Phytochemistry, biological activities and economical uses of the genus Sterculia and the related genera: A reveiw

Efficacy of Sterculia diversifolia Leaf Extracts: Volatile Compounds, Antioxidant and Anti-Inflammatory Activity, and Green Synthesis of Potential Antibacterial Silver Nanoparticles

Sterculia diversifolia, widely distributed in Jordan as an ornamental plant, is a synonoum for Brachychiton populneus. Phytochemical studies examining the volatile chemicals in Sterculia diversifolia leaves are limited, despite the rising demand for their numerous applications. Furthermore, it was only recently that a report described the friendly synthesis of silver nanoparticles (AgNPs) using aqueous extract derived from Brachychiton populneus leaves. Therefore, AgNPs were produced using either aqueous plant extracts (AgWPE) or ethanolic plant extracts (AgEPE), and Shimadzu GC-MS equipment was used to detect volatile compounds in the ethanolic leaf extracts. GC-MS profile of leaf ethanolic extracts of the Jordanian chemotypes of S. diversifolia revealed the existence of major components: (3β)-Lup-20(29)-en-3-ol acetate (30.97%) and 1-octadecyne (24.88). Other compounds are squalene (7.19%), germanicol (6.23), dl-α-tocopherol (5.24), heptacosane (4.41), phytol (3.54) and pentacosane (2.89). According to published studies, these reported chemicals have numerous uses, including as animal feed, vitamin precursors, possible eco-friendly herbicides, antioxidants, and anti-inflammatory agents. Aqueous extracts of S. diversifolia leaves had total phenolic of 5.33 mg GAE/g extract and flavonoid contents of 64.88 mg QE/g extract, respectively. The results indicated the contribution of phenolic and flavonoids to this plant’s anti-inflammatory and antioxidant properties. The reduction in AgNO₃ to AgNPs using S. diversifolia leaf extracts was confirmed by the change in solution color from colorless to dark black. Further characterization was attempted by X-ray diffraction, Malvern zeta-sizer and scanning electron microscope. The efficacy of synthesized Ag nanoparticles using aqueous or ethanolic plant extract of S. diversifolia against the Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus showed appreciable activity at 25 µg/mL concentration compared to the source plant extracts.

Chemical constituent with cytotoxicity from Sterculia diversifolia

One new coumarin (stercularin), along with eleven known compounds, was isolated for the first time from ethyl acetate fraction of Sterculia diversifolia. The structures of isolated compounds were characterized by spectroscopic techniques such as EIMS, ¹H-NMR and ¹³C-NMR. Compound 1 showed significant cytotoxicity by brine shrimp lethality assay (LD₅₀: 8.00 μg/ml) and PC-3 cell lines protocol (IC₅₀: 3.92 ± 0.20 μg/ml), respectively.

In vitro antioxidant and antimicrobial potential of Sterculia urens Roxb. root extract and its bioactive phytoconstituents evaluation

Background

The plant Sterculia urens Roxb. of Malvaceae family is comparatively understudied. Genus Sterculia is widely recognized by its phytomedicinal and ethnomedicinal attributes. The study is aimed to evaluate the qualitative analysis, Fourier transform infrared (FT-IR), thin layer chromatography (TLC), total phenolic content (TPC), antioxidant and antimicrobial activities of the crude hydro-methanolic extract of S. urens root.

Results

The antioxidant activity, antimicrobial assay for clinical isolates, and TPC were measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity, agar well diffusion method, and Folin–Ciocalteu assay respectively. Hydro-methanolic extract confirmed the presence of alkaloids, flavonoids, tannins, phenols, saponins, steroids, and glycosides as primary and secondary metabolites, which was later confirmed by TLC. FT-IR spectroscopy revealed the presence of alkanes, alkenes, alkyl halides, halogen compounds, primary alcohol, tertiary alcohol, aldehyde, aromatic amine, secondary amines, amide group, and carboxylic acid. The crude extract was composed of a significant quantity of total phenolic content with 705 ± 0.40 mg GAE/g. Synergistically, the IC50 value of the crude extract and ascorbic acid was found to be 27.055 μg/ml and 37.244 μg/ml, respectively, which suggests that root extract possesses strong antioxidant properties. The majority of the microbial strains exhibited varying degrees of sensitivity to the root extract with a notable inhibitory effect against Escherichia coli, Klebsiella pneumoniae, and Penicillium glaucum.

Conclusion

The findings of this analysis suggest that the hydro-methanolic extract from S. urens root exhibit antioxidant activity quantified by its ability to scavenge DPPH; antimicrobial activity displayed appreciable microbial sensitivity. These properties are associated with the presence of high phenolic content, different secondary metabolites, and their functional groups. The results are suggestive that S. urens root is rich in bioactive compounds, which serve as a novel natural source for potential therapeutic applications.

Graphical abstract

Important Flavonoids and Their Role as a Therapeutic Agent

Flavonoids are phytochemical compounds present in many plants, fruits, vegetables, and leaves, with potential applications in medicinal chemistry. Flavonoids possess a number of medicinal benefits, including anticancer, antioxidant, anti-inflammatory, and antiviral properties. They also have neuroprotective and cardio-protective effects. These biological activities depend upon the type of flavonoid, its (possible) mode of action, and its bioavailability. These cost-effective medicinal components have significant biological activities, and their effectiveness has been proved for a variety of diseases. The most recent work is focused on their isolation, synthesis of their analogs, and their effects on human health using a variety of techniques and animal models. Thousands of flavonoids have been successfully isolated, and this number increases steadily. We have therefore made an effort to summarize the isolated flavonoids with useful activities in order to gain a better understanding of their effects on human health.

Leaf transcriptome data of two tropical medicinal plants: Sterculia lanceolata and Clausena excavata

The data presented in this article are associated to the research articles, “DOI: 10.1007/s11295-019-1348-3”, [1]; and “DOI: 10.1007/s13205-018-1162-x” [2]. Clausena excavata Burm. f. and Sterculia lanceolata Cav. are medicinal tree plants [3,4] native to Southeast Asia and China, and most members of both the genus Clausena and the genus Sterculia contain various valuable secondary metabolites with a great potential for drug development. Though many phytochemical studies have been conducted using plant extracts from various parts of these plants [4,5], there are very limited genetic resources available. RNA sequencing of C. excavata and S. lanceolata was conducted using pair-end Illumina HiSeq2500 sequencing system, from which the first de novo transcriptome data were produced for both genus Clausena and Sterculia. Transcriptome shotgun assembly using three different assembly tools [2] generated a total of 16,638 non-redundant contigs (N50, 900 bp) from C. excavata and 7,857 (N50, 423 bp) from S. lanceolata. The data are accessible at NCBI BioProject: PRJNA428402 for C. excavata [2] or PRJNA435648 for S. lanceolata[1].

Stercufoetin A, new oleanane-type triterpenoid from the leaves of Sterculia foetida L

From the leaves of Sterculia foetida L., one new oleanane-type triterpenoid, named stercufoetin A (1) together with four known ones, vergatic acid (2), β-amyrin (3), oleanolic acid (4) and maslinic acid (5) were purified by diversely chromatographic methods. Their structures were proposed by HR-APCI-MS and NMR experiments. Compounds (2-5) were notified for the first time from this species. Compound 1 showed weak cytotoxic effect against three human cancer cell lines (MCF-7, HepG2 and HeLa) using SRB assay.

Yan-Hou-Qing formula attenuates allergic airway inflammation via up-regulation of Treg and suppressing Th2 responses in Ovalbumin-induced asthmatic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Yan-Hou-Qing (YHQ), a Chinese medicine formula containing fourteen kinds of materials, has been designed for pharyngitis and cough treatment in Oriental medicine. In the present study, the anti-allergic effects and underlying mechanisms of YHQ in inhibition of airway hyper responsiveness (AHR) was explored in an ovalbumin (OVA)-induced allergic asthma mouse model.

MATERIALS AND METHODS

BALB/c mice were sensitized by OVA and cholera toxin (CT) and challenged with OVA intranasally to induce allergic asthma mouse model. YHQ (200 mg/kg) was orally administered for 3 weeks from week-2 after OVA sensitization. The AHR and histological changes of lung tissues were evaluated by whole-body barometric plethysmography analysis and hematoxylin and eosin (H&E) staining, respectively. The serum concentration of OVA-specific IgE and T helper 2 (Th2) cytokines (IL-4 and IL-13) were determined by enzyme-linked immune sorbent assay (ELISA). Flow cytometry was performed to evaluate the percentage of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Treg) in the spleen.

RESULTS

The elevated AHR responses, heavier inflammatory cell infiltration and Th2 cytokines in allergic asthma group indicated Ovalbumin-induced asthmatic mouse models were built successfully. Compared to allergic asthma group, OVA-induced AHR responses and eosinophil infiltration in lung were improved significantly, and the productions of OVA-specific IgE and Th2 cytokines, IL-4 and IL-13, in the serum were also reduced dramatically after the treatment of YHQ. Moreover, YHQ treatment significantly increased the percentage of CD4⁺CD25⁺Foxp3⁺ Treg in OVA-induced allergic asthma mouse model.

CONCLUSIONS

YHQ improves the allergic asthma related symptoms via promotion of CD4⁺CD25⁺Foxp3⁺ Treg and suppression of Th2 responses in mouse model, suggesting YHQ can be used as a potent agent to alleviate allergic asthma related symptoms.

Sterculia and Brachychiton: a comprehensive overview on their ethnopharmacology, biological activities, phytochemistry and the role of their gummy exudates in drug delivery

OBJECTIVES

Sterculia and Brachychiton are two related genera (Malvaceae) containing more than 300 species. Most of these species are ornamental trees that are native to Australia and widely cultivated in many countries. Different members of the two genera were used by various cultures for medicinal and economical purposes. This review sheds light on the medicinal values and chemical composition of various species of these two genera.

KEY FINDINGS

Sterculia and Brachychiton species were used traditionally for the treatment of gastrointestinal disorders, microbial infection, skin diseases, inflammation and many other conditions. The seeds of various species were roasted and eaten by many traditional tribes. Plants from the two genera revealed their anti-inflammatory, antioxidant, antimicrobial, antidiabetic, antiulcer, insecticidal and analgesic activity. These activities may be attributed to the presence of a wide range of secondary metabolites as flavonoids, phenolic acids, coumarins, terpenoids particularly sesquiterpenes and triterpenes in addition to sterols and fatty acids. Moreover, the gummy exudates obtained from some members of these genera played an important role in different pharmaceutical dosage forms and drug-delivery systems.

CONCLUSIONS

More research is recommended on other species of Sterculia and Brachychiton to discover new molecular entities with potential biological and economic values.