Furuncles or boils develop as a consequence of bacterial infection and treatment with antimicrobial agents eases the discomfort by eradicating the causal organism. Assessment of the antimicrobial effect of A. montanus showed that the aqueous root extract demonstrated moderate antimicrobial activity against clinically isolated strains of P. aeruginosa and S. aureus, the causal organisms mostly implicated in boils . The effect of the extract was higher against S. aureus than P. aeruginosa which is an indication of greater susceptibility of the former implicated as the major causal organism of boils . However, the magnitude of the antimicrobial activity seems not to suggest that the roots derive their acclaimed potency in treatment of furuncles from antimicrobial effect. Although treatment of boils with antimicrobial agents may be curative in this instance (depending on the size of the boil), anti-inflammatory agents provide instant relief from the pain and other discomfort caused by the inflammatory reactions invoked by the causal organisms. Our study showed that topical and systemic administration of the extract resulted to inhibition of the development of acute edema. Topical application of the extract is consistent with traditional use and the relief obtained in the treatment of boils may also derive from suppression of acute inflammatory reactions. Thus, phytochemical constituents of the roots are likely capable of permeating inflamed skin to exert antimicrobial and anti-inflammatory effects.
The acute inflammatory reaction is a physiological characteristic of vascularized tissues  and increased vascular permeability associated with it is known to cause exudation of fluid rich in plasma proteins including immunoglobulins, coagulation factors and cells into the injured tissues with subsequent edema at the site [38, 39]. Increased vascular permeability is a major feature of acute inflammation  and results from contraction and separation of endothelial cells at their boundaries to expose the basement membrane which is freely permeable to plasma proteins and fluid . In this study, the extract moderately inhibited increased vascular permeability induced by acetic acid in the mouse peritoneum. Acetic acid causes an immediate sustained reaction that is prolonged over 24 h [12, 40] and the inhibition caused by the extract suggests it may suppress exudation and its consequences and thus modulate the magnitude of the inflammatory response associated with boils. On the proliferative phase of inflammation, the extract was not effective in ameliorating the overall outcome of formaldehyde arthritis event notwithstanding the fact that it inhibited the early stages (which is likely an extension of its effect on acute inflammation). The usefulness of the extract may be limited to acute inflammatory conditions such as obtained in boils and which is consistent with the ethnomedicinal use of the plant roots. As such, the extract may not offer any relief when used in disorders of chronic inflammation such as rheumatoid arthritis.
Another key aspect of the inflammatory response is cellular infiltration due to the pivotal role played by leukocytes in inflammation. These cells are found in boil cavities where the dead cells and necrotic tissues form components of pus . As part of their defensive roles during inflammation, these cells release their lysosomal contents such as bactericidal enzymes and proteases, at sites of inflammation which cause further tissue damage and inflammation . Stabilization of the membranes of these cells inhibits lysis and subsequent release of the cytoplasmic contents which in turn limits the tissue damage and exacerbation of the inflammatory response. In vitro assessment of the effect of the extract on membrane stabilization showed that it inhibited heat- and hypotonicity-induced lysis of ox red blood cells. Although we do not know the precise mechanism of membrane stabilization in this case, direct interaction of constituents of the extract with membrane components such as proteins seems most probable. Membrane proteins are largely responsible for the physical properties of the cell membrane and may contribute to the regulation of the volume and water content of cells by controlling the movement of sodium and potassium ions  through the protein channels which make up ion channels in the cell membrane . Since pathological conditions can alter surface-volume ratio of the cell through loss of membrane surface or gain in volume , the physical integrity of the treated cell membranes may have been enhanced by the extract (through a direct protective interaction with the membrane proteins) to hinder cell lysis including that caused by products such as those of the complement system involved in the inflammatory response cascade and hypotonic solutions that cause the cell to swell and rupture . The stability of biological membranes is also affected by reactive oxygen species and we have in an earlier study (data not shown) shown that the extract exhibited antioxidant effect by inhibiting lipid peroxidation induced by CCl4 and ferrous sulphate in the rat kidney and liver . This action suggests that the extract may enhance membrane stability through antioxidant effect and protect the tissues from damage due to injurious products of oxidative stress implicated in the pathogenesis of inflammatory disorders . Furthermore, inhibition of cell migration or infiltration is associated with anti-inflammatory effect. Cellular migration involves a sequence of well-documented events [46–49]. Expression of chemoattractant factors and response of these cells to chemotactic signals are central to their migration. In addition to enhancing neutrophil migration, chronic administration of the extract to mice increased the population of macrophages which migrated to the peritoneum in response to stimulation. These independent but related tests confirm that the root extract may stimulate or enhance cellular migration. However, the extent of interaction of the extract with the processes associated with cell recruitment is not known to us. Like neutrophils, macrophages also migrate in response to chemotactic factors and the enhancement of their migration by the extract may involve similar mechanisms. Since inhibition of cell migration is known to contribute to anti-inflammatory activity, enhancement or stimulation of migration by the extract runs counter to the anti-inflammatory activity. Our result also showed that increasing the dose of the extract reduced the extent or magnitude of cell migration which suggests that the extract may as well inhibit cell migration under acute inflammatory response. However, the occurrence of this effect only at high doses not likely employed in traditional use of the roots in treatment of boils indicates that inhibition of cell migration may not contribute to the anti-inflammatory effect and most unlikely to play any role in the relief obtained. Thus, although anti-inflammatory effect may relieve the discomfort caused by boils, constituents of roots of this plant may owe part of their action in furuncles to a more fundamental mechanism the magnitude of which may be dependent on the extent of cell migration which they appear to enhance.
In furtherance of their defensive roles at sites of infection, leukocytes engage in phagocytosis to contain the microbial invasion. Evaluation of the effect of the extract on phagocytosis showed that it enhanced the phagocytic activity of mouse peritoneal macrophages quantified as increase in the number of macrophages that ingested C. albicans. The phagocytic activity of these cells also results to the generation of the necrotic tissue debris and dead cells known to be components of pus  and may be the major mechanism responsible for the acceleration of pus formation seen when the root is used in the treatment of boils. In addition to phagocytic activity, we also studied the effect of the extract on specific immune responses mediated by the T lymphocytes which is important for host defense against intracellular parasites . Our results showed that the extract inhibited the development of DTHR induced by SRBCs in rats. The DTHR is characterized by a heavy infiltration of T cells and macrophages  in response to antigenic stimulation which in this case was the SRBCs. Inhibition of T lymphocyte infiltration seems to contradict the enhancement of leukocyte migration earlier noted. The disparity in the effect of the extract on cell types may lie in the mechanisms involved in the migration of these different species of leukocytes. Neutrophils migrate in response to chemoattractant gradient and chemotactic factors while the migration of lymphocytes is stimulated by specific antigens, mitogens and other non-specific factors produced by lymphocytes . Lymphocytes though motile cells, do not respond to most of the chemotactic factors that act on polymorphonuclear leukocytes and macrophages . Consequently, we may safely assume that the extract promotes the expression of chemotactic/chemoattractant factors although we do not know its extent of interaction with processes involved in antigen recognition which is the initial stimulus for T cell activation . This makes it also most likely that phytochemical constituents of the root responsible for its effectiveness in furuncle treatment may largely interfere with or suppress immune processes with other mechanisms such as antimicrobial and anti-inflammatory activities playing supportive roles.
The phytochemical constituents responsible for these activities are yet to be identified. The pharmacological actions of the saponins  and the gammaceranes- acanthusol and its 3-O-β-D-glucopyranoside  isolated form this plant are not known as well as their roles in the activities studied. Phytochemical analysis of the root extract revealed an abundant presence of alkaloids and carbohydrates while saponins, glycosides, and terpenoids occurred moderately. The relatively high presence of alkaloids and carbohydrates suggests that these constituents may largely account for the pharmacological activities of the plant roots.
Oral and intraperitoneal administration of the extract to mice caused no deaths at doses ranging from 10–5000 mg/kg suggesting an oral and i.p LD50 greater than 5000 mg/kg. The high LD50 value implies a remote risk of acute intoxication and a high degree of relative safety independent of route of administration. Although the roots are used externally, the relative safety is obviously advantageous since systemic administration and or systemic absorption of the root extract from site of topical application (as employed in ethnomedicine) may pose no risk of acute toxicity.