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Plants of the Clerodendrum genus, known for their rich phytochemical profiles, are used in traditional Chinese, Korean, Japanese, and Indian medicine to treat various ailments, including inflammation, hypertension, diabetes, hyperlipidemia, and cancer. Due to the limited natural availability of these plants, there is a growing interest in utilizing in vitro culture techniques to produce their bioactive compounds sustainably. In this study, the effects are compared of Murashige and Skoog (MS), Woody Plant medium (WP), Gamborg B5 (B5), and Schenk and Hildebrandt (SH) basal media on growth, biomass accumulation, and polyphenolic compound production in shoot cultures of Clerodendrum colebrookianum and Clerodendrum trichotomum . The composition of the culture medium significantly influenced the growth and metabolic profiles of both species. C. trichotomum exhibited the highest proliferation potential on WP and SH media, while C. colebrookianum was similar on WP, SH, and B5 media (multiplication factor of about 20). Dry weight accumulation was highest in C. trichotomum grown on SH medium (0.292 g/culture), while C. colebrookianum achieved a comparable biomass on SH and WP media (0.240 g/culture and 0.228 g/culture, respectively). The chemical analysis showed similar secondary metabolite profiles between the two Clerodendrum species with phenylethanoids such as acteoside being the predominant bioactive compounds in hydromethanolic extracts. WP medium was the most favorable for polyphenol accumulation in C. colebrookianum (64.5 mg/g DW), while the SH medium yielded the highest total polyphenol content in C. trichotomum (36.6 mg/g DW). In this study, the importance is underscored of basal medium selection in optimizing the in vitro production of bioactive polyphenolic compounds in Clerodendrum species, providing a foundation for the sustainable and scalable production of these pharmacologically significant metabolites.

Abiotic elicitation with heavy metals has demonstrated considerable potential to stimulate the production of industrially important secondary metabolites in plant in vitro cultures. The present study investigates the effect of exogenous silver nitrate and cadmium chloride supplementation on flavonoid and phenolic acid production, as well as other indicators of oxidative stress, in shoot cultures of Dracocephalum ruyschiana L. Owing to the presence of bioactive polyphenolic compounds, this Mongolian medicinal plant is traditionally used as an anti-inflammatory, antibacterial and antipyretic agent. The shoots were cultured for three weeks, and then, cadmium (Cd 2+ ) and silver (Ag + ) ions (50 or 100 µM) were added to the medium. The maximum proliferation rate was observed in the presence of 100 µM Ag + (almost 5), the highest chlorophyll content in the presence of 100 µM Cd 2+ (0.6 mg/g FW) and the highest biomass was observed with both these treatments (73.4-75.7 g FW and 7.53-7.72 g DW). UPLC-PDA-ESI-MS analysis revealed four phenolic acids and five flavonoid derivatives in the hydromethanolic extract of D. ruyschiana shoots. All treatments stimulated the production of rosmarinic acid (RA), which was the dominant compound in the analyzed culture; the highest level of RA, i.e., about three times higher than the control, was noted in shoots exposed to 50 µM Cd 2+ (14.72 mg/g DW), whereas the level of most flavonoids in the culture increased most significantly when exposed to Cd 2+ at a concentration of 100 µM. Moreover, the shoots grown in the presence of 100 µM Cd 2+ exhibited significantly higher antioxidant potential in comparison to the control. Our findings indicate that heavy metals are able to stimulate phenolic compound biosynthesis in Dracocephalum shoots without any negative impact on their growth. These results could be of significant importance for the medical, nutraceutical and agronomic industries.

Harlequin glory bower ( Clerodendrum trichotomum ) is a shrub or small tree belonging to the Lamiaceae family, native to Japan, Korea, and eastern China. It has esthetic value and in Europe, it is cultivated as an ornamental plant. Its sweet-smelling flowers have a white or pink crown. The calyx turns from green to pink-purple over time, providing an especially decorative touch around surrounding the ripe deep-blue fruits that persist until winter. In the areas of its natural occurrence, the leaves and young shoots of C. trichotomum , and sometimes the roots, flowers and fruits, are used in folk medicine due to its anti-inflammatory, analgesic, anticancer, sedative, and hypotensive effects. Products based on Harlequin glory are also used in the treatment of rheumatoid arthritis, joint pain, skin inflammation, or asthma. Preliminary research on the composition of raw material suggests that its health-promoting effect is associated with the presence of numerous secondary metabolites, including phenylpropanoids, flavonoids, lignans, terpenoids, steroids, alkaloids, and anthraquinones. This work reviews the current state of knowledge about the phytochemistry and in vitro and in vivo pharmacological properties of the extracts and main active components isolated from C. trichotomum . It also indicates that before it can be used in modern medicine, further research is necessary regarding the safety and efficacy of the raw material, its mechanisms of action, and dosage.

Salvia miltiorrhiza is a medicinal plant that synthesises biologically-active tanshinones with numerous therapeutic properties. An important rate-limiting enzyme in the biosynthesis of their precursors is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). This study presents the organ-specific expression profile of the S. miltiorrhiza HMGR4 gene and its sensitivity to potential regulators, viz. gibberellic acid (GA 3 ), indole-3-acetic acid (IAA) and salicylic acid (SA). In addition, it demonstrates the importance of the HMGR4 gene, the hormone used, the plant organ, and the culture environment for the biosynthesis of tanshinones. HMGR4 overexpression was found to significantly boost the accumulation of dihydrotanshinone I (DHTI), cryptotanshinone (CT), tanshinone I (TI) and tanshinone IIA (TIIA) in roots by 0.44 to 5.39 mg/g dry weight (DW), as well as TIIA in stems and leaves. S. miltiorrhiza roots cultivated in soil demonstrated higher concentrations of the examined metabolites than those grown in vitro. GA 3 caused a considerable increase in the quantity of CT (by 794.2 µg/g DW) and TIIA (by 88.1 µg/g DW) in roots. In turn, IAA significantly inhibited the biosynthesis of the studied tanshinones in root material.