INTRODUCTION:

The term Herbo is considered as plant and the some means cell like. Most of the compounds of plat origin are polar or water soluble molecules. Because of the cellular lipid structure and the large molecular size of the polar soluble phytoconstituents (viz. flavonoids, tannins, glycosides etc) these cannot absorb by passive diffusion or due to their poor lipid solubility, severely limiting their ability to pass across the lipid rich biological membrane which results the poor bioavailability of the active constituents. Since ancient time phytomedicines have been used for the treatment of various ailments.

Various plant material have been exhibited a variety of biological activity such as hepatoprotective activity, antilipidemicactivity, anticancer activity, hypoglycemic activity etc. Phytomedicines complex chemical mixtures prepared from plants have been used for health maintenance since ancient’s times. But many phytomedicines are limited in their effectiveness because they are poorly absorbed when taken by mouth. Currently, as many as one-third to approximately one-half of all the drugs available are derived from plants or other natural sources^[1]_.

The chemical complexity of the crude or partially purified extract appears to be crucial for the bioavailability of the active constituents; hence standardization of herbal extracts has become imperative. Although having excellent bioactivity in vitro, plant extracts often exhibit poor effectiveness in vivo or in animal models. The basic reasons for the low bioavailability of herbal extracts are that the bioactive components of these herbs possess multi- ring molecular structures which cannot be absorbed into the blood by simple passive diffusion and the bioactive phytoconstituents are mostly water soluble, hence, their poor lipid solubility limits their ability to pass across lipid biomembranes. This has restricted the use of pharmacologically effective polyphenolic plant actives for treating different disorders. Moreover, when taken orally, bioactive phytoconstituents are destroyed by or lost to the gastric environment or they may be rendered less effective by interaction with other drugs or nutraceuticals [2].

Phytomedicines, complex chemical mixtures prepared from plants have been used for health maintenance since ancient’s times. But many phytomedicines are limited in their effectiveness because they are poorly absorbed when taken orally. The phytosome technologies, developed by Indena S.P.A. Italy, markedly enhance the bioavailability of selected phytomedicines, by incorporating phospholipids into standardized extracts and vastly improve their absorption and utilization. [3].

These herbosomes have proven to be highly efficient in the protection of pharmaceutically active herbal extracts against gastric secretions and gut bacteria. The herbosomes of herbal extracts of ginseng, milk thistle, grape seed, green tea and hawthorn are available in the market ^[4]. Hence the details of Herbosomes preparation, evaluation, merits, demerits and advantages are illustrated momentarily and it assist the researchers working for herbosomes to acquire better formulation.

2. Herbosome technology:

Prerequisite for herbosome formation

1. Standardized extract or an active phytoconstituent

2. Carrier Phospholipid

3. Solvent

Standardized extract or an active phytoconstituents selection^{[5, 6, 7 8]}

1. Basically, either active constituents or standardized extract were selected for phospholipid complex formulation. However, natural products after isolation and purification may lead to a limited or total loss of specific biological activity so, in such cases whole plant extracts are selected. Usually, phospholipid complex formulations are prepared according to weight basis for standardized extract, whereas molar ratios for active constituent.

2. Selection of plant extract depends on its phytochemical (such as polyphenols, triterpenoids, tannins, alkaloids and saponins) and pharmacokinetic profile. Usually they have multiple ring molecules which are too large to be absorbed by simple diffusion and have low permeability across the cellular lines of the intestine.

3. A drug which contains an active hydrogen atom like –COOH, -OH, -NH₂, -NH etc., which have the ability to form hydrogen bond between the drug and N-(CH₃) of PC molecules.

4. Any drugs which possess π electrons can be formulated into different complexes with phospholipid molecules.

5. Both hydrophilic and lipophilic actives can be complexed to improve bioavailability.

Phospholipids and their importance^{. [5, 9]}.

In general, fats, phospholipids, and steroids are different types of lipids present in the body and perform various functions. Among them, phospholipids which are major components of cell membranes also serve as a vehicle, thus making the design of drug delivery systems more flexible, and are suitable for the body needs. Phospholipids are bio friendly and offer various advantages such as formulation flexibility and the choice of different NDDS based on the intended use. Phospholipids are lipids containing phosphorus, a polar portion and non-polar portion in their structures.

A human biological membrane constitutes different classes of phospholipids, like phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidic acid (PA), and phosphatidylserine (PS). PC possess two neutral tail groups and a positive head group which contains an oxygen atom in the phosphate group that has a strong tendency to gain electrons, while nitrogen to lose electrons, a rare molecular characteristic that makes PC miscible in both water and lipid environments. Earlier “Lecithin” is a word which created perplexity in researchers for identification but later on it was clearly discussed by Wendel. In commercial perspective, lecithin refers to PC, PE, PS, PI and other phospholipids. But in historical point of view lecithin includes lipids which contains phosphorous obtained from brain and egg. However, scientifically lecithin refers to PC.

Phospholipid source and its additional benefits as adjuvant. ^{[5, 9]}.

Phospholipids are obtained from both natural and synthetic source. Phospholipids are widely found in plants and animals, and the main sources are vegetable oils soya bean, sunﬂower seed, rapeseed, and cotton and animal tissues include e.g. egg yolk and bovine brain. Most of the literature suggests the use of soya bean phosphatidylcholine while few others have used egg lecithin, in the preparation of phytophospholipid complex. In fact, phospholipids are one of the most abundantly present lipid fractions in biological membranes and can form bilayers and act as amphipathic molecules. After oral administration of phospholipids, they are absorbed to a great extent and reach the peak plasma concentration within 6 hours. FDA and German Cancer Research Centre, Heidelberg stated that Soy phosphatidylcholine has no carcinogenicity and no risk in formation of tumour. Additionally, PC is said to have varied advanced beneficial properties like hepatoprotective activity, nutritional supplement to support brain health, role in membrane fluidity, shows superior host defences (like enhancing NK cell activity and phagocytosis), excellent emulsifying activity, major component of the gastric mucosa lining of the stomach protecting from ulcer, precursor for acetylcholine, reducing serum cholesterol, improving the perception of taste and smell, recuperate fatigue and even in nourishing skin.

3. Preparation of Herbosomes:

Phytosomes are prepared by different methods by interacting 3-2 moles natural or synthetic phospholipid, mainly phosphotidylcholine with one mole of phytoconstituent. The most preferable ratio for complexes formation between these two moieties is in the range from 0.5 to 2.0 mole^[10].

Solvent evaporation method:

A natural or synthetic phospholipid phosphotidylcholine and phytoconstituent is suspended in an appropriate solvent, further refluxed for few hours. The resultant clear mixture is being evaporated under vacuum^[11].

Salting out method:

The phytoconstituent or standardized extract and phosphotidylcholine is dissolved in an aprotic solvent, such as dioxane or acetone where the solution is being stirred overnight then the formed complex is isolated from by precipitation from non-solvent like n-hexane^[12].

Lyophilization technique:

Both natural or synthetic phospholipid and phytoconstituent is dissolved in different solvent and further solution containing phytoconstituent were added to a solution containing phospholipid followed by stirring till complex formation takes place. The formed complex is isolated by lyophilization^[13].

The phospholipid which are used in preparation of phytosome consist of acyl group which may be same or different in phosphatidylcholine, phosphatidylserine, phosphatidyl ethanolamine and mostly derived from palmitic, stearic, oleic, and linoleic acid^[14,15]. In phytosome active principle becomes an integral part of the membrane as the active principle is anchored to the polar head of phospholipid^[16].

Role of phosphatidylcholine in Herbosome preparation:

Phospholipid serves as a major moiety in composition of cellular and subcellular membrane. They are basic substance to maintain life activity. The human body uses phosphpolipid as emulsifiers and also enhances the absorption of fat-soluble substances. Furthermore, it act as surface active agent in the pleura and alveoli of lung, joints, pericardium, etc^[17]. They can be extracted from egg yolk or soybeans through mechanical or chemical methods with the aid of hexane. Phosphatidylcholine has two groups mainly lipophilic, phosphatidyl group, and the choline group which is a hydrophilic moiety. Choline moiety improves memory function and aids muscle control. The choline portion binds to the herbal extract while thephosphatidyl group covers the phytoconstituents like a cell form which further protects the active constituent from destruction from the digestive juices. Due to drugphospholipid complex formation the bioavailability of the active constituent is increased, along with prolonged duration of action ^[18].

4. Properties of Herbosomes:

Physical Properties

· Herbosome has lipophilic substances with a clear melting point.

· Average size of herbosome range is 50 nm to a few hundred μm.

· They are easily soluble in non-polar solvents, insoluble in water and moderately soluble in fats.

· Liposomal like structures of miscellar shape are formed when herbosome are treated with water ^[19].

Chemical properties:

On the basis of their physicochemical and spectroscopic data, it has been shown that, the phospholipids-substrate interaction is due to the formation of hydrogen bond between the polar heads of phospholipids (i.e. phosphate and ammonium groups) and the polar functional groups of substrate. In herbosomes the active principle is anchored to the polar head of phospholipids, becoming an integral part of the membrane [19, 20, 21].

5. Advantages:

· These systems show enhanced permeation of drug through skin for transdermaland dermal delivery.

· These are platform for the delivery of large and diverse group of drugs (peptides, protein molecules).

· The vesicular system is passive, non-invasive and is available for immediate commercialization.

· Their composition is safe and the components are approved for pharmaceutical and cosmetic use.

· High market attractiveness for products with proprietary technology.

6. Merits of Herbosomes:

· Herbosomes show better stability as chemical bond is formed between phospholipid molecule and phytoconstituent (s).

· Dose of phytoconstituents is reduced due to more bioavailability of phytoconstituents in the complex form.

· Duration of action is increased.

· Herbosomes are simple to manufacture.

· Phytoconstituents complex with phospholipids are more stable in gastric secretion and resist the action of gut bacteria. 6. Enhanced permeability of phytoconstituents across the biological membranes^[22].

7. Demerits of herbosomes:

· In herbosomes, phytoconstituents are rapidly eliminated.

· It has short half-life.

· Hydrolysis, fusion, leakage and oxidation is undergone by the phospholipids.

· It has a high cost of production and sometimes occurrence of allergic reactions to the herbosomal constituents may be observed.

· Because of their larger size problems can occur while trying to target to the various tissues ^[23].

8. Characterization Techniques:

Visualization

Transmission electron microscopy and scanning electron microscopy are used for visualization of phytosomes^[24].

Vesical size and zeta potential:

Dynamic light scattering (DLS) using computerized inspection system and photon correlation spectroscopy (PCS) used to determined vesical size and zeta potential^[25].

Entrapment efficiency:

Ultracentrifugation technique is used to determined entrapment efficiency ^[26].

Transition temperature:

Differential scanning calorimetry is used to determine transition temperature of vesicular lipid system^[26].

Surface tension measurement:

Surface tension activity can be measured by ring method in a Du Nouy ring tensiometerof the drug in aqueous solution ^[27].

Vesicle stability:

Assessing the size and the structure of vesicles overtime gives the idea about stability of vesicles. Structural changes are monitored by TEM and mean size is measured by DLS^[28].

Drug content:

Modified high-performance liquid chromatographic method or suitable spectroscopic method used to quantify the amount of drug present.^[29].

9. In vivo evaluation:

Experimental models are chosen on the basis of anticipated therapeutic activity of the plant constituent in phytosome for in vivo and in vitro examination. For example, examination of antihepatotoxic activity can be assessed by antioxidant or free radical scavenging property of phytosome. The in vivo anti-hepatotoxic studies on animals through the effect of phytosome on alcohol induced or paracetamol-induced hepatotoxicity.^[30]

10. Application of Herbosome

· Herbosome are used in the treatment of liver diseases including alcoholic hepatic steatosis, drug induced liver damage and hepatitis.

· Herbosomes are used in anti-inflammatory activity as well as in pharmaceutical and cosmetic composition.

· Herbsomes are used to treat acute and chronic liver diseases of toxic metabolic or infective origin or of degenerative nature.

· Herbosomes are used as brain tonic, immunomodulatory, skin improver, antiwrinkle, anti-aging etc.

· Herbosomes are used as anticancer and antioxidant, eg- grape seed.

· Herbosomes are used in hyperlipidemia, vein and skin disorder.

· Herbosomes are used as cancer chemo preventive agent and used to treat benign prostate hyperplasia.

· It also used to treat hypertension.

11. Commercially Marketed Formulations:

There are various Herbosomes formulation available in the market, and important formulations are illustrated in table 1.

Table 1: Herbosomes available in the market.

Trade name	Phytoconstituents complex	Daily dose	Indications
Silybinphytosome	Silybin from Silibiummarianum	120 mg	Hepatoprotective, Antioxidant
Silyphos milk thistle	Silybin from Silibiummarianum	150 mg	Antioxidant, Hepatoprotective
Grape seed (Leucoselect) Phytosomes	Procyanidins from vitisvinifera	50-300 mg	Antioxidant, Anticancer
Ginseng phytosome	Ginsenosides from panax ginseng	150 mg	Immunomodulator
Hawthorn phytosome	Flavonoids from crataegus species	100 mg	Antihypertensive, Cardioprotective
Sericosidephytosome	Sericoside from Terminalia sericea	-	Skin improver, Anti-Wrinkles
Ginko select phytosome	Flavonoids from Ginkobiloba	120 mg	Anti-aging, Protects Brain & Vascular lining
Olea select phytosome	Polyphenols from Oleaeuropea	120 mg	Anti–hyperlipidemic, Anti-inflammatory
Green select phytosome	Epigallocatechin from Thea sinensis	50-300mg	Anti-cancer, Antioxidant
Echinacea phytosome	Echinacosides from Echinacea angustifolia	-	Immunomodulatory, Nutraceuticals
Bilberry (Mertoselet) phytosome	Anthocyanosides from Vaccinium myritillus	-	Antioxidant, Improvement of Capillary Tone
Palmetto (sabalselect) phytosome	Fattyacids, alcohols & sterols from Serenoarepens	-	Anti-oxidant, Benign, Prostatic hyperplasia
Centellaphytosome	Trepans’ from Centellaasitica	-	Brain tonic, Vein and Skin Disorder

12. CONCLUSION:

Herbosomes are novel formulations which offer improved bioavailability of hydrophilic flavonoids and other similar compounds through the skin or gastrointestinal tract. It has many distinctive advantages over other conventional formulations. As far as the potential of herbosome technology is concerned, it has a great future for use in formulation technology and applications of hydrophilic plant compounds.

Standardized plant extracts or mainly polar phytoconstituents like flavonoids, terpenoids, tannins, xanthones when complexed with phospholipids like phosphatidylcholine give rise to a new drug delivery technology called herbosome showing much better absorption profile following oral administration owing to improved lipid solubility which enables them to cross the biological membrane, resulting enhanced bioavailability i.e. more amount of active principle in the systemic circulation. This means more amount of active constituent becomes present at the site of action (liver, brain, heart, kidney etc) at similar or less dose as compared to the conventional plant extract. Hence, the therapeutic action becomes enhanced more detectable and prolonged. Several excellent phytoconstituents have been successfully delivered in this way exhibiting remarkable therapeutic efficacy in animal as well as in human models.

Recently Mukherjee and co associates have regarded herbosomes as a value added drug delivery system. Thorough study of literature reveals that several plant extracts (crude, partially purified or fractionated) are reported to possess different significant pharmacological or health promoting properties. These extracts can be standardized accordingly and may be formulated as Herbosomes for systematic investigation for any improved potential to be used rationally. In this way after screening and selection of potential extracts or constituents from plants, herbosomes can be developed for different therapeutic purposes like cardiovascular, anti-inflammatory, immunomodulator, anticancer, antidiabetic etc or for prophylactic and health purposes as nutraceuticals, induecourse.

13. ACKNOWLEDGEMENT:

First author ex tend gratitude to the Gurukula Kangri Vishwavidyalaya Haridwar (UK) India, for granting the academic leave to perform the research work.

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Received on 11.08.2020 Modified on 19.09.2020

Research J. Pharm. and Tech. 2021; 14(1):471-476.

DOI: 10.5958/0974-360X.2021.00086.X