Indonesian threatened Zingiberaceae: Exploring their potential traditional and modern uses

As human populations continue to grow and natural habitats shrink, there is an urgent need to understand and protect plant species that have the potential to benefit both humans and the environment. Zingiberaceae is one such plant family with many species known has traditional and scientific uses. The family is primarily found in tropical regions, with the highest species diversity in Southeast Asia and South America. Indonesia is home to approximately 500 species of Zingiberaceae out of a global total of 1,500 species. However, more than 100 species of Zingiberaceae in Indonesia are threatened with extinction, mainly due to habitat loss by logging and land conversion, putting their potential uses at risk. This review explores the traditional and modern uses of threatened Zingiberaceae species in Indonesia based on their genus. We surveyed the literature and compiled data on the traditional uses of the Indonesian Zingiberaceae species as medicine and any scientific studies investigating their prospective as a drug. There is widespread utilization from a third of Zingiberaceae genera with threatened species, highlighting the substantial untapped potential that requires further investigation on the species facing a considerable risk of extinction. Unfortunately, efforts to conserve the threatened Zingiberaceae species are currently limited, with only less than ten per cent of species being conserved in Indonesian botanic gardens.


Introduction
Indonesia is a vast archipelago, consisting of more than 17,000 islands, and spans over 5,000 kilometers from east to west.Its unique geographic location and tropical climate have contributed to the country's rich biodiversity, making it one of the world's top mega-diverse countries [1].As a result, Indonesia is home to more than 28,000 species of plants and animals, many of which are endemic and found nowhere else on earth.The country's vast archipelago has created isolated habitats for flora and fauna to evolve independently, leading to the formation of new species.The large number of islands also offers different ecosystems, ranging from rainforests, savannas, coral reefs, and mangroves, resulting in high biodiversity [2,3].This unique geographical feature of Indonesia has resulted in the formation of hotspot areas for endemic species, particularly in the Wallacea region [2], Kalimantan, Sumatra, and Papua [3].
Wallacea which lies between the Asian and Australian continents, has been recognized as a biodiversity hotspot, with a high degree of endemism [4].Kalimantan, the third-largest island in the world, is known for its vast rainforests and is home to many endemic species [5].Sumatra, the sixthlargest island in the world, is also known for its unique biodiversity.While Papua, located in the eastern part of Indonesia, is known for its unique biodiversity.Papua's isolation from other regions has allowed it to develop its own set of endemic species.The island's rich and unique biodiversity has attracted many researchers and naturalists, making it one of the most studied regions in the world [3].Despite the rich biodiversity, Indonesia is also facing several environmental challenges that threaten its endemic species.Deforestation, illegal logging, and forest fires are among the leading causes of habitat destruction, affecting the country's endemic species [6,3].
Zingiberaceae is the largest family in the order Zingiberales, consisting of 53 genera [7].This plant family contains aromatic compounds, and most of its members have many benefits as spices and medicines.Indonesia is home to approximately 500 species of Zingiberaceae [8] out of a global total of 1,500 species [9].According to taxonomist Axel Dalberg Poulsen from the Royal Botanic Garden Edinburgh, Wallacea, Kalimantan, and Sumatra are among the centers of wild Zingiberaceae diversity in Indonesia, and most of them are endemic species.However, more than 100 species of Zingiberaceae in Indonesia are threatened with extinction [10] due to forest conversion and deforestation in the the past few decades [11].Wild Zingiberaceae is a highly potential source of germplasm.Unfortunately, only a few Zingiberaceae species have been utilized by humans.It is estimated that only about 40-50 Zingiberaceae species have been utilized by humans for various purposes [12].
Ethnobotany and pharmacology studies have revealed that most Zingiberaceae members are a source of traditional medicines and contain various active compounds that have potential in the discovery of modern medicines [13].Zingiberaceae is reported to have various potential biological and pharmacological activities, including as antioxidants [14,15], antibacterial, anti-inflammatory, anticancer, antitumor, antiarthritis [16], anthelmintic [17], and anti-hypertensive [14].Several secondary metabolite compounds that have potential as sources of medicines have also been successfully identified and isolated from Zingiberaceae, such as phenolic compounds and 6-gingerol in Zingiber officinale Roscoe [18] have been proven to have high antioxidant activity.Meanwhile, flavonoid and phenolic compounds contained in Etlingera elatior (Jack) R.M.Sm.have strong antibacterial activity against Staphylococcus aureus [19].
Building upon the background information presented, this study aims to explore the potential of wild and threatened Zingiberaceae species in Indonesia, focusing on their traditional and modern uses based on their genus.This paper not only contributes to understanding the traditional and modern medicinal potential of the Indonesian threatened Zingiberaceae species but also emphasizes the importance of conserving these valuable plants.By investigating their unique traditional uses and uncovering their potential as sources of modern medicines, this research highlights their significance in traditional healing practices and contemporary drug discovery efforts.Furthermore, by identifying their diverse biological activities and valuable secondary metabolites, the study emphasizes the urgent need to protect and conserve these species.Preserving the rich biodiversity of Zingiberaceae ensures the availability of medicinal resources, supports the preservation of indigenous knowledge, and fosters the development of alternative treatments for various health conditions.Ultimately, this paper contributes to scientific knowledge and promotes sustainable conservation practices for the benefit of present and future generations.

Materials and methods
The list of Indonesian Zingiberaceae species threatened with extinction was extracted from The IUCN Red List of Threatened Species [10] which also provided data on the endemicity, population trends, and the utilization if any.The information was subsequently processed using Microsoft Excel to generate relevant tables, charts, and diagrams.However, the list of species was grouped based on their genus due to the lack of information on the utilization of these threatened species.Information about the uses of species belonging to these genera was collected by reviewing the 50 most relevant scholarly documents in the Web of Science Core Collection database (https://www.webofscience.com/).The query for these documents was "Zingiberaceae AND use AND Indonesia."The data pertaining to the utilization of threatened Indonesian Zingiberaceae species was employed to depict their potential usage.The collected data on utilization were primarily focused on traditional uses for medicinal treatments and biological or pharmacological activity assessments, thereby excluding other benefits like culinary spices or food wrappings.The current efforts to save this threatened species were reviewed based on a list of species conserved in Indonesian botanic gardens.The data were traced from the Indonesian botanic gardens collection database called Makoyana (https://makoyana.brin.go.id/).Makoyana is a database managed by the National Research and Innovation Agency of Indonesia (BRIN).This database serves as a centralized platform for integrating information about plant species that are conserved ex-situ, meaning outside their natural habitats, across a range of botanical gardens.The database encompasses not only botanical gardens managed directly by BRIN but also those managed by external entities not affiliated with BRIN.

Results and discussion
Based on data from the IUCN [10], the Zingiberaceae family in Indonesia had 80 species across 20 genera listed as treathened in 2020.However, the latest information from the IUCN [10] in 2023 reveals an alarming increase, with the number of threatened species rising to 105, distributed among 23 genera (see Table 1).Most of these species are categorized as endangered, with vulnerable and critically endangered species following (Figure 1).The addition of 25 species and three genera to the IUCN Red List of Threatened Species within fewer than three years, combined with the majority falling into the endangered category, leads to a valid assertion that uncommon species within the Zingiberaceae family in Indonesia face a substantial threat.Approximately 68.57% of the total species in question are recognized as endemic plant species.These species are categorized into four regions within Indonesia: Borneo, Sumatra, Sulawesi, and Java (Figure 2).In addition to their notable endemicity and conservation status, the population trend raises concerns.Over time, 55% of the threatened Zingiberaceae species in Indonesia have experienced a decline (Figure 3).This decline could be attributed to the small size of their natural populations and limited utilization within local communities.The number of species utilized by the community accounts for less than 10% of the total number of plant species.Among the genera, Etlingera is the most widely used, with five species, followed by Curcuma with two species, and then Plagiostachys and Zingiber with a single species each.The primary use of these species is as a food ingredient (Curcuma sumatrana, Etlingera aurantia, Etlingera baculeta, Etlingera baramensis, Etligera loerzingii, Etlingera muriformis, Plagiostachys crocydocalyx, and Zingiber album).Other uses include medicinal purposes for the skin (C.sumatrana), cosmetics (E.baramensis), spiritual practices (P.crocydocalyx), and unidentified purposes intended for sale (Curcuma colorata).2).Among all the genera utilized, Curcuma and Zingiber are the most commonly employed in traditional medicine, with 34 and 29 recorded u ses, respectively.Etlingera and Alpinia are also widely utilized for medicinal purposes, offering 13 and 12 benefits, respectively.Boesenbergia follows with 6 uses, while Hedychium and Wurfbainia have 5 and 3 uses, respectively.It is worth noting that Hornstedtia, although not traditionally utilized for medicinal purposes, has been studied for its anticancer and antioxidant activities.Regarding the assessment of biological and/or pharmacological activity, Zingiber, Alpinia, Curcuma, Hedychium, and Boesenbergia exhibit more than five potential activities each.On the other hand, Etlingera, Wurfbainia, and Horndstedtia have been tested for five, three, and two activities, respectively.Species belonging to the eight genera of Zingiberaceae listed in Table 2 have a long history of traditional usage in Indonesia for treating a wide range of health issues, totaling at least 67 ailments.These health concerns span from external wounds to internal diseases.Interestingly, several genera exhibit similar effectiveness, indicating that at the species level, there are multiple alternative options for treating the same health conditions.For instance, to address issues like appetite, stamina, and aphrodisiac effects, there are species available from four to five different genera.Another example, ailments such as cholesterol, cold, cough, fever, hypertension, and rheumatic conditions can be alleviated using species from any of the three genera specified in Table 2.As a note, Zingiberaceae species are not only utilized individually in traditional medicine but are also combined with other Zingiberaceae species or even with species from other plant families [21,22,28].
Based on the data obtained from testing the active compound content (Table 2), there are at least 13 biological and/or pharmacological activity found in eight Zingiberaceae genera.The entire eight genera possess antioxidant capabilities.Moreover, the majority of genera exhibit activities such as anticancer, antibacterial, antifungal, anti-HIV-1, and antidiabetic properties.Additionally, four genera demonstrate antiaging effects, specifically targeting glycation.Whereas analgesic, essential oil, larvacidal, neuroprotective, and treatment of androgen-dependent disorders potential are unique to specific genera, with each activity found in just one genus.The specific activities found within Zingiberaceae species reflect the high diversity of active compounds in this family, indicating its potential to address a wide range of diseases.
Shifting our focus to the conserved species, according to the Makoyana website, there are only eight out of 105 threatened species of Indonesian Zingiberaceae that are currently conserved.Among them, living specimens of C. sumatrana, E. loerzingii, Etlingera solaris, Globba variabilis, Hedychium roxburghii, and Hornstedtia mollis are cultivated in Bogor Botanic Gardens.
Plagiostachys crocydocalyx is maintained in Bali Botanic Gardens, while Zingiber odoriferum plants are conserved in both Bogor and Bali Botanic Gardens.Upon closer examination, half of these conserved species are categorized as vulnerable in the IUCN Red List, three others are endangered, and only one is critically endangered.Interestingly, only three of these species have documented utilization notes.For instance, the water decoction of C. sumatrana leaves has been traditionally used to alleviate itching, while E. loerzingii and E. solaris have been employed as food ingredients.These findings emphasize the need for further conservation efforts to protect the threatened species of Indonesian Zingiberaceae.Additionally, it is crucial to explore these species' potential, enabling their biodiversity's economic benefits to become explicit so that it can be compared to other economic activities [50].

Conclusion
There is a concerning rise in the number of Indonesian threatened Zingiberaceae species, with most falling into the endangered category.The endemicity and population decline of these species raises significant conservation concerns.Only three of the 105 threatened species have information on their medicinal uses.At a higher taxon, eight of 23 Zingiberaceae genera with threatened species have much information on their use as traditional and modern medicine.The widespread utilization from a third of Zingiberaceae genera with threatened species reflects the substantial untapped potential that requires further investigation on the species facing a considerable risk of extinction.This emphasized the need to protect and conserve these species to ensure the availability of medicinal resources and support the development of alternative treatments.Efforts to conserve the threatened Zingiberaceae species are currently limited, with only less than ten per cent of species being conserved in Indonesian botanic gardens.Further conservation efforts and exploration of the economic benefits of these species are crucial to safeguard their biodiversity and promote sustainable practices for the benefit of present and future generations.

Figure 3 .
Figure 3. Population trend of Indonesian threatened Zingiberaceae species

Table 1 .
List of Indonesian threatened Zingiberaceae species as of 29 th March 2023 Figure 1.Red list category of Indonesian threatened Zingiberaceae species as of 29 th March 2023

Table 2 .
Use as traditional medicine and biological or pharmacological activity of the Zingiberaceae genus which has threatened species