TONGKAT ALI AND APHRODISIAC PROPERTY: FACT OR FOLKLORE?

VI. TONGKAT ALI AND APHRODISIAC PROPERTY: FACT OR FOLKLORE?

The possibility of bioactive aphrodisiacs, substances that stimulate sexual desire and that may be derived from animals, minerals, and plants (55), has been attractive throughout recorded history and the passion of man since time immemorial.

Most of these ideas originated from the ancient belief in the therapeutic efficacy of ‘‘signature’’—the notion that plants or animal organs resembling

the genitalia would impart sexual powers. As such, among them are rhinoc-

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eros horn and reindeer antler, which have been extensively used by men to enhance sexual drive, based on the association between their shapes and the erect penis.

Reindeer shed their antlers annually; collected shedded antlers are im- ported from Canada, Finland, Norway, and Sweden into Japan for aphro- disiac purpose. Although the fresh antlers are supposed to be more powerful, removal of live antlers from the animals is forbidden in Scandinavia. There- fore, live reindeers have been imported to provide the best possible aphrodis- iac quality (56).

Rhinoceros horn is considered a panacea in East Asia and the horns are widely used to increase male sexual capacity including the capacity for erection. Chemical analysis of powdered horn extracts reveals only polypep- tides, sugars, phosphorus, ethanolamine, and free amino acids such as aspartic acid, threonine, ornithine, lysine, histidine, and arginine (which has been suggested to increase the intensity of sensation during sex) (57). Rhinoc- eros horn is, after all, only a modified epidermis.

Mylabris, an alcoholic extract from the dried bodies of China blister beetles (Pan mao), or Spanish fly (the generic name for a variety of species of beetles including Cantharis vesicatoria, Lytta vesicatoria, Epicauta funebris, and Mylabris phalerata), is used in China today as an aphrodisiac and to in- duce abortions. The active principle, called cantharidin, is a potent vesicant with an estimated fatal dose in humans of 32 mg. It causes irritation of the urethra, resulting in priapism (58).

Other popular aphrodisiacs include lion-tailed macaque (59), tiger penis, bear paws, and snake bile (60). The study of plants exhibiting aphrodisiac property is becoming more important because of international pressure against the slaughter of animals since this eventually will cause many animals to become endangered or extinct.

Punica granatum has been a symbol of love, fertility, and immorality in Oriental regions (61). The yohimbine-rich bark of Corynanthe yohimbe, indigenous to West Africa, has been employed for centuries as an aphrodisiac (62). It contains the indole alkaloid, which has been used as a sexual stimulant for domestic animals and, more recently, to treat impotence in men (63–66).

Chelidonium majus , Heracleum sphondylium, and Satureja montana have been formulated into topical preparations by the European community for vaginal douches to increase sexual desire in women (67). Similarly, Hindu medicine still claims that Aristolochia indica, Crocus sativus, Alpinia galanga, and Allium cepa are potent aphrodisiacs (68).

In Malaysia, tongkat Ali has also gained notoriety as a male aphrodisiac and this has caused rampant, excessive, and uncontrolled encroachments into forest reserves. The raids have become so frequent and massive that the

Eurycoma Iongifolia Jack (Tongkat Ali) 649

Forestry Department in Malaysia is worried that the plant species may become extinct if immediate steps are not taken to stop the wanton uprooting (69).

Numerous scientific investigations pertaining to the aphrodisiac prop- erty of this plant have been exhaustively carried out using both the in vivo and in vitro animal models. However, the definitive criteria used to establish the aphrodisiac value of a compound still remain elusive. Nevertheless, it was found that higher erectile function observed in a treated animal provides evidence for responses and an increase in sexual pleasure (70).

Male sexual activity evaluation of the effect of this plant showed that in the absence of receptive females, sexually normal male rodents treated with various extracts of this plant did not exhibit any homosexuality during the observation period (71), unlike PCPA ( p-chlorophenylalanine ester), which did lead to homosexuality (72). In addition, the treated male rodents exhibited increase in the penile erection index (71), using the methods previously described (73,74), in an observation cage (75).

In addition, the effects of this plant on the pendiculation activities (act of yawning and stretching) in the male rodents were studied following the method previously described (74), since it is pertinent that yawning, alone or associated with stretching, is considered to be an ancestral vestige surviving throughout evolution, which subserves the purpose of sexual arousal (76). Results showed that the extracts enhanced pendiculation activities in sexually normal male rodents (77) as well as in middle-aged, 9-month-old, retired breeder male rodents, but to a smaller degree (78). Thus, these results provided further evidence of erectile responses and increase in sexual pleasure (70).

The above interesting results led to further investigations on the masculine copulatory behavior of treated sexually normal (79) and middle- aged (80) male rodents in the presence of receptive females (81,82). Results showed that treated sexually normal male rodents exhibited increase in ejaculation latencies-1, -2, and -3 (79), thus suggesting that these extracts increased the sexual performance of the male rodents by extending the duration of coitus (83,84). In addition, the increase in the above three parameters and also decrease in both postejaculatory intervals -1 and -2 (79) led to the conclusion that these extracts intensified the sexual activity of the male rodents in a sustained manner by decreasing the refractory period between the different series of copulation. This was also observed in middle- aged rodents but to a smaller degree (80).

Further investigations were also carried out pertaining to the effect of this plant on the libido of sexually experienced male rodents. Sexual arousal or motivation with mount tests following penile anesthetization is a reliable index of pure libido unaffected by the reinforcing effect of genital sensation (85,86). Results showed that these extracts enhanced the libido of sexually

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experienced male rodents, providing evidence that this plant is a potent stimulator of sexual arousal in intact, sexually vigorous male rodents in the absence of feedback from genital sensation (87).

Further studies were also carried out pertaining to the orientation activities of the treated sexually experienced male rodents using the methods previously described (88,89) because modification of orientation activities is one of the criteria in determining male sexual behavior (88,90). Results showed that this plant enhanced the orientation activities of treated males toward receptive females by causing them to display vigorous anogenital investigatory behavior, and further intensified self-orientation as evidenced by increased grooming of their own genitalia (91). These improved the sexual performance of treated sexually experienced male rodents (84,92).

In addition, there was an enhancement of the sexual motivation in the treated sexually naı¨ve male mice (93), middle-aged male rats (94), and noncopulator male rats (95).

Similarly, there was also a slow and transient reduction in the hesitation time before the treated sexually naı¨ve male mice crossed the electrical grid (maintained at 0.12 mA) in the copulation cage to reach the goal cage, besides an increase in the percentage of sexually naı¨ve male mice scoring ‘‘right choice’’ (goal cage with an estrous female mouse) throughout the investiga- tion period (96). An electrical grid was used as an obstruction in the copu- lation cage to determine how much a negative stimulus (crossing an electrical grid) a male mouse was willing to overcome to reach the sexual contact. Sim- ilar results were obtained in sexually naı¨ve male rats (97) and noncopulator male rats (98). Longitudinal study showed that these extracts were able to maintain sexual activity in aging rats (99).

Further results also indicated that these extracts promoted the growth of accessory sexual organs , viz. ventral prostate and seminal vesicles in the inexperienced castrated male rats (100), penis in the sexually experienced castrated male rats (101), levator ani muscle in both the uncastrated and testosterone-stimulated castrated intact male rats (102).

Potency activity of the aphrodisiac property was also evaluated in male rats treated with these extracts. Results showed that these extracts produced a dose-dependent, recurrent, and significant increase in the episodes of penile reflexes as evidenced by increase in quick flips, long flips, and erections during the observation period (103).

Other scientific investigators pursued the study of the aphrodisiac effects of aqueous extract of the roots in male rodents and found that they showed intense copulatory behavior and a 480% increase in the serum testosterone (104,105).

In addition, the sperm quality and parameters were also investigated after the rodents were dosed with extracts from this plant (106,107). Results

Eurycoma Iongifolia Jack (Tongkat Ali) 651

showed that there was a significant increase in the total sperm count, motility, forward velocity, and fructose concentration in the cauda epididymal semen, which were probably due to an increase of androgen, caused by the proan- drogenic effect of these extracts, which enhanced the physiological matura- tion of sperms (107).

The total sperm count and motility were calculated using the method previously described (108) and the forward velocity was calculated using the method previously described (109). Fructose concentration in the cauda epi- didymal semen was analyzed according to the method previously described (110).

In conclusion, the above studies clearly showed that various extracts from E. longifolia Jack had aphrodisiac property and this may be attributed to the presence of the active compounds in more than one fraction.

Although these studies lend further support for the use of this plant by the indigenous population as a traditional aphrodisiac, it is suggested that a detailed toxicological study should also be carried.

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