Revista Facultad Nacional de Agronomía Medellín

Phytochemical constituents

To date, only a limited number of studies (approximately 10 publications) have investigated the phytochemical composition of Artocarpus tonkinensis. These studies indicate an uneven distribution of secondary metabolites among different plant parts, with the leaves being the most extensively studied. The major classes of compounds identified from the leaves and their associated biological activities are summarized in Table 1. The leaves are the most thoroughly and in-depth studied part, both in terms of the number of isolated compounds and the evaluation of biological activities. From the n-butanol extract of the leaves, two important flavonoids were isolated, the auronol glycosides maesopsin 4-O-glucoside and the alphitonin 4-O-glucoside. They showed significant immunosuppressive effects through inhibition of lymphocyte proliferation and induction of apoptosis in activated T cells, as well as the inhibition of NOS2 activity and IL-6 expression in macrophages. Among the flavonoid glycosides isolated from the leaves, maesopsin 4-O-glucoside and alphitonin 4-O-glucoside were shown to exert strong immunomodulatory and anti-inflammatory effects. These compounds suppressed osteoclastogenesis via downregulation of the RANK-Src pathway, protected bone and cartilage, and inhibited Th17 lymphocyte proliferation (Thuy et al. 2004; Orecchini et al. 2021). Another flavonoid glycoside from the leaves, artonkin 4′-O-glucoside, was reported to modulate pro-inflammatory cytokines, including TNF-α, IL-6, and IFN-γ, in an experimental arthritis model (Dang et al. 2009). Some prenylated flavonoid compounds, such as cycloartocarpesin and artonin E, were isolated from the aqueous extract of the leaves and have also been reported to possess anticancer and immunomodulatory effects in vitro, as evidenced by the inhibition of lymphocyte proliferation and modulation of inflammatory mediator production (Thủy et al. 2015), although data on them are still limited.

Table 1: Secondary metabolites with biological activity isolated from A. tonkinensis

Chemical investigations of A. tonkinensis leaves revealed the presence of 2-arylbenzofuran derivatives, a class of benzofuran-type phenolic compounds, mainly isolated from organic solvent extracts and structurally characterized by NMR and MS analyses (Guo et al. 2024). To date, no specific biological activities have been reported for these compounds from A. tonkinensis. In addition, polyphenols in both glycoside and aglycone forms were detected in the 70% ethanol leaf extract, including the flavonoid glycosides hovetrichoside C and alphitonin-4-O-β-D-glucopyranoside. These compounds mainly belong to flavonoids and glycosides, as identified by chromatographic and spectroscopic analyses, suggesting a potential contribution to antioxidant properties, although direct bioactivity evaluations remain limited (Quan et al. 2018). Some prenylated flavonoids, such as cycloartocarpesin and artonin E, were isolated from organic solvent extracts of the leaves and were reported to exhibit anticancer and immunomodulatory effects, mainly evaluated through in vitro and in vivo experimental models (Thủy et al. 2016), although available data remain limited.

Furthermore, ethyl acetate (EtOAc) extracts of the leaves have shown the ability to slow down graft rejection and inhibit the growth of lymphocytes in animal models (Ha et al. 1994; Lien et al. 1998).

Notably, some compounds such as cycloartocarpesin, which is a natural triterpenoid, have been detected in the leaves of Artocarpus elasticus (Ramli et al. 2013), also occur in A. tonkinensis, suggesting chemical overlap within the genus Artocarpus. This is consistent with the observation of Lathiff et al. (2021), indicating that compounds such as cycloartocarpesin, p-hydroxybenzoic acid, and stigmasterol-previously reported to possess anticancer, antioxidant, antimicrobial, and anti-inflammatory activities-are common constituents in many Artocarpus species, especially in the leaves and bark. In addition, EtOAc extracts of different plant parts, including roots, leaves, and bark, were reported to contain various secondary metabolites, such as lectins, the stilbene oxyresveratrol, the triterpenoid β-amyrin acetate, and several flavonoids, including afzelechin 3-O-α-rhamnopyranoside, catechin, kaempferol, and ampelopsin. Specifically, afzelechin 3-O-α-rhamnopyranoside, catechin, kaempferol, and ampelopsin were isolated from the ethyl acetate extracts of the leaves and bark, whereas β-amyrin acetate and oxyresveratrol were mainly identified from root and bark extracts. Ampelopsin (dihydromyricetin), a flavonoid widely reported in other Artocarpus species and related genera, has been associated with antioxidant, anti-inflammatory, and hepatoprotective activities in various in vitro and in vivo models, although its biological activity has not yet been directly evaluated in A. tonkinensis (George et al. 2016).

About the roots, although not as extensively investigated as the leaves, be a rich source of valuable prenylated flavonoids, including artotonin A, artotonin B, morusin, cudraflavone C, and cyclocommunol. These compounds exhibited potent in vitro cytotoxic activity against various cancer cell lines, such as liver (SMMC-7721) and stomach (BGC-823, SGC-7901) (Ma et al. 2010). The presence of the prenylated flavonoid group in the root demonstrates its biological potential, especially in the field of cancer treatment.

The stem is the least studied part; however, some recent studies have shown the presence of 2-arylbenzofuran derivatives with an uncommon benzofuran scaffold compared to the major phenolic classes typically found in Artocarpus (Guo et al. 2024). Although no in-depth evaluation of biological activity has been performed, the biological activities of these compounds remain unexplored.

In contrast, the fruit of A. tonkinensis remains poorly investigated, with no reports to date on its chemical composition or biological activity. Despite its traditional consumption by ethnic minority communities in the mountainous regions of Northern Vietnam. Elucidating its phytochemical profile may provide a scientific basis for future applications in medicinal and functional food development.

Immunomodulator activity

Artocarpus tonkinensis has been shown to have potent immunomodulator effects in multiple models in vitro and in vivo (Table 2). The anti-inflammatory mechanism of this plant is thought to be mainly related to its ability to modulate T-cell-mediated immune responses and pro-inflammatory cytokines (Thuy et al. 2004).

Table 2: Immunomodulator activity of A. tonkinensis.

In an in vivo collagen-induced arthritis (CIA) mouse model, the leaf extract of A. tonkinensis, administered intraperitoneally at 15 mg kg^-1 per day, significantly reduced inflammation and delayed disease onset through the suppression of TNF-α, IFN-γ, and IL-6. In complementary in vitro assays, the extract showed no significant cytotoxicity at therapeutically relevant concentrations, indicating a favorable safety profile.

Studies have shown that A. tonkinensis leaf extract has the ability to inhibit lymphocytic cell proliferation and reduce the expression of inflammatory cytokines such as TNF-α, IL-6, and IFN-γ. In a collagen-induced arthritis (CIA) model in mice, ethyl acetate (EtOAc) extract from the leaves significantly reduced the level of inflammation, joint edema, and tissue damage (Thuy et al. 2017). This is explained by the inhibitory effect on T cell activation and apoptosis induction in peripheral lymphocytes, thereby limiting the chronic inflammatory process.

Within this immunomodulatory context, previous studies have demonstrated that the activity of A. tonkinensis leaf extracts is mainly attributed to flavonoid glycosides, particularly maesopsin-4-O-glucoside and artonkin-4′-O-glucoside. These compounds were shown to inhibit T-cell proliferation and suppress the production of pro-inflammatory cytokines in vitro (Dang et al. 2009).

Furthermore, some prenylated flavonoids isolated from the roots also showed certain immunomodulatory activities (Ma et al. 2010). Besides, ethyl acetate extract from A. tonkinensis leaves and roots showed significant immunomodulatory activity in an experimental arthritis model, through T-cell inhibition (Ngoc et al. 2005; Jagtap and Bapat 2010).

Taken together, the present results suggest the potential application of A. tonkinensis as a natural source of anti-inflammatory and immunomodulatory agents, particularly for chronic diseases associated with excessive immune responses, such as rheumatoid arthritis. However, further studies are needed to better understand the molecular mechanisms and to evaluate clinical safety and efficacy.

Anti-cancer potential

A. tonkinensis has shown great promise in the field of cancer research due to the presence of prenylated flavonoids that have potent cytotoxic activity against several cancer cell lines. Specifically, artotonins A and B were isolated from the roots, along with other compounds such as morusin, cudraflavone C, and cyclocommunol. The artotonin compounds exhibited significant cytotoxic activity in vitro against liver (SMMC-7721), gastric (BGC-823, SGC-7901), and cervical (HeLa) cancer cell lines, with IC50 values ranging from 2 to 15 µM (Ma et al. 2010). In addition, morusin was shown to inhibit proliferation and induce apoptosis in HT-29 colorectal cancer cells through mechanisms involving the p53 and caspase-3 pathways (Pozzesi et al. 2011).

Auronol glycosides and polyphenols in Artocarpus species, such as morusin, artocarpin, and artonin E, have been reported to exhibit significant anticancer activity through the inhibition of cancer cell proliferation and the induction of apoptosis in various human cancer cell lines (Somashekhar et al. 2013).

The study of A. tonkinensis secondary metabolites with anticancer activity becomes necessary because of the possibility of multitargeted cancer therapeutic applications, including proliferation inhibition, apoptosis induction, and suppression of tumor-associated inflammation.

Antioxidant activity

Although no published studies have directly evaluated the antioxidant activity of A. tonkinensis using methods such as DPPH, ABTS, or FRAP, the secondary metabolites identified in this species suggest significant antioxidant potential. Flavonoid glycosides, such as maesopsin-glucoside and alphitonin-glucoside, the polyphenols, and prenylated flavonoids, have been reported to exhibit antioxidant activity in other Artocarpus species, particularly A. heterophyllus and A. altilis, where compounds such as artocarpin, morusin, and related prenylated flavonoids showed strong radical-scavenging activity and inhibition of oxidative enzymes (Palupi et al. 2020).

For example, the aqueous extract from A. heterophyllus exhibited strong DPPH radical scavenging activity with an IC50 value of 73.5 μg mL-1, while the aqueous fraction of this species showed the highest efficiency in the FRAP assay with an IC50 = 72.0 μg mL-1 (Loizzo et al. 2010). Besides, many flavonoids of the genus Artocarpus were reported to scavenge DPPH radicals with IC50 values ranging from 18.7 to 42.2 µM, while also exhibiting inhibitory activity against xanthine oxidase, a key enzyme involved in endogenous antioxidant mechanisms, with IC50 values between 43.3 and 73.3 µM (Lin et al. 2009).

Data from species in the genus partly support the hypothesis that A. tonkinesis may have significant antioxidant activity. However, the lack of specific experimental evidence raises the need for further studies to determine active fractions, active secondary metabolites, the specific activity levels, and mechanisms of action of the compounds in this species.

Toxicity and safety regulations

Preliminary existing toxicity studies show that the extract from Artocarpus tonkinensis leaves has a relatively high biosafety profile, especially at doses commonly used in traditional medicine.

In a study by Dang et al. (2009), in vitro safety and biological activity were first evaluated using murine splenocytes and macrophage-related immune cell models. The isolated flavonoid glycosides, particularly artonkin-4′-O-glucoside and maesopsin-4-O-β-D-glucoside, showed no significant cytotoxicity at concentrations up to 50 μg mL-1 after 48 h of exposure, maintaining cell viability above 95%. These compounds inhibited T-cell proliferation and reduced pro-inflammatory cytokine production under stimulated conditions. Subsequently, in vivo evaluation was conducted in a collagen-induced arthritis (CIA) mouse model, where the leaf ethyl acetate extract, administered intraperitoneally at 15 mg kg-1 per day for 21 consecutive days, did not induce changes in body weight or abnormal behavior, indicating good tolerability. Together, these results demonstrate that both the isolated flavonoid glycosides and the leaf extract of A. tonkinensis exhibit favorable safety profiles in vitro and in vivo, supporting their further investigation as immunomodulatory agents (Dang et al. 2009).

In an acute toxicity study in mice, the ethanolic residue of chay leaves did not cause any abnormal symptoms or death at a maximum oral dose of 42.9 g kg-1 body weight - the highest dose that could be tested. During the 7-day follow-up period, no significant toxic manifestations were observed (Thủy et al. 2016).

In addition, an 8-week subchronic toxicity test on rabbits showed that, at both dose levels (0.6 g kg-1 per day and 1.8 g kg-1 per day), TAT-2 did not negatively affect general physiological status, growth rate, hematological indices, as well as liver function (AST, ALT, bilirubin, albumin) and kidney function (creatinine). Histological observations of organs such as liver and kidney also did not record any significant damage, confirming the high safety level of TAT-2 under short- and medium-term use conditions (Thủy et al. 2016).

In another study, maesopsin 4-O-β-D-glucoside (TAT-2), isolated from the ethanolic extract of A. tonkinensis leaves, did not show signs of acute toxicity at the highest tested dose of 2,000 mg kg-1 body weight in tumor-bearing mice. At therapeutic doses of 100 and 200 mg kg-1 body weight, TAT-2 exhibited significant antitumor activity, as evidenced by reduced tumor growth, increased survival rate, and improvement of hematological and biochemical parameters, although LD50 values and chronic toxicity data have not yet been reported (Thuy et al. 2016). Similarly, Quan et al. (2018) reported that administration of the ethanolic leaf extract in a mouse model of arthritis at 15 mg kg-1 per day did not affect behavior, body weight, survival rate, or liver enzyme levels (AST and ALT), indicating good tolerability.

Overall, the available toxicity data indicate that the pharmacological activities of A. tonkinensis, including anti-inflammatory, immunomodulatory, and anticancer effects, occur at doses that are well tolerated in both in vitro and in vivo models. This supports the potential of A. tonkinensis and its flavonoid glycosides as promising candidates for further preclinical and applied pharmacological research.

Prospects for the application of medicinal herbs - functional foods

With its diverse chemical composition and a wide range of reported biological activities, including anti-inflammatory, anticancer, and antioxidant effects, Artocarpus tonkinensis has been regarded as a promising plant for the development of medicinal preparations and functional food products intended to support disease management (Table 3).

Table 3: Traditional uses, experimental evidence, and application prospects of Artocarpus tonkinensis.

In Vietnam, A. tonkinensis is commonly used in folk medicine with many different uses. The leaves are often boiled to make drinking water to support the treatment of bone and joint diseases and improve overall health (Vượng and Dương 2017). In northern Vietnam, it is used by the Hmong ethnic minority to treat arthritis and back pain (Delfino et al. 2016; Adorisio et al. 2016).

According to Reichart and Nguyen (2008), ripe fruits of A. tonkinensis are traditionally consumed fresh or as juice (5-7 fruits per use) to support respiratory and digestive health. When fresh fruits are unavailable, dried fruits (≈16 g) or root decoctions are used. The fruit is also incorporated into traditional dishes, and the bark is occasionally added during betel chewing to enhance astringency.

The roots and leaves are commonly used in remedies for bone and joint pain, rheumatism, with a usual dose of about 10-20 g per day in the form of a decoction. To enhance therapeutic efficacy, these remedies are often combined with other medicinal plants, such as Smilax glabra, rather than used alone. In addition, the roots of A. tonkinensis are also employed in the treatment of gynecological conditions, including menstrual disorders, menorrhagia, and vaginal discharge (Bích et al. 2006).

As functional foods, a preliminary evaluation of the sensory properties and total soluble solids (TSS) content of two types of A. tonkinensis fruit was conducted. The fruits were characterized by red- and yellow-fleshed types. Both types exhibited a distinct sour taste; however, the red-fleshed fruit showed a stronger flavor intensity and a sweeter aftertaste. The TSS values were approximately 13%, indicating a relatively high content of soluble solids, mainly sugars and organic acids. Based on these sensory characteristics, A. tonkinensis fruit was considered unsuitable for general fresh consumption but showed potential for processing into value-added products such as jam, dried fruit, fermented beverages, or as a flavoring ingredient in functional food formulations. This processing-oriented utilization was regarded as more appropriate given the intrinsic sensory properties of the raw material and consumer preferences for mildly sour flavors.

Challenges and future

The development of A. tonkinensis into medicinal products or functional foods faces many challenges: the lack of information on the importance of seasonality in its biological properties, the instability of raw material sources, the lack of standardized cultivation systems and extraction processes, the limited consumer and market awareness, the lack of clinical data and long-term safety evidence, and the legal barriers and lack of commercialization strategy.

A. tonkinensis trees are often scattered in the high mountainous regions of Northern Vietnam. Most of the current raw material sources still depend on natural exploitation, and there is no concentrated growing area. The fruit usually ripens and is harvested from June to August every year (Lợi 2004). However, due to the uneven distribution of trees and the influence of climatic conditions, annual fruit yields can fluctuate significantly. In addition, harvesting fruit during the rainy season is prone to post-harvest quality risks such as mold or damage, making storage and transportation difficult. These factors make standardization of raw materials and large-scale product development challenging.

Currently, the cultivation, care, harvesting, and processing of A. tonkinensis are mainly based on folk experience or scattered instructions, without a systematic, standardized, and strict quality control process. This can affect the quality of input materials, active ingredient content, and stability of the processed product.

Although used in folk medicine, very few people know about the presence of A. tonkinensis fruit in Vietnam. Consumer awareness of the value of this plant is limited, while product promotion and development activities in the market have not been focused on.

Some preclinical studies have shown safety at traditional doses, chronic toxicity, and reproductive toxicity; however, human studies are still lacking. This limits the ability to register products as functional foods or standardized herbal medicines, especially in demanding markets such as the EU or the US.

In addition, traditional decoctions prepared from leaves or roots, which are widely used in folk medicine, require further scientific validation to confirm the stability of bioactive compounds, the remaining biological activity after thermal processing, and the reproducibility of pharmacological effects. Systematic studies on optimal preparation methods, effective dosage ranges, and safety margins of decoctions are therefore necessary.

There are no specific technical regulations or quality standards for raw materials or products from A. tonkinensis. At the same time, the lack of connection between scientists, businesses, and localities is also a barrier to developing a closed value chain for this medicinal herb.

In short, the potential for A. tonkinensis development is huge, especially in the trend of searching for products from natural herbs with diverse biological activities. However, to exploit it effectively and sustainably, a synchronous strategy is needed from research, cultivation, standardization, to commercialization and consumer education.