Phytochemical Profile and Insecticidal Potential of Leaf Essential Oil of Psidium guajava Growing in North Central Nigeria Lamidi Ajao Usman, Etimbuk Daniel Akpan, Olusegun Adebayo Ojumoola, Ridwan Olanrewaju Ismaeel, Aliu Bola Simbiat Journal of the Mexican Chemical Society, 2025 Loss of stored maize grains via infestation by Sitophylus zeamais contributes to food insecurity. This necessitates the use of synthetic chemicals by farmers to curtail the pest. Unfortunately, the pesticides are toxic to humans and unsafe for the environment. Interestingly, some plants possess phytochemicals that exhibit insecticidal activity without these drawbacks. This activity is linked to the type of phytochemicals, whose presence depends on environmental conditions that change with time of collection of plant samples. It is on this basis that we investigated how time of harvest affects the phytochemicals and insecticidal activity of P. guajava leaf essential oils. To accomplish these, pulverized leaves (500 g) from 7.00am and 1.00pm harvests were hydrodistilled individually for three hours using a Clevenger set up. GC–MS technique was used to characterize the oils while contact toxicity bioassay was used to assess the insecticidal activity of the oils. The yields of essential oils obtained from the leaves were 0.27±0.015 and 0.24±0.018 (w/w)%. β-Caryophyllene (14.7 and 18.2%), α-guaiene (13.7 and 10.6%), α-selinene (10.9 and 12.9%), globulol (9.5 and 8.1%), caryophyllene oxide (7.8 and 7.0 %) and eucalyptol (5.6 and 5.8 %) existed in higher quantities in the GC-MS results. Both oils were active against S. zeamais with LT50 of 59.23 and 121.09 hours and the highest activity was recorded for the oil of afternoon harvest. The oil from afternoon harvest can therefore serves as a cheaper and more innocuous substitute to synthetic insecticide for S. zeamais management in stored maize.
Effect of Time of Harvest on the Chemical Composition and Antioxidant Potential of Leaf Essential Oil of Syzygium guineense Growing in North Central Nigeria (Willd.) Dc. Var. Ajao Lamidi Usman, Ridwan Olanrewaju Ismaeel, Alfanla Kamaldeen Musa Journal of the Mexican Chemical Society, 2024 The use of synthetic antioxidants to ameliorate oxidative stress goes with side effects. Some plants are known to be sources of natural antioxidants and, hence, could be used as alternatives to synthetic antioxidants without side effects. Meanwhile, the presence of the phytochemicals that exhibit antioxidant activity in plants depends on environmental conditions that vary with the time of harvest of plant materials. This study, therefore, investigated the effect of time of harvest on the chemical composition and antioxidant potential of leaf essential oil of Syzygium guineense native to North central Nigeria. To accomplish these, pulverized (500 g) leaves of S. guineense harvested in the morning and afternoon were separately hydrodistilled and yielded 0.25 ± 0.002 % (w/w) and 0.27 ± 0.003 % (w/w) of essential oils. Characterization of the oils using GC-MS revealed the presence of twenty-two and twenty-three compounds in the oils from morning and afternoon harvests. The most abundant compound in the oils was β-bergamotene (30.1 % and 27.3 %). D-limonene (2.9 % and 5.6 %), β-ocimene (4.2 % and 10.2 %), α-santalene (7.4 % and 7.7 %), α-cedrene (8.6 % and 9.0 %), β-farnesene (9.1 % and 10.2 %) and calamenene (7.1 % and 5.2 %) were detected in significant quantities in the oils. DPPH radial scavenging assay was used to evaluate the antioxidant activity of the oils with butylated hydroxyl toluene (BHT) as standard. The oils exhibited antioxidant activity with IC50 of 41.92 μg/mL and 33.12 μg/mL for the oils from morning and afternoon harvests. Although the oils exhibited lower antioxidant activity than the standard (IC50 of 28.63 μg/mL), but the oils could be used to ameliorate oxidative stress after clinical trials.
PHYTOCHEMICAL PROFILE, ANTIOXIDANT AND ANTIDIABETIC POTENTIAL OF ESSENTIAL OIL FROM FRESH AND DRIED LEAVES OF Eucalyptus globulus L. A. Usman, O. S. Oguntoye, R. O. Ismaeel Journal of the Chilean Chemical Society, 2022 Pathogenesis of type 2 diabetes has been linked to oxidative stress. Synthetic drugs in use for the management of the stress and type 2 diabetes are expensive and their usage are associated with side effects. Some essential oils exhibited antioxidant and antidiabetic properties devoid of the side effects. Their activities are attributed to the type of phytochemicals whose presence in the oils of the fresh and dried samples are determined by environmental factors. This study therefore aimed at monitoring the effect of air-drying at ambient temperature on the phytochemical profile, antidiabetic and antioxidant potentials of leaf essential oils of E. globulus. To achieve this, 500 g of fresh and dried leaves of E. globulus were separately pulverized and hydrodistilled for three hours. The leaves yielded oils in the range of 0.22–0.55% (w/w). GC and GC–MS analyses of the oils revealed predominance of α-phellandrene (4.6–10.5%), D-limonene (18.5%), β-myrcene (20.8%), m-cymene (5.0-29.8%), terpinen-4-ol (0.4-4.7%), globulol (3.1-10.5%) and spathulenol (4.9-18.8%). The antioxidant activity of the oils was determined by DPPH and FRAP assays using ascorbic acid as standard. α-Amylase and α-glucosidase inhibitory assays were used to determine the antidiabetic potential of the oils using acarbose as standard. The oils exhibited antioxidant and antidiabetic activities that compared favourably with the standards. Meanwhile, the oil obtained from the leaves air-dried for three days showed the highest activities with competitive mode of α-amylase and α-glucosidase inhibitions. The oil could serve as alternative for the management of oxidative stress and type 2 diabetes.
Chemical Composition of Root Essential oil of Peperomia pellucida (L.) Kunth. Grown in Nigeria L.A. Usman, R.O. Ismaeel Journal of Essential Oil Bearing Plants, 2020 Essential oil from leaf, root, and stem of Peperomia pellucida native to different countries have been isolated and characterized. Variations in the chemical composition of the essential oil from the same part of the plant were established. Meanwhile, the root essential oil of P. pellucida native to Nigeria has not been studied. This work aimed at characterizing the root essential oil of P. pellucida growing in Nigeria. To achieve this, pulverized roots (500 g) of P. pellucida were hydrodistilled and yielded 0.03±0.12 % (w/w) of essential oil. Analysis of the essential oil using GC and GC/MS showed the presence of twenty-three chemical compounds. The essential oil was predominated by sesquiterpenoids, which constituted 87.5 % of the oil. Monoterpenoids constituted 2.9 % of the oil. β-fernesene (22.2 %) was the most predominant compound in the essential oil. Other principal constituents of the oil were; β-bisabolene (14.8 %), β-bergamotene (10.7 %), 1,4- cadinadiene (7.4 %), α-copaene (6.6 %) and isosativene (6.5 %). Terpinen-4-ol (2.3 %) was the major monoterpenoid in the oil, while neryl acetate (0.6 %) existed in appreciable quantity. The predominance of β- fernesene in the oil implied that the oil was of β-farnesene chemotype.
Chemical Composition and Antioxidant Potential of Fruit Essential Oil of Laggera pterodonta (DC.) Benth Grown in North Central, Nigeria L.A. Usman, R.O. Ismaeel Journal of Biologically Active Products from Nature, 2020 This study aimed at isolating, characterizing and evaluating the antioxidant potential of fruit essential oil of Laggera pterodonta native to Nigeria. Pulverized fruits (500 g) of L. pterodonta were hydrodistilled for 3 hours and yielded 0.07±0.02 % (w/w) of essential oil. The oil was analyzed using GC and GC-MS. The analyses revealed the predominance of sesquiterpenoids (92.7 %), while monoterpenoids constituted 1.5 % of the oil. The major compounds in the oil were α-bergamotene (29.3 %), β-bisabolene (16.9 %), α-copaene (8.8 %) and α-bisabolol (6.0 %). Terpinen-4-ol (0.5 %) and α-terpineole (1.0 %) were the only monoterpenoids detected in the oil. The antioxidant activity of the oil was determined using 2,2-diphenyl- 1-picryl hydrazyl (DPPH) radical scavenging assay. The oil exhibited antioxidant activity by scavenging DPPH radicals with IC50 of 6.05 μL/mL. The activity of the oil was higher than the activity of ascorbic acid with IC50 of 12.84 μl/ml used as standard. Therefore, the oil could serve as an alternative to synthetic drugs for the amelioration of oxidative stress.
Effect of Seasonal Variation on Chemical Composition, Antidiabetic and Antioxidant Potentials of Leaf Essential Oil of Eucalyptus globulus L. L.A. Usman, O.S. Oguntoye, R.O. Ismaeel Journal of Essential Oil Bearing Plants, 2020 This study investigated the effect of seasonal variation on the chemical composition, antioxidant and antidiabetic activities of essential oil from leaves of Eucalyptus globulus. Pulverized leaves (500 g) of E. globulus from dry and rainy season harvests afforded 0.54 and 0.43 % (w/w) of essential oils respectively when subjected to hydrodistillation. GC and GC/MS analyses revealed the presence of forty-five and thirty-three compounds that represented 95.4 and 98.4 % of the oils obtained from leaves harvested during the dry and rainy seasons. The principal constituents of the essential oils were; D-limonene, m-cymene, o-cymene, 6-camphenol, terpinen-4-ol, globulol, diosphenol and spathulenol. The oils showed scavenging activity for DPPH radical with IC50 of 20.15 (dry) and 11.23 μL/mL (rainy). The essential oils showed significant reducing powers of 356.46±0.88 (dry) and 394.34±0.95 (rainy) FRAP equivalent. The oils inhibited the activity of α-amylase with IC50 of 8.37 (dry) and 6.78 (rainy) μg/mL. The IC50 for the α-glucosidase inhibition of the oils were 6.19 (dry) and 7.20 (rainy) μg/mL. The antioxidant and antidiabetic activities of the oils compared favourably with the standards used for the study. Hence, the essential oils can serve as an alternative to synthetic drugs to ameliorate oxidative stress and management of type 2 diabetes.
Antidiabetic Potentials of Citrus aurantifolia Leaf Essential Oil Fatima Ibrahim, Lamidi Usman, Jubril Akolade, Oluwafemi Idowu, Azeemat Abdulazeez, Aliyu Amuzat Drug Research, 2019 Citrus aurantifolia leaf essential oil was extracted via hydrodistillation, chemical composition of the oil was analyzed using gas chromatography-mass spectrometry and its antidiabetic potentials was assessed in alloxan-induced hyperglycaemic rats using metformin as the reference drug for comparison. Chemical analysis showed that D-limonene (57.84%) was the major constituent of the oil. Other notable compounds identified were neral (7.81%), linalool (4.75%), sulcatone (3.48%) and isogeraniol (3.48%). Intraperitoneal administration of C. aurantifolia oil (100 mg/Kg b.wt.) to hyperglycaemic rats for 14 days caused significant reduction in fasting blood and hepatic glucose, whereas hepatic concentration of glycogen was significantly increased. Also, improvement in dyslipidaemia was observed in C. aurantifolia essential oil-treated hyperglycaemic rats; serum concentration of total cholesterol, triacylglycerol and low density lipoprotein-cholesterol were significantly reduced and high density lipoprotein-cholesterol was increased, resulting in decreased predisposition of rats to cardiac risks. Antihyperglycaemic potential of administration of the oil was lower but compared favourably with the oral antihyperglycaemic agent used as reference antidiabetic drug. Overall, data from this study showed that essential oil from the leaf of C. aurantifolia grown in North-Central Nigeria is a D-limonene chemotype. The oil showed considerable glucose lowering effect as well as the potential to ameliorate hyperglycaemia-induced dyslipidaemic complications in alloxanized rats.
Effect on germination and nutrient composition of storing cowpea [Vigna unguiculata (L.) Walp.] seeds in a hermetic atmosphere modified with essential oil vapour from leaves of sweet basil [Ocimum basilicum (L.)] Tropical Agriculture, 2018
Preservation of smoked African catfish, clarias gariepinus burchell against dermestes maculatus de geer (Coleoptera: Dermestidae) using neem seed oil-iodized salt mixtures Agriculturae Conspectus Scientificus, 2016
Bioactivity of rhizome essential oils from two varieties of Cyperus articulatus (L.) grown in Nigeria, using brine shrimp (Artemia salina) lethality tests Journal of Medicinal Plants Research, 2011
Effect of oral administration of ethanolic leaf extract of acanthospermum hispidium DC from Nigeria on some selected rat kidney enzyme activities Iranian Journal of Pharmaceutical Sciences, 2010
Chemical constituents and anti-inflammatory activity of leaf essential oil of Nigerian grown Chenopodium album L Excli Journal, 2010
