Data obtained from literature review.

**Source:** Maisuthisakul (2007)

Table 4. Partition coefficient of solvent used and Betel leaf extract extracted by different solvents¥

The phenolic compounds in Betel leaf from the literature include low polarity compounds such as chavicol (log P = 2.50±0.21), chavibetol (log P = 2.30±0.23), chavibetol acetate (log P = 2.39±0.24), and eugenol (log P = 2.20±0.23). Normally, a frequently used descriptor for the estimation of the lipophilicity of phenolic compounds is the partition coefficient. The partition coefficients of Betel leaf extracts were those of low polarity compounds since the value is higher than 0 (Munishwar, et al., 1997) (Table 4). Less polar solvents showed higher extraction efficacy due to the low polarity of the phenolic compounds of Betel leaf extract. Compounds, which have a polarity similar to the solvent, are able to dissolve more than compounds with different polarity. It can be noted here that Betel leaf extract is rich in less polar phenolic compounds. The solvent used for extraction also affected the total phenolic content in the extracts.

The ratios of solvents used in mixed solvents affected the phenolic content extracted from some Thai plants. *Careya sphaerica* Roxb. (Kradonbok), *Cratoxylum formosum* Dyer. (Teaw) and *Sauropus andrugynus* Merr. (Phak whan ban) leaves were used to study the effect of ethanol concentration used in the extraction. The total phenolic content of plant extracts readily increased with increasing concentration of ethanol from 80% to 95%, but there was no significant difference between the extracts using ethanol concentrations of 95% and 99% for each plant. The effect of ethanol concentration on antioxidant activity and total phenolic content was similar (Fig. 12).

The inflorescence, leaves, stem and root of *Stachytarpheta indica* Vahl were extracted with three methanol and water solvent mixtures, namely water, 75% methanol and 50% methanol. The results showed that the leaf extract from 75% methanol had the highest antioxidant activity in both fresh and dry samples (Ongard & Dara, 2010).

**Extraction temperature effect**; the temperature of extraction affects the compounds' stability due to the decomposition of phenolic compounds. The effect of temperature has been studied in the extraction of anthocyanins. They were shown to be degraded since the visible spectrum showed both a reduction in the peak at 400-500 nm and reduction in the red color. The temperature during extraction can affect extractable compounds to different extents; boiling and resting increases the total phenol content extracted from *Quercus suber* cork (Conde et al., 1998). Milder extraction temperatures are desirable in those cases where some compounds can be degraded, e.g. carnosic acid (Ibañez et al., 1999).

**Source**: Adapted from Maisuthisakul (2007)

Fig. 12. Total phenolic contents and antioxidant activity of the extracts from *Careya sphaerica* Roxb., *Cratoxylum formosum* Dyer. and *Sauropus andrugynus* Merr. leaves obtained with various ethanol concentrations.

**Other factors**; such as extraction time, pH, the particle size of materials, and extraction methods were reported to affect the antioxidant activity and concentrations of phenolic compounds extracted. Sheabar & Neeman (1988) reported the maximum solubility of phenolic compounds from olive rape at pH 4 in the organic phase. The yield of extracted phenolics was correlated with plant cell wall breakdown. Particle size reduction significantly increased the antioxidant activity as a result of both increased extractability and enhanced enzymatic degradation of polysaccharides (Weinberg et al., 1999). Various process conditions (refluxing, shaking and ultrasonic extraction) also affected the concentrations of antioxidants in extracts from balm leaves (Herodež et al., 2003).

#### **5. Conclusion**

206 Phytochemicals – A Global Perspective of Their Role in Nutrition and Health

Solvent used Partition coefficient of solvent# Partition coefficient of extract

Note: ¥ Data followed by different letters within each column are significantly different according to Duncan's multiple range test at *P* < 0.05. Data were represented as means from three replicate

Table 4. Partition coefficient of solvent used and Betel leaf extract extracted by different

The phenolic compounds in Betel leaf from the literature include low polarity compounds such as chavicol (log P = 2.50±0.21), chavibetol (log P = 2.30±0.23), chavibetol acetate (log P = 2.39±0.24), and eugenol (log P = 2.20±0.23). Normally, a frequently used descriptor for the estimation of the lipophilicity of phenolic compounds is the partition coefficient. The partition coefficients of Betel leaf extracts were those of low polarity compounds since the value is higher than 0 (Munishwar, et al., 1997) (Table 4). Less polar solvents showed higher extraction efficacy due to the low polarity of the phenolic compounds of Betel leaf extract. Compounds, which have a polarity similar to the solvent, are able to dissolve more than compounds with different polarity. It can be noted here that Betel leaf extract is rich in less polar phenolic compounds. The solvent used for extraction also affected the total phenolic

The ratios of solvents used in mixed solvents affected the phenolic content extracted from some Thai plants. *Careya sphaerica* Roxb. (Kradonbok), *Cratoxylum formosum* Dyer. (Teaw) and *Sauropus andrugynus* Merr. (Phak whan ban) leaves were used to study the effect of ethanol concentration used in the extraction. The total phenolic content of plant extracts readily increased with increasing concentration of ethanol from 80% to 95%, but there was no significant difference between the extracts using ethanol concentrations of 95% and 99% for each plant. The effect of ethanol concentration on antioxidant activity and total phenolic

The inflorescence, leaves, stem and root of *Stachytarpheta indica* Vahl were extracted with three methanol and water solvent mixtures, namely water, 75% methanol and 50% methanol. The results showed that the leaf extract from 75% methanol had the highest

**Extraction temperature effect**; the temperature of extraction affects the compounds' stability due to the decomposition of phenolic compounds. The effect of temperature has been studied in the extraction of anthocyanins. They were shown to be degraded since the visible spectrum showed both a reduction in the peak at 400-500 nm and reduction in the red color. The temperature during extraction can affect extractable compounds to different extents; boiling and resting increases the total phenol content extracted from *Quercus suber* cork (Conde et al., 1998). Milder extraction temperatures are desirable in those cases where some

antioxidant activity in both fresh and dry samples (Ongard & Dara, 2010).

compounds can be degraded, e.g. carnosic acid (Ibañez et al., 1999).

2.02 0.01a 2.09 0.02ab 2.15 0.01b 2.31 0.03c


Methanol Ethanol Acetone Ethyl acetate

measurements.

solvents¥
