1 Introduction

Flemingia grahamiana, a Fabaceae family member, is a scientifically significant plant with diverse phytoconstituents and potent pharmacological activities. Its adaptability to tropical and subtropical regions and unique morphological features aid in identification and traditional medicine practices [1]. The plant’s bioactive compounds, including isoflavones, flavones, aurones, anthraquinone, emodin, and Chalcones like Flemingin A, B, C, G, H, and O, etc. make it an attractive resource for drug discovery [2]. Further research may lead to novel medicines derived from F. grahamiana, advancing herbal medicine and modern drug discovery.

A systematic search on databases such as Google Scholar, ResearchGate, PubMed, and Springer, etc. was used to perform a full review of F. grahamiana The study concentrated on phytoconstituents, pharmacological activity, traditional applications, bioactive substances, and traditional medicine. Articles published in English between the earliest accessible date and the most recent date were included, with no limitation on publication year. Exclusion criteria maintained quality and relevance by rejecting irrelevant, non-English, duplicate, and inadequate studies. Inclusion criteria assured the reliability of investigations by examining relevance, original research, publication type, and language. The search generated a significant number of articles, which were screened using the requirements. Relevant full-text papers were chosen for data extraction and analysis, providing significant data about F. grahamiana and its possible therapeutic applications. The combined data benefits the scientific community and stimulates further research.

Flemingia grahamiana, a member of the Leguminosae (Fabaceae) family, is a captivating plant with a rich history of traditional use in folk medicines across different parts of the world. Belonging to a botanical genus comprising approximately 30–50 species, primarily found in tropical and subtropical regions, F. grahamiana, commonly known as ‘Warrus’, stands out as an intriguing species within this diverse family [1, 3]. Its botanical characteristics, taxonomic classification, and geographical distribution have been subjects of interest, along with its vital role in traditional medicine, where it is used to address various health conditions.

This review article aims to provide a comprehensive overview of F. grahamiana, consolidating existing knowledge from various sources. The plant’s unique features, including its erect herb or sub-shrub structure with tomentose young shoots and deep roots, occasionally exhibiting tuberous growth, add to its visual allure. Noteworthy are the digitately 3-foliate leaves, auxiliary inflorescence, densely fasciculate racemes, and distinctive yellow-white or pink corollas of its bisexual flowers. The inflated oblong pods, often adorned with red viscous glands, further contribute to its intriguing botanical attributes [4,5,6].

Although native to Africa, F. grahamiana has a wide distribution, extending to various regions in Asia, such as India, Laos, Myanmar, Vietnam, and Yemen. It thrives in diverse ecological niches, including open and wooded savanna, riverine vegetation near water bodies, hill slopes, termite mounds, and road edges. The plant's adaptability to varying environments has undoubtedly contributed to its popularity as a subject of interest for researchers and scientists worldwide [4].

The Leguminosae family, to which F. grahamiana belongs, is renowned for its ethnobotanical uses in traditional medicines across the globe. Members of this family have been recognized for their effectiveness in treating diverse ailments, ranging from stomach problems, diarrhea, dysentery, chest pain, and coughs to serving as aphrodisiacs, purgatives, and anti-helminthic agents, and even as antidotes for snake bites. Furthermore, many of these plants have additional applications, such as food sources, vegetables, and fodder, contributing significantly to nitrogen fixation and soil conservation [7,8,9].

The phytochemistry of Flemingia species, including F. grahamiana, has been a subject of interest, revealing various compounds such as isoflavones, chalcones, flavanones, and others. The isolation and characterization of these compounds have shed light on the plant's potential pharmacological activities and therapeutic significance. Notably, the presence of compounds with antioxidant, anticancer, and antibacterial properties in F. grahamiana offers exciting prospects for further exploration in drug discovery and development [2, 3, 10, 11].

By synthesizing information from various sources, this review article aims to shed light on the medicinal value of F. grahamiana and its potential as a valuable resource for both traditional and modern medicine. We will delve into its phytochemical constituents and explore their potential pharmacological activities, encompassing antioxidant, anticancer Michigan Cancer Foundation-7 (MCF-7), antibacterial, and cytotoxic properties. The wealth of knowledge accumulated through this exploration may pave the way for future research, ultimately leading to the development of novel therapeutic agents derived from this remarkable plant species [3, 10, 11].

1.1 Botanical information

Flemingia is a genus of 30–50 species found in tropical and subtropical climates. Flemingia is a synonym for Moghania, an altered variety of Maughania [1].

Up to 1.8 m tall, F. grahamiana is an erect plant or subshrub (Fig. 1) with tomentose young shoots and deep (sometimes tuberous) roots. Digitately three-foliate, its stipules are lanceolate or elliptic-lanceolate and around 1 cm long. The plant bears an additional inflorescence that is densely fasciculate, raceme-shaped, and has imbricate bracts on rachises that are 1 to 5 cm long. Flowers are bisexual and have a 2-mm long pedicel, a 1.5-cm long tubular calyx, and an oblong, standard-length corolla that is either yellow-white or pink. The inflated, rectangular, 2-seeded, hairy, and frequently coated in red viscous glands pods are 1 cm in length [4].

Fig. 1
figure 1

Morphology of Flemingia grahamiana Wight & Arn. defining Leaves and pods

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It is found throughout tropical Africa from Ethiopia to Cameroon, Ghana to South Africa, and grows in termite mounds, open and wooded savannas, often close to water in riverine vegetation, and along roadside edges. In addition to Southern Arabia (Yemen and Oman), the plant is also widespread in South Western Asia, including India (Karnataka, Tamil Nadu), Laos, Myanmar, and Vietnam [4, 12,13,14].

M. Mosango conducts extensive investigation of F. grahamiana by drying the leaves at 60 ℃. The analysis aimed to determine the following constituents: Ash content (4.0%), Nitrogen (3.28 ± 0.02), Carbon (54.3 ± 3.72%), Cellulose (28.1%), Hemicellulose (6.3%), and Lignin (18.9%). Furthermore, the research encompassed the evaluation of the Active fraction content (42.7%) and the computation of the L/N ratio (5.8) and C/N ratio (16.6). This thorough analysis offers insightful information on the biology and features of F. grahamiana. [15]

1.2 Taxonomic classification [16]

Kingdom: Plantae

Division: Magnoliophyta

Class:Magnoliopsida

Order: Fabales

Family: Leguminosae (Fabaceae)

Subfamily: Papilionoideae (Faboideae)

Genus: Flemingia

Species: grahamiana

1.3 Ethnobotanical uses

Worldwide, traditional medicines employ plants from the Leguminosae family to treat a wide range of illnesses. They are used to cure a variety of conditions, such as coughs, chest pain, diarrhea, dysentery, and syphilis. They are employed as aphrodisiacs, purgatives, laxatives, anti-helminthics, and snake bite antidotes [7,8,9].

Numerous members of this family of plants are employed as food and vegetable producers, as well as livestock feed for soil conservation. Some are utilized in live and dry fences, particularly those that have thorns and spines [7]. F. grahamiana is widely used in traditional medicine in different parts of the world, as summarized in Table 1.

Table 1 Region-wise ethnobotanical applications of Flemingia grahamiana used by the localites
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1.4 Phytochemistry

The Flemingia grahamiana has been linked to a variety of chemicals. These include isoflavones, chalcones (including the nine newly discovered Flemingins G-O and the known Flemingins A-C), flavanones, along with deoxyhomoflemingin and emodin, which were extracted from F. grahamiana leaf extract. It was discovered that the isolated chalcones had a geranyl substituent changed into a chromene ring with a residual chain [2, 5, 10, 21,22,23].

The chemical structures for Flemingins, Deoxyhomoflemingin, and Emodin are shown with the Chalcone nucleus for Flemingins and their associated substitutes in Figs. 2 and 3, and Table 2 respectively.

Fig. 2
figure 2

Chalcone nucleus defining abundant active phytoconstituent Flemingins from Flemingia grahamiana

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Fig. 3
figure 3

Chemical structures of other phytoconstituents from Flemingia grahamiana a Flemingin O,  b Deoxyhomoflemingin, and c Emodin

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Table 2 R1, R2, R3 substituents of chalcone nucleus outlining various structural derivatives of Flemingins
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1.5 Pharmacological activities

Graphical representation of pharmacological activities is shown in Fig. 4.

Fig. 4
figure 4

Graphical representation of various pharmacological activities of Flemingia grahamiana

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1.5.1 Radical scavenging activity

To evaluate the radical scavenging ability of crude extracts made from F. grahamiana’s roots and leaves, Ivan Gumula studied the DPPH test. Table 3’s findings revealed that the leaf extract had a high ability to scavenge free radicals. It was previously believed that the Flemingin’s extraordinary capacity to scavenge free radicals was due to the 2ʹ, 5ʹ-para dihydroxylation present in the B-ring, which resulted in the production of a stable quinone after radical scavenging processes described in Fig. 5 [2, 24].

Table 3 Radical scavenging Activity and Anti-TB Activity of selected compound
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Fig. 5
figure 5

Chemical conversion of P-dihydroxy chalcones into quinones by DPPH explaining the antioxidant potential of Flemingin C

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1.5.2 Anti-TB activity

Flemingin A demonstrated strong activity against Mycobacterium tuberculosis in the Low Oxygen Recovery Assay (LORA) test, moderate activity in the Methicillin-Resistant Staphylococcus aureus (MABA) test, and strong cytotoxicity against Vero cells, as reported in Table 3. This highlights the efficacy of Flemingin A in the treatment of renal and malignancies associated with the kidney [2].

1.5.3 Antioxidant activity

A study was conducted by Latifa Nasser et al. to investigate the antioxidant activities of methanol and aqueous extracts made from F. grahamiana warrus pods. The researchers evaluated the antioxidant activity using the 1, 1-Diphenyl-2-picryl hydrazyl (DPPH) technique. A link between the antioxidant properties of both extracts and their concentration was seen. The IC50 values for F. grahamiana Warrus extracts were 3.95 μg/ml and 0.71 μg/ml for methanol and aqueous extracts, respectively. Notably, the standard ascorbic acid’s IC50 value was determined to be 3.35 μg/ml [3].

1.5.4 Anticancer activity

Gumula et al. isolated F. grahamiana leaf fractions using methanol and dichloromethane, then assessed the leaf fractions’ cytotoxicity against MCF-7 cells. When compared to other flemingin derivatives, their research showed that flemingin A and C had the highest cytotoxic potencies, with IC50 values of 8.9 and 7.6 µM, respectively. Additionally, Abdulqawi et al. investigated the extracts of F. grahamiana’s anticancer potential against MCF-7 cells. They discovered that substantial anticancer effects were shown by both methanol and water extracts, however significant inhibition required concentrations higher than 25 µg/ml. The combined results highlight the potential effectiveness of F. grahamiana and its derivatives against human breast cancer cells [10, 24, 25].

1.5.5 Antibacterial activity

The antibacterial potential of methanolic and aqueous crude extracts obtained from F. grahamiana was the topic of a research investigation carried out by Abdul Qawi et al. The researchers tested the extract’s effectiveness against six common bacterial infections in Aurangabad, India, using the Well-diffusion method in vitro. These pathogens included Escherichia coli (ATCC25922), P. mirabilis, K. pneumoniae (clinical samples), S. aureus, and P. aeruginosa. Different concentrations of the extracts (2.5, 5, 7.5, and 10 mg/well) were studied [11].

The findings of this antimicrobial evaluation showed that F. grahamiana methanol extracts demonstrated considerable inhibitory effects, especially at a dosage of 10 mg/well. With significant zone sizes of 25.2 mm and 25.7 mm, respectively, Proteus mirabilis and Staphylococcus aureus were the two pathogens most strongly affected by these effects. However, neither Klebsiella pneumonia nor Escherichia coli (ATCC 25922) displayed any inhibitory zones in response to these extracts [11].

The study examined the Minimum Inhibitory Concentration (MIC) over a range of concentrations from 25 mg/ml to 0.781 mg/ml to better understand the potency of the extracts. The MIC of F. grahamiana's methanolic extract was 0.781 mg/ml against MRSA and Staphylococcus aureus, while that of the aqueous extract was 0.781 mg/ml exclusively against MRSA [11].

Nadia Hassan Al-Asbahi et al.’s study emphasizes how important it is to look into the antibacterial qualities of natural extracts and improve extraction techniques for possible medicinal uses. According to this viewpoint, the study assessed the antibacterial activity of many extracts, including F. grahamiana glandular hairs of the pods, against Staphylococcus aureus. At 2.5 mg, 5 mg, and 10 mg of extract, the methanolic extract of F. grahamiana displayed inhibition zones with diameters of 10 ± 0.29 mm, 10 ± 1 mm, and 12 ± 1.73 mm, respectively; at no tested dosage, the aqueous extract did not demonstrate any inhibition zones. These results highlight the F. grahamiana glandular hairs' modest antibacterial activity in a methanolic extract. As an antibacterial agent, F. grahamiana seeds are typically ineffective [26, 27].

1.5.6 Other activities

In Zimbabwe and Malawi, the plant's root decoction is used to treat diarrhea and dysentery. In India, the plant is also used internally as a purgative and to treat colds in addition to being used externally to treat skin conditions [13, 28].

2 Conclusion

The fascinating plant F. grahamiana, a member of the Fabaceae family, has enormous potential for use in both conventional and modern medicine. This article gives a thorough summary of its pharmacological effects, ethnobotanical uses, and botanical characteristics. Multiple databases were included in the systematic search technique, which produced a lot of data. Researchers are drawn to F. grahamiana because of its capacity to adapt to a variety of habitats and its distinctive morphological features. The bioactive components of the plant, such as isoflavones, flavones, and chalcones, offer intriguing possibilities for therapeutic development. F. grahamiana has been used in traditional medical practices around the globe to treat a range of medical issues. The review emphasizes the adaptability, distribution, and previous uses of the plant. Potential therapeutic uses are made possible by the phytochemistry of the plant, particularly by substances with antioxidant, anticancer, and antibacterial properties. The significance of F. grahamiana in bridging the gap between conventional methods and contemporary drug development is highlighted by this review. Future improvements in medicine are possible thanks to F. grahamiana, which combines historical knowledge with modern research.