchard test. Forpolyphenols, FeCl3 was used for their revelation, whilesaponin was determined by persistent foam method (Koffi etal., 2009). The revelation of tannins was done by FeCl3(Karumi, 2004).
Determination of total polyphenols
The content of total polyphenols was determined with themethod of (Singleton and Rossi, 1965), with modification(Amri et al., 2018), using folin-ciocalteu gallic acid was usedas standard and the results are expressed as mg AGE/ g drymatter.
Flavonoid assay
Flavonoid determination was performed with aluminumchloride (Amri et al., 2018). A standard range was performedwith rutin and the results are expressed as μg rutinequivalent/mg dry matter.
DPPH free radical scavenging activity
The DPPH radical scavenging assay was determined according tothe method reported by Masuda et al. (1999). The percentageinhibition of the DPPH radical was calculated according to theformula :
% 𝑜𝑓 𝑖𝑛ℎ𝑖𝑏𝑖𝑡𝑖𝑜𝑛 𝑜𝑓 𝐷𝑃𝑃𝐻 =𝐴𝑐 − 𝐴𝑠
𝐴𝑐𝑋 100
Ferric reducing antioxidant power FRAP
The FRAP technique consists in evaluating the antioxidantcapacity of a sample through the reduction of a ferric complexinto another ferrous one, this technique was carried outaccording to the Benzie and Strain 1996 method. The results areexpressed in µmol ascorbic acid equivalent antioxidantcapacities (AAEAC)/mg DW.
Statistical analysis
All the tests performed in this study were done in triplicate. Theresults of the different parameters studied are expressed asmean ± SE. The significant difference in the phytochemical studywas carried out by Student's test. Using IBM SPSS software (baseversion 26).
RESULTS
Secondary metabolites Thymus saturieioides
Er-rich
Thymus saturieioides
Rheriss
Tanins +++ +++
Saponines ++ ++
sterols ++ +
Polyphenols ++ ++
Free quinones ++++ ++++
Table 1 shows the results of the qualitative phytochemicalscreening, and demonstrates the presence of polyphenols,tannins, saponins and free quinones at the same intensity inboth varieties of Thymus saturieioides, except for sterols wherethe Er-rich variety is more intense.
DescriptionThymus saturieioides is a shrub of 10 to 30 cm, very aromaticperennial, with woody stem, growing in rather dry stonygrounds.
Thymus saturieioides
Er-rich
Thymus saturieioides
Rheriss
Polyphenols mg AGE/ g DW 70.75± 1.92a 73.02± 4.8a
Flavonoïds μg RE/mg DW 184.4 ±9.7a 155.5± 3.12b
MATERIALS AND METHODS
The results of the polyphenol assay did not show anysignificant difference between the Er-rich and Rherissharvests. The results Thymus saturieioides Er-rich is moreconcentrated in flavonoid.(Table 2).
Thymus saturieioides
Er-rich
Thymus saturieioides
Rheriss
IC 50 DPPH mg/ml 0.81± 0.064a 0.57 ± 0.053b
FRAP µmol (AAEAC)/mg DW 39.69± 1.43a 47.05± 4.47b
Both varieties tested showed antioxidant activity. According tothe statistical tests the antioxidant activity is more intense inThymus saturieioides Rheriss (Table3).
The results show that Thymus saturieioides is a plant of thelamiaceae family, containing high concentrations of secondarymetabolites which explains its biological effects, especially theantioxidant activity. Thymus saturieioides Rheriss showed amore intense antioxidant activity, this can be explained by thedifference in altitude which is greater for the latter.
Table 1 : phytochemical screening of to region Er-rich and Rheriss Thymus saturieioides
Table 2 : Polyphenols and Flavonoïds concentration of Thymus saturieioides of Er-rich and Rheriss
CONCLUSION
Table 3 : antioxydant activity of Er-rich and Rheriss Thymus saturieioides
