Natural plants are God gifted treasures for humans which possess a widespread variety of biological compounds involved in pharmaceutical and agricultural industry. These products contain substantial potential as natural antioxidant and also commonly used against various insects 25,26.
Citrullus colocynthis is a valuable source of antioxidant potential such as butanol extract from C. colocynthis fruit showed IC50 values as 6 µgmL− 1 whereas, fruit aqueous extract presented IC50 values as 241.25 µgmL− 1. Antioxidant properties of C. colocynthis leaves and roots extract was also documented as 45.98, 39.81% and 36.65 from leaves as well as 29.12, 35.51 and 33.83% DPPH inhibition was recorded from hexane, aqueous and ethanol extract respectively 12. Results documented by Benariba et al. 28 are also in accordance with our findings who reported inhibition of DPPH radical from seed extract of C. colocynthis being IC50 values as 500, 580 and 350 µgmL− 1 via aqueous, hydro-methanolic and ethyl acetate extract respectively. The analysis of C. colocynthis extracts documented the existence of various biochemical compounds as tannins, terpenoids, flavonoids and coumarins responsible for the pronounced antioxidant as well as other biological activities of this plant 29. Initial screening for phytochemical of C. colocynthis revealed the existence of plenty of flavonoids and phenols showed the significant antioxidant activity as 88.8% from fruit extract with potential free radical scavenging consequences at a concentration of 2500 µg mL− 1 4. The quantification of phenolic and flavonoids contents from solvent extract of C. colocynthis roots, leaves and fruits extracts was evaluated to compare the antioxidant activities. The amounts of total phenolic and flavonoids contents were (3.07–18.6 mgg− 1 and 0.51–13.9 mgg− 1 of dry sample respectively, followed by roots and fruits extract. Ethanol extract of leaves possessed the highest antioxidant activity as well as DPPH radical scavenging activities from roots and fruits extract 30.
In a study documented by Chawech et al. 31 reported the antibacterial activity of isolated compound Cucurbaticin E and Gluco- Cucurbaticin E from C. colocynthis against Bacillus cereus and Enterococcus faecalis. The minimum inhibitory concentration (MIC) values were 0.625 and 1.25 mgmL− 1 respectively. Moreover, all of the populations of C. colocynthis extract showed antibacterial activity against Pseudomonas aeruginosa and Escherichia coli, Enterococcus faecalis and Staphylococcus aureus and antifungal activity against four Candidia species i.e. Candida krusei, Candida glabrata, Candida parapsilosis and Candida albicans 32.
Extracts and essential oils from plant origin contain secondary metabolite; phenolic, steroid and terpenoids compounds which are toxic in nature and are stored in the plant cells and bears bio-pesticidal properties against pathogens and insect pests. Moreover, they are easily biodegradable, benefiting their existence without causing severe damage to the environment and humans 33–35. Literature review showed that there are several examples of plant products used in plant protection measures as a broad spectrum of plant pathogenic fungi, for instance, thymol and carvacrol have antifungal activity against Botrytis cinerea and Fusarium spp. Results indicated that these compounds could be employed independently as fungicidal agents against various phytopathogenic fungi 36. Besides, α-cadinol and T-muurolol compounds isolated from the Calocedrus macrolepis exhibit significant fungicidal activity against Fusarium oxysporum and Rhizoctonia solani 37. On the other hand, methanolic extract from the rhizome of Acorus gramineus comprises of numerous chemical compounds such as caryophyllene, a-asarone, methyl isoeugenol, isoasarone safrole possessed antifungal activities however, asaronaldehyde (2,4,5-trimethoxybenzaldehyde) presented complete control of Phytophthora infestans in potatoes and tomatoes whereas, it showed 75% control of R. solani 38. Our findings on antifungal activity of triterpenoids (Spinasterol, 22,23-dihydrospinasterol) were supported by Quiroga et al. 39 that lactones, sesquiterpen and triterpenes from Schinus molle's fruits and leaves possessed antifungal potential against Alternaria alternate, Penicillium cyclopium, Aspergillus niger, Aspergillus flavus Microsporum griseum and Penicillium italicum. Similarly, a flavonoid 4’-methoxy-5,7-dihydroxyflavone 6-C-glucoside isolated from the stem and leaves of Aquilegia vulgaris, presented its antifungal activity against mold A. niger 40. The antimycotoxigenic and antifungal activity of alcoholic and distilled water extracts of C. colocynthis were evaluated against Aspergillus flavus and Aspergillus ochraceus and showed an excellent antifungal activity against A. ochraceus with good antiochratoxigenic power in the liquid medium which supported findings about antifungal activity and triterpenoids spinasterol, 22,23-dihydrospinasterol 41.
Activity of some of the biological compounds such as camphor, pulegone and verbenone which were isolated from Myristica fragrans was assessed against German cockroach Blattellea germanica with LC50 values as 0.07 mgcm− 1, 0.06 mgcm− 1 and 0.07 mgcm− 1 respectively 42. Similarly, other compounds like, carvecol, eugenol, p-cymene, isoeugenol and thymol had displayed anti-adulticidal potential at 1 mgadult− 1 against B. germanica 43. Likewise, Spinasterol, 22,23-dihydrospinasterol exhibited medicinal and cytotoxic properties, moreover, the same was characterized from Bougainvillea spectabillis exhibited sturdy inhibition of enzyme xanthine oxidase with IC50 values as 39.21 µM 16. Our results on toxicity of spinasterol, 22,23-dihydrospinasterol revealed that it exhibited potential insecticidal activity and caused significant mortality of M. persicae. Similar outcomes were described by Torkey et al. 44 who reported activity of the 2-O-β-D-glucapyranosylcucurbitacin E isolated from C. colocynthis against Aphis craccivora with momentous mortality of this pest with LC50 of 11,003 ppm. Moreover, insecticidal activity of isolated compound from Eupatorium adenophorum 9-oxo-10,11-dehydroageraphorone was appraised against Pseudoregma bambucicola exhibited mortality of 73.33% at 2 mgmL− 1 with 6 h exposure. Moreover, 100% control of this pest was recorded at the similar concentration at one month of post exposure in a field experiment 45.
Contact toxicity of a new botanical insecticide Dayabon (SL 10%) was evaluated on different life stages of M. persicae. The estimated LC50 on first, second, third and fourth instar nymphs and adults were 3254, 3387, 4194, 3839 and 3508ppm, respectively without leaving residues 46. The extract of Solanum incanum fruits sap at different concentrations showed some level of insecticidal and deterrent activities against green peach aphid 47. However, the insecticidal and deterrent activity of Solanum incanum may attributed to the existence of saponins, which caused changing of feeding behavior, molting process and causing death at different developmental stages 32–34.
The efficacy of extract from Xanthium strumarium, Tanacecetum parthenium, Hypericum calycinum were assessed on M. persicae showed nymphal mortality of 89, 88 and 57% respectively however, the adults mortality at the same concentration was recorded as 12, 82 and 88% respectively 48. Similarly, 49 evaluated the leaf extract of Ricinus communis against M. persicae and the results demonstrated that Ricinus communis was most toxic to M. persicae (553ppm) followed by Robinia pseudoacacia to 1150ppm at exposure of 24 h however, Lantana camara was the least toxic at 6660 ppm. In a study, 50 described that, essential oil from Foeniculum vulgare caused significant mortality, however, this mortality may attribute to the major compounds like trans-anethole (67.9%) and fenchone (25.5%), with (LC50 = 0.6 and LC90 = 2.4 mL L− 1) however, found safe on non-target organism. These results are in accordance with our results on mortality of M. persicae using Spinasterol 22, 23 dihydrospinasterol.
Our results also showed that antioxidant activity of Spinasterol, 22, 23-dihydrospinasterol versus antifungal and insecticidal is highly significant.
Although, different studies had been conducted on extracts, essential oils and isolated compounds from natural plants as their antioxidant, antimicrobial, antifungal an insecticidal activities but such activities of Spinasterol, 22,23-dihydrospinasterol was not evaluated so for. Thus, this research work was performed for the first time to investigate the antioxidant, antifungal and continued to assess aphicidal properties against adults of M. persicae.