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Guava leaves polyphenolics-rich extract inhibits vital enzymes implicated in gout and hypertension in vitro.

Irondi EA, Agboola SO, Oboh G, Boligon AA, Athayde ML, Shode FO - J Intercult Ethnopharmacol (2016)

Bottom Line: Hence, this study characterized the polyphenolics composition of guava leaves extract and evaluated its inhibitory effect on XO and ACE in vitro.The extract effectively inhibited XO, ACE and Fe(2+)-induced lipid peroxidation in a dose-dependent manner; having half-maximal inhibitory concentrations (IC50) of 38.24 ± 2.32 μg/mL, 21.06 ± 2.04 μg/mL and 27.52 ± 1.72 μg/mL against XO, ACE and Fe(2+)-induced lipid peroxidation, respectively.The extract also strongly scavenged DPPH* and ABTS*(+).

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences and Biotechnology, Biochemistry Unit, Kwara State University, Malete, P.M.B., 1530, Ilorin, Nigeria.

ABSTRACT

Background/aim: Elevated uric acid level, an index of gout resulting from the over-activity of xanthine oxidase (XO), increases the risk of developing hypertension. However, research has shown that plant-derived inhibitors of XO and angiotensin 1-converting enzyme (ACE), two enzymes implicated in gout and hypertension, respectively, can prevent or ameliorate both diseases, without noticeable side effects. Hence, this study characterized the polyphenolics composition of guava leaves extract and evaluated its inhibitory effect on XO and ACE in vitro.

Materials and methods: The polyphenolics (flavonoids and phenolic acids) were characterized using high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD). The XO, ACE, and Fe(2+)-induced lipid peroxidation inhibitory activities, and free radicals (2,2-diphenylpicrylhydrazyl [DPPH]* and 2,2´-azino-bis-3-ethylbenzthiazoline-6-sulphonic [ABTS]*(+)) scavenging activities of the extract were determined using spectrophotometric methods.

Results: Flavonoids were present in the extract in the order of quercetin > kaempferol > catechin > quercitrin > rutin > luteolin > epicatechin; while phenolic acids were in the order of caffeic acid > chlorogenic acid > gallic acids. The extract effectively inhibited XO, ACE and Fe(2+)-induced lipid peroxidation in a dose-dependent manner; having half-maximal inhibitory concentrations (IC50) of 38.24 ± 2.32 μg/mL, 21.06 ± 2.04 μg/mL and 27.52 ± 1.72 μg/mL against XO, ACE and Fe(2+)-induced lipid peroxidation, respectively. The extract also strongly scavenged DPPH* and ABTS*(+).

Conclusion: Guava leaves extract could serve as functional food for managing gout and hypertension and attenuating the oxidative stress associated with both diseases.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of proposed tripartite mechanism of anti-hypertensive effect of guava leaves extract. Purine CP: Purine catabolic pathway, XO: Xanthine oxidase, RAP: Rennin-angiotensin pathway, ACE: Angiotensin I-converting enzyme, GLE: Guava leaves extract, O2•−: superoxide anion radical, ONOO−: Peroxynitrite, ↑: Increase. The numbers: 1, 2 and 3 in rectangular boxes indicate the XO inhibition, ACE inhibition; and scavenging of reactive oxygen specie (respectively) by guava leaves extract
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Figure 4: Schematic diagram of proposed tripartite mechanism of anti-hypertensive effect of guava leaves extract. Purine CP: Purine catabolic pathway, XO: Xanthine oxidase, RAP: Rennin-angiotensin pathway, ACE: Angiotensin I-converting enzyme, GLE: Guava leaves extract, O2•−: superoxide anion radical, ONOO−: Peroxynitrite, ↑: Increase. The numbers: 1, 2 and 3 in rectangular boxes indicate the XO inhibition, ACE inhibition; and scavenging of reactive oxygen specie (respectively) by guava leaves extract

Mentions: Thus, the mechanism of the anti-hypertensive activity of guava leaves extract could be viewed to be tripartite; the first is the inhibition of XO with a concomitant decrease in ROS generation; the second is the inhibition of ACE resulting in the decreased production of angiotensin II (a vasoconstrictor), with a concomitant activation of bradykinin (a vasodilator); the third is the scavenging of the ROS generated by the two pathways (XO- and ACE-catalyzed pathways), thereby attenuating the formation of the cytotoxic ONOO− from the reaction of the O2•− with NO, and maintaining the vasorelaxant effect of the NO. A proposed scheme of this tripartite mechanism of action is shown in Figure 4.


Guava leaves polyphenolics-rich extract inhibits vital enzymes implicated in gout and hypertension in vitro.

Irondi EA, Agboola SO, Oboh G, Boligon AA, Athayde ML, Shode FO - J Intercult Ethnopharmacol (2016)

Schematic diagram of proposed tripartite mechanism of anti-hypertensive effect of guava leaves extract. Purine CP: Purine catabolic pathway, XO: Xanthine oxidase, RAP: Rennin-angiotensin pathway, ACE: Angiotensin I-converting enzyme, GLE: Guava leaves extract, O2•−: superoxide anion radical, ONOO−: Peroxynitrite, ↑: Increase. The numbers: 1, 2 and 3 in rectangular boxes indicate the XO inhibition, ACE inhibition; and scavenging of reactive oxygen specie (respectively) by guava leaves extract
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835986&req=5

Figure 4: Schematic diagram of proposed tripartite mechanism of anti-hypertensive effect of guava leaves extract. Purine CP: Purine catabolic pathway, XO: Xanthine oxidase, RAP: Rennin-angiotensin pathway, ACE: Angiotensin I-converting enzyme, GLE: Guava leaves extract, O2•−: superoxide anion radical, ONOO−: Peroxynitrite, ↑: Increase. The numbers: 1, 2 and 3 in rectangular boxes indicate the XO inhibition, ACE inhibition; and scavenging of reactive oxygen specie (respectively) by guava leaves extract
Mentions: Thus, the mechanism of the anti-hypertensive activity of guava leaves extract could be viewed to be tripartite; the first is the inhibition of XO with a concomitant decrease in ROS generation; the second is the inhibition of ACE resulting in the decreased production of angiotensin II (a vasoconstrictor), with a concomitant activation of bradykinin (a vasodilator); the third is the scavenging of the ROS generated by the two pathways (XO- and ACE-catalyzed pathways), thereby attenuating the formation of the cytotoxic ONOO− from the reaction of the O2•− with NO, and maintaining the vasorelaxant effect of the NO. A proposed scheme of this tripartite mechanism of action is shown in Figure 4.

Bottom Line: Hence, this study characterized the polyphenolics composition of guava leaves extract and evaluated its inhibitory effect on XO and ACE in vitro.The extract effectively inhibited XO, ACE and Fe(2+)-induced lipid peroxidation in a dose-dependent manner; having half-maximal inhibitory concentrations (IC50) of 38.24 ± 2.32 μg/mL, 21.06 ± 2.04 μg/mL and 27.52 ± 1.72 μg/mL against XO, ACE and Fe(2+)-induced lipid peroxidation, respectively.The extract also strongly scavenged DPPH* and ABTS*(+).

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences and Biotechnology, Biochemistry Unit, Kwara State University, Malete, P.M.B., 1530, Ilorin, Nigeria.

ABSTRACT

Background/aim: Elevated uric acid level, an index of gout resulting from the over-activity of xanthine oxidase (XO), increases the risk of developing hypertension. However, research has shown that plant-derived inhibitors of XO and angiotensin 1-converting enzyme (ACE), two enzymes implicated in gout and hypertension, respectively, can prevent or ameliorate both diseases, without noticeable side effects. Hence, this study characterized the polyphenolics composition of guava leaves extract and evaluated its inhibitory effect on XO and ACE in vitro.

Materials and methods: The polyphenolics (flavonoids and phenolic acids) were characterized using high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD). The XO, ACE, and Fe(2+)-induced lipid peroxidation inhibitory activities, and free radicals (2,2-diphenylpicrylhydrazyl [DPPH]* and 2,2´-azino-bis-3-ethylbenzthiazoline-6-sulphonic [ABTS]*(+)) scavenging activities of the extract were determined using spectrophotometric methods.

Results: Flavonoids were present in the extract in the order of quercetin > kaempferol > catechin > quercitrin > rutin > luteolin > epicatechin; while phenolic acids were in the order of caffeic acid > chlorogenic acid > gallic acids. The extract effectively inhibited XO, ACE and Fe(2+)-induced lipid peroxidation in a dose-dependent manner; having half-maximal inhibitory concentrations (IC50) of 38.24 ± 2.32 μg/mL, 21.06 ± 2.04 μg/mL and 27.52 ± 1.72 μg/mL against XO, ACE and Fe(2+)-induced lipid peroxidation, respectively. The extract also strongly scavenged DPPH* and ABTS*(+).

Conclusion: Guava leaves extract could serve as functional food for managing gout and hypertension and attenuating the oxidative stress associated with both diseases.

No MeSH data available.


Related in: MedlinePlus