Silybin A and B are two major hepatoprotective flavonolignans produced predominantly in Silybum marianum fruits. Similar to other plant secondary metabolites, silybin production is enhanced by biotic or abiotic stresses under the expanse of plant growth and yield. In this study, a novel strategy for enhancing silybin production was investigated by applying a natural plant growth enhancer, moringa leaf extract (MLE), to the S. marianum plants cultivated under salinity abiotic stress. The experiment was conducted using a split-plot design with salinity as the main factor and MLE concentrations as the sub-factor. The individual and combined effects of salinity and MLE on the growth, yield, and silybin content of S. marianum were recorded. The MLE at concentrations of 5 g/L or 10 g/L was applied as foliar spray to S. marianum plants, which were irrigated with either tap water or saline (2000 ppm or 4000 ppm). Our results revealed that 10 g/L MLE effectively enhances the growth, yield, and silybin (A + B) content in S. marianum plants not exposed to salinity stress. On the other hand, for plants that were exposed to 4000 ppm salinity, the application of MLE was able to alleviate the salinity-induced adverse effects on some of the plant growth parameters but did not significantly increase their silybin (A + B) compositions. The current study also indicated that the increase in silybin contents was accompanied by the upregulation of the chalcone synthase 1 and 3 genes, which have been implicated in the synthesis of silybin.

ZnO nanoparticles (NPs) can be considered a highly efficient Zn source that has been widely used in agriculture to promote crop development and productivity. The turmeric (Curcuma longa) plant has several medical properties, and its rhizome is utilized as a spice in the food sector. In this work, C. longa leaves were sprayed with various concentrations of ZnO NPs to inspect their effect on growth, yield, and bioactive compound compositions. ZnO NPs considerably increased tumeric productivity, yield, and curcuminoid content versus the control treatment. The ZnO NPs concentration of 10 mgL⁻¹ was found to be the optimum concentration for producing the highest C. longa yields, while the concentration of 40 mgL⁻¹ promoted positive effects on photosynthetic pigments, bisdemethoxycurcumin, demethoxycurcumin, and curcumin contents. This demonstrates that ZnO nano-fertilizer promotes plant growth, yield characteristics, and curcuminoid component synthesis, and its application is therefore notably beneficial for progressive sustainable C. longa agriculture.

Simmondsia chinensis is a dioecious, long-lived perennial shrub. Its leaves contain several antioxidant flavonoids that have numerous pharmacological effects. Various strategies have been explored to propagate jojoba with enhanced pharmacological values. This research evaluates the bio-stimulatory impacts of He–Ne laser seed irradiation on seed germination, plantlet growth, and alteration of the composition and bioactivities of phytochemicals in jojoba plants. Jojoba seeds were irradiated for 5, 10, and 15 min before in vitro germination. Germination, growth, and multiplication parameters were recorded during germination, multiple-shoot induction, and rooting stages. The wound healing and antimicrobial activities of methanolic extracts from plant lines obtained from the non-irradiated (control) and 10 min irradiated seeds were compared by excision wound model in Wistar male rats and zone of inhibition assay. Our study revealed that laser irradiation increased seed germination, with the highest percentage observed in seeds irradiated for 10 min. Plant lines from the 10 min irradiated seeds produced more explants with higher explant heights and numbers of leaves, more roots, and higher photosynthetic pigment contents than those of control and other laser testings. By comparing plant extracts from the control and 10 min treatments, we observed that extracts from the 10 min treatment exhibited higher percentages of wound contraction and shorter epithelialization periods. In addition, these extracts also resulted in higher levels of angiogenesis elements (VEGF, TGF-β1, and HIF-1α) and reduced the inflammation regulators (IL-1β, IL-6, TNF-α, and NFκB) in the experimental rats. In concordance, extracts from the 10 min treatment also explained raised antibacterial activities towards Staphylococcus aureus and Escherichia coli. Our findings show that pre-sowing seed treatment with a He–Ne laser (632.8 nm) could be a good technique for stimulating S. chinensis plant growth and increasing the impact compound levels and biological activities.

The application of exogenously applied salicylic acid plays important roles in improving the growth, yield, and bioactive compound compositions of different plant species. Curcuma longa is a medicinal plant that is commonly used as a spice and food additive, and has antioxidant potential. In this study, an innovative strategy for enhancing active compound production was investigated by applying a natural plant growth enhancer—namely, salicylic acid (SA)—to C. longa plants. The experiment was conducted using a complete randomized block design. The effects of SA on the growth, yield, and chemical compound contents of C. longa were recorded. Our findings demonstrated that SA significantly improved C. longa growth, yield, and curcuminoid content when compared to control treatment, with SA at 10⁻³ M having the greatest effect. The study also indicated that the increase in the curcuminoid content was accompanied by the overexpression of the curcumin synthase 1 (CURS1), 2 (CURS2), and 3 (CURS3) genes, as well as the diketide-CoA synthase (DCS) gene, which have been implicated in the synthesis of curcuminoids.

Achillea fragrantissima Forssk. (Family: Asteraceae) has been used as a natural remedy in the Arabian region for its antihyperglycemic activity. As a result of the intensive demand for this plant in folk medicinal uses, its scarcity has become problematic. This study has explored methods that produce an efficient in vitro culture protocol for the conservation of this plant as well as the enhancement of its hypoglycemic activity. A. fragrantissima cultures on Murashige and Skoog (MS) medium supplemented with 3.6 µM/L of 6-benzyl aminopurine (BAP) for a two month period resulted in maximum in vitro shoot proliferation (12.33 shoots/explant) while MS medium supplemented with 2.4 µM/L 1-naphthalene acetic acid (NAA) provided maximum in vitro adventitious root formation (2.46 roots/shoot tip explant). Callus induction was favored by leaf explants cultured on MS medium and supplemented with 3 µM/L BAP and 3 µM/L IAA media in dark conditions. Further in vivo study of some selected feedings determined that the best hypoglycemic activity was obtained in either indole-3-butyric acid (IBA)-fed plants (24%) or NAA-fed plants (22%). Both treatments enhanced insulin-like activity in STZ-treated diabetic Sprague-Dawley rats when compared with the wild plant (10%). Moreover, the IBA-fed plants showed significant antioxidant activity while the NAA-fed plants inhibited salivary alpha amylase. The framework of this study provides in vitro culture methods that can sustain the cultivation of this over-exploited A. fragrantissima plant as well as increase its antioxidant and insulin-like activities.

Silymarin, a secondary metabolite found mainly in the Silybum marianum L. fruits, has been associated with the hepatoprotective activity of the plant. Among various elicitors, salicylic acid, a “Generally Regarded As Safe” compound recognized by the Food and Drug Administration, is one of those being used in the induction and enhancement of valuable plant secondary metabolite production in various plant species. In this study, two concentrations (10⁻⁴ and 10⁻³ molar) of salicylic acid have been applied to the S. marianum plants as foliar spray to investigate their effects on plant growth and yield, as well as the production of its bioactive compound, silymarin. Our results indicated that both concentrations of salicylic acid increased the plant height, the number of branches, leaves, and capitula, as well as the dried weight of roots, aerial parts, and fruits. The enhancement effects in plant growth and yield were accompanied by an increase in photosynthetic pigments such as chlorophyll-a, b, and carotenoids as well as element contents such as nitrogen, phosphorus, and potassium. The potential of salicylic acid as an elicitor for the enhancement of secondary metabolites in S. marianum was supported by the increase in silymarin’s major components, silybin (A + B), in the salicylic acid-treated plants. Concomitant expressions of CHS1, 2, and 3 genes that have been associated with the production of silymarin in S. marianum were also observed in the salicylic acid-treated plants. A lower concentration (10⁻⁴ M) of salicylic acid was found to be a better elicitor as compared with the 10⁻³ M salicylic acid. An increase of 3.4 times in capitula number and fruit dried weight as well as 2.6 times in silybin (A + B) contents were observed in plants sprayed with 10⁻⁴ M of salicylic acid as compared with the control.