Abstract
Objective/Background
The genus Diospyros L. (Ebenaceae) includes about 778 species worldwide, with over 500 of them known for their significant health benefits. Among them, Diospyros mollis Griff. has been used as a tonic and treatment for many diseases related to digestive disorders and intestinal parasites. Furthermore, the fruit has also been used for dyeing silk fabrics. The purpose of this comprehensive review is to provide researchers with important information about D. mollis, particularly regarding its chemical composition and biological effects. This information can support current understanding and future studies to develop novel herbal formulations based on this species. Additionally, this review aims to compile and summarize the available literature on this species, covering its botanical, ethnomedicinal, phytochemical, and pharmacological properties reported to date.
Methods
The relevant information on D. mollis was collected via online electronic and databases, including Scopus, Pubmed, Web of Science, Google Scholar, ScienceDirect, Springer Link, SciFinder, and other scientific databases.
Results
A comprehensive review of the literature reveals that D. mollis contains various chemical constituents such as naphthalene and naphthoquinone derivatives, triterpenoids, alkaloids, sterols, glycosides, and fatty acid esters isolated from the berry, root, bark, and leaf of this species, with several pharmacological effects and other applications. Many pharmacological effects, such as hyaluronidase inhibitory, anthelmintic, and antiparasitic activities of various extracts and isolated compounds of D. mollis, are reported in this review. The review demonstrates the importance of D. mollis in the treatment of diseases, its application in fabric dyeing techniques, and its traditional use.
Conclusion
In conclusion, D. mollis emerges as a promising botanical resource with its rich history in traditional medicine and diverse chemical constituents, paving the way for potential future applications and innovations in the field of herbal medicine and drug development.
Introduction
Ebenaceae is a medium-sized perennial woody plant family that mainly occurs in the tropics and subtropics, with a smaller representation in the temperate zone. 1 The Ebenaceae family, consisting of 3 genera, Diospyros L., Euclea L., and Lissocarpa Benth, has been recognized.2,3 Among these, the genus Diospyros is the largest and most widely distributed in China, Korea, Japan, India, Pakistan, Brazil, Turkey, Italy, the Middle East, and parts of Africa and the United States.4–8
This genus (eg, Diospyros kaki L.f., Diospyros virginiana L., Diospyros oleifera W.C.Cheng, Diospyros lotus L.) is economically important; particularly, several species are well known for their use as timber or as edible fruit.8,9 For example, the D. kaki fruit has been used as an important food resource in China, Korea, and Japan. 8 D. virginiana has been used for multiple purposes, such as turnery, plane stocks, shoe lasts, shuttles, and golf club heads, due to its heavy, hard, strong, and very closely-grained wood. 10
Additionally, this genus has remarkable health benefits with over 500 species. 11 Previous studies have also shown that the genus Diospyros is a plant genus with great potential in the field of medicine.8,11 In China, India, Japan, Pakistan, Korea, Thailand, Vietnam, and other regions, many species of Diospyros are known as tonics for improving human health. These species are associated with various biological effects, including antioxidant, anti-inflammatory, antimicrobial, fungicidal, anthelmintic, analgesic, antipyretic, antidiabetic, neuroprotective, hepatoprotective, antihypertensive, cytotoxicity, anti-tumor, sedative, and so on8,11–17 For example, in folk medicine, various parts of D. kaki, such as its leaves, bark, and roots, have been utilized to treat conditions like hiccoughs, hypertension, and dyspnea. Similarly, the leaves of D. lotus have found use in traditional remedies as a sedative and to alleviate fever. 11
Phytochemically, several species have so far been investigated with many typical groups of active ingredients such as naphthoquinones (eg, diospyrin, ebenone, 8-hydroxydiospyrin, plumbagin), triterpenoids (eg, lupane, lupeol, oleanane, taraxerol), alkaloids, steroids, lignans, tannins, flavonoids (eg, kaempferol, quercetin), fatty acid esters, minerals (eg, calcium, zinc, copper, iron, magnesium, sodium, potassium), and so on.4,5,11,15–18
Among the mentioned chemical groups, the genus Diospyros L. is a rich source of naphthoquinones, specifically 1-4 naphthoquinones within the juglone class. Most phytochemical studies related to Diospyros focus on the identification and isolation of these compounds. These species are characterized by their ability to produce 1-4 naphthoquinones, including several monomers, dimers, a few trimers, and tetramers, which serve as valuable chemical markers in taxonomic research. Plumbagin and 7-methyljuglone are the most widely distributed monomeric naphthoquinones and are found to accumulate in multiple Diospyros species. The 1-4 naphthoquinones of Diospyros can be classified into 2 major groups: (1) substituted metabolites of plumbagin and 7-methyljuglone and (2) oligomeric metabolites of plumbagin and 7-methyljuglone. 19 Several studies have shown the biological activities of plumbagin, which possesses antioxidant, antibacterial, antifungal, analgesic, anti-inflammatory, and anticancer properties. 20 Similarly, 7-methyljuglone has been documented to exhibit a range of pharmacological effects, including antibacterial, antifungal, anticancer, antitubercular, anti-inflammatory, and antiviral properties. 21
Diospyros mollis Griff. is commonly known as “maeklua,” “Maakgleua,” “Ma Kluea” or “Maklua” (มะเกลือ) in Thai, or “mac nua” in Vietnamese.22,23 It is a big tree that primarily grows in the wet tropical biome.24–26 This species can be found in Indo-China and many Southeast Asian countries, including Thailand, Cambodia, Laos, Myanmar, Vietnam, and so on.24–26 This species is used in traditional medicine to treat intestinal parasites, diarrhea, and digestive disorders.22,27–29 It is also ultilized for timber, art object production, and fabric dyeing by extracting colorant from leaves and seeds. 25
Up to the present, there is limited coverage in existing review articles about the morphological characterization, distribution, ethnomedicinal, phytochemical, and pharmacological properties of D. mollis. Therefore, our current work provides a detailed overview of D. mollis. Within the scope of this review, our main objective is to compile a wide range of literature and incorporate valuable information into the field of natural chemistry and pharmacology from different parts of this species.
Methodology of Research
Search Method and Study Inclusion
To gather data for this review, we utilized the SciFinder search engine to access databases such as MEDLINE and CAPlus. This review goal was to identify all scientific papers published until June 2023 using the keywords “Diospyros mollis,” its synonyms, and common name (eg, “maeklua,” “Maakgleua,” “Ma Kluea,” “Maklua,” and “mac nua”). Additionally, the relevant information on D. mollis was collected via online electronic and databases, including Scopus, Pubmed, Web of Science, Google Scholar, ScienceDirect, Springer Link, SciFinder, and other scientific databases.
Initially, we retrieved 359 records for further evaluation. Subsequently, after a thorough screening, we included 29 studies that met our criteria, focusing on D. mollis, while 330 were excluded due to inadequate or irrelevant information.
Plant taxonomy and morphological characteristics were also collected through websites, such as https://powo.science.kew.org/, 24 https://www.worldfloraonline.org/, 26 http://www.theplantlist.org/, 30 http://www.efloras.org/. 31 These websites were used as references for botanical information due to their credibility, comprehensive data, adherence to standardized nomenclature, and their ability to provide reliable information on plant taxonomy, distribution, and characteristics. They also support research with citations, illustrations, and additional resources.
The chemical structures were searched using the open chemistry database PubChem (https://pubchem.ncbi.nlm.nih.gov/) and drawn using ChemDraw Professional 16.0.
Inclusion and Exclusion Criteria
The inclusion criteria are:
- Studies related to D. mollis, cover botanical descriptions, chemical constituents, ethnomedicinal or traditional uses, as well as pharmacological and biological activities. - Research about the Diospyros genus that also contains information about D. mollis. - Abstracts or full texts written in English. - Studies concerning the medicinal importance of D. mollis. - Studies with irrelevant or insufficient information. - Studies not directly related to medicinal aspects, or those related but not associated with D. mollis.
The exclusion criteria are as follows:
Botanical Description
Taxonomy
The species Diospyros mollis Griff. is categorized within the realm of angiosperms and further classified as an eudicot. D. mollis belongs to the genus Diospyros L., the family Ebenaceae, part of the order Ericales, class Eudicots, phylum Angiospermae, and kingdom Plantae. Its taxonomical information has been identified in various databases, including “The Plant List (http://www.theplantlist.org/),” “Plants of the World Online (http://www.powo.science.kew.org/),” “The World Flora Online (http://www.worldfloraonline.org/),” and “Flora of China” (http://www.efloras.org/).”24,26,30,31
Morphological Characteristics and Geographical Distribution
The Ebenaceae family consists of 3 genera: Diospyros L., Euclea L., and Lissocarpa Benth., with around 802 accepted species. Among these, Diospyros L. is recognized as one of the largest and most significant genera, including 778 accepted species.24,30
Diospyros mollis Griff., a species of Diospyros L., is commonly known as “maeklua,” “Maakgleua,” “Ma Kluea” or “Maklua” (มะเกลือ) in Thai, or “mặc nưa” in Vietnamese.22,23 It is an evergreen perennial shrub or medium-sized tree that primarily grows in the wet tropical biome. Indigenous to the Indochina region, this species can be found in many South-Eastern Asian countries, including Thailand, Vietnam, Cambodia, Laos, Myanmar, and so on,24,26,30,31 and is used as a timber, art object production, and fabric dyeing by extracting colorant from leaves and seeds. 25
The species can reach a height up to 30 m tall, with unarmed twigs. Cross-section of tree trunks reveal 2 distinct layers: a greenish-brown outer layer and an inner core (heartwood) composed of sturdy, heavy, and durable jet-black wood, ideal for furniture production due to its high quality. 32
The leaves of D. mollis are ovate to ovate-oblong or obovate-lanceolate, measuring approximately 5.5 to 13.0 cm in length and 2.5 to 4.0 cm in width. They feature an acute, obtuse, or rounded base and an apex that is either acute or acuminate. The leaves are chartaceous and initially pubescent but later become glabrescent, at least on the upper side. The leaves exhibit 10 to 15 pairs of secondary nerves that faintly ascend toward the apex, and some may show a network-like pattern. These nerves, along with the reticulation, are conspicuous on both leaf surfaces. The petiole is 5 to 10 mm long and pubescent. When dried, the leaves appear black.26,31
The species in the Diospyros L. is mostly evergreen dioecious, rarely monoecious, or polygamous. 2 D. mollis usually flowers from January to September and fruits from August to December. The tree produces male flowers in cymes and 4-merous. The pedicel of the male flowers is pubescent and approximately 1 mm long. The campanulate calyx of the male flowers is 1.0 to 2.0 mm long, divided to the middle, with a pubescent outer surface and a glabrous inner surface. The urceolate corolla measures 6.0 to 8.0 mm in length, divided to the middle, and glabrous on both sides. The male flowers contain 14 to 24 glabrous stamens. The rudimentary ovary of the male flowers can be either pilose or glabrous. The female flowers of D. mollis are solitary and 4-numerous. The pedicel of the female flower ranges from 1.0 to 3.0 mm and is pubescent. The calyx and corolla of the female flowers are similar to those of the male flowers but are larger in size, like most of the Diospyros species. The ovary of the female flowers is ovoid, pubescent, and 8-locular. The flowers have 4 pubescent styles and 8 to 10 glabrous staminodes. The corolla of both male and female flowers is golden-yellow in color.26,30,31
The tree develops globose fruits, each with a diameter of approximately 1.5 to 2.0 cm. The fruit has a rounded base and a rounded or obtuse apex. These fruits are not succulent and appear black when dry. The fruiting calyx may or may not be divided to the middle, with a pubescent outer surface and a glabrous inner surface. The lobes of the calyx are reflexed, lacking any plicate or undulate margins, and they have inconspicuous nerves. The fruit is supported by a 2.0 to 5.0 mm long fruit stalk, and its endosperm is smooth.26,30,31
Phytochemistry
Extensive research has been conducted on the Ebenaceae family to determine the chemical constituents present in the plant species within the family, particularly those belonging to the Diospyros genus.
A variety of chemical compounds have been isolated and identified from fruits, roots, bark, leaves, branches of D. mollis, including naphthalene and naphthoquinone derivatives, triterpenoids, sterols, glycosides, antiarol derivatives, alkaloid, amino acid, lignan, esters of fatty acids, and other compounds.25,32,37–41 Notice that chemical components in D. mollis vary greatly, influenced by factors including environment, geographical source, maturation stage, tree parts, harvest time, and storage time. A list of compounds isolated from D. mollis is summarized and presented in Table 1.
Chemical Components Isolated From D. mollis.
Naphthalene and Naphthoquinone Derivatives
In total 18 diospyrol compounds and their glycoside derivatives have been isolated from different parts of D. mollis.
The most significant compound considered responsible for the anthelmintic effects of D. mollis is 6,6′-dimethyl-2,2′-binaphthalene-1,1′,8,8′-tetrol, also known as diospyrol
In the tree trunk (heartwood) of D. mollis, 4 compounds, named one naphthoquinone dimer (8-hydroxy-8′-methoxy-3′,6-dimethyl-23,4′a,8′a-tetrahydro-[2,2′-binaphthalene]-1,1′,4,4′-tetrone (
From the acidified acetone extract of D. mollis green fruits, one mixture of acetylated diospyrol and diglucosides of diospyrol, namely diospyrol 8,8′-di-O-(β-D-glucopyranoside)
Paphassarang et al.
39
conducted extensive research to identify the glycosides of diospyrol. As a result, diospyrol 8,8′-di-O-(6-β-D-apiofuranosyl-β-O-glucopyranoside)
Recently, 7 known diospyrol compounds and their glycoside derivatives, including diospyrol 8,8′-di-O-(6-β-D-apiofuranosyl-β-D-glucopyranoside)
Structurally, the compound
Triterpenoids
Triterpenoids are also common chemical constituents of the Diospyros species8,11 and D. mollis contains about 10 triterpenoids isolated from various parts of the plant (ie, fruits, roots, bark, leaves, and branches), including lupenone
Others
Sterols
Secondary metabolites, stigmasterol
Fatty Acid Esters
In a study by Sturm and Zilliken,
38
they found methyl esters of palmitic acid (
Antiarol Derivatives
(+)-Syringaresinol
Amino Acid, Lignan, and Alkaloid
L-tryptophan
Phenolic glycosides
Besides the above-identified compounds, several phenolic glycosides from D. mollis leaves and branches, including capparoside A
In Diospyros genus, mamegakinone
In conclusion, these findings contribute significantly to the understanding of the chemical makeup and potential pharmacological properties of D. mollis, paving the way for further studies in medicinal and chemical research.
Pharmacological Properties
Anthelmintic and Antiparasitic Effects
Table 2 provides information about the pharmacological and toxic effects of D. mollis. In traditional Thai medicine, D. mollis fruits have long been used to combat tapeworms and other parasites. Traditional reports also suggest that warm water, coconut milk, or dilute aqueous hydroxide fruit extracts of D. mollis display an anthelmintic effect.22,52 Numerous studies have been conducted to assess its anthelmintic activity.
Pharmacological and Toxic Effects of D. mollis.
In a study by Neamsuvan et al. 53 on surveying folk remedies for gastrointestinal diseases in 3 southern border provinces (Pattani, Yala, and Narathiwat) of Thailand. The results revealed that the raw fruit of D. mollis for parasitic diseases was mostly prepared by boiling. It is used in the form of a decoction with a dose of 200 ml before bedtime. 53
In the search for a more affordable treatment for Ascaris lumbricoides (hookworm) in Thailand, Sadun and Vajrasthira conducted a preliminary study with 112 patients. 27 For the study, 4380 g of D. mollis green berries were mixed with 1.0 L of fresh coconut milk. After filtering to remove particles, it was adjusted to 3.0 L with additional coconut milk and cane sugar was added for flavor. The treatment was immediately administered to minimize air exposure. The dosage for each patient was calculated as 3.0 mL per year of their age, with a maximum of 75 mL. The treatment results were evaluated by examining patients’ stools using the Willis-Malloy salt flotation concentration method for 1.0 mL samples and a modified Stoll technique for 4.0 mL samples mixed with a sodium hydroxide solution to quantify hookworm eggs. If Willis was positive and Stoll was negative, the egg count was assumed to be 100 eggs per mL of feces. These tests were conducted during the dry season to minimize hookworm reinfection. The research consists of 2 experiments with distinct objectives. In experiment 1, 72 participants (33 males and 39 females, aged 5 to 61) were involved in an effort to determine the extent of hookworm reduction, as assessed by egg counts after administering a single dose of D. mollis. Six days after treatment, stool samples were collected from 72 patients, 9 of whom were excluded due to various reasons. Before treatment, all the patients tested positive for hookworm infection using either of 2 methods. Among the 63 patients in the experimental group, their average hookworm egg count was 1720 per mL of feces, ranging from 600 to 8000. Following a single dose of D. mollis, 9 patients remained positive when assessed using the Stoll technique, while 22 patients were identified as positive when employing the Willis technique. The Stoll method yielded egg counts ranging from 200 to 800 eggs per mL of feces for the 9 positive cases. Assuming a value of 100 for the 13 patients who tested negative with the Stoll method but positive with the Willis technique, the mean egg count for the treated group was 71. Additionally, a few patients experienced mild side effects, such as vomiting, mild nausea, and mucous diarrhea lasting 2 days. No other signs of toxicity were observed. 27
Experiment 2 was conducted to compare the effectiveness of D. mollis with hexylresorcinol and to ascertain whether the reduction in egg count in the subjects’ stools represented complete elimination or just temporary sterilization of the worms. The experiment involved 40 children, 20 males and 20 females, aged 9 to 14. Additionally, 18 of them were infected with Ascaris lumbricoides and 15 with Trichuris trichiura. One student treated with D. mollis did not provide stool samples and was excluded from the analysis. Among the 23 patients treated with hexylresorcinol, their average hookworm egg count in stools before treatment was 4780 eggs per mL (range from 1000 to 15,800). The 16 patients treated with D. mollis had an average egg count of 4470 eggs per mL (range from 1200 to 11,600). Using the Willis technique, 6 days after treatment, 4 out of 23 patients treated with hexylresorcinol had no hookworm eggs in their stools, and they remained infection-free when re-examined 90 days later. Using the Stoll technique, eggs were found in the stools of 30% of the hexylresorcinol-treated group, with egg counts ranging from 1000 to 10,201 eggs per mL of formed feces. Ninety days after treatment, eggs were found in the stools of 52% of this group. For the 16 patients treated with D. mollis, 11 had no hookworm eggs in their stools 6 days after treatment using the Willis technique, and 7 remained infection-free when re-examined 90 days later. Using the Stoll technique, no hookworm eggs were found in the stools of any of the children 6 days after treatment. Ninety days after treatment, only 1 patient had a positive result with a count of 400 eggs per mL of feces. In patients with Ascaris lumbricoides infections, negative smears were obtained in most cases (9/10 for hexylresorcinol and 6/8 for D. mollis) 6 days after treatment, and most of which remained negative 90 days after treatment (7 for hexylresorcinol and 4 for D. mollis). However, for Trichuris infections, hexylresorcinol treatment resulted in more positive cases 6 and 90 days after treatment compared to D. mollis (7/9 in 6 days and 8/9 in 90 days compared to 4/6 in 6 and 90 days). Two patients who received hexylresorcinol reported mild nausea, but no other toxic symptoms were observed in either treatment group. Although it was not possible to recover the worms from the feces of the treated persons in view of the fact that tests were carried out in out-patient field clinics, the low hookworm egg counts 90 days after treatment suggest a true worm elimination and not just a temporary sterilization. The researchers stated that the effectiveness of treatment is significantly reduced unless green berries are used shortly after being collected and emphasized the need for caution due to the limited amount of research on the therapeutic properties and toxicology of D. mollis. Nonetheless, the preliminary results indicate the potential of D. mollis as an anthelmintic agent, and it warrants further investigation. 27
In 1960, research findings by Mokkhasmit and Harinasuta indicated that D. mollis was able to completely eliminate Ancylostoma duodenale, Necator americanus, Enterobius vermicularis, Strongyloides stercoralis, Fasciolopsis buski, Taenia saginata, and Taenia solium in humans and dogs after a single treatment of 2 to 4 g/kg body weight. 54 Moreover, a study by Ramsuk and coworkers 55 reported that treatments of Stellantchasmus falcatus were performed with Gallus gallus domesticus, using niclosamide, D. mollis, and Cymbopogon citratus (DC. ex Nees) Stapf. The study was designed into 4 experimental groups (n = 5), including the control, niclosamide-treated, D. mollis-treated, and C. citratus-treated groups. The chicks were force-fed 500 S. falcatus larvae orally and then given anthelminthic medications. The results indicated that niclosamide (40 mg/kg) was able to eradicate the parasite effectively. A comparable result was observed in the D. mollis-treated group (1.6 mL/kg). C. citratus had no influence on the number of parasites recovered. However, the groups treated with niclosamide and D. mollis had considerably higher numbers of parasites retrieved from their small intestines than the control group (P < .05). It can be concluded that D. mollis can be used as an anthelminthic plant, with similar results to niclosamide. In other words, at a single dose of 1.6 mL/kg body weight, the crude extract of D. mollis was able to eradicate S. falcatus in chicks (Gallus gallus domesticus). 55
Maki et al. 56 evaluated the effects of the ethanol extract from D. mollis fruits against the adults and larvae of dwarf tapeworm, Hymenolepis nana, and the impact on egg infectivity on mice models. The experimentally infected mice were administered a single oral dose of 10 to 1000 mg/kg of fruit extract or flubendazole wt 1, 2, 3, 4, or 12 days and then autopsied 14 days later. It revealed that the extract was able to be effective in eliminating adult tapeworms, with an ED50 of 79 mg/kg. However, the ethanol extract from D. mollis fruit had no efficacy against the larvae. 56 Significant effects of the extract on the motility and structure of adult worms were observed, leading to a decrease in their numbers over time after drug administration. Further investigation showed that the reduction in egg output observed after the medication was due to severe damage to the gravid segments of the remaining worms in the host intestine. This damage caused a significant reduction in egg production. Additionally, the study found that the extract reduced the infectivity of fresh eggs both in vitro and in vivo. In comparison, the anthelmintic effect of flubendazole, a broad-spectrum anthelmintic drug, was minimal, showing limited efficacy against both adult worms and larvae. These findings suggest that D. mollis fruit extract may have potential as an anthelmintic agent against certain helminths, particularly adult tapeworms. 56
Sritong et al. 57 conducted research on the anthelmintic efficacy of dry herbal D. mollis, Combretum quadrangulare Kurz, and Euphorbia heterophylla L. on adult using a chick model. The experiment included various treatment approaches, such as a negative control diet containing cassava starch at a dosage of 11 g/kg, a positive control diet containing piperazine at a dosage of 15 g/kg, and a treatment diet containing dry D. mollis, C. quadrangulare, or E. heterophylla at a dosage of 1.0 g/kg. These herbs were separately mixed into the feed and administered to the animals for 5 days before assessing their efficacy. The study involved evaluating the presence of Ascaridia galli eggs in the feces of 160 experimental chickens using the formalin ethyl acetate sedimentation method. 57
The results demonstrated that the effectiveness of D. mollis was relatively low during the initial 2 days after deworming, with a success rate of 25%. However, it notably increased to a range of 88% to 91% from day 9 to day 23 post-deworming (P < .05). The efficacy of C. quadrangulare in eliminating adult A. galli parasites was also modest at the beginning, registering 38% in the first 2 days post-treatment, similar to D. mollis. However, it began to rise, reaching 70% efficacy from day 9 to day 23 post-treatment. The dry herb treatment exhibited effectiveness ranging from 63% to 87% (P < .05). E. heterophylla treatment displayed considerable efficacy within the first 2 days post-treatment (84%) and maintained a high level of effectiveness up to day 16 post-treatment, with a minor reduction to approximately 75% on day 23 post-treatment (P < .05). The results indicated that the effectiveness of D. mollis, C. quadrangulare, and E. heterophylla against adult A. galli at 23 days after treatment was 88.0%, 75.0%, and 63.0%, respectively. 57
As for piperazine, it exhibited substantial effectiveness (97%) from day 9 post-treatment and maintained this high level of efficacy continuously until day 23 post-treatment, achieving 100% effectiveness in Ascaridia galli elimination. In comparison to the herb groups, this difference was statistically significant (P < .05). In contrast, the cassava starch treatment proved to be entirely ineffective, with an effectiveness rate of 0%. 57
Atjanasuppat et al. 58 conducted an in vitro screening to explore the anthelmintic properties of various ethnomedicinal plants from Thailand against 3 worm species, including Caenorhabditis elegans, Paramphistomum epiclitum, and Schistosoma mansoni. The anthelmintic activities of the extracts were categorized into 4 groups based on their IC50 values: ≤20 μg/mL (active), >20 to 100 μg/mL (moderately active), >100 to 1000 μg/mL (weakly active), and >1000 μg/mL (inactive). The study utilized albendazole, mebendazole, and praziquantel as positive controls for anthelmintic activity. IC50 values of albendazole, mebendazole, and praziquantel with C. elegans were 5.09 × 102 μg/mL, 3.89 × 105 μg/mL, and 4.84 × 102 μg/mL, respectively. For P. epiclitum, praziquantel exhibited active anthelmintic activities, with IC50 = 1.96 μg/mL, albendazole and mebendazole exhibited no activity. Furthermore, only praziquantel showed moderately active anthelmintic activities on S. mansoni, with IC50 = 82.57 μg/mL. Concerning D. mollis, the methanol extract from the berries showed no activity against C. elegans and P. epiclitum. There is no available data regarding S. mansoni since no assay was conducted on this species for this extract. However, the methylene chloride extract exhibited weakly active anthelmintic activity against P. epiclitum (IC50 = 9.50 × 102 μg/mL) and C. elegans (IC50 = 2.49 × 102 μg/mL). 58
Furthermore, the researchers assessed the selectivity indices (SI) of the extract for the worms. The IC50-NLM represented the IC50 value of the crude extract on the normal human fibroblast cell line (NLM). Both albendazole and praziquantel showed IC50-NLM values >104 μg/mL, and mebendazole showed IC50-NLM values of 1.23 × 102 μg/mL. Regarding the methylene chloride extracts of D. mollis, IC50-NLM values were determined to be >104 μg/mL. The SI was calculated for each worm by taking the ratio of IC50-NLM against the IC50 of the worm. For C. elegans, the SI of albendazole, mebendazole, and praziquantel were 1.6 × 103, 3.2 × 10−4, and 291.3, respectively. For P. epiclitum and S. mansoni, the SI of praziquantel was >104 and 1.7 × 103, respectively. While SI of the methyl chloride extract of D. mollis was found to be 1.4 × 103 for C. elegans and 371.58 for P. epiclitum. Notably, an SI > 1000 indicates extremely high anthelmintic selective activity. 58
The study did not yet identify the active compounds in the methylene chloride extract, but given the recorded IC50 values and high SI values, 58 further investigation is warranted to determine the identities of the active pure compounds extracted.
Regarding the investigation of the possible toxicity of D. mollis, a few studies have been conducted. In the research carried out by Colegate et al., 52 they examined diospyrol, the main component found in fresh fruits of D. mollis, by administering it to healthy rats through intraperitoneal injection. At a dose of 70 mg/kg, no signs or symptoms of clinical toxicity, such as salivation, breathing difficulties, alterations in fur condition, or weight loss, were observed. When administered at a dose of 140 mg/kg, diospyrol induced significant depressive effects in the rats. Furthermore, when administered at a higher dose of 200 mg/kg, rats experienced mortality within 16 h. 52
Hyaluronidase Inhibitory Activity
A lipopolysaccharide, hyaluronan (also known as hyaluronic acid [HA] or hyaluronate), plays an important role in biological processes in both bacteria and higher animals including humans. It is produced by hyaluronan synthases in nature and destroyed by an enzyme family known as hyaluronidases.59,60 During tissue remodeling, hyaluronidase hydrolyzes HA in the extracellular matrix, and chronic inflammatory conditions increase hyaluronidase activity. 61 The use of hyaluronidase inhibitors is advised for both the prevention and treatment of inflammatory diseases. 62 Therefore, the use of traditional plants against inflammatory-related illnesses is due to the hyaluronidase enzyme inhibitory activity that has been demonstrated by the extract of the plant.63,64
Research findings by Suwama and colleagues indicated that lupeol caffeate
Application in Fabric Dyeing Technique
Traditionally, D. mollis fruits have been used as natural dyes for black cotton and silk fibers due to their importance as extra family economic support.33,65 To date, a number of natural dyeing technologies have been discovered and developed from natural sources towards green technology and sustainable development (Table 3).
Application in Fabric Dyeing Technique of D. mollis.
Bunfueang et al. 65 reported that pre-treated cotton yarns with the additives (eg, chitosan, microcrystalline chitosan solution, quaternized chitosan, or Sera® Fast C-NC) and the aqueous extract from D. mollis fruit, are then dyed with the annatto dye from Bixa orellana L. (Achiote) seed extract. The result shows a better color depth (K/S) and also improved light-fastness and wash-fastness properties. 65
Recently, a team of researchers examined the natural dyeing color from D. mollis fruit, which is extracted by diethyl ether, acetone, ethanol, and distilled water. These researchers found that the acetone extract of D. mollis fruit, among other solvents, exhibits silk fabric with better color strength and fastness (ratings 4-5). 34
Research conducted by Thi and coworkers revealed that the aqueous extract of D. mollis fruit could dye polyamide fabric materials with beautiful black color and 4 to 5 times more colorfastness and strength properties. To achieve this result, the dyeing technology was optimized with conditions, including temperature dyeing, dyeing time, and the ratio of extract/water that were 90 °C, 60 min, and 1/3.5, respectively. 66
In a similar study, findings by Chitichotpanya and coworkers also demonstrated that the aqueous extract of D. mollis fruit at the optimal pH (pH 4), dyeing concentration (200%owf), dyeing temperature (92 °C), and mordant concentration (5.4%owf) significantly increase black hue, suggesting good color strength and color fastness (ratings >4), especially antibacterial action against both Staphylococcus aureus and Escherichia coli (bacterial colony reduction >90%) and strong UV protection feature with the maximum UPF (40+) level. 35
In this field, it will be interesting to study different fabric dyeing processes using natural medicinal sources with eco-friendly solvents to produce products for application in the fabric dyeing industry on a green industrial scale.
Ethnomedicinal Uses
Diospyros species have been utilized in many countries as traditional herbal medicine to treat various diseases. Notably, several effects reported from the various part of Diospyros species are antibacterial, antifungal, anti-molluscicidal, anti-inflammatory, antiprotozoal, and cytotoxic effects. 12
The roots, bark, hardwood, leaves, and fruits of Diospyros species have been used as tonics and to treat various illnesses, such as infectious diseases, gastrointestinal disorders, skin diseases, diabetes, snake bites, oral cavity infections, and so on.11,17,67 For example, the decoction of Diospyros kaki L.f. leaves, traditionally used to treat diarrhea, asthma, cough, dyspnea, hypertension, and skin diseases. Common usage includes powder, decoction, or poultice for external use as an astringent and to treat skin diseases (eg, Diospyros gracilipes Hiern, Diospyros ismailii Ng, Diospyros rufa King & Gamble), febrifuge, carminative, atherosclerosis, lumbago, antifungal, hemorrhage (eg, Diospyros virginiana L.), insomnia (eg, Diospyros decandra Lour.), deworming (eg, Diospyros lotus L.), bedwetting in children (eg, Diospyros crassinervis (Krug & Urb.) Standl.), and so on.11,17
Interestingly, the decoction of D. mollis fruit has been used as a tonic in traditional Thai medicine to treat emaciation and wasting. Its various parts are also used for the treatment of a wide range of illnesses, such as vomiting, nausea, diarrhea, and intestinal parasites.22,27–29 Roots, bark, leaves, and fruits, in particular, are eaten fresh as fruit and nutritious. In Thai folklore, D. mollis is also used to treat skin diseases by boiling the roots, bark, and leaves and then mixing them with water to bathe. 23 Its fruit is frequently used to dye silk due to its black hue.33–36 The ethnomedicinal uses of different parts of D. mollis are summarized in Table 4.
Ethnomedical Uses of of D. mollis.
Critical Assessment and Discussion
This review provides a comprehensive overview of D. mollis, including its taxonomy, ethnomedicinal, phytochemical, pharmacological properties, and other applications of the species. From Indo-China (Cambodia, Laos, and Vietnam) to Myanmar and Thailand, D. mollis has been consumed and used in various traditional medicinal practices. Due to its several therapeutic applications, the “maeklua” tree has considerable potential for exploitation in both traditional and contemporary drug development.
The pharmacological investigations detailed herein encompass nearly all the ethnomedicinal applications of this species, highlighting its potential in many pharmacological fields, including anti-anthelmintic, antiparasitic, antibacterial, and anti-inflammatory activities, among others (eg, application in fabric dyeing techniques, etc).
So far, approximately 50 compounds have been identified from D. mollis, including 18 naphthalene/naphthoquinone and their glycoside derivatives, 10 terpenoids, 2 sterols, 4 fatty acid esters, 4 antiarol derivatives, 1 amino acid, 1 lignan, 1 alkaloid, and 9 phenolic glycosides. Different extracts and bioactive compounds isolated from various parts of D. mollis showed anthelmintic and parasitic abilities both in vitro and in vivo. Moreover, other studies indicated the anti-inflammatory activity via hyaluronidase inhibitory activity of compounds isolated from D. mollis. In other words, a rich and diverse array of compounds isolated from different parts of this plant suggests that these compounds may have many potential biological activities. In particular, diospyrol and its derivatives, as well as terpenoids are the major compounds found in D. mollis.
A number of triterpenoid compounds, mainly substituted lupeol, lupenone, betulin, betulinic acid, taraxerol, α-amyrin, oleanolic acid, and their derivatives (lupeol caffeate, betulin acetate), were discovered in D. mollis. These compounds are also found in several Diospyros species, such as D. kaki, D. lotus, Diospyros leucomelas Poir., Diospyros peregrina (Gaertn.) Gürke, Diospyros melanoxylon Roxb., Diospyros rubra C.F.Gaertn., Diospyros gracilescens Gürke, and so on.11,12,17,67,68 Many bioactive compounds in these Diospyros species have been reported. For example, previous studies have shown that lupeol, lupenone, and betulinic acid have a wide range of important pharmacological properties, including anti-inflammatory, antioxidant, anticancer, antitumor, immunomodulatory, antileishmanial, antimalarial, antibacterial, and other biological effects.68–75
However, the active compounds responsible for most of the biological effects of D. mollis have not yet been identified, with the exception of diospyrol, lupeol caffeate, and lupeol. Therefore, further phytochemical and pharmacological research is needed, as well as elucidation of the mechanisms of action, bioavailability, and pharmacological validation of these active compounds.
Moreover, the literature reporting the safety, including in vitro and in vivo toxic effects, of D. mollis is also limited. This lack of research information would limit its further application. In order to bridge this gap, further toxicological studies are needed to determine the potential toxicity of this species as well as the dosage that can be safely used by humans. These results have laid the groundwork for further clinical trials and the possible clinical use of D. mollis.
Previous studies concluded that synthetic textile dyes represent a large group of organic substances that could have negative impacts on the environment and perhaps constitute a risk to human health.76,77 The focus on interdisciplinary and cooperative research in the field of the textile dyeing industry not only highlights the progressive direction research should take but also underscores the potential treasures hidden within D. mollis. This is the dye source for green technology from D. mollis. In other words, D. mollis is a source of natural colorants in the fabric dyeing industry. In addition to providing color-fast, heat-resistant, and antibacterial fabric fibers, D. mollis extract reduces the effects of wastewater pollution from chemical dyes on the environment. Only through such a cohesive approach can we ensure that the numerous advantages of D. mollis are discovered, comprehended, and utilized to their fullest potential.
Conclusion
D. mollis is one of a number of plants that can be used for food, medicine, and other auxiliary uses. Based on a review of many published articles, several areas worthy of further investigation have been compiled and covered. A comprehensive evaluation of the botanical, ethnomedicinal, chemical composition, pharmacological effects, and other applications of D. mollis was performed to evaluate the chemical composition and biological activities. Different studies provided insights into the properties of D. mollis as an effective anthelmintic but are still in need of further research to explore its effectiveness against other helminths and its potential use as a treatment in humans under controlled trial conditions. These results will help us gain an understanding of the value-added applications of this species and aim to highlight its use in the treatment of diseases and as a source of natural materials for green dyeing technology.
In conclusion, this review has synthesized further investigations and studies on naturally derived compounds from D. mollis, especially diospyrol and lupeol caffeate, as the basis for the development of new drugs for the treatment of various diseases and also as a field of important research. All aspects of this species were elucidated for the first time in this review. Additionally, this review is expected to be a valuable source of reference information for researchers inclined to investigate more of its interesting and useful aspects.
Footnotes
Abbreviations
Author Contributions
Research idea: TV Chen; document overview and writing: TV Chen, NT Nghia, LVN Truong, NHK Linh; reading and revising the manuscript: TV Chen.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethical Approval
Ethical approval is not applicable for this review article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Statement of Human and Animal Rights
This review article does not contain any studies with human or animal subjects.
Statement of Informed Consent
There are no human subjects in this review article and informed consent is not applicable.
