PREMNA ODORATA Blanco
Premna caranii H. Lam.
Premna oblongata Miq. var. puberula H. Lam.
Premna pubescens Blume var. odorata H. Lam.
Premna serratiflolia Blanco.
Premna vestita Schauer
Other names: Alagau , abgau , adgau, adiyo, agbau, agdau, alagau, anobran, argau, duragau , guachal, lagau, lassi, pumuhat tangli, tibangñgen.
Alagau is common in thickets and secondary forest at a low altitude, sometimes purposely planted around dwellings from the Batan Islands and northern Luzon to Mindanao, in most island provinces. This species is found only in the Philippines.
This plant is small, hairy tree 3 to 8 meters in height. The leaves are ovate to broadly ovate and 10 to 20 centimeters long, with broad, rounded or somewhat heart-shaped base, and pointed tip. These are very aromatic when crushed. The flowers are greenish-white or nearly white, 4 to 5 millimeters long and borne on terminal inflorescences (cymes) 8 to 20 centimeters in diameter. The fruit is fleshy, dark purple, rounded and about 5 millimeters in diameters.
According to Sunico-Suaco and Valenzuela the leaves do not contain any alkaloid, tannin, saponin, or cyanogenetic substance. The leaves, however, yielded 0.02 per cent of essential oil, which was yellowish-green and had the characteristics aroma of alagau leaves; and an oleoresin, which m. p. 112.5°C., whose constants were: acid number 103; saponification number 246.5 ester number 143.5, and acetyl value 416.2. the oleoresin contained 2.87 per cent methoxyl.
In the Philippines a decoction of the leaves with sugar and a little “calamansi” juices is taken as a drink, and it not only loosens phlegm but it also effective for coughs. A decoction of the fresh leaves is also prescribed for vaginal irritation. It may be given also in syrup form for coughs. “Kochol,” which is local patent preparation, is claimed to benefit tuberculosis. Father Alzina reports that the leaves, applied over the bladder, facilitate urination. Father de Sta. Maria states that masticating the roots and swallowing the saliva is prescribed for cardiac troubles. He adds that an infusion of the leaves is carminative and that a decoction of the shoot is used as a parasiticide. According to Guerrero a decoction of the roots, leaves, flowers, and fruit is used as a sudorific and pectoral, and is said to be carminative. The leaves, with coconut or sesame oil, are applied to the abdomens of the children to cure tympanites. The leaves are boiled in water, the water being used for bathing babies, and also as a treatment for beriberi. In the latter case the boiled leaves are applied to the affected part of the patient’s body. The plant is used as a headache cure. It may be added that alagau has become a popular drug.