HOW CAN THE WORLD OVERLOOK Sapindus rarak BIOPROSPECTION? A NICHE FOR INDONESIA

This research was conducted from July to September 2022 in the LLNP. This study used stationaries, laptops with ArcMap GIS 10.5 software, Microsoft Office Word, Microsoft Excel, and SPSS 22. The materials used hotspot data from the TERRA/AQUA satellites, SNPP, and MODIS-NASA (with a medium (30 - 79%) and high (80 - 100%) confidence level) for the period 2017 to 2021 in LLNP, monthly rainfall data for Sigi District (Gimpu and Sungku Stations) and Poso District (Doda, North Lore, Lore Piore, and Maholo Stations) for the 2017-2021 period from the Meteorology, Climatology, and Geophysics Agency (BMKG), and LLNP land cover data which is the result of LLNP's proprietary land cover analysis and in collaboration with a third party.This research, conducted in January–February 2023, employed a bibliometrics analysis method by following the approaches of Fahimnia et al. (2015); Ma et al. (2022); and Nurfauzan & Faizatunnisa (2021) with some modifications. The methodology included defining search keywords, extracting initial data, refining results, compiling metadata, and mapping authors, keywords, and collaboration networks (see Figure 1).

The research employed Scopus and Google Scholar for data search, and Harzing's Publish or Perish software (Harzing 2007) for data extraction. The results were saved in RIS and CSV formats and imported into the reference manager Zotero (Roy Rosenzweig Center for History & New Media 2016). After obtaining a list of articles, we excluded patents, irrelevant studies, or duplicate literature, resulting in a final dataset containing information such as the number and list of authors, titles, year of publications, publishers, article type, total citations, and citations per document. Data compilation was performed using Microsoft ExcelTM 2013 (Microsoft Corporation).

Furthermore, bibliometric analysis was conducted based on Scopus. The world map depicting the number of publications for each country was derived through the online application (www.datawrapper.de). Meanwhile, author mapping, keywords, and collaboration networks were visualized using VOSviewer (van Eck & Waltman 2018). Author and country mapping provided information about disciplinary leaders, while keywords indicated the hot topics. Collaboration patterns and citation networks represented teamwork and primary literature from different periods, describing the field’s evolution and projecting future developments (Ma et al. 2022).

Meanwhile, the scoping review included determining research objectives and questions, defining the scope, selecting studies through an iterative team approach, extracting data, summarizing qualitative and quantitative analysis, reporting results, preparing the considerations of implications in research, and optionally consulting with stakeholders (Levac et al. 2010). The purpose and scope of this review were to map S. rarak bioprospection. The dataset inputted for the bibliometrics was also involved in the scoping review, although no stakeholder consultation occurred during this process.

RESULTS AND DISCUSSION

Defining the Appropriate Search Keywords

The preliminary bibliometrics analysis started with the keywords ‘Sapindus rarak’ AND ‘leaves’ to investigate the overlooked bioprospection of S. rarak leaves. Despite expecting abundant data, Scopus identified only three articles. Expanding the keyword to ‘Sapindus rarak’ increased the total to 32 documents, which was unexpectedly low (Table 1). Meanwhile, on Google Scholar, using the keywords ‘Sapindus rarak’ AND ‘leaves’ yielded 39 documents, and the keyword ‘Sapindus rarak’ alone retrieved 221 documents. Although this number was smaller compared to bibliometrics analyses for other plants like M. oleifera, which reached 2,345 documents (George et al. 2021), the limited global publications on S. rarak allowed an opportunity for an in-depth review.

Extracting the Initial Data

Scopus https://www.scopus.com/, managed by Elsevier publishing, was selected over Web of Science (WoS) www.clarivate.com. Although both are widely recognized inputs for bibliometrics analysis, the analysis based on each can provide different results (Echchakoui 2020). Despite WoS being established earlier in 1997 than Scopus in 2004, Scopus accommodates a broader range publications from developing countries, encompassing non-English language. WoS covers 54% of journals indexed by Scopus, while Scopus contains 84% of journals indexed by WoS (Gavel & Iselid 2008). This research specifically utilized Scopus considering its expected wider coverage compared to WoS.

Utilizing Harzing's Publish or Perish (Harzing 2007) for Scopus with ‘a title’ and ‘a keyword’ queries, 32 documents were obtained. Additionally, we retrieved publications from Google Scholar for comparison, considering the limited global research related to S. rarak in Scopus. Here, Google Scholar showed numerous interesting local publications on S. rarak bioprospection.

Refining Results

All 32 documents from Scopus met the requirements, with no irrelevant or duplicated data, resulting in a total retention of 32 documents (100%). In contrast, Google Scholar indexed numerous redundant documents, leading to a final result of 91% documents with 1176 citations (Table 1). Despite recording a higher publication count than Scopus, Google Scholar included national publications, majority in Indonesian (Table 2), highlighting the predominant local development of S. rarak research in Indonesia. For rigorous data analysis, further bibliometrics analysis was performed using Scopus.

Compiling Initial Metadata

The literature on S. rarak involves 23 authors in 32 documents spanning 20 years (1992–2022), accumulating 387 citations. Initiated by Matthias Hamburger in 1992 (Figure 2), the study of S. rarak progressed slowly until 2004, experiencing a crucial development from 2005–2010. This phase saw significant contributions from Elizabeth Wina, Toshio Morikawa, and Yosunabu Asao. Elizabeth Wina emerged as the most influential author, holding the highest citation rank. Substantial contributions from Evi Maryanti and Sri Suharti occurred from 2011–2019. While several researchers began to contribute during this period, their impact was relatively modest.

Sixteen institutions contributed to this field with the Indonesian Research Institute for Animal Production (Indonesia) standing out as the most influential. While Kinki University, Université de Lausanne, and the University of Illinois at Chicago published fewer articles, their citation number was notably high (Table 3). Indonesia led the research on S. rarak (Figure 3), which is not surprising given that the plant is native to Indonesia, widely cultivated, sold in markets throughout the year, and commonly used by the community as a natural detergent. Due to the excellent potency and existence of S. rarak in Indonesia, it holds the potential to become a point of Indonesian competitiveness.

Mapping Authors’ Collaboration, Keywords, and Field Evolution Patterns

Co-authorship network analysis revealed the collaboration trend and the leader in a particular field (Fonseca et al. 2016). Elizabeth Wina from Indonesia was the most influential author (Figure 4). Indonesian researchers (S. Suharti, D. Astuti, A. Kurniawati, and T. Toharmat) were interconnected with foreign researchers (S. Muetzel, K. Becker, E. Hoffmann, and H. Makkar) through this author.

Research on S. rarak focused on four hot topics: chemistry, biology, medicine, and physics. Based on its chronological development, research on the biological aspect was developed first, followed by the exploration of the medicinal aspects, deepening into chemistry, and lastly, the investigation of physical properties. Furthermore, chemistry became the most developed field compared to other topics (Figure 5).

The most prominent author network, centered on Elizabeth Wina, focused on the study of microbial population dynamics and animal rumen fermentation due to the supplementation of S. rarak fruit extract. The Morikawa, Asao, and Chang group explored the chemical structure and in vitro biological activity of S. rarak phytoconstituents. Koysap contributed to bridging the evolution of the interlinked field between medicine and phytochemicals (Figure 6).

Scoping Review Analysis

An in-depth review of 32 publications revealed the diverse potentials of S. rarak. Table 4 presents a summary of the scoping review analysis results, including the primary utilization aspect of S. rarak, identifying alternative sources of S. rarak beyond the fruit, evolving extraction techniques, common form of S. rarak, and regions contributing the most in providing S. rarak materials.

As shown in Table 4, S. rarak research focuses on its potential as livestock supplementation (12 documents), alongside applications as molluscicide, herbicide, antimicrobial, antitumor, anti-obesity, anti-inflammatory agents, nanoparticle, soil remediation, surfactant, catalyst, and sweetener. All studies exclusively reported on fruit and seed of S. rarak, neglecting the potential of leaves, despite significant biological activity in other Sapindaceae species leaves. For instance, Litchi chinensis leaves exhibit anti-inflammatory effect (Besra et al. 1996), S. mukorrossi demonstrates antioxidant activity (Singh & Kumari 2015), and S. saponaria shows antimicrobial (Garcia et al. 2012) and antiulcer (Meyer Albiero et al. 2002) activity. While S. rarak leaves contain fewer saponins than fruit (Pratiwi & Nurlaeni 2022), exploring their potential extends beyond saponin extraction to uncover other beneficial phytochemical groups. The leaves, being abundant organs that do not compete with reproductive functions, warrant consideration (Chen et al. 2016).

Additional S. rarak research discussed the extraction method. To enhance saponin yield, a variety of solvents were considered, with methanol frequently chosen. Ultrasound-assisted extraction (UAE), particularly green UAE, and raising the extraction temperature were able to increase saponin yield (Aryanti et al. 2020, 2021; Nafiunisa et al. 2019). The prevalent use of crude extract over powder, pure saponin, and biochar is noted. Consistent with bibliometrics results, the majority of samples sourced from Indonesia.

While the discussion regarding the efficacy of S. rarak as a detergent material is limited in internationally reputable publications, numerous national publications on Google Scholar address this aspect. S. rarak fruit, whether in its raw form, boiled, or incorporated into soap with additional additives, is widely sold throughout the year in the Indonesian market for washing Batik and baby cloth diapers (Muttafaq et al. 2019; Nia et al. 2018). Detergent formulated from S. rarak is safe for clothing fiber and color, effectively removing any stains compared to conventional detergents (Muttafaq et al. 2019). Moreover, the environmental friendliness of S. rarak is noteworthy as the fruit generates abundant foam with just water soaking (Pratiwi & Nurlaeni 2022), eliminating the need for resource-intensive processes like detergent manufacturing, known for their high carbon footprint (de Koning et al. 2010). The formulated S. rarak detergent has a potential to replace non-renewable petroleum-based detergents ( Maurad et al. 2017) and excess phosphates often used as detergent builders, contributing to water eutrophication (Kogawa et al. 2017). Additionally, detergent waste from S. rarak will easily decompose in the environment.

To gain a broader perspective, we suggest future exploration using Google Scholar to understand national research trends, particularly regarding the application of S. rarak as a detergent. This database can also reveal information about Indonesian scientist teams involved in S. rarak research for various applications. In the field of S. rarak as livestock supplementation, Elizabeth Wina is a notable figure, but not the first Indonesian scientist in this domain. The team from the Indonesian Research Institute for Animal Production, including Mohammad Winugroho, Amlius Thalib, Yeni Widiawati, and Dwi Yulistiani, initiated the research.

In terms of feedstock supplementation, saponin impacts rumen fermentation by modifying the microbial community's structure and activity, acting as a defaunation agent that suppresses protozoa without affecting bacterial growth, leading to improved fiber digestion efficiency or decreased protein degradation (Wina et al. 2005). However, saponin’s toxicity negatively impacts beneficial bacteria and fungi and their enzyme activity in an in vivo study using rumen liquor from goats fed S. rarak extract (Wina et al. 2004). Conversely, a moderate level of S. rarak reduced the protozoa community from cow rumen cultured in vitro without affecting fibrolytic bacterial and fungi (Wina et al. 2005). Further study showed that short-term saponin exposure in goat reduced xylanase activity and Ruminococcus, but Fibrobacter, being Gram-negative, resisted saponins. Long-term exposure in sheep rumen depressed protozoa and fibrolytic enzyme carboxymethylcellulase (CMC) activity but had no effect on Ruminococcus, suggesting potential bacterial adaptation mechanism (Wina et al. 2006b).

The disparity in results between in vitro and in vivo studies triggers the idea of interval feeding (Wina et al. 2006a), although S. rarak reduces protozoa in both feeding methods with no significant differences at any dose. CMC and xylanase activity decreased in both regimes, and higher doses led to lower enzyme activity. Although high saponins doses tended to reduce ammonia concentration, nitrogen balance remained unaffected, and the decrease in fibrolytic enzymes did not impact the digestive tract (Wina et al. 2006a).

The S. rarak supplement has been introduced in various formulations, including mineral blocks (Suharti et al. 2010), microencapsulation with canola oil (Suharti et al. 2019), and combination with garlic extract for ammoniated rice straw substrate enrichment (Prayitno et al. 2013), in addition to oil palm frond substrate, and Saccharomyces cerevisiae fermentation with S. rarak extract (Zain et al. 2016). Furthermore, the addition of S. rarak has been tested in cassava leaf diets (Yuliana et al. 2019a) and incorporated with Hibiscus rosa-sinensis in the cassava leaf silage (Yuliana et al. 2019b). These efforts have increased beneficial bacterial communities, enhanced protein flow from the rumen to the blood, and improved ammonia concentration, dry matter, and organic matter digestibility, body weight gain, and suppression of protozoa populations.

The decreased protozoa, as host for methanogenic bacteria, suppress methane production, the second most impactful greenhouse gas after CO2, with a higher global warming potential. Ruminant methane (CH4) emissions harm the environment, increase the greenhouse impact, and reduce animal energy and production efficiency. Therefore, ruminant methane emissions must be reduced (Sun et al. 2021). The dynamics of the methanogenic bacteria within the rumen undergo a shift from methane to propionate production (Suharti et al. 2011). Hence, saponin indirectly contributes to mitigating climate change by reducing methane emission (Króliczewska et al. 2023).

Although S. rarak fruit can improve fermentation performance in the digestive tract of goats, sheep, dairy, and beef cattle, the results can vary dependent upon saponin type, dosage, fermentation substrate, and combination with other ingredients. Further research is required to develop patented feed supplementation products, exemplified by the patent for the ‘Complete Rumen Modifier’ formula (certificate number IDP000057123), a feed additive for ruminant livestock that has tS. rarak exhibits molluscicidal properties attributed to four newly identified triglycoside saponins (Hamburger 1992). Meanwhile, the S. rarak extract serves as a repellent and induces mortality in giant african land snails (Lissachatina fulica) without harming vegetable Brassica rapa L. (Koysap et al. 2022). Additionally, it demonstrates herbicidal activity against Leptochloa chinensis and Fimbristylis milacea weeds. The aqua extract has no adverse effects on rice growth, while the methanol extract inhibits rice height without affecting root length and leaf number (Pujisiswanto et al. 2022). he potential to enhance their growth while reducing enteric methane production (Thalib et al. 2010).

S. rarak exhibits molluscicidal properties attributed to four newly identified triglycoside saponins (Hamburger 1992). Meanwhile, the S. rarak extract serves as a repellent and induces mortality in giant african land snails (Lissachatina fulica) without harming vegetable Brassica rapa L. (Koysap et al. 2022). Additionally, it demonstrates herbicidal activity against Leptochloa chinensis and Fimbristylis milacea weeds. The aqua extract has no adverse effects on rice growth, while the methanol extract inhibits rice height without affecting root length and leaf number (Pujisiswanto et al. 2022).

In terms of antimicrobial properties, the ethanol extract of S. rarak seeds effectively degrades extracellular polymeric substances in pathogenic polymicrobial biofilms, as observed by scanning electron microscopy (Pratiwi & Hamzah 2020). Furthermore, S. rarak microparticles administered in drinking water perform similarly to commercial anticoccidials in reducing Eimeria sp. and E. coli (Pasaribu et al. 2022). Coccidiosis is an important enteric health problem in poultry, leading to reduced feed efficiency, weight gain, bloody stools, and mortality. The gastrointestinal tract in chickens has a wide range of microorganisms that play a vital part in the processes of digestion and defense. The infection of Eimeria spp. parasites disrupts the gut environment, leading to an imbalance in intestinal homeostasis. This imbalance promotes the growth of pathogens, including Clostridium species (Madlala et al. 2021). S. rarak as a natural antibiotic potentially can replace the banned feed additives containing anticoccidial agents due to the risk of multidrug resistance (Han et al. 2022).

The alternative use of antibiotic growth promoters (AGP), such as S. rarak saponin, is crucial due to the prohibition on AGP. These alternatives should easily blend with feed, lack tissue residual effects, and improve feed intake, gain, and conversion rates. Additionally, they should enhance immunity and digestion, nutrient availability, possess antimicrobial effects, maintain unaffected carcass characteristics, act as antioxidants and anti-inflammatory agents, compete against stress factors, and provide wholesome organic products for human consumption (Abd El-Hack et al. 2022). As the emphasis on a healthy lifestyle and organic farming grows, consumer preferences are increasingly favoring products from antibiotic-free livestock (Seidavi et al. 2021).

S. rarak presents sesquiterpene saponins inhibiting tumor necrosis factor-α-induced cytotoxicity in L929 fibrosarcoma cells (Morikawa et al. 2010). It also demonstrate anti-obesity effects by inhibiting pancreatic lipase activity (Morikawa et al. 2009) and has passed toxicity tests, suggesting potential benefits in weight management (Asao et al. 2009; Fajriaty et al. 2014). Moreover, S. rarak finds application in the synthesis of silver (Yudha et al. 2013) and ZnO nanoparticles (Maryanti et al. 2014), useful for photo-degrading rhodamin B as environmental pollutants (Umar et al. 2022). It can also be synthesized with sulfur as a catalyst (Banon et al. 2022). Additionally, its derivative compounds exhibit potential as acid surfactants (Cahyana et al. 2020) and sweet principles (Chung et al. 1997). Lastly, scoping review showed that S. rarak biochar has the potential to improve andosol soil quality (Arum & Wikaningrum 2022).

CONCLUSION

The substantial number of publications written in Indonesian, as indexed by Google Scholar, highlights the enthusiastic involvement of Indonesian researchers in the exploration of S. rarak bioprospection. Scopus indexed 32 scientific articles regarding S. rarak, composed by 23 authors between 1990 and 2022, with a cumulative citation count of 387. Notably, Indonesia, the Indonesian Research Institute for Animal Production, and Elizabeth Wina stand out as the most productive country, institution, and author, respectively. The research is clustered based on chemistry, biology, medicine, and physics approach. The bioprospection of S. rarak fruit encompasses various applications, including animal feed supplementation, molluscicide, herbicide, antimicrobial, antitumor, anti-obesity, surfactant, catalyst, nanoparticle, and soil remediation. Surprisingly, research on the efficacy of detergents derived from S. rarak has not been published in a highly reputable international journal, despite its traditional utilization over an extended period. Despite the exclusive focus on S. rarak fruit or seed as promising organ in all articles, none have addressed leaves or other plant organs. In the future, Indonesian researchers are encouraged to comprehensively explore the potential of S. rarak, especially its leaves, for additional valuable phytochemicals beyond saponin. This exploration could position S. rarak as a signature bioresource with significant economic value, serving as a source for medicine, animal feed supplements, and organic pesticides, expanding beyond its current use in detergents within society.

REFERENCES