Antioxidant, antifungal, and aphicidal activity of the triterpenoids spinasterol and 22,23-dihydrospinasterol from leaves of Citrullus colocynthis L.

Abstract

Terpenoids from natural plant sources are valuable for their diverse biological activities that have important roles in the medical and agrochemical industries. In this study, we assessed the antioxidant, antifungal, and aphicidal activities of a mixture of spinasterol and 22,23-dihydrospinasterol from the leaves of Citrullus colocynthis. We used 1,1-diphenyl-2-picrylhydrazyl (DPPH) to assess antioxidant activity, and we measured antifungal activity using mycelium growth inhibition assays with three pathogenic fungi, Magnaporthe grisea, Rhizoctonia solani, and Phytophthora infestans. Aphicidal activity against adults of Myzus persicae was determined using in vitro and in vivo assays. Spinasterol and 22,23-dihydrospinasterol exhibited moderate antioxidant activity, even at lower concentrations: 19.98% at 0.78 µg mL−1, 31.52% at 3.0 µg mL−1, 36.61% at 12.5 µg mL−1, and 49.76% at 50 µg mL−1. Spinasterol and 22,23-dihydrospinasterol showed reasonable levels of fungicidal activity toward R. solani and M. grisea, with EC50 values of 129.5 and 206.1 µg mL−1, respectively. The positive controls boscalid and carbendazim were highly effective against all fungi except boscalid for M. grisea (EC50 = 868 µg mL−1) and carbendazim for P. infestans (EC50 = 8721 µg mL−1). Significant insecticidal activity was observed in both residual and greenhouse assays, with LC50 values of 42.46, 54.86, and 180.9 µg mL−1 and 32.71, 42.46, and 173.8 µg mL−1 at 72, 48, and 24 h, respectively. The antioxidant activity of spinasterol and 22,23-dihydrospinasterol was strongly positively correlated with their antifungal and insecticidal activity. Spinasterol and 22,23-dihydrospinasterol therefore show good antioxidant and aphicidal activity with moderate fungicidal activity, making them suitable candidates for an alternative to synthetic agents.

In Vitro Sprouted Plantlets of Citrullus colocynthis (L.) Schrad Shown to Possess Interesting Levels of Cucurbitacins and Other Bioactives against Pathogenic Fungi

“…susceptibility to C. colocynthis extracts greatly relies on the species and, within the same species, on the extraction solvent [ 10 ]. On the other side, if antifungal properties of both botanicals and pure compounds isolated from C. colocynthis have been variously described against some phytopathogens (for example, a mixture of spinasterol and 22,23-dihydrospinasterol obtained from the leaves [ 49 ], our observations didn’t provide any significant cue with respect to the aflatoxigenic species selected in this study. However, findings showing the absence of any antifungal or fungistatic potential of extracts on the A. flavus mycelium long-term growth weren’t completely unexpected: in fact, various studies have reported that several compounds, both synthetic and natural, are effective in lowering AF production without apparently interfering with the fungal hyphae elongation or mycelium development [ 13 , 50 , 51 , 52 , 53 ]; this phenomenon has been ascribed to the induction of physiological responses that possibly affect hyphal branching but not apex elongation, and thus result in unaltered colony marginal expansion—which is necessary for efficient colonization and utilization of the substrate.…”

Dynamic Variation of Amino Acid Contents and Identification of Sterols in Xinyang Mao Jian Green Tea

“…It is generally assumed that phytosterols play a key role in stabilizing the cell membranes in plants (as cholesterol does in animals) [ 30 ]; however, the chemical composition of sterols from XYMJ tea tree leaves remains elusive. Spinasterol and 22,23-dihydrospinasterol are triterpenoids that are produced by a number of plants [ 31 ]. An extract from the leaves of Mukia maderaspatana indicated that spinasterol and 22,23-dihydrospinasterol have potential antioxidant properties.…”

Pharmacology of α‐spinasterol, a phytosterol with nutraceutical values: A review

“…In cell-based in vitro studies and in animal experiments, α-spinasterol showed antiinflammatory and antioxidant activities through multiple mechanisms (Figure 3). Even at a very low concentration (0.8 μg/mL), spinasterol and 22,23-dihydrospinasterol showed significant antioxidant activity (Ahmed et al, 2022).…”