HELICHRYSUM LONGIFOLIUM AND HELICHRYSUM PEDUNCULATUM: A COMPARATIVE ANALYSIS OF THEIR MEDICINAL USES, CHEMISTRY AND BIOLOGICAL ACTIVITIES

Helichrysum longifolium and Helichrysum pedunculatum have a long history of medicinal use, particularly managing wounds acquired during male circumcision rites in South Africa. There is a need to evaluate the existence of any correlation between the ethnomedicinal applications, the phytochemistry and pharmacological properties of the species. Therefore, in this review, analyses of the botanical, medicinal, and chemical and biological activities of H. longifolium and H. pedunculatum are presented as well as exploring the potential of the two species as important sources of health and pharmaceutical products. Information on the botany, medicinal uses, and phytochemistry and biological activities of H. longifolium and H. pedunculatum was assembled from several internet sources which included Scopus, Google Scholar, Elsevier, Science Direct, Web of Science, PubMed, SciFinder, and BMC. Additional information was sourced from journal articles, scientific reports, theses, books, and book chapters obtained from the University library. This study showed that alkaloids, flavonoids, linoleic acid, oleic acid, phenol, proanthocyanidin, saponins, and tannins have been identified from the leaves of H. longifolium and H. pedunculatum. The pharmacological research showed that H. longifolium and H. pedunculatum extracts and compounds isolated from the species have antibacterial, antifungal, anti-inflammatory, antioxidant, antiplasmodial, antiprotozoal, and cytotoxicity activities. For local communities to use H. longifolium and H. pedunculatum extracts with confidence as herbal medicines, there is a need for extensive phytochemical and pharmacological studies. Further research is required to establish the safety profiles of different H. longifolium and H. pedunculatum preparations.


BOTANICAL DESCRIPTION OF H. LONGIFOLIUM AND H. PEDUNCULATUM
Both H. longifolium and H. pedunculatum are perennial herbs growing up to 60 cm from a woody rootstock [46,50]. The leaves of H. longifolium are linear-lanceolate to oblong-lanceolate in shape, 100 mm to 250 mm in length and 7 mm to 20 mm in width [60]. The leaves are rosetted, apex more or less acute, base broad, clasping and bicolored with white hairs below. The leaves of H. pedunculatum are broader but shorter in length than those of H. longifolium, 80 mm-130 mm in length and 20 mm-40 mm in width [51]. The leaves of H. pedunculatum are elliptic in shape, apex acute, tapering to a broad, clasping petiole-like base, and upper surface glabrous, while the lower surface has a white silky-woolly-felted skin-like indumentum. Flowers of H. longifolium are yellow in color while those of H. pedunculatum are reddish-brown in color [52]. H. longifolium has been recorded in sandy grassland biome at an altitude ranging from 10 m to 915 m above sea level in the Eastern Cape and KwaZulu Natal Provinces in South Africa [40] and Mozambique [52,53] (Fig. 1). H. pedunculatum has also been recorded in a grassland biome at an altitude ranging from 30 m to 1525 m above sea level in the Eastern Cape, Free State and the Western Cape Provinces in South Africa and Lesotho [46] (Fig. 1).

PHARMACOLOGY OF H. LONGIFOLIUM AND H. PEDUNCULATUM
Some phytochemical constituents including alkaloids, flavonoids, linoleic acid, oleic acid, phenol, proanthocyanidin, saponins, and tannins ( Table 2) which are considered important for some of the biological activities have been isolated from the leaves of H. longifolium and H. pedunculatum. There appear to be similarities in terms of the content of total flavonoids, phenol, and proanthocyanidin of H. longifolium and H. pedunculatum (Table 2). Research by Kumar and Pandey [79] and Marín and Máñez [80] showed that flavonoids and other phenolic compounds, in general, have antibacterial, antiprotozoal, antifungal, anti-inflammatory, antiviral, antioxidative activities, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, estrogenic, antidiabetic, or antithrombotic agents, and anticancer activities. Marín and Máñez [80] argued that flavonoids and other phenolic compounds in herbal medicines correlate with their activities as an antioxidant or anti-infectious agents. The observed flavonoids and phenolic compounds in leaf extracts of H. longifolium and H. pedunculatum are of importance since the current interest in the medicinal uses of these two species is focusing on their antimicrobial, anti-inflammatory, and antioxidant effects, particularly in the management and treatment of circumcision wounds, colds, coughs, skin infections, respiratory, and stomach problems (Table 1).

Antibacterial activities
Dilika et al. [56] [85] also evaluated the effect of combining acetone and waterleaf extracts of H. pedunculatum and first-line antibiotics which included penicillin G sodium salt, amoxicillin, chloramphenicol, oxytetracycline, tetracycline hydrochloride, erythromycin, ampicillin sodium salt, and ciprofloxacin against B. cereus, P. vulgaris, M. kristinae, S. aureus, P. aeruginosa, and Salmonella spp. by means of checkerboard and time-kill methods. In the checkerboard method, the synergy of 45.8% was observed while time-kill assay resulted in the synergy of 45.8% [85].
Dilika et al. [56] evaluated antibacterial activities of methanol leaf extracts of H. longifolium against S. pyogenes, S. viridans, and E. coli using the agar diffusion method. The extracts exhibited activities against all tested pathogens [56]. Dilika et al. [45] evaluated the antibacterial activities of acetone leaf extracts of H. longifolium against S. aureus by direct bioautography on TLC. The extract inhibited the growth of S. aureus and activities decreased with an increase in temperature [45]. Aiyegoro et al. [47] evaluated the antibacterial activities of aqueous, acetone, chloroform, ethyl acetate, and methanol leaf extracts of H. longifolium against P. aeruginosa, S. aureus, S. faecalis, B. cereus, B. pumilus, P. vulgaris, S. marsecens, A. calcaoceticus, A. calcaoceticus anitratus, K. pneumoniae, S. flexneri, Salmonella spp., E. coli, M. luteus, and M. kristinae using the agar-well diffusion method. All the extracts with the exception of aqueous extract were active against all tested pathogens with MIC and minimum bactericidal concentration values ranging from 0.1 mg/ml to >5.0 mg/ml [47]. Aiyegoro et al. [47] also evaluated the rate of kill of acetone, chloroform, ethyl acetate, and methanol leaf extracts of H. longifolium by determining the bacterial cell-death time against P. aeruginosa, S. aureus, S. faecalis, B. cereus, B. pumilus, P. vulgaris, S. marsecens, A. calcaoceticus, A. calcoaceticus anitratus, K. pneumoniae, S. flexneri, Salmonella spp., E. coli, M. luteus, and Maroyi M. kristinae. The effect of the extracts on tested pathogens was time-and concentration-dependent, eliminating most of the test organisms within 12 h of exposure time [47]. Aiyegoro et al. [48] evaluated the effect of combining acetone, chloroform, ethyl acetate, and methanol leaf extracts of H. longifolium against first-line antibiotics which included penicillin G sodium, amoxicillin, chloramphenicol, oxytetracycline, erythromycin, and ciprofloxacin using the time-kill and the Chequerboard methods against P. aeruginosa, S. aureus, B. cereus, B. pumilus, P. vulgaris, A. calcaoceticus anitratus, S. flexneri, Salmonella spp., and M. kristinae. In the time-kill assay, a synergistic response constituted about 65.0%, while indifference and antagonism constituted about 28.3% and 6.7%, respectively. In the Chequerboard method, the synergistic response was 61.7%, indifference and antagonistic interactions were 26.7% and 11.76%, respectively [48]. Mathekga [60] evaluated the antifungal activities of acetone extracts of aerial parts of H. longifolium against Aspergillus niger, Aspergillus flavus, Cladosporium sphaerospermum, Cladosporium cladosporioides, Microsporum canis, and Cladosporium cucumerinum using agar dilution method. The extract showed activities against all tested pathogens with the MIC values ranging from 0.1 mg/ml to 1.0 mg/ml [60].

Anti-inflammatory activities
Bilika [61] evaluated the anti-inflammatory activities of aqueous leaf extracts of H. pedunculatum using adenosine and opiate receptor binding assays. The extract was found to be active on both adenosine and opiate receptors with >70.0% inhibition [61].

Antiplasmodial activities
Mokoka et al. [86] evaluated antiplasmodial activities of dichloromethane:methanol (1:1) whole plant extracts of H. pedunculatum using the (G-3 H) hypoxanthine incorporation assay using Plasmodium falciparum as the test organism with chloroquine (IC 50 =0.05 µM) as the positive control. The extract exhibited weak antiplasmodial activities with half maximal inhibitory concentration (IC 50 ) value of 6.5 µg/mL which was higher than 0.003 µg/mL exhibited by the positive control [86].

Cytotoxicity activities
Mokoka et al. [86] evaluated cytotoxicity activities of dichloromethane:methanol methanol (1:1) whole plant extracts of H. pedunculatum against rat myoblast (L6-cells) using the Alamar Blue assay with podophyllotoxin (IC 50 =0.05 µM) as the positive control. The extract exhibited very weak cytotoxicity activities with IC 50 value of 57.9 µg/mL with selectivity index value of 9.0. The observed IC 50 value was higher than 0.008 µg/mL exhibited by the positive control [86].

CONCLUSION
The present review summarizes the botanical, medicinal, and chemical and biological activities of H. longifolium and H. pedunculatum. Based on the presented information, these two species are closely related and deemed as highly potent traditional medicines for treating wounds acquired during male circumcision rites in South Africa. H. longifolium and H. pedunculatum have an overlapping distributional range in the Eastern Cape Province in South Africa and morphologically, the two species are quite similar, therefore, often confused when growing together. There are similarities and overlaps in terms of phytochemistry and biological activities of the two species. Therefore, these preliminary findings call for advanced phytochemical and pharmacological studies aimed at evaluating the variation of these aspects in the two species. Future studies should establish whether there are phytochemical compounds and pharmacological properties that could be used to distinguish these two species, and also supplement the currently known ethnomedicinal uses and taxonomical characters used to distinguish H. longifolium and H. pedunculatum. There is a lack of in vivo and clinical research on H. longifolium and H. pedunculatum extracts and compounds isolated from the species. Further research is required to establish the safety profiles of different H. longifolium and H. pedunculatum preparations.

ACKNOWLEDGMENTS
The author would like to express his gratitude to the National Research

Foundation, South Africa and Govan Mbeki Research and Development
Centre, University of Fort Hare for financial support to conduct this study.

AUTHORS' CONTRIBUTIONS
The author declares that this work was done by the author named in this article.

CONFLICTS OF INTEREST
No conflicts of interest are associated with this work.