**5. Polyphenol composition in SB and phytochemistry**

Polyphenols from SB have antioxidant [1], anti-inflammatory [7, 8], cardioprotective [9, 10] and anticancer [2] properties, associated with metabolic-health enhancement including weight management, improvement of lipid and glucose profiles, pancreatic regeneration, and reduction of hypertension (**Figure 1**) [11–16].

#### **Figure 1.**

*Main mechanism of action and associated health benefits of Sea Buckthorn polyphenols.*


*Seabuckthorn Polyphenols: Characterization, Bioactivities and Associated Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.98706*


**Table 1.**

*Identification and quantification of the main polyphenolic compounds present in SB; taken from [17–19].*

Particularly, kaempferol, quercetin, and their derivatives, proanthocyanidins (PAC), catechins, phenolic acid and tannins demonstrated significant health-promoting benefits. Isorhamnetin, kampferol, quercetin, catechins and procyanidins represent some active molecules with well-known health benefits.

SB represents a good source of phenolic compounds acting in synergy with PUFA such as omegas 3, 6, 7 and 9, vitamins (vitamin C), organic acids, making SB a suitable candidate for dietary supplement and food fortification. SB polyphenols are mainly phenolic acids and flavonoids. Polyphenolic content ranges from 29 to 38.8 mg/g (GAE), with more than 100 polyphenolic compounds identified (**Table 1**). The estimated content in polyphenols is higher than in mulberry, blueberry, raspberry or pomegranate [1]. Polyphenol content varies from species to species, geographical origin, the degree of maturity at the harvest, and the production process, such as drying temperature, method of extraction and storage. Comparing species, flavonoid content was the highest in *H. rhamnoides L susbp sinensis* and *yunnanensis.* Phenolic acids are divided into hydroxybenzoic acid, hydroxycinnamic acid, and their derivatives. The main phenolic acids naturally occurring in SB fruit are gallic acid, protocatechuic acid, salicylic acid, vanillic acid, caffeic acid, ferulic acid, P-coumaric acid and chlorogenic acid (**Table 1**). Flavonoids commonly found in SB include isorhamnetin, quercetin, kaempferol, myricetin, catechin, epicatechin and rutin. Condensed tannins or PAC constitutes the third category of polyphenols in SB. There is also a significant amount of carotenoids (including ß-carotene, zeaxanthin and lycopene) in SB. **Table 1** summarizes the main polyphenols identified and quantified in SB berry preparations in recent publications.

### **6. Effects of SB polyphenols on cellular function**

Ethanolic extract of SB berry (SBB) exerts significant cytoprotective properties against sodium nitroprusside induced oxidative stress in lymphocytes [20]. SBB extract also attenuated nicotine-induced oxidative stress in rat liver and heart [21]. Moreover, the total flavones of SB provided protection against H2O2-induced apoptosis on vascular endothelial cells with the lowering the caspase-3 expression [22]. SBB also showed immunomodulating effect against T-2 toxin-induced immunodepression in 15-day-old chicks [23]. The SBB extract also had a protective effect on antioxidant enzyme levels and contributed to the reduction of lipid peroxidation, leading to reduced levels of cellular oxidation processes. Furthermore, Yasukawa et al. reported that an ethanolic fraction of SB containing (+)-catechin, (+)-gallocatechin, (−)-epigallocatechin and ursolic acid exhibited anti-tumor activity [24]. When tested on cell proliferation in the Caco-2 and HepG2 cancer cell lines, SBB extracts induced apoptotic activity and apoptotic morphological changes of the nucleus. This included chromatin condensation in HL-60 cells treated with flavonols isolated from SB such as quercetin, kaempferol and myricetin [25–27].

A flavonoid extract of SB containing isorhamnetin and quercetin exerted protective effects on myocardial ischemia and reperfusion, on microcirculation and on the regulation of thyroid function [2]. Isorhamnetin isolated from SB has also been investigated for its cytotoxicity and its influence on human hepatocellular carcinoma cells. The cytotoxic effect of isorhamnetin was showed to be dose and time-dependent against hepatocellular carcinoma cells after treatment with isorhamnetin for 72 h [28].

Polyphenolic compounds in SBB juice at different phases of digestion exerts beneficial effects on colonic microbial diversity, with an increase in total phenolic content and in total antioxidant activity during gastric and small intestine digestion, and the release of quercetin from the food matrix in the colon. Colonic fermentation resulted in an increase in quercetin and caffeic acid, along with a decrease in rutin and chlorogenic acid after 36 h of fermentation. The Shannon diversity index of beneficial groups including Lactic acid bacteria, Bacteroides/Prevotella and Bifidobacteria was increased by 35%, 71% and 17%, respectively. As a consequence, SB juice seems to represent a good source of prebiotic substrate for the proliferation of beneficial gut microbiota [29].

### **7. Safety of SB extracts**

The safety of SB leaf and berry extracts was assessed in several studies [30–32]. In a sub-acute study, the absence of any sign of toxicity at the highest dose used established the LD50 at >10 g/kg bw for SB leaf extract. In a chronic 90-day repeated gavage administration study, no changes were observed at any of the doses used with regard to body weight and organ weight for animal of both sexes, when compared to control rats [31]. Moreover, no significant changes in biochemical parameters were noticed relative to lipid metabolism as well as renal or hepatic function. The absence of histopathological lesions in the main organs at any dose suggests a NOAEL superior to 500 mg/kg bw. In addition, the safety of herbal antioxidants composed of SB pulp and extract thereof was studied [32]. There were no significant alterations in hematological and biochemical parameters at any dose. Histopathological analysis of vital organs showed normal architecture and absence of lesions in all treated groups, which was associated with no difference in weight gain and relative organ weight in treated groups compared to controls. Even at high dose of 2,000 to 8,000 mg/kg bw [32], an absence of toxicity and side effects was reported, confirming that SBB extract is a safe product.

### **8. Health benefits of SB leaf and seed polyphenols**

#### **8.1 Lead intoxication model**

The efficacy of SB leaf aqueous extract (SLE) was assessed in a model of lead toxicity in Wistar rat model, at a daily dose of 100 mg/kg bw for 60 days [33]. Administration of SLE to lead intoxicated Wistar rats resulted in normalization of almost all the safety

*Seabuckthorn Polyphenols: Characterization, Bioactivities and Associated Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.98706*

parameters studied - albumin, creatinine, blood urea, total proteins. Significant improvement in total protein levels after SLE treatment in lead intoxicated animals may be due to its antioxidant properties and its hepatoprotective effect, normalizing protein synthesis. SLE treatment of lead intoxicated rats resulted in normalization of serum urea and creatinine levels, suggesting a normalization of glomerular filtration rate in kidney. Supplementation of SLE in lead intoxicated rats resulted in normalization of elevated cholesterol levels, that may due to the presence of flavonoids, terpenoids, carotenoids.

#### **8.2 Cardiometabolic risk improvement, anti-obesity and hepatoprotective effects**

SB leaf tea (SBLT) included at levels of 1 and 5% of total diet, in a high fat diet (HFD) for 6 weeks, suppressed body weight gain in a dose-dependent manner and significantly reduced visceral fat, plasma levels of leptin, triglyceride, total cholesterol and ALT activity compared with high-fat-fed control mice [34]. SBLT also decreased hepatic triglyceride, serum cholesterol and lipid accumulation. Moreover, its consumption normalized the expression of several hepatic lipid metabolic markers such as glucose-6-phosphate dehydrogenase, phosphatidate phosphohydrolase, beta-oxidation, and carnitine palmitoyltransferase. Intra-abdominal deposition of visceral adipose tissue is a major risk factor for the development of hypertension, insulin resistance, metabolic syndrome, diabetes mellitus and hyperlipidemia. SBLT supplementation seemed to have a direct effect on lipid metabolism, and it exhibited significant anti-visceral obesity property, while also reducing hepatic lipid accumulation when compared with the high-fat-fed control animals. The hypolipidemic effect of SBLT supplementation seemed likely to be due to a decrease in hepatic triglycerides synthesis through a modulation of the fatty acid esterification pathway. Compared to high-fat-fed control mice, SBLT lowered CYP2E1 activity which participates to the production of reactive oxygen species and overall oxidative stress. Both 1% and 5% SBLT supplementation effectively improved ALT activity. SBLT supplementation may prevent hepatic damage of HFD by enhancing the antioxidant defense system and the attenuation of microsomal CYP2E1 induction. Therefore, SBLT exerts antioxidant, anti-obesity and hepatoprotective effects by modulating hepatic lipid metabolism.

Total flavones from SB fruit seed residues were administered at the daily concentrations of 50, 100 or 150 mg/kg/day for 8 weeks in sucrose-fed rats model [35]. Sucrose-fed rats displayed increases of 25.6% in systolic blood pressure, 114% in plasma insulin, 85% in triglycerides (TG), as well as an increase in activated angiotensin in both heart and kidney. SB flavones significantly suppressed the elevated hypertension, hyperinsulinemia and dyslipidemia. It also led to the normalization of systolic blood pressure by at least improving insulin sensitivity and the increase in plasma angiotensin II after 8 weeks of SB consumption, especially at the daily dose of 150 mg/ kg. The antihyperinsulinemia abilities of SB total flavones from fruit seed residues and irbesartan were comparable. SB flavones reversed the abnormalities in plasma triglyceride, cholesterol and FFA levels and low content of HDL. Administration of SB seed residues at a daily dose of 400 mg/kg bw for 4 weeks significantly decreased serum glucose, TG and nitric oxide levels in diabetic rats and increased serum superoxide dismutase activity and glutathione level [36]. Therefore, SB seed extract has hypoglycemic, hypolipidemic and antioxidant effects in diabetic rats.

These findings were confirmed in another study where an ethanolic extract of SB leaves (SBLE) at daily doses of 500 and 1,000 mg/kg was administered for 13 weeks to mice fed high-fat diet (HFD) [37]. Oral administration of SBLE significantly reduced

energy intake, body weight gain, epididymal fat pad weight, hepatic triglyceride, hepatic and serum total cholesterol levels, as well as serum leptin levels when compared to control HFD mice. Glucose tolerance assessed by OGTT was significantly improved at both daily doses of SBLE. Lipid droplet infiltration in the liver was significantly reduced at the lower dose of SBLE and absent at the higher dose of SBLE, confirming hepatoprotective action against triglycerides accumulation in the liver, as well as steatosis. SBLE modulates liver lipid metabolism by the upregulation of PPARa, PPARy and CPT1 and downregulation of acetylCoA carboxylase.
